ORCID Profile
0000-0003-1316-0145
Current Organisations
University of Western Australia
,
Maastricht University
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Publisher: Scientific Societies
Date: 05-2016
DOI: 10.1094/PDIS-11-15-1249-RE
Abstract: Pea seed-borne mosaic virus (PSbMV) stability in sap and its contact transmission between field pea plants were investigated in glasshouse experiments. When infective leaf sap was kept at room temperature and inoculated to plants in the absence of abrasive, it was still highly infective after 6 h and low levels of infectivity remained after 30 h. PSbMV was transmitted from infected to healthy plants by direct contact when leaves were rubbed against each other. It was also transmitted when intertwining healthy and PSbMV-infected plants were blown by a fan to simulate wind. When air was blown on plants kept at 14 to 20°C, contact transmission of PSbMV occurred consistently and the extent of transmission was enhanced when plants were dusted with diatomaceous earth prior to blowing. In contrast, when plants were kept at 20 to 30°C, blowing rarely resulted in transmission. No passive contact transmission occurred when healthy and infected plants were allowed to intertwine together. This study demonstrates that PSbMV has the potential to be transmitted by contact when wind-mediated wounding occurs in the field. This may play an important role in the epidemiology of the virus in field pea crops, especially in situations where contact transmission expands initial crop infection foci before aphid arrival.
Publisher: Wiley
Date: 12-08-2022
DOI: 10.1111/REC.13503
Abstract: Mining activity causes major changes in site topography, soil physical and chemical properties, hydrology, and biological assemblages. Reassembling plant communities in these highly altered environments is dependent on interactions between environmental drivers and management intervention techniques through time, yet the long‐term effects of these interactions have rarely been quantified. This study examined a 19‐year‐old, postmining woodland restoration chronosequence in southwest Australia to understand plant community compositional development in postmine restoration sites. We tested the effects of environmental drivers (rainfall regimes, site aspect, slope) and management intervention techniques (substrate ripping and material properties) in terms of four restoration criteria: species richness, plant density, vegetation cover, and compositional similarity to reference sites. Irrespective of environmental drivers or management intervention techniques, vegetation cover increased through time, while plant density and species richness declined. Bray–Curtis similarity to reference communities remained unchanged. Within these trends, ripping and first‐year rainfall significantly affected restoration criteria outcomes species richness and plant density were greatest when rainfall in the first winter immediately following site restoration was low but followed by a high summer rainfall. The most effective ripping depth was dependent on rainfall, deep‐ripped sites performed best when rainfall was high, and nonripped sites performed best under low‐mean rainfall conditions. Measured restoration criteria had not reached the levels of the target reference community after 19 years, which may be attributable to the still‐developing vegetation structure. This emphasizes the importance of assessing postmining restoration outcomes over longer time frames ( years) with implications for determining appropriate, time‐dependent completion criteria.
Publisher: Wiley
Date: 07-02-2019
DOI: 10.1002/ECY.2590
Publisher: Wiley
Date: 08-08-2023
DOI: 10.1111/REC.13989
Abstract: Post‐mining scenarios present challenges for restoration in a wide range of environments, especially in the context of climate change. The source of seed for restoration has been an issue of intense focus, as seed provenance can impact plant fitness and restoration outcomes. However, post‐mining landscapes require substrate reconstruction prior to vegetation re‐establishment. Critically, the relative importance of provenance and substrate in ecosystem recovery has been rarely quantified in a statistically rigorous framework. We established a large provenance trial with Banksia attenuata and Eucalyptus todtiana at two Western Australian mine sites in post‐mining reconstructed and adjoining un‐mined substrates. We show that site and substrate were 4 and 26 times more important than provenance in explaining survival for B. attenuata and E. todtiana , respectively. At one site, there was 100% mortality in the post‐mining substrate but high survival and no clear provenance effect in the un‐mined substrate. At the second site, there was again no clear provenance effect, but E. todtiana survival was higher in the post‐mining than un‐mined substrate. Our results show that post‐mining substrate changes can overwhelm provenance issues. Consequently, where substrates are highly impacted, alternative restoration targets and/or greater investment in substrate research are needed to improve restoration outcomes. Due to the thousands of mines across the world, this is an internationally relevant finding with important implications for investment into global ecosystem recovery.
Publisher: Wiley
Date: 09-2013
DOI: 10.1890/12-1881.1
Abstract: Shifts in disturbance regime have often been linked to invasion in systems by native and nonnative species. This process can have negative effects on bio ersity and ecosystem function. Degradation may be ameliorated by the reinstatement of the disturbance regimes, such as the reintroduction of fire in pyrogenic systems. Modeling is one method through which potential outcomes of different regimes can be investigated. We created a population model to examine the control of a native invasive that is expanding and increasing in abundance due to suppressed fire. Our model, parameterized with field data from a case study of the tree Allocasuarina huegeliana in Australian sandplain heath, simulated different fire return intervals with and without the additional management effort of mechanical removal of the native invader. Population behavior under the different management options was assessed, and general estimates of potential bio ersity impacts were compared. We found that changes in fire return intervals made no significant difference in the increase and spread of the population. However, decreased fire return intervals did lower densities reached in the simulated heath patch as well as the estimated maximum bio ersity impacts. When simulating both mechanical removal and fire, we found that the effects of removal depended on the return intervals and the strategy used. Increase rates were not significantly affected by any removal strategy. However, we found that removal, particularly over the whole patch rather than focusing on satellite populations, could decrease average and maximum densities reached and thus decrease the predicted bio ersity impacts. Our simulation model shows that disturbance-based management has the potential to control native invasion in cases where shifted disturbance is the likely driver of the invasion. The increased knowledge gained through the modeling methods outlined can inform management decisions in fire regime planning that takes into consideration control of an invasive species. Although particularly applicable to native invasives, when properly informed by empirical knowledge these techniques can be expanded to management of invasion by nonnative species, either by restoring historic disturbance regimes or by instating novel regimes in innovative ways.
Publisher: Public Library of Science (PLoS)
Date: 15-08-2018
Publisher: CSIRO Publishing
Date: 14-09-2021
DOI: 10.1071/SB21012
Abstract: In the present study, we tested the chronological and geographic origins of the mostly arid Australian Ptilotus (Amaranthaceae) and its close relatives (i.e. the ‘aervoids’) by reconstructing a dated phylogeny with near-comprehensive s ling for Ptilotus and estimating ancestral geographic ranges. We investigated climatic niche evolution within Ptilotus and identified likely climatic origins and subsequent niche shifts by reconstructing ancestral states of climatic variables on the phylogeny, which was visualised using a phyloecospace approach. Geospatial analyses were employed to identify probable ersification hotspots within Australia. We inferred that the aervoids originated in Oligocene Africa–Asia and that Ptilotus arrived in northern Australia by dispersal in the Early Miocene. Subsequent ersification of Ptilotus was rapid, giving rise to all major clades in the western Eremaean by the time of an aridification pulse in the Middle Miocene. Climatic niche shifts from the arid Eremaean into monsoonal northern and temperate southern Australia are apparent for multiple independent species groups. Our analyses support the hypothesis that a pre-adaptation to aridity and early arrival in an aridifying Australia were integral to the success of Ptilotus, and that the Eremaean has been a source of bio ersity in the genus and for independent radiations into neighbouring climatic zones.
Publisher: Elsevier BV
Date: 10-2015
Publisher: Elsevier BV
Date: 2017
Publisher: Elsevier BV
Date: 02-2021
Publisher: Elsevier BV
Date: 06-2013
DOI: 10.1016/J.MBS.2013.02.005
Abstract: Computer simulation models can provide a relatively fast, safe and inexpensive means to judge and weigh the merits of various pest control management options. However, the usefulness of such simulation models relies on the accurate estimation of important model parameters, such as the pest mortality under different treatments and conditions. Recently, an in idual-based simulation model of population dynamics and resistance evolution has been developed for the stored grain insect pest Rhyzopertha dominica, based on experimental results showing that alleles at two different loci are involved in resistance to the grain fumigant phosphine. In this paper, we describe how we used three generalized linear models, probit, logistic and Cauchy models, each employing two- and four-parameter sub-models, to fit experimental data sets for five genotypes for which detailed mortality data was already available. Instead of the usual statistical iterative maximum likelihood estimation, a direct algebraic approach, generalized inverse matrix technique, was used to estimate the mortality model parameters. As this technique needs to perturb the observed mortality proportions if the proportions include 0 or 1, a golden section search approach was used to find the optimal perturbation in terms of minimum least squares (L2) error. The results show that the estimates using the probit model were the most accurate in terms of L2 errors between observed and predicted mortality values. These errors with the probit model ranged from 0.049% to 5.3%, from 0.381% to 8.1% with the logistic model and from 8.3% to 48.2% with the Cauchy model. Meanwhile, the generalized inverse matrix technique achieved similar results to the maximum likelihood estimation ones, but is less time consuming and computationally demanding. We also describe how we constructed a two-parameter model to estimate the mortalities for each of the remaining four genotypes based on realistic genetic assumptions.
Publisher: Oxford University Press (OUP)
Date: 13-03-2009
DOI: 10.1093/JXB/ERP021
Abstract: Leaf photosynthesis (A) is limited by mesophyll conductance (g(m)), which is influenced by both leaf structure and the environment. Previous studies have indicated that the upper bound for g(m) declines as leaf dry mass per area (LMA, an indicator of leaf structure) increases, extrapolating to zero at a LMA of about 240 g m(-2). No data exist on g(m) and its response to the environment for species with LMA values higher than 220 g m(-2). In this study, laboratory measurements of leaf gas exchange and in vivo chlorophyll a fluorescence were used concurrently to derive estimates of g(m) in seven species of the Australian sclerophyllous genus Banksia covering a wide range of LMA (130-480 g m(-2)). Irradiance and CO(2) were varied during those measurements to gauge the extent of environmental effects on g(m). A significant decrease of g(m) with increasing LMA was found. g(m) declined by 35-60% in response to increasing atmospheric CO(2) concentrations at high irradiance, with a more variable response (0-60%) observed at low irradiance, where g(m) was, on average, 22% lower than at high irradiance at ambient CO(2) concentrations. Despite considerable variation in A and LMA between the Banksia species, the CO(2) concentrations in the intercellular air spaces (C(i), 262+/-5 micromol mol(-1)) and in the chloroplasts (C(c), 127+/-4 micromol mol(-1)) were remarkably stable.
Publisher: Elsevier BV
Date: 10-2017
Publisher: Wiley
Date: 22-06-2013
DOI: 10.1002/PS.3341
Abstract: The evolution of resistance to pesticides is often conceptualised and modelled at a population level, but population-based approaches ignore important aspects of variability between in iduals within populations that may be essential drivers of resistance. Here it is argued that in idual-based modelling has the potential to generate new insights and perspectives, thus deepening our understanding of the complexities of the evolutionary dynamics of resistance to pesticides.
Publisher: Oxford University Press (OUP)
Date: 05-08-2011
DOI: 10.1093/AOB/MCR131
Publisher: Wiley
Date: 04-05-2021
DOI: 10.1111/ECOG.05671
Abstract: Rainfall regimes in many parts of the world have become increasingly dominated by fewer, but more extreme, rainfall events. Understanding how tree growth responds to changes in the frequency and intensity of rain events is critical to predicting how climate change will impact on forests and woodlands in the future. In this study, we used five tree‐ring records of the native Australian conifer Callitris columellaris that span a large ( 20°) latitudinal and climatic gradient from the mesic (tropical) north to the xeric (semi‐arid) south of Australia to investigate how inter‐annual and spatial variation in the delivery of rainfall (the intensity and frequency of rain events) influences tree growth. In semi‐arid biomes (~300–400 mm rainfall annually), tree growth is most strongly related to the amount of rainfall from heavy ( 75th percentile) rain days or the number of extreme ( 90th percentile) rain days, regardless of differences in the seasonal distribution and average intensity of rainfall among sites. Our findings also indicate that there is likely a minimum threshold amount of daily rainfall (~5 mm) that is required to stimulate tree growth in the semi‐arid zone. In contrast, in the tropics ( 800 mm annual rainfall), inter‐annual variation in growth is best explained by total growing season rainfall or the number of rain days ~5 mm (~50th percentile of rain days) rather than extreme rainfall. Our findings indicate that not all rain events are important for driving tree growth, which has important implications for interpreting climatic signals in tree rings. Our findings also indicate that projected increases in the intensity of extreme rain events are likely to have contrasting impacts on tree growth across biomes, with greater and positive impacts on growth in semi‐arid biomes and potentially negative impacts on growth in tropical biomes of Australia.
Publisher: Elsevier BV
Date: 06-2015
DOI: 10.1016/J.PBI.2015.04.002
Abstract: Mycorrhizas play a pivotal role in phosphorus (P) acquisition of plant roots, by enhancing the soil volume that can be explored. Non-mycorrhizal plant species typically occur either in relatively fertile soil or on soil with a very low P availability, where there is insufficient P in the soil solution for mycorrhizal hyphae to be effective. Soils with a very low P availability are either old and severely weathered or relatively young with high concentrations of oxides and hydroxides of aluminium and iron that sorb P. In such soils, cluster roots and other specialised roots that release P-mobilising carboxylates are more effective than mycorrhizas. Cluster roots are ephemeral structures that release carboxylates in an exudative burst. The carboxylates mobilise sparingly-available sources of soil P. The relative investment of biomass in cluster roots and the amount of carboxylates that are released during the exudative burst differ between species on severely weathered soils with a low total P concentration and species on young soils with high total P concentrations but low P availability. Taking a modelling approach, we explore how the optimal cluster-root strategy depends on soil characteristics, thus offering insights for plant breeders interested in developing crop plants with optimal cluster-root strategies.
Publisher: Oxford University Press (OUP)
Date: 05-2010
DOI: 10.1093/AOB/MCQ040
Publisher: Wiley
Date: 22-02-2018
DOI: 10.1111/PPA.12837
Publisher: Frontiers Media SA
Date: 2013
Publisher: Cambridge University Press (CUP)
Date: 05-2018
DOI: 10.1017/WSC.2018.9
Abstract: Harvest weed seed control (HWSC) techniques have been implemented in Australian cropping systems to target and reduce the number of weed seeds entering the seedbank and thereby reduce the number of problematic weeds emerging in subsequent years to infest subsequent crops. However, the influence of HWSC on ameliorating herbicide-resistance (HR) evolution has not been investigated. This research used integrated spatial modeling to examine how the frequency and efficacy of HWSC affected the evolution of resistance to initially effective herbicides. Herbicides were, in all cases, better protected from future resistance evolution when their use was combined with annual HWSC. Outbreaks of multiple HR were very unlikely to occur and were nearly always eliminated by adding annual, efficient HWSC. The efficacy of the HWSC was important, with greater reductions in the number of resistance genes achieved with higher-efficacy HWSC. Annual HWSC was necessary to protect sequences of lower-efficacy herbicides, but HWSC could still protect herbicides if it was used less often than once per year, when the HWSC and the herbicides were highly effective. Our results highlight the potential benefits of combining HWSC with effective herbicides for controlling weed populations and reducing the future evolution of HR.
Publisher: Elsevier BV
Date: 09-2019
Publisher: Wiley
Date: 06-07-2009
Publisher: International Seed Testing Association
Date: 31-12-2022
DOI: 10.15258/SST.2022.50.3.10
Abstract: Flash flaming has shown promise as a seed enhancement technology that improves the handling properties of bulky or irregularly shaped seed material, which in turn benefits logistical and ecological aspects of large-scale direct seeding. To date, only a small number of grass species, that possess similar morphological characteristics, have been tested. This paper describes the application of flash flaming to diaspores (i.e. the dispersal unit comprising the seed and any surrounding or attached tissues) of 19 erse dryland species from the Amaranthaceae, Asteraceae, Chenopodiaceae and Poaceae critical to ecological restoration in the mining intensive Pilbara region of Western Australia. Flash flaming parameters for each species were tested to identify and maximise volume and mass reduction, reduce particle cohesiveness and maximise flow through a mechanical seeding device, whilst maximising germination. Flaming of all species resulted in reductions in batch volume and mass, and improvements to flow characteristics. For 17 species, flaming either benefited or did not impact on germinability. For two species in the Amaranthaceae, flaming with the settings tested here resulted in a reduction in germinability however, flaming enabled the diaspores to pass through a mechanical seeding device enabling mechanical distribution which is critical if the species are to be used in large scale restoration.
Publisher: Wiley
Date: 09-10-2023
DOI: 10.1111/GEB.13771
Publisher: CSIRO Publishing
Date: 2013
DOI: 10.1071/BT12297
Abstract: Widespread decline of Mediterranean-type ecosystem (MTE) woodlands can result in a loss of soil- and canopy-stored seed banks. This can drive woodlands across a biotic threshold, where natural regeneration cannot occur. Without management intervention, these woodlands will suffer local extinction. Using a Mediterranean-type, degraded woodland as a case study, we undertook field trials over 3 years, with the aim of increasing revegetation success by (1) introducing propagules of key canopy species to overcome this biotic threshold and (2) applying commonly used revegetation treatments (abiotic treatments such as the addition of nutrient and water resources, two types of tree guards, and combinations of these). We found that (1) control plants had low establishment success, confirming the crossing of a biotic threshold and the practical irreversibility of the degraded state without intervention, (2) plant establishment was often significantly higher for treated than for control seedlings and (3) supplementation of nutrient and water resources seems to be critical in terms of increasing early seedling establishment for some species. We suggest that in declining woodlands that have crossed biotic thresholds, merely adding propagules does not ensure successful revegetation. The present study has practical implications for restoration activities in degraded MTE communities where biotic thresholds may have already been crossed.
Publisher: Wiley
Date: 28-01-2013
DOI: 10.1002/PS.3459
Abstract: The eradicability of rain-splashed crop diseases was examined by modelling the spread of lupin anthracnose over a spatially heterogeneous landscape. Two hypotheses were investigated: (i) in most cases, rain-splashed diseases are unlikely to be eradicable because spread will be too extensive by the time the disease is detected (ii) there are recognisable characteristics of an incursion that can be used to identify cases when the disease will be eradicable. Results indicate that the eradication of a rain-splashed crop disease is heavily dependent on the surveillance effort, on how detectable the disease is and on whether there are susceptible hosts outside the cropping area. These simple indicators can be used to estimate the potential for success of an eradication scheme. Eradication targeting only the crop area is destined to fail, unless it is certain that no susceptible host lies adjacent to the cropping area. A failed eradication attempt can be costly, and a simple set of indicators for the likelihood of success is extremely useful. These indicators can aid decision-makers when faced with a new incursion, identifying when there is little hope of success. © 2012 Society of Chemical Industry.
Publisher: Wiley
Date: 17-03-2014
Publisher: Oxford University Press (OUP)
Date: 07-08-2006
DOI: 10.1093/JXB/ERL075
Abstract: This study aims to explore and model the changes in growth unit (GU) branching patterns during tree ontogeny. The question was addressed in apple trees cv. "Fuji", by analysing the relative impact of GU length and within-tree position. The development of two 6-year-old trees was recorded over 6 years. The fate of axillary buds along each GU was represented as a sequence of symbols corresponding to five types of lateral growth: latent buds, short, medium, long, and floral lateral GUs. Based on an exploratory analysis of data and a priori hypotheses, a hidden semi-Markov chain was estimated from all of these GU sequences. This model was composed of six transient states representing successive branching zones along the GUs. The accuracy of this global model was a posteriori assessed by fitting the characteristic distributions computed from model parameters to the corresponding empirical characteristic distributions extracted from the observed sequences. The observed sequences were then grouped hierarchically according to the GU length, year of growth, and branching order. Comparing model parameters between these sub-groups revealed similarities between GUs. These similarities were based on particular branching zones whose composition and relative position within the GUs remained invariant across the subgroups: the latent zones, floral zone, and short-lateral zone. The probability of occurrence of the floral zone varied with the year, showing the alternate fruiting of "Fuji". It is shown that, during tree ontogeny, as GU length decreases, branching patterns tend to progressively simplify due to the disappearance of the most central zones and a progressive reduction in the length of the floral zone.
Publisher: Springer Science and Business Media LLC
Date: 04-10-2012
DOI: 10.1007/S00248-011-9949-X
Abstract: Many of the fungal pathogens that threaten agricultural and natural systems undergo wind-assisted dispersal. During turbulent wind conditions, long-distance dispersal can occur, and airborne spores are carried over distances greater than the mean. The occurrence of long-distance dispersal is an important ecological process, as it can drastically increase the extent to which pathogen epidemics spread across a landscape, result in rapid transmission of disease to previously uninfected areas, and influence the spatial structure of pathogen populations in fragmented landscapes. Since the timing of spore release determines the wind conditions that prevail over a dispersal event, this timing is likely to affect the probability of long-distance dispersal occurring. Using a Lagrangian stochastic model, we test the effect of seasonal and diurnal variation in the release of spores on wind-assisted dispersal. Spores released during the hottest part of the day are shown to be more likely to undergo long-distance dispersal than those released at other times. Furthermore, interactions are shown to occur between seasonal and diurnal patterns of release. These results have important consequences for further modelling of wind-assisted dispersal and the use of models to predict the spread of fungal pathogens and resulting population and epidemic dynamics.
Publisher: Elsevier BV
Date: 05-2011
Publisher: Springer Science and Business Media LLC
Date: 03-03-2012
Publisher: Oxford University Press (OUP)
Date: 19-05-2010
DOI: 10.1093/JXB/ERQ128
Publisher: American Association for the Advancement of Science (AAAS)
Date: 13-01-2017
Abstract: Soil biota, including symbionts such as mycorrhizal fungi and nitrogen-fixing bacteria, as well as fungal and bacterial pathogens, affect terrestrial plant ersity and growth patterns (see the Perspective by van der Putten). Teste et al. monitored growth and survival in Australian shrubland plant species paired with soil biota from plants of the same species and from other plants that use different nutrient acquisition strategies. Plant-soil feedbacks appear to drive local plant ersity through interactions between the different types of plants and their associated soil biota. Bennett et al. studied plant-soil feedbacks in soil and seeds from 550 populations of 55 species of North American trees. Feedbacks ranged from positive to negative, depending on the type of mycorrhizal association, and were related to how densely the same species occurred in natural populations. Science , this issue p. 134 , p. 173 see also p. 181
Publisher: Elsevier BV
Date: 10-2012
Publisher: Springer Science and Business Media LLC
Date: 16-06-2016
Publisher: Elsevier BV
Date: 08-2011
DOI: 10.1016/J.JTBI.2011.05.010
Abstract: Evolution of herbicide resistance in weeds is a growing problem across the world, and it has been suggested that low herbicide rates may be contributing to this problem. An in idual-based simulation model that represents weed population dynamics and the evolution of polygenic herbicide resistance was constructed and used to investigate whether using lower herbicide rates or standard rates at reduced efficacy could reduce the sustainability of cropping systems by causing faster increases in weed population density as herbicide resistance develops. A number of different possible genetic bases for resistance were considered, including monogenic resistance and polygenic resistance conferred by several genes. The results show that cutting herbicide rates does not affect the rate at which weed densities reach critical levels when resistance is conferred exclusively by a single dominant gene. In some polygenic situations, cutting herbicide rates substantially reduces sustainability, due to a combination of faster increase in resistance gene frequency and reduced kill rates in all genotypes, while in other polygenic situations the effect is small. Differences in sustainability depend on combined strength of the resistance genes, variability in phenotypic susceptibility and rate delivered, level of control due to alternative measures, and degree of genetic dominance and epistasis. In the situation where resistance can be conferred by both a single dominant major gene or a number of co-dominant minor genes in combination, the difference made by low rates depends on the relative initial frequency of the major and minor genes. These results show that careful consideration of herbicide rate and understanding the genetic basis of resistance are important aspects of weed management.
Publisher: Wiley
Date: 12-03-2015
DOI: 10.1111/BRV.12095
Abstract: Seed persistence is the survival of seeds in the environment once they have reached maturity. Seed persistence allows a species, population or genotype to survive long after the death of parent plants, thus distributing genetic ersity through time. The ability to predict seed persistence accurately is critical to inform long-term weed management and flora rehabilitation programs, as well as to allow a greater understanding of plant community dynamics. Indeed, each of the 420000 seed-bearing plant species has a unique set of seed characteristics that determine its propensity to develop a persistent soil seed bank. The duration of seed persistence varies among species and populations, and depends on the physical and physiological characteristics of seeds and how they are affected by the biotic and abiotic environment. An integrated understanding of the ecophysiological mechanisms of seed persistence is essential if we are to improve our ability to predict how long seeds can survive in soils, both now and under future climatic conditions. In this review we present an holistic overview of the seed, species, climate, soil, and other site factors that contribute mechanistically to seed persistence, incorporating physiological, biochemical and ecological perspectives. We focus on current knowledge of the seed and species traits that influence seed longevity under ex situ controlled storage conditions, and explore how this inherent longevity is moderated by changeable biotic and abiotic conditions in situ, both before and after seeds are dispersed. We argue that the persistence of a given seed population in any environment depends on its resistance to exiting the seed bank via germination or death, and on its exposure to environmental conditions that are conducive to those fates. By synthesising knowledge of how the environment affects seeds to determine when and how they leave the soil seed bank into a resistance-exposure model, we provide a new framework for developing experimental and modelling approaches to predict how long seeds will persist in a range of environments.
Publisher: Cold Spring Harbor Laboratory
Date: 27-06-2020
DOI: 10.1101/2020.06.26.156463
Abstract: Transcriptomes from sponges are important resources for studying the stress responses of these ecologically important filter feeders, the interactions between sponges and their symbionts, and the evolutionary history of metazoans. Here, we generated reference transcriptomes for two common and cosmopolitan Indo-Pacific sponge species: Carteriospongia foliascens and Cliona orientalis. We also created a reference transcriptome for the primary symbiont of C. orientalis – Gerakladium endoclionum . To ensure a full repertoire of transcripts were included, clones of each sponge species were exposed to a range of in idual stressors: decreased salinity, elevated temperature, elevated suspended sediment concentrations, sediment deposition and light attenuation. RNA extracted from all treatments was pooled for each species, using equal concentrations from each clone. Sequencing of pooled RNA yielded 409 and 418 million raw reads for C. foliascens and C. orientalis holobionts (host and symbionts), respectively. Reads underwent quality trimming before assembly with Trinity. Assemblies were filtered into sponge-specific or, for G. endoclionum , symbiont-specific assemblies. Assemblies for C. foliascens, C. orientalis , and G. endoclionum contained 67,304, 82,895, and 28,670 contigs, respectively. Contigs represented 15,248-37,344 isogroups (∼genes) per assembly, and N50s ranged 1,672-4,355 bp. Gene ortholog analysis verified a high level of completeness and quality for sponge-specific transcriptomes, with an average 93% of core EuKaryotic Orthologous Groups (KOGs) and 98% of single-copy metazoan core gene orthologs identified. The G. endoclionum assembly was partial with only 56% of core KOGs and 32% of single-copy eukaryotic core gene orthologs identified. These reference transcriptomes are a valuable resource for future molecular research aimed at assessing sponge stress responses.
Publisher: Wiley
Date: 09-2015
DOI: 10.1111/JVS.12318
Publisher: Wiley
Date: 03-01-2013
DOI: 10.1002/PS.3457
Abstract: Control of pests in stored grain and the evolution of resistance to pesticides are serious problems worldwide. A stochastic in idual-based two-locus model was used to investigate the impact of two important issues, the consistency of pesticide dosage through the storage facility and the immigration rate of the adult pest, on overall population control and avoidance of evolution of resistance to the fumigant phosphine in an important pest of stored grain, the lesser grain borer. A very consistent dosage maintained good control for all immigration rates, while an inconsistent dosage failed to maintain control in all cases. At intermediate dosage consistency, immigration rate became a critical factor in whether control was maintained or resistance emerged. Achieving a consistent fumigant dosage is a key factor in avoiding evolution of resistance to phosphine and maintaining control of populations of stored-grain pests when the dosage achieved is very inconsistent, there is likely to be a problem regardless of immigration rate.
Publisher: CSIRO Publishing
Date: 2008
DOI: 10.1071/FP08081
Abstract: Construction of tree architectural databases over years is time consuming and cannot easily capture event dynamics, especially when both tree topology and geometry are considered. The present project aimed to bring together models of topology and geometry in a single simulation such that the architecture of an apple tree may emerge from process interactions. This integration was performed using L-systems. A mixed approach was developed based on stochastic models to simulate plant topology and mechanistic model for the geometry. The succession of growth units (GUs) along axes and their branching structure were jointly modelled by a hierarchical hidden Markov model. A biomechanical model, derived from previous studies, was used to calculate stem form at the metamer scale, taking into account the intra-year dynamics of primary, secondary and fruit growth. Outputs consist of 3-D mock-ups – geometric models representing the progression of tree form over time. To asses these models, a sensitivity analysis was performed and descriptors were compared between simulated and digitised trees, including the total number of GUs in the entire tree, descriptors of shoot geometry (basal diameter, length), and descriptors of axis geometry (inclination, curvature). In conclusion, despite some limitations, MAppleT constitutes a useful tool for simulating development of apple trees in interaction with gravity.
Publisher: Elsevier BV
Date: 10-2011
DOI: 10.1016/J.MBS.2011.06.005
Abstract: Computational simulation models can provide a way of understanding and predicting insect population dynamics and evolution of resistance, but the usefulness of such models depends on generating or estimating the values of key parameters. In this paper, we describe four numerical algorithms generating or estimating key parameters for simulating four different processes within such models. First, we describe a novel method to generate an offspring genotype table for one- or two-locus genetic models for simulating evolution of resistance, and how this method can be extended to create offspring genotype tables for models with more than two loci. Second, we describe how we use a generalized inverse matrix to find a least-squares solution to an over-determined linear system for estimation of parameters in probit models of kill rates. This algorithm can also be used for the estimation of parameters of Freundlich adsorption isotherms. Third, we describe a simple algorithm to randomly select initial frequencies of genotypes either without any special constraints or with some pre-selected frequencies. Also we give a simple method to calculate the "stable" Hardy-Weinberg equilibrium proportions that would result from these initial frequencies. Fourth we describe how the problem of estimating the intrinsic rate of natural increase of a population can be converted to a root-finding problem and how the bisection algorithm can then be used to find the rate. We implemented all these algorithms using MATLAB and Python code the key statements in both codes consist of only a few commands and are given in the appendices. The results of numerical experiments are also provided to demonstrate that our algorithms are valid and efficient.
Publisher: Oxford University Press (OUP)
Date: 29-07-2012
DOI: 10.1093/AOB/MCS166
Publisher: CSIRO Publishing
Date: 2013
DOI: 10.1071/BT13172
Abstract: The anthropogenic movement of Eucalyptus species beyond their natural distributions is increasing the opportunity for interspecific hybridisation. The conservation implications arising from hybridisation between indigenous and introduced eucalypt species in modified urban landscapes is an increasingly important management issue that requires an assessment of risk. It has been claimed that much of the tuart (Eucalyptus gomphocephala DC., Myrtaceae) seed in Kings Park, a large urban bushland remnant in Perth, Western Australia, is of hybrid origin with introduced eastern Australian eucalypts, and especially with E. cladocalyx. Using molecular markers, we tested this claim and determined whether hybridisation in tuart is a conservation management issue in Kings Park, as well as the adjacent Bold Park. Eight microsatellite markers were used to genotype 220 open-pollinated tuart seedlings from 19 families. Allele frequency estimates for tuart were generated by genotyping 42 mature tuart trees. Forty-four trees of four alternative species thought to be capable of hybridising with tuart in these parks, including two non-indigenous species, E. cladocalyx and E. camaldulensis, and two indigenous species, E. decipiens and E. rudis, were also genotyped. Pairwise FST between tuart and each alternative species for these markers ranged from 0.105 to 0.204. A hybrid-index analysis of seedling genotypes showed no significant evidence for hybridisation, and no alternative species private alleles (n = 35) were found in any tuart offspring genotypes. A likelihood analysis showed that the maximum likelihood of observing no private alleles of the alternative species in the progeny occurred at a hybridisation frequency of zero for all four alternative species. We conclude that hybridisation between tuart and non-indigenous species is not currently a conservation management issue in Kings Park and Bold Park. Rather, the invasion of pure non-indigenous species, and in particular E. cladocalyx, as weeds into bushland is of greater management concern.
Publisher: Elsevier BV
Date: 09-2020
Publisher: Elsevier BV
Date: 05-2017
Publisher: The Royal Society
Date: 03-2018
DOI: 10.1098/RSOS.171784
Abstract: We investigated how an invading organism's dispersal characteristics affect the efficacy of different surveillance strategies aimed at detecting that organism as it spreads following a new incursion. Specifically, we assessed whether, out of the surveillance strategies tested, the best surveillance strategy for an organism varied depending on the way it disperses. We simulated the spread of invasive organisms with different dispersal characteristics including leptokurtic and non-leptokurtic kernels with different median dispersal distances and degrees of kurtosis. We evaluated surveillance strategies with different s ling arrangements, densities and frequencies. Surveillance outcomes compared included the time to detection, the total spread of the invasion and the likelihood of the invasion reaching new areas. Overall, dispersal characteristics affected the surveillance outcomes, but the grid surveillance arrangement consistently performed best in terms of early detection and reduced spread within and between fields. Additionally, the results suggest that dispersal characteristics may influence spread to new areas and surveillance strategies. Therefore, knowledge on an invasive organism's dispersal characteristics may influence how we search for it and how we manage the invasion to prevent spread to new areas.
Publisher: Wiley
Date: 16-05-2018
Publisher: JMIR Publications Inc.
Date: 07-07-2023
DOI: 10.2196/50636
Publisher: Elsevier BV
Date: 12-2021
Publisher: Wiley
Date: 21-04-2021
DOI: 10.1111/REC.13360
Abstract: Long‐term studies of vegetation recovery following post‐mining restoration in low‐productivity, high‐stress areas are limited, but essential for understanding underlying ecological processes and evaluating management practices. This study's goal was to describe temporal patterns of recovery (up to 37 years) in vegetation structure, floristic ersity, and composition following post‐mining restoration at two sites, and identify potential drivers of restoration outcomes, in the nutrient‐poor, seasonally dry, species‐rich, fire‐prone kwongan vegetation of southwest Western Australia. Vegetation development is progressing and restoration measures are within range of native reference values, but there is large variation in both patterns observed and restoration outcomes. Several patterns described share similarities with post‐fire recovery of kwongan, and post‐disturbance recovery of other low‐productivity, high‐stress, fire‐prone systems. However, differences in some patterns between sites indicate differences in the underlying mechanisms of recovery. Many management and environmental variables emerge as significant drivers of restoration outcomes but age, fire, and the planting of seedlings account for the largest amount of variation. Adaptive management at both sites appears to be facilitating improved restoration outcomes over time. Using a combination of space‐for‐time, plot level, and linear mixed effects modeling perspectives to examine patterns provides greater insights into restoration recovery than a chronosequence perspective alone. This study will inform restoration practices and outcomes not only in kwongan but in other comparable systems also.
Publisher: Oxford University Press (OUP)
Date: 28-07-2022
Abstract: The origin of allometric scaling patterns that are multiples of one-fourth has long fascinated biologists. While not universal, quarter-power scaling relationships are common and have been described in all major clades. Several models have been advanced to explain the origin of such patterns, but questions regarding the discordance between model predictions and empirical data have limited their widespread acceptance. Notable among these is a fractal branching model that predicts power-law scaling of both metabolism and physical dimensions. While a power law is a useful first approximation to some data sets, nonlinear data compilations suggest the possibility of alternative mechanisms. Here, we show that quarter-power scaling can be derived using only the preservation of volume flow rate and velocity as model constraints. Applying our model to land plants, we show that incorporating biomechanical principles and allowing different parts of plant branching networks to be optimized to serve different functions predicts nonlinearity in allometric relationships and helps explain why interspecific scaling exponents covary along a fractal continuum. We also demonstrate that while branching may be a stochastic process, due to the conservation of volume, data may still be consistent with the expectations for a fractal network when one examines sub-trees within a tree. Data from numerous sources at the level of plant shoots, stems, and petioles show strong agreement with our model predictions. This theoretical framework provides an easily testable alternative to current general models of plant metabolic allometry.
Publisher: Elsevier BV
Date: 12-2019
Publisher: National Inquiry Services Center (NISC)
Date: 20-12-2022
Publisher: CSIRO Publishing
Date: 2015
DOI: 10.1071/CP14135
Abstract: In cropping systems where one type of crop dominates for economic reasons, farmers may employ alternative cropping or pasture options for strategic purposes such as controlling weed populations, reducing crop disease, and accumulating soil nitrogen. Tactical decisions regarding break crops often involve understanding the economic implications of several interacting bio-physical factors, along with complex trade-offs between short-term benefits, such as immediate profit, and long-term ecological problems, such as increased weed seedbank. Modelling analysis regarding tactical crop-sequencing and break-crop decisions has generally not addressed these longer term dynamic factors. In this study we adapted an analysis and modelling framework (LUSO), originally designed to aid understanding of the long-term strategic planning of agricultural crop and pasture rotations, so that it can be used to analyse immediate tactical decisions regarding break crops and sequencing, while still accounting for both short- and long-term implications of these decisions. We show how the revised framework was applied to two ex le scenarios and demonstrate that in both cases it can be used for simple decision-support, as well as more in-depth analysis and insight into the factors influencing the immediate decision.
Publisher: Cambridge University Press (CUP)
Date: 06-2019
DOI: 10.1017/S0960258519000126
Abstract: The regeneration niche defines the specific environmental requirements of the early phases of a plant's life cycle. It is critical for the long-term persistence of plant populations, particularly for obligate seeders that are highly vulnerable to stochastic events in fire-prone ecosystems. Here, we assessed germination characteristics and the relationship between population structure, soil seed bank density and fire response in Stachystemon vinosus (Euphorbiaceae), a rare endemic shrub from Western Australia, from burnt and long unburnt habitats. Many plants in long unburnt habitat were similar in size to those in recently burnt habitat. Soil seed bank density was related to plant abundance and fire history with density lower in burnt than unburnt sites. Thus, inter-fire recruitment may play a critical role in the requirements of the study species. To assess the dormancy status and germination requirements we used a ‘move-along’ experiment with temperatures from six seasonal phases of the year. Seeds were incubated under light and dark conditions, with and without smoked water, and with and without dry after-ripening. Germination was most effective when seeds were treated with smoked water and incubated in the dark at temperatures resembling autumn/winter conditions. After-ripening increased germination in light and dark incubated seeds in the absence of smoked water but was unnecessary for optimal germination in smoked water treated seeds. Irrespective of treatment, seeds showed a requirement for cooler temperatures for germination. These results suggest that rising temperatures and changes in fire regime associated with global warming may alter future germination responses of Stachystemon vinosus .
Publisher: Wiley
Date: 24-07-2016
DOI: 10.1111/WRE.12219
Publisher: Springer Science and Business Media LLC
Date: 02-06-2020
Publisher: Wiley
Date: 07-04-2019
DOI: 10.1111/AEC.12759
Publisher: Wiley
Date: 28-01-2011
Publisher: Elsevier BV
Date: 2013
Publisher: Wiley
Date: 05-11-2011
Publisher: Wiley
Date: 30-03-2012
Publisher: Elsevier BV
Date: 05-2010
Publisher: Wiley
Date: 09-04-2014
DOI: 10.1002/PS.3757
Abstract: The potential for human-driven evolution in economically and environmentally important organisms in medicine, agriculture and conservation management is now widely recognised. The evolution of herbicide resistance in weeds is a classic ex le of rapid adaptation in the face of human-mediated selection. Management strategies that aim to slow or prevent the evolution of herbicide resistance must be informed by an understanding of the ecological and evolutionary factors that drive selection in weed populations. Here, we argue for a greater focus on the ultimate causes of selection for resistance in herbicide resistance studies. The emerging fields of eco-evolutionary dynamics and applied evolutionary biology offer a means to achieve this goal and to consider herbicide resistance in a broader and sometimes novel context. Four relevant research questions are presented, which examine (i) the impact of herbicide dose on selection for resistance, (ii) plant fitness in herbicide resistance studies, (iii) the efficacy of herbicide rotations and mixtures and (iv) the impacts of gene flow on resistance evolution and spread. In all cases, fundamental ecology and evolution have the potential to offer new insights into herbicide resistance evolution and management.
Publisher: Springer Science and Business Media LLC
Date: 07-06-2017
DOI: 10.1007/S00572-017-0782-Z
Abstract: Fine root endophytes (FRE) are arbuscule-forming fungi presently considered as a single species-Glomus tenue in the Glomeromycota (Glomeromycotina)-but probably belong within the Mucoromycotina. Thus, FRE are the only known arbuscule-forming fungi not within the arbuscular mycorrhizal fungi (AMF Glomeromycotina) as currently understood. Phylogenetic differences between FRE and AMF could reflect ecological differences. To synthesize current ecological knowledge, we reviewed the literature on FRE and identified 108 papers that noted the presence of FRE and, in some, the colonization levels for FRE or AMF (or both). We categorized these records by geographic region, host-plant family and environment (agriculture, moderate-natural, low-temperature, high-altitude and other) and determined their influence on the percentage of root length colonized by FRE in a meta-analysis. We found that FRE are globally distributed, with many observations from Poaceae, perhaps due to grasses being widely distributed. In agricultural environments, colonization by FRE often equalled or exceeded that of AMF, particularly in Australasia. In moderate-natural and high-altitude environments, average colonization by FRE (~10%) was lower than that of AMF (~35%), whereas in low-temperature environments, colonization was similar (~20%). Several studies suggested that FRE can enhance host-plant phosphorus uptake and growth, and may be more resilient than AMF to environmental stress in some host plants. Further research is required on the functioning of FRE in relation to the environment, host plant and co-occurring AMF and, in particular, to examine whether FRE are important for plant growth in stressful environments. Targeted molecular primers are urgently needed for further research on FRE.
Publisher: CSIRO Publishing
Date: 2010
DOI: 10.1071/FP09284
Abstract: Age-dependent changes in leaf photosynthetic characteristics (i.e. parameters of the light response curve (maximum photosynthetic rate (Pmax), quantum yield (Φ) and the convexity parameter (θ)), stomatal conductance (gs) and dark respiration rate (Rd)) of an exotic perennial legume, Medicago sativa L. (lucerne), and two potential pasture legumes native to Australia, Cullen australasicum (Schltdl.) J.W. Grime and Cullen pallidum A. Lee, grown in a glasshouse for 5 months at two phosphorus (P) levels (3 (P3) and 30 (P30) mg P kg–1 dry soil) were tested. Leaf appearance rate and leaf area were lower at P3 than at P30 in all species, with M. sativa being the most sensitive to P3. At any leaf age, photosynthetic characteristics did not differ between P treatments. However, Pmax and gs for all the species and Φ for Cullen species increased until full leaf expansion and then decreased. The convexity parameter, θ, did not change with leaf age, whereas Rd decreased. The estimates of leaf net photosynthetic rate (Pleaf) obtained through simulations at variable Pmax and Φ were lower during early and late leaf developmental stages and at lower light intensities than those obtained when Φ was assumed to be constant (e.g. for a horizontally placed leaf, during the 1500°C days developmental period, 3 and 19% reduction of Pleaf at light intensities of 1500 and 500 µmol m–2 s–1, respectively). Therefore, developmental changes in leaf photosynthetic characteristics should be considered when estimating and simulating Pleaf of these pasture species.
Publisher: Wiley
Date: 26-01-2005
DOI: 10.1111/J.1469-8137.2005.01330.X
Abstract: Functional-structural plant models that include detailed mechanistic representation of underlying physiological processes can be expensive to construct and the resulting models can also be extremely complicated. On the other hand, purely empirical models are not able to simulate plant adaptability and response to different conditions. In this paper, we present an intermediate approach to modelling plant function that can simulate plant response without requiring detailed knowledge of underlying physiology. Plant function is modelled using a 'canonical' modelling approach, which uses compartment models with flux functions of a standard mathematical form, while plant structure is modelled using L-systems. Two modelling ex les are used to demonstrate that canonical modelling can be used in conjunction with L-systems to create functional-structural plant models where function is represented either in an accurate and descriptive way, or in a more mechanistic and explanatory way. We conclude that canonical modelling provides a useful, flexible and relatively simple approach to modelling plant function at an intermediate level of abstraction.
Publisher: Scientific Societies
Date: 04-2019
DOI: 10.1094/PHYTO-06-18-0206-R
Abstract: Potato cyst nematodes (PCN) are damaging soilborne quarantine pests of potato in many parts of the world. There are two recognized species, Globodera pallida and G. rostochiensis, with only the latter species—the golden cyst nematode—present in Australia. PCN was first discovered in Australia in 1986 in Western Australia, where it was subsequently eradicated and area freedom for market access was reinstated. In Victoria, PCN was first detected in 1991 east of Melbourne. Since then, it has been found in a small number of localized regions to the south and east. Strict quarantine controls have been in place since each new detection. It has previously been speculated that there were multiple separate introductions of PCN into Victoria. Our study utilized a historic (years 2001 to 2014) PCN cyst reference collection to examine genetic variability of Victorian PCN populations to investigate potential historical origins and subsequent changes in the populations that might inform patterns of spread. DNA was extracted from single larvae dissected from eggs within cysts and screened using nine previously described polymorphic microsatellite markers in two multiplex polymerase chain reaction assays. Sequence variation of the internal transcribed spacer region of the DNA was also assessed and compared with previously published data. A hierarchical s ling strategy was used, comparing variability of larvae within cysts, within paddocks, and between local regions. This s ling revealed very little differentiation between Victorian populations, which share the same microsatellite allelic variation, with differences between local regions probably reflecting changes in allele frequencies over time. Our molecular assessment supports a probable single localized introduction into Victoria followed by limited spread to nearby areas. The Australian PCN examined appear genetically distinct from populations previously s led worldwide thus, any new exotic incursions, potentially bringing in additional PCN pathotypes, should be easily differentiated from existing established local PCN populations.
Publisher: CSIRO Publishing
Date: 2011
DOI: 10.1071/CP10218
Abstract: Biserrula (Biserrula pelecinus L.) is a recently domesticated annual pasture legume developed for ley farming systems that have traditionally relied upon subterranean clover (Trifolium subterraneum L.). This study examined competitive interactions between biserrula and subterranean clover and the common broad-leaf weed capeweed (Arctotheca calendula L.) during seedling establishment and vegetative growth, in order to develop guidelines for successful legume pasture management. Two glasshouse experiments were conducted to investigate the allocation of biomass to roots and shoots in biserrula, capeweed, and subterranean clover and its relationship with competitive ability in the first 100 days after sowing. In Experiment 1, capeweed had a higher relative growth rate of shoots and roots than the two legumes and developed a more extensive root system. Experiment 2 consisted of growing binary mixtures of the three species at different densities. The effect of competition on the biomass of biserrula, capeweed, and subterranean clover was best modelled by a power–exponential model. Increasing capeweed densities suppressed the biomass production of both biserrula and subterranean clover, whereas capeweed biomass increased with increasing densities of subterranean clover. This study suggests that the competitive advantage of capeweed is mainly conferred during the seedling stage. It also suggests that biserrula and subterranean clover germinating at the same time can co-exist as a mixed sward, at least up until flowering, if biserrula density is high relative to subterranean clover.
Publisher: Springer Science and Business Media LLC
Date: 05-01-2014
DOI: 10.1007/S00442-013-2873-7
Abstract: The nervous system of animals serves the acquisition, memorization and recollection of information. Like animals, plants also acquire a huge amount of information from their environment, yet their capacity to memorize and organize learned behavioral responses has not been demonstrated. In Mimosa pudica-the sensitive plant-the defensive leaf-folding behaviour in response to repeated physical disturbance exhibits clear habituation, suggesting some elementary form of learning. Applying the theory and the analytical methods usually employed in animal learning research, we show that leaf-folding habituation is more pronounced and persistent for plants growing in energetically costly environments. Astonishingly, Mimosa can display the learned response even when left undisturbed in a more favourable environment for a month. This relatively long-lasting learned behavioural change as a result of previous experience matches the persistence of habituation effects observed in many animals.
Publisher: CSIRO Publishing
Date: 02-05-2022
DOI: 10.1071/CP21745
Abstract: Rotations and associated management practices in rainfed farming systems of southwest Australia have shifted towards intensified cropping. Survey data from 184 fields spanning 14 Mha of southwest Australia were used to document water use efficiency (WUE) and water-limited yield potential (WLYP) of commercial crops and crop sequences and identify biophysical variables influencing WUE. WUE achieved in commercial wheat crops was 10.7 kg grain/ha.mm. Using a boundary function Ywl = 25 × (WU − 45), farmers achieved 54% of WLYP. Climate variables affected WUE more than management and biotic variates, the highest latitude region having WUE of 9.0 kg grain/ha.mm, compared to 11.8 kg grain/ha.mm for regions further south. Increased soil nitrogen and nitrogen fertiliser increased WUE, as did sowing earlier in keeping with farmers in southern Australia sowing crops earlier and trebling fertiliser nitrogen usage since 1990. Wheat yield and WUE increased a small amount after break crop or pasture (12.5 kg grain/ha.mm) compared to wheat grown after wheat (11.2 kg grain/ha.mm), due to good weed and root pathogen control, and high fertiliser nitrogen application. However, WUE of wheat declined to 8.4 kg grain/ha.mm when more than three wheat crops were grown in succession. Farmers continue to improve WUE with increased inputs and new technologies replacing some traditional functions of break crops and pasture. However, break crops and pastures are still required within the rotation to maintain WUE and break effects need to be measured over several years.
Publisher: Inter-Research Science Center
Date: 06-02-2013
DOI: 10.3354/CR01138
Publisher: Wiley
Date: 19-11-2009
Publisher: Springer Science and Business Media LLC
Date: 12-03-2014
Publisher: IEEE
Date: 10-2012
Publisher: Springer Science and Business Media LLC
Date: 21-06-2023
DOI: 10.1007/S11104-023-06092-6
Abstract: Belowground interspecific plant facilitation is supposed to play a key role in enabling species co-existence in hyper erse ecosystems in extremely nutrient-poor, semi-arid habitats, such as Banksia woodlands in southwestern-Australia. Manganese (Mn) is readily mobilised by Banksia cluster root activity in most soils and accumulates in mature leaves of native Australian plant species without significant remobilisation during leaf senescence. We hypothesised that neighbouring shrubs are facilitated in terms of Mn uptake depending on distance to surrounding cluster root-forming Banksia trees. We mapped all Banksia trees and selected neighbouring shrubs within a study site in Western Australia. Soil s les were collected and analysed for physical properties and nutrient concentrations. To assesses the effect of Banksia tree proximity on leaf Mn concentrations [Mn] of non-cluster-rooted woody shrubs, s les of similarly aged leaves were taken. We used multiple linear models to test for factors affecting shrub leaf [Mn]. None of the assessed soil parameters showed a significant correlation with shrub leaf Mn concentrations. However, we observed a significant positive effect of very close Banksia trees (2 m) on leaf [Mn] in one of the understorey shrubs. We found additional effects of elevation and shrub size. Leaf micronutrient concentrations of understorey shrubs were enhanced when growing within 2 m of tall Banksia trees. Our model predictions also indicate that belowground facilitation of Mn uptake was shrub size-dependent. We discuss this result in the light of plant water relations and shrub root system architecture.
Publisher: Elsevier BV
Date: 2021
Publisher: Wiley
Date: 27-07-2019
DOI: 10.1002/PS.5534
Abstract: Weed resistance to foliar herbicides has dramatically increased worldwide in the last two decades. As a consequence, current practices of weed management have changed, with an increased adoption of soil-applied herbicides to restore control of herbicide-resistant weeds. We foresee metabolism-based resistance and cross-resistance to soil-applied herbicides as a potential global consequence to the increased and widespread adoption of new and old soil-applied herbicides. Thus, the aim of this study is to use computer simulation modelling to quantify and rank the risk of weeds evolving resistance to soil-applied herbicides under different usage strategies (single herbicide use, rotations and mixtures) and population genetic hypotheses. Simulations indicate that without rotation it takes twice as long to select for resistance to a particular soil-applied herbicide - trifluralin - than to any other herbicide option considered. Relative to trifluralin-only use, simple herbicide rotation patterns have no effect in delaying resistance, whereas more complex rotation patterns can delay resistance two- or three-fold. Herbicide mixtures further delay resistance up to six-fold in comparison to single use or simple herbicide rotations. By computer modelling simulations we demonstrate that mixtures maximize herbicide effectiveness and the selection heterogeneity of soil-applied herbicides, and delay herbicide resistance evolution in weedy plants. Our study is consistent with previous state-of-art scientific evidence (i.e. epidemiological and modelling studies across different systems and pests) and extension efforts (i.e. 'rotate herbicide mixtures') to provide insight to manage the selection and evolution of weed resistance. © 2019 Society of Chemical Industry.
Publisher: Elsevier BV
Date: 10-2020
Publisher: Oxford University Press (OUP)
Date: 23-01-2018
DOI: 10.1093/AOB/MCX156
Publisher: Elsevier BV
Date: 12-2020
Publisher: Wiley
Date: 15-12-2020
Publisher: Oxford University Press (OUP)
Date: 07-02-2015
DOI: 10.1093/AOB/MCV014
Publisher: Elsevier BV
Date: 08-2023
Publisher: Springer Science and Business Media LLC
Date: 05-03-2011
Publisher: Scientific Societies
Date: 06-2017
DOI: 10.1094/PDIS-08-16-1203-RE
Abstract: Drivers of Pea seed-borne mosaic virus (PSbMV) epidemics in rainfed field pea crops were examined under autumn to spring growing conditions in a Mediterranean-type environment. To collect aphid occurrence and PSbMV epidemic data under a erse range of conditions, 23 field pea data collection blocks were set up over a 6-year period (2010 to 2015) at five locations in the southwest Australian grain-growing region. PSbMV infection levels in seed sown (0.1 to 13%), time of sowing (22 May to 22 June), and cultivar (Kaspa or PBA Twilight) varied with location and year. Throughout each growing season, rainfall data were collected, leaf and seed s les were tested to monitor PSbMV incidence in the crop and transmission from harvested seed, and sticky traps were used to monitor flying aphid numbers. Winged migrant Acyrthosiphon kondoi, Lipaphis erysimi, Myzus persicae, and Rhopalosiphum padi were identified in green tile traps in 2014 and 2015. However, no aphid colonization of field pea plants ever occurred in the blocks. The deductions made from collection block data illustrated how the magnitude of PSbMV spread prior to flowering is determined by two primary epidemic drivers: (i) PSbMV infection incidence in the seed sown, which defines the magnitude of virus inoculum source for within-crop spread by aphids, and (ii) presowing rainfall that promotes background vegetation growth which, in turn, drives early-season aphid populations and the time of first arrival of their winged migrants to field pea crops. Likely secondary epidemic drivers included wind-mediated PSbMV plant-to-plant contact transmission and time of sowing. PSbMV incidence at flowering time strongly influenced transmission rate from harvested seed to seedlings. The data collected are well suited for development and validation of a forecasting model that informs a Decision Support System for PSbMV control in field pea crops.
Publisher: CSIRO Publishing
Date: 2010
DOI: 10.1071/CP10026
Abstract: The break crop effect, where a non-cereal crop provides relief from soil pathogens, may increase soil nitrogen reserves for a cereal and help minimise populations of herbicide resistant weeds. It is widely used in agriculture to maximise the economic return and yield of cereal crops. In Western Australia, cereal crops are being grown with increasing frequency, at the expense of less profitable break crops and we have developed a land use sequence optimiser (LUSO) to analyse strategic break crop decisions across a suite of price, yield, nitrogen fertiliser cost, soil borne disease load and weed load thresholds. The model is flexible and can easily be parameterised for a wide range of economic, edaphic and biotic parameters. We demonstrate its use in a strategic sense to determine economic and biotic thresholds that force a rotation change in a typical Western Australian cropping system.
Publisher: Elsevier BV
Date: 2014
Publisher: Oxford University Press (OUP)
Date: 2012
Publisher: Wiley
Date: 10-09-2013
DOI: 10.1111/EVA.12098
Publisher: IEEE
Date: 11-2018
Publisher: Wiley
Date: 13-06-2012
Publisher: Wiley
Date: 08-12-2011
Publisher: Elsevier BV
Date: 02-2022
Publisher: CSIRO Publishing
Date: 2015
DOI: 10.1071/BT14310
Abstract: Beyeria cockertonii Halford & R.J.F.Hend. and Beyeria villosa Halford & R.J.F.Hend. (Euphorbiaceae) are two short-range endemic monoecious congeners from southern Western Australia. We sought to determine whether life-history characteristics were responsible for their limited distribution and to identify aspects of their ecology that might render them vulnerable to current threatening processes. We investigated reproductive phenology in relation to climate, pollinator activity and synchronicity of male and female flowering. In addition seed dispersal, regeneration, demography and seed viability were examined and ex situ germination experiments conducted to determine seed-dormancy mechanisms. Flowering in the conservation-listed B. cockertonii was significantly correlated with temperature, whereas fruit set was correlated with pollinator abundance and movement male and female flowering showed limited synchrony. The presence of soil-stored seeds lacking a caruncle at sites absent of adult plants of either species suggests that seed may be ant-dispersed (myrmecochory). Fresh seeds of B. cockertonii were significantly more viable than those of its more common congener, B. villosa (72 vs 0.5%, P 0.001). Fresh B. cockertonii seeds would not germinate with an intact caruncle caruncle removal elicited germination of 64% and 60% (10°C and 15°C, respectively). Aqueous smoke further stimulated germination to 72% and 83% germination (10°C and 15°C, respectively), providing a link between fire and germination. Beyeria villosa was affected by high levels of pre-dispersal predation (up to 70%) and seed abortion (88%) and appeared to have lower reproductive fitness than B. cockertonii. Life-history strategies did not explain the greater abundance and wider distribution of B. villosa than those of the conservation-listed B cockertonii, nor was the greater rarity of B. cockertonii fully explained by habitat specificity, with both species being restricted to ultra-mafic volcanic rock associated with Achaean greenstone. However, an apparent dependence of B. cockertonii on a specific insect pollinator from the family Miridae may render this species vulnerable to threatening processes.
Publisher: Cambridge University Press (CUP)
Date: 28-11-2014
DOI: 10.1017/S0376892913000490
Abstract: As climates change, some plant species will need to migrate across landscapes fragmented by unsuitable environments and human activities to colonize new areas with suitable climates as previously habited areas become uninhabitable. Previous modelling of plant's migration potential has generally assumed that climate changes at a constant rate, but this ignores many potentially important aspects of real climate variability. In this study, a spatially explicit simulation model was used to investigate how interannual climate variability, the occurrence of extreme events and step changes in climate might interact with gradual long-term climate change to affect plant species’ capacity to migrate across fragmented landscapes and persist. The considered types of climate variability generally exacerbated the negative effects of long-term climate change, with a few poignant exceptions where persistence of long-lived trees improved. Strategic habitat restoration ameliorated negative effects of climate variability. Plant functional characteristics strongly influenced most results. Any modelling of how climate change may affect species persistence, and how actions such as restoration may help species adapt, should account for both short-term climate variability and long-term change.
Publisher: Wiley
Date: 20-02-2017
DOI: 10.1002/PS.4509
Abstract: Across several agricultural systems the evolution of herbicide resistance has occurred more rapidly to post-emergence than pre-emergence herbicides however, the reasons for this are not clear. We used a new simulation model to investigate whether interactions between differences in order of application and weed cohorts affected could explain this historically observed difference between the herbicide groups. A 10 year delay in resistance evolution was predicted for a shorter-acting residual pre-emergence (cf. post-emergence), when all other parameters were identical. Differences in order of application between pre- and post-emergence herbicides had minimal effect on rates of resistance evolution when similar weed cohorts were affected. This modelling suggested that the historically observed lower levels of resistance to pre-emergence herbicides are most likely to be due to the smaller number of weed cohorts affected by many pre-emergence herbicides. The lower number of weed cohorts affected by pre-emergence herbicides necessitated the use of additional, effective control measures, thereby reducing resistance evolution. This study highlights the advantages of applying multiple control measures to each weed cohort. © 2016 Society of Chemical Industry.
Publisher: Springer Science and Business Media LLC
Date: 28-12-2013
DOI: 10.1007/S00248-012-0165-0
Abstract: Diurnal patterns of spore release have been observed in a number of fungal pathogens that undergo wind-assisted dispersal. The mechanisms that drive these patterns, while not well understood, are thought to relate to the ability of dispersing spores to survive their journey and infect new hosts. In this paper, we characterise the diurnal pattern of ascospore release by a Western Australian population of Leptosphaeria maculans. Although L. maculans has been previously shown to exhibit diurnal patterns of ascospore release, these patterns appear to vary from region to region. In order to characterise the pattern of release in the Mediterranean climate of Western Australia, we analysed historical data describing the bi-hourly count of airborne ascospores at Mt Barker, Western Australia. Results of this analysis showed diurnal patterns that differ from those previously observed in other countries, with ascospore release in our study most likely to occur in the afternoon. Furthermore, we found that the time of peak release can shift from month to month within any one season, and from year to year. In explaining the hourly pattern of spore release over an entire season, time since rainfall, time since last release, temperature, hour and month were all shown to be significant variables.
Publisher: Elsevier BV
Date: 10-2012
Publisher: Wiley
Date: 06-09-2018
DOI: 10.1111/REC.12561
Publisher: Elsevier BV
Date: 02-2022
Publisher: Cambridge University Press (CUP)
Date: 06-2011
Abstract: Herbicide rate cutting is an ex le of poor use of agrochemicals that can have potential adverse implications due to rapid herbicide resistance evolution. Recent laboratory-level studies have revealed that herbicides at lower-than-recommended rates can result in rapid herbicide resistance evolution in rigid ryegrass populations. However, crop-field-level studies have until now been lacking. In this study, we examined the impact of low rates of diclofop on the evolution of herbicide resistance in a herbicide-susceptible rigid ryegrass population grown either in a field wheat crop or in potted plants maintained in the field. Subsequent dose–response profiles indicated rapid evolution of diclofop resistance in the selected rigid ryegrass lines from both the crop-field and field pot studies. In addition, there was moderate level of resistance in the selected lines against other tested herbicides to which the population has never been exposed. This resistance evolution was possible because low rates of diclofop allowed substantial rigid ryegrass survivors due to the potential in this cross-pollinated species to accumulate all minor herbicide resistance traits present in the population. The practical lesson from this research is that herbicides should be used at the recommended rates that ensure high weed mortality to minimize the likelihood of minor herbicide resistance traits leading to rapid herbicide resistance evolution.
Publisher: Wiley
Date: 21-02-2010
Publisher: Elsevier BV
Date: 2013
Publisher: MDPI AG
Date: 28-05-2021
DOI: 10.3390/SU13116109
Abstract: Habitat loss has reduced the available resources for apiarists and is a key driver of poor colony health, colony loss, and reduced honey yields. The biggest challenge for apiarists in the future will be meeting increasing demands for pollination services, honey, and other bee products with limited resources. Targeted landscape restoration focusing on high-value or high-yielding forage could ensure adequate floral resources are available to sustain the growing industry. Tools are currently needed to evaluate the likely productivity of potential sites for restoration and inform decisions about plant selections and arrangements and hive stocking rates, movements, and placements. We propose a new approach for designing sites for apiculture, centred on a model of honey production that predicts how changes to plant and hive decisions affect the resource supply, potential for bees to collect resources, consumption of resources by the colonies, and subsequently, amount of honey that may be produced. The proposed model is discussed with reference to existing models, and data input requirements are discussed with reference to an Australian case study area. We conclude that no existing model exactly meets the requirements of our proposed approach, but components of several existing models could be combined to achieve these needs.
Publisher: Elsevier BV
Date: 09-2017
DOI: 10.1016/J.VIRUSRES.2017.05.018
Abstract: An empirical model was developed to forecast Pea seed-borne mosaic virus (PSbMV) incidence at a critical phase of the annual growing season to predict yield loss in field pea crops sown under Mediterranean-type conditions. The model uses pre-growing season rainfall to calculate an index of aphid abundance in early-August which, in combination with PSbMV infection level in seed sown, is used to forecast virus crop incidence. Using predicted PSbMV crop incidence in early-August and day of sowing, PSbMV transmission from harvested seed was also predicted, albeit less accurately. The model was developed so it provides forecasts before sowing to allow sufficient time to implement control recommendations, such as having representative seed s les tested for PSbMV transmission rate to seedlings, obtaining seed with minimal PSbMV infection or of a PSbMV-resistant cultivar, and implementation of cultural management strategies. The model provides a disease forecast risk indication, taking into account predicted percentage yield loss to PSbMV infection and economic factors involved in field pea production. This disease risk forecast delivers location-specific recommendations regarding PSbMV management to end-users. These recommendations will be delivered directly to end-users via SMS alerts with links to web support that provide information on PSbMV management options. This modelling and decision support system approach would likely be suitable for use in other world regions where field pea is grown in similar Mediterranean-type environments.
Publisher: Elsevier BV
Date: 15-09-2010
Publisher: Oxford University Press (OUP)
Date: 23-06-2014
DOI: 10.1093/JPE/RTU005
Publisher: Wiley
Date: 28-04-2014
DOI: 10.1002/PS.3773
Abstract: Computer simulation modelling is an essential aid in building an integrated understanding of how different factors interact to affect the evolutionary and population dynamics of herbicide resistance, and thus in helping to predict and manage how agricultural systems will be affected. In this review, we first discuss why computer simulation modelling is such an important tool and framework for dealing with herbicide resistance. We then explain what questions related to herbicide resistance have been addressed to date using simulation modelling, and discuss the modelling approaches that have been used, focusing first on the earlier, more general approaches, and then on some newer, more innovative approaches. We then consider how these approaches could be further developed in the future, by drawing on modelling techniques that are already employed in other areas, such as in idual-based and spatially explicit modelling approaches, as well as the possibility of better representing genetics, competition and economics, and finally the questions and issues of importance to herbicide resistance research and management that could be addressed using these new approaches are discussed. We conclude that it is necessary to proceed with caution when increasing the complexity of models by adding new details, but, with appropriate care, more detailed models will make it possible to integrate more current knowledge in order better to understand, predict and ultimately manage the evolution of herbicide resistance.
Publisher: Elsevier BV
Date: 08-2011
Publisher: Elsevier BV
Date: 06-2005
Publisher: Wiley
Date: 14-06-2017
DOI: 10.1111/PBI.12742
Publisher: Wiley
Date: 10-2012
Publisher: Scientific Societies
Date: 12-2016
DOI: 10.1094/PDIS-05-16-0670-RE
Abstract: From 2013 to 2015, incidences of Pea seed-borne mosaic virus (PSbMV) infection were determined in semi-leafless field pea (Pisum sativum) crops and trial plots growing in the Mediterranean-type environment of southwest Australia. PSbMV was found at incidences of 2 to 51% in 9 of 13 crops, 1 to 100% in 20 of 24 cultivar plots, and 1 to 57% in 14 of 21 breeding line plots. Crops and plots of ‘PBA Gunyah’, ‘Kaspa’, and ‘PBA Twilight’ were frequently PSbMV infected but none of PSbMV resistance gene sbm1-carrying ‘PBA Wharton’ plants were infected. In 2015, 14 new PSbMV isolates obtained from these various sources were sequenced and their partial coat protein (CP) nucleotide sequences analyzed. Sequence identities and phylogenetic comparison with 39 other PSbMV partial CP nucleotide sequences from GenBank demonstrated that at least three PSbMV introductions have occurred to the region, one of which was previously unknown. When plants of ‘Greenfeast’ and PBA Gunyah pea (which both carry resistance gene sbm2) and PBA Wharton and ‘Yarrum’ (which carry sbm1) were inoculated with PSbMV pathotype P-2 isolate W1, resistance was overcome in a small proportion of plants of each cultivar, showing that resistance-breaking variants were likely to be present. An improved management effort by pea breeders, advisors, and growers is required to diminish infection of seed stocks, avoid sbm gene resistance being overcome in the field, and mitigate the impact of PSbMV on seed yield and quality. A similar management effort is likely to be needed in field pea production elsewhere in the world.
Publisher: Elsevier BV
Date: 06-2021
Publisher: Elsevier BV
Date: 09-2017
DOI: 10.1016/J.VIRUSRES.2017.04.005
Abstract: Pea seed-borne mosaic virus (PSbMV) infection causes a serious disease of field pea (Pisum sativum) crops worldwide. The PSbMV transmission efficiencies of five aphid species previously found landing in south-west Australian pea crops in which PSbMV was spreading were studied. With plants of susceptible pea cv. Kaspa, the transmission efficiencies of Aphis craccivora, Myzus persicae, Acyrthosiphon kondoi and Rhopalosiphum padi were 27%, 26%, 6% and 3%, respectively. Lipaphis erysimi did not transmit PSbMV in these experiments. The transmission efficiencies found for M. persicae and A. craccivora resembled earlier findings, but PSbMV vector transmission efficiency data were unavailable for A. kondoi, R. padi and L. erysimi. With plants of partially PSbMV resistant pea cv. PBA Twilight, transmission efficiencies of M. persicae, A. craccivora and R. padi were 16%, 12% and 1%, respectively, reflecting putative partial resistance to aphid inoculation. To examine aphid alighting preferences over time, free-choice assays were conducted with two aphid species representing efficient (M. persicae) and inefficient (R. padi) vector species. For this, alatae were set free on multiple occasions (10-15 repetitions each) amongst PSbMV-infected and mock-inoculated pea or faba bean (Vicia faba) plants. Following release, non-viruliferous R. padi alatae exhibited a general preference for PSbMV-infected pea and faba bean plants after 30min-4h, but preferred mock-inoculated plants after 24h. In contrast, non-viruliferous M. persicae alatae alighted on mock-inoculated pea plants preferentially for up to 48h following their release. With faba bean, M. persicae preferred infected plants at the front of assay cages, but mock-inoculated ones their backs, apparently due to increased levels of natural light there. When preliminary analyses were performed to detect PSbMV-induced changes in the volatile organic compound profiles of pea and faba bean plants, higher numbers of volatiles representing a range of compound groups (such as aldehydes, ketones and esters) were found in the headspaces of PSbMV-infected than of mock-inoculated pea or faba bean plants. This indicates PSbMV induces physiological changes in these hosts which manifest as altered volatile emissions. These alterations could be responsible for the differences in alighting preferences. Information from this study enhances understanding of virus-vector relationships in the PSbMV-pea and faba bean pathosystems.
Publisher: CSIRO Publishing
Date: 2012
DOI: 10.1071/CP11338
Abstract: Cullen australasicum is a legume species from Australia that holds promise for development as a drought-tolerant perennial pasture species, yet only a few accessions have been evaluated for agronomic traits. Several Cullen species aside from C. australasicum may also have potential for use as perennial pastures. We compared the field survival and aboveground biomass production of 100 germplasm accessions from 9 Cullen species, 2 lucerne (Medicago sativa) cultivars and 2 perennial Lotus species over 18 months in a low-rainfall region of the wheatbelt of Western Australia. Nutritive value of selected Cullen accessions was also compared with lucerne and L. australis. Several accessions of C. australasicum demonstrated good survival, productivity and nutritional value, and some accessions of C. discolor, C. lachnostachys, C. pallidum and C. pustulatum also showed promise in some or all of these traits. Significant phenotypic variation was seen among accessions of C. australasicum, C. pallidum, C. cinereum and C. tenax for some agronomic traits. We discuss the implications of this variation for further experiments or development of Cullen species. While survival and productivity of many Cullen accessions was similar to lucerne, only a few C. australasicum accessions were more productive than lucerne. We conclude that C. australasicum is currently the best prospect among Cullen species for cultivar development as a perennial pasture legume, and our analysis has highlighted accessions of particular interest. In addition, further work on C. discolor, C. lachnostachys, C. pallidum and C. pustulatum may also, in the longer term, provide useful pasture species.
Publisher: CSIRO Publishing
Date: 22-06-2022
DOI: 10.1071/CP21778
Abstract: Context Rotations in rainfed farming systems of southwest Australia have shifted towards intensified cropping and it is necessary to reassess soilborne pathogens and plant parasitic nematodes within this context. Aims We tested the hypothesis that these recent changes in rotations and agronomy have altered the efficacy with which rotations reduce the incidence of common root pathogens and plant parasitic nematodes. Methods We tracked changes in common pathogen DNA in soil and the incidence and severity of crop root damage in 184 paddocks, over 6 years from 2010 to 2015, and related this to farmer practices. Key results Overall, severe root damage was rare, with 72% of plant s les showing no damage or only a trace and only 1% severely damaged. We found that the reduction of paddocks in pasture and resultant very low weed populations, combined with early sowing, reduced persistence of pathogens and nematode pests. But some aspects of crop management had the opposite effect: high rates of herbicide, increased frequency of cereals and canola at the expense of lupin and increased N fertiliser use. Conclusions Current agronomic practices and the frequency of non-host crops in rotations appear to be effective in controlling common root pathogens and plant parasitic nematodes. But the aspects of agronomic management that increased populations of pathogens should be applied cautiously. Implications Studies such as this that link multiple productivity constraints, such as pathogens and nematode pests, weeds and nutrients, to management practices are important to understand the sustainability of current or proposed production methods.
Publisher: Springer Science and Business Media LLC
Date: 20-11-2021
Publisher: CSIRO Publishing
Date: 2013
DOI: 10.1071/CP12398
Abstract: Herbaceous perennial legumes that can provide forage in the summer–autumn dry period are urgently required in Mediterranean climates to complement annual pastures and the perennial legume lucerne (Medicago sativa). This study evaluated the establishment, survival, and herbage production of tedera (Bituminaria bituminosa var. albomarginata) and Cullen spp. native to Australia. Two experiments were replicated at Buntine (warmer site) and Newdegate (cooler site) in the low-rainfall cropping zone ( mm average annual rainfall) of Western Australia from June 2008 to September 2010. In the first experiment, established by transplanting seedlings, survival and herbage production of two accessions each of B. bituminosa and C. australasicum were studied under densities of 1, 2, 4, 8, and 16 plants/m2 with 0, 1, 2, or 3 cuts in summer–autumn in addition to a winter–spring cut. In the second experiment, established from seed, emergence and survival of several accessions of B. bituminosa, C. australasicum, and M. sativa were studied, along with C. pallidum and C. cinereum. In the first experiment, B. bituminosa survived better than C. australasicum (70–80% v. 18–45%), especially at Buntine, but there was little impact of density or cutting frequency on survival. Plant death was highest during summer. Shoot dry weight (DW) accumulation varied greatly with site, year, and plant density. When rainfall was close to average, shoot DW was greater at Newdegate (B. bituminosa ≤7.4 t/ha, C. australasicum ≤4.5 t/ha) than at Buntine (≤2.3 t/ha), and both species produced much of their shoot DW in summer–autumn (e.g. 6 t/ha for B. bituminosa and 3 t/ha for C. australasicum at Newdegate). An early-summer cut reduced the DW that could be harvested later in summer–autumn. In the second experiment, emergence of B. bituminosa was either similar to, or higher than, emergence of the other species, being 43% at Buntine and 44% at Newdegate. Survival of B. bituminosa, compared with M. sativa, was similar at Buntine (13%) and slightly lower at Newdegate (14%). Emergence and survival of Cullen spp. varied among species and accessions, with survival of the best performing accession of C. australasicum (SA4966) similar to that of B. bituminosa and M. sativa at both sites. We conclude that B. bituminosa shows promise as a perennial summer forage for low-rainfall zones, with a density of 8–16 plants/m2 and cutting frequency of 3 cuts/year (i.e. cut twice in summer–autumn), while C. australasicum and C. pallidum warrant further study.
Publisher: Elsevier
Date: 2014
Publisher: Springer Science and Business Media LLC
Date: 05-04-2017
DOI: 10.1007/S00442-017-3862-Z
Abstract: Because water is essential to life, organisms have evolved a wide range of strategies to cope with water limitations, including actively searching for their preferred moisture levels to avoid dehydration. Plants use moisture gradients to direct their roots through the soil once a water source is detected, but how they first detect the source is unknown. We used the model plant Pisum sativum to investigate the mechanism by which roots sense and locate water. We found that roots were able to locate a water source by sensing the vibrations generated by water moving inside pipes, even in the absence of substrate moisture. When both moisture and acoustic cues were available, roots preferentially used moisture in the soil over acoustic vibrations, suggesting that acoustic gradients enable roots to broadly detect a water source at a distance, while moisture gradients help them to reach their target more accurately. Our results also showed that the presence of noise affected the abilities of roots to perceive and respond correctly to the surrounding soundscape. These findings highlight the urgent need to better understand the ecological role of sound and the consequences of acoustic pollution for plant as well as animal populations.
Publisher: Frontiers Media SA
Date: 14-11-2017
Publisher: Elsevier BV
Date: 11-2018
Publisher: Wiley
Date: 10-11-2021
Abstract: Negative conspecific interactions have been shown to promote ersity in plant communities, as have some heterospecific interactions such as intransitive competition and facilitation. However, it is unclear whether combinations of conspecific and other heterospecific interactions can also promote ersity in plant communities. We therefore investigated the effects of heterospecific plant interaction network architecture with and without conspecific interactions on alpha ersity, beta ersity and long‐term ersity. We simulated long‐term plant community dynamics for theoretical plant interaction scenarios with modular, ring and nested networks of positive or negative heterospecific interactions and conspecific interactions, using a spatially explicit cellular automaton model that accounted for stochastic effects. Throughout the simulations several measures of ersity were recorded. The way that heterospecific interactions affected ersity depended strongly on various characteristics of the architecture of the interaction network. Negative conspecific interactions generally promoted alpha ersity and reduced beta ersity, with a few key exceptions. Positive heterospecific ring interactions that resulted in cyclic appearance and disappearance of species groups led to the greatest long‐term ersity (a measure of the total ersity over time). This study provides new theoretical insights into how the network architecture of heterospecific plant interactions can affect the ersity of plant communities over time and provides the first evidence that heterospecific plant interactions can increase long‐term ersity more than negative conspecific interactions alone. A free Plain Language Summary can be found within the Supporting Information of this article.
Publisher: Springer Science and Business Media LLC
Date: 12-11-2020
DOI: 10.1038/S41598-020-76788-7
Abstract: Rotating crop cultivars with different resistance genes could slow the evolution of virulent strains of fungal pathogens, but could also produce highly virulent pathogen strains. We present a new model that links polycyclic pathogen epidemiology and population genetics in order to predict how different strategies of rotating cultivars with different resistances will affect the evolution of pathogen virulence and the breakdown of crop resistance. We modelled a situation where there were four different resistance genes that can be deployed within each crop cultivar, and four virulence genes that may be present within the pathogen. We simulated four different rotational management strategies: (i) no rotation (ii) a different gene every year (iii) a different gene every 5 years and (iv) a different combination of two stacked genes each year. Results indicate that rotating cultivars can lead to longer periods of disease suppression but also to the selection of highly virulent strains. The efficacy and relative advantage of different resistant cultivar rotation strategies depended on the fitness penalties, initial virulence allele frequencies, and ability of non-virulent pathogen genotypes to grow and reproduce on resistant cultivars. By capturing the essential processes involved, our model provides a useful new tool for investigating the evolutionary dynamics of pathogen virulence and crop resistance breakdown.
Publisher: Public Library of Science (PLoS)
Date: 04-05-2021
DOI: 10.1371/JOURNAL.PONE.0249959
Abstract: Globally, many biomes are being impacted by significant shifts in total annual rainfall as well as increasing variability of rainfall within and among years. Such changes can have potentially large impacts on plant productivity and growth, but remain largely unknown, particularly for much of the Southern Hemisphere. We investigate how growth of the widespread conifer, Callitris columellaris varied with inter-annual variation in the amount, intensity and frequency of rainfall events over the last century and between semi-arid ( mm mean annual rainfall) and tropical ( mm mean annual rainfall) biomes in Australia. We used linear and polynomial regression models to investigate the strength and shape of the relationships between growth (ring width) and rainfall. At semi-arid sites, growth was strongly and linearly related to rainfall amount, regardless of differences in the seasonality and intensity of rainfall. The linear shape of the relationship indicates that predicted future declines in mean rainfall will have proportional negative impacts on long-term tree growth in semi-arid biomes. In contrast, growth in the tropics showed a weak and asymmetrical (‘concave-down’) response to rainfall amount, where growth was less responsive to changes in rainfall amount at the higher end of the rainfall range ( mm annual rainfall) than at the lower end ( mm annual rainfall). The asymmetric relationship indicates that long-term growth rates of Callitris in the tropics are more sensitive to increased inter-annual variability of rainfall than to changes in the mean amount of rainfall. Our findings are consistent with observations that the responses of vegetation to changes in the mean or variability of rainfall differ between mesic and semi-arid biomes. These results highlight how contrasting growth responses of a widespread species across a hydroclimatic gradient can inform understanding of potential sensitivity of different biomes to climatic variability and change.
Publisher: Springer Science and Business Media LLC
Date: 07-12-2017
Publisher: Springer Science and Business Media LLC
Date: 2013
Publisher: Wiley
Date: 10-2018
DOI: 10.1111/AVSC.12399
Publisher: Wiley
Date: 22-03-2012
DOI: 10.1111/J.1469-8137.2012.04093.X
Abstract: • This paper presents two models of carrier-dependent long-distance auxin transport in stems that represent the process at different scales. • A simple compartment model using a single constant auxin transfer rate produced similar data to those observed in biological experiments. The effects of different underlying biological assumptions were tested in a more detailed model representing cellular and intracellular processes that enabled discussion of different patterns of carrier-dependent auxin transport and signalling. • The output that best fits the biological data is produced by a model where polar auxin transport is not limited by the number of transporters/carriers and hence supports biological data showing that stems have considerable excess capacity to transport auxin. • All results support the conclusion that auxin depletion following apical decapitation in pea (Pisum sativum) occurs too slowly to be the initial cause of bud outgrowth. Consequently, changes in auxin content in the main stem and changes in polar auxin transport/carrier abundance in the main stem are not correlated with axillary bud outgrowth.
Publisher: Cambridge University Press (CUP)
Date: 03-2012
Abstract: A wild population of a plant species, especially a cross-pollinated species, can display considerable genetic variation. Genetic variability is evident in differential susceptibility to an herbicide because the population can show continuous phenotypic variation. Recent, recurrent selection studies have revealed that phenotypic variation in response to low herbicide rates is heritable and can result in rapid evolution of herbicide resistance in genetically variable cross-pollinated rigid ryegrass. In this study, the heritable genetic variation in an herbicide-susceptible rigid ryegrass population was exploited to shift the population toward greater herbicide susceptibility by recurrent selection. To enhance herbicide susceptibility, herbicide-susceptible rigid ryegrass plants were ided into two identical clones, and one series of cloned plants was treated with a low rate of herbicide (diclofop). The nontreated clones of in iduals that did not survive the herbicide treatment were selected and bulk-crossed to obtain the susceptible progeny. After two cycles of selection, the overall susceptibility to diclofop was doubled. The results indicate that minor genes for resistance are present in an herbicide-susceptible rigid ryegrass population, and their exclusion can increase susceptibility to diclofop.
Publisher: Elsevier BV
Date: 06-2012
Publisher: Wiley
Date: 04-2019
DOI: 10.1002/ECS2.2656
Publisher: Oxford University Press (OUP)
Date: 20-03-2014
DOI: 10.1093/AOB/MCU018
Publisher: Cambridge University Press (CUP)
Date: 04-07-2011
DOI: 10.1017/S0021859611000566
Abstract: The present paper compares standard and novel methods for analysing aggregated patterns of plant death in designed field experiments these methods include binomial (BN), beta-binomial (BBN), logistic-normal-binomial (LNB), BN models with random blocks, BN models with smooth-scale spatial components and principal coordinates of neighbour matrices (PCNM). PCNM is a relatively new technique used in ecology to determine how much observed variability can be explained by spatial and environmental variables, and has not yet been applied to agricultural studies. The survival data of two pasture species, collected from a designed field experiment that was replicated at multiple locations, were used. First, the occurrence of overdispersion was tested using the BN and BBN distributions. Goodness-of-fit tests proved that the BBN model provided a better description (better fit) of the observed data in some cases than did the BN distribution, indicating overdispersion was present. When overdispersion was not present, the BN distribution was adequate to describe the data, and the use of the BBN distribution was superfluous. It is then shown that the PCNM approach, the BN model with smooth-scale spatial components and the LNB model were able to account for some of the variation as spatial variability, thus reducing the species effect compared with that explained under the standard BN model. The amount of variation among species according to the BN model and the BN model with random blocks was similar. Therefore, it is argued that the novel PCNM approach warrants further testing when exploring the spatial variability in designed experiments in agriculture and using LNB, PCNM and BN with smooth-scale spatial components may provide better predictions of species effects than do other, more conventional, approaches.
Publisher: Springer Science and Business Media LLC
Date: 10-06-2012
Publisher: Public Library of Science (PLoS)
Date: 22-05-2012
Publisher: CSIRO Publishing
Date: 2020
DOI: 10.1071/CP19509
Abstract: Six years of survey data taken from 184 paddocks spanning 14 million ha of land used for crop and pasture production in south-west Western Australia were used to assess weed populations, herbicide resistance, integrated weed management (IWM) actions and herbicide use patterns in a dryland agricultural system. Key findings were that weed density within crops was low, with 72% of cropping paddocks containing fewer than 10 grass weeds/m2 at anthesis. Weed density and herbicide resistance were not correlated, despite the most abundant grass weed species (annual ryegrass, Lolium rigidum Gaudin) testing positive for resistance to at least one herbicide chemistry in 92% of monitored paddocks. A wide range of herbicides were used (369 unique combinations) suggesting that the ersity of herbicide modes of action may be beneficial for reducing further development of herbicide resistance. However, there was a heavy reliance on glyphosate, the most commonly applied active ingredient. Of concern, in respect to the evolution of glyphosate resistant weeds, was that 45% of glyphosate applications to canola were applied as a single active ingredient and area sown to canola in Western Australia expanded from 0.4 to 1.4 million hectares from 2005 to 2015. In order to minimise the weed seed bank within crops, pastures were used infrequently in some regions and in 50% of cases pastures were actively managed to reduce weed seed set, by applying a non-selective herbicide in spring. The use of non-selective herbicides in this manner also kills pasture plants, consequently self-regenerating pastures were sparse and contained few legumes where cropping intensity was high. Overall, the study indicated that land use selection and utilisation of associated weed management actions were being used successfully to control weeds within the survey area. However, to successfully manage herbicide resistant weeds land use has become less erse, with pastures utilised less and crops with efficacious weed control options utilised more. Further consideration needs to be given to the impacts of these changes in land use on other production factors, such as soil nutrient status and plant pathogens to assess sustainability of these weed management practices in a wider context.
Publisher: Wiley
Date: 03-06-2015
DOI: 10.1111/AEC.12274
Publisher: Springer Science and Business Media LLC
Date: 21-03-2019
Publisher: Wiley
Date: 02-06-2019
DOI: 10.1111/AEC.12786
Publisher: JMIR Publications Inc.
Date: 07-07-2023
Abstract: o address the growing prevalence of youth mental health problems in the Netherlands, prevention and early intervention is crucial to minimize in idual, societal, and economic impacts. Indicative prevention aims to target emerging mental health complaints before the onset of a full-blown disorder. By intervening at this early stage, fewer psychosocial and neurobiological consequences occur, and in iduals are more responsive to treatment, resulting in cost-effective outcomes. The Moderated Online Social Therapy (MOST) platform, that was successfully implemented and proven effective in Australia, is a digital peer- and clinically moderated treatment platform designed for young people. The Netherlands is the first country outside Australia to implement this platform, under the name ENgage YOung people earlY (ENYOY) and it has the potential to reduce the likelihood of young people developing serious mental health disorders. he objective of our study was to investigate the long-term outcomes in youngsters using the ENYOY-platform in relation to psychological distress, psychosocial functioning, and positive health parameters, such as quality of life. utch-speaking young people with emerging mental health complaints (N = 131) participated on the ENYOY-platform for six months in a longitudinal within-subjects study. Psychological distress, psychosocial functioning and positive health parameters were assessed at baseline, three-, six-, and 12-months. Repeated Measures Analysis of Variance was conducted and adjusted for age, gender, therapy- and community activity. Reliable Change Index (RCI) and Clinically Significant Index (CSI) were computed to compare baseline measurement with six-month and 12-month measurements. The missing data rate was 22.54% and drop-out rate 37%. total of N = 81youngster completed all measurements. Over time, psychological distress reduced, and psychosocial functioning improved with large effect sizes (both p .001, ηp² =.239 and .318 respectively) independent of age, gender, therapy- and community activity (p .05). Likewise, secondary analyses showed significant effects of time on positive health parameters quality of life, well-being, and meaningfulness (p .05 and ηp² = .062, .140, and .121 respectively). Improvements were found between baseline, 3 and 6 months (p .05) and sustained at 12-months follow-up (p .05). RCI showed improvements in psychological distress for approximately 38% of cases, no change in 55%, and worsening in 6%. For psychosocial functioning, the percentages were 51%, 43%, and 6% respectively. CSI demonstrated clinically significant change in 76% of cases for distress and 90% for functioning. his trial has demonstrated that the ENYOY-platform holds promise as a transdiagnostic intervention for addressing emerging mental health complaints among young people in the Netherlands and has laid the groundwork for further clinical research. Additionally, it would be of great relevance to expand the population on - and service delivery of the platform. rial Register ID NL8966, retrospectively registered. R2-10.1186/s12888-021-03315-x
Publisher: Oxford University Press (OUP)
Date: 18-04-2018
DOI: 10.1093/AOB/MCY050
Publisher: Springer Science and Business Media LLC
Date: 06-08-2011
Publisher: Informa UK Limited
Date: 10-2012
DOI: 10.4161/PSB.21517
Publisher: Wiley
Date: 28-06-2018
DOI: 10.1002/PS.5057
Abstract: Surveillance strategies are often standardized and completed on grid patterns to detect pest incursions quickly however, it may be possible to improve surveillance through more targeted observation that accounts for landscape heterogeneity, dispersal and the habitat requirements of the invading organism. We simulated pest spread at a local scale, using grape phylloxera (Daktulosphaira vitifoliae (Fitch)) as a case study, and assessed the influence of incorporating spatial heterogeneity into surveillance compared with current, standard surveillance strategies. Time to detection and spread within and beyond the vineyard were reduced by conducting surveys that target s ling effort in soil that is highly suitable for the invading pest in comparison with standard surveillance strategies. However, these outcomes were dependent on the virulence level of phylloxera because phylloxera is a complex pest with multiple genotypes that influence spread and detectability. Targeting surveillance strategies based on local-scale spatial heterogeneity can decrease the time to detection without increasing the survey cost, and surveillance that targets highly suitable soil is the most efficient strategy for detecting new incursions. In addition, combining targeted surveillance strategies with buffer zones and hygiene procedures, and updating surveillance strategies as additional species information becomes available, will further decrease the risk of pest spread. © 2018 Society of Chemical Industry.
Publisher: CSIRO Publishing
Date: 2015
DOI: 10.1071/CP14185
Abstract: Crop rotation, in which a legume, pasture, fallow or oilseed ‘break crop’ is grown after a cereal crop to manage soil-borne disease and weeds and, on occasions, to fix nitrogen, is one of the oldest techniques in agriculture. Valuing of crop rotations is complicated because the profitability of particular crop species changes with the prevalence of biotic stresses and varies with seasonal factors such as rainfall. With the Land Use Sequence Optimiser (LUSO) and the Agricultural Production Systems Simulator (APSIM) crop model, we generate an optimum land-use strategy for various biotic stresses and land-use options for a semi-arid grain-growing region in Australia. Over a 10-year time horizon, we compare the performance and variability of an optimal sequence with three sequences recommended by local agronomists. The agronomists recommended strategic sequences to manage weeds and disease and to maximise profit. The optimal crop sequence, with perfect knowledge, selected a mixture of grain legume, oilseed, cereal crops and pastures to manage biotic stresses and generate profit. This sequence precisely timed a period of exploitation, when high-profit crops were repeatedly grown and the biotic stresses increase, with a period of rehabilitation, when low-profit break crops are grown to reduce the biotic stresses. The agronomists’ strategic sequences were either slightly more exploitative, grew more crops and allowed the biotic stresses to increase, or were more conservative and grew fewer profitable crops while managing the biotic stresses. Both strategic approaches were less profitable than the optimal crop sequence. The value of knowledge about a particular stress increases as its rate of accumulation in the farming system increases. With high levels of biotic weed stress, perfect knowledge was worth an additional AU$73 ha–1 year–1. In scenarios with lower levels of biotic weed stress, perfect knowledge was worth just $24 ha–1 year–1. Several measures of risk were defined, but there was no trade-off between profit and risk. Variability at the crop or enterprise scale did not necessarily translate into variability in profit when viewed over 10 years. Tools such as LUSO can help to determine the optimal crop sequence for a given series of enterprise options and a given level of biotic stress and explore the variability and risk associated with different enterprise choices.
Publisher: Wiley
Date: 28-03-2018
DOI: 10.1111/WRE.12304
No related grants have been discovered for Michael Renton.