ORCID Profile
0000-0001-8369-1238
Current Organisations
Universitat Hohenheim
,
University of Queensland
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Research Topics
In Research Link Australia (RLA), "Research Topics" refer to ANZSRC FOR and SEO codes. These topics are either sourced from ANZSRC FOR and SEO codes listed in researchers' related grants or generated by a large language model (LLM) based on their publications.
Top 5 Research Topics
ANZSRC Field of Research (FoR)
Natural Resource Management | Plant Physiology | Plant Biology | Global Change Biology | Ecology | Terrestrial Ecology | Environmental Science and Management | Other Biological Sciences | Food Engineering | Plant Nutrition | Tree Improvement (Selection, Breeding And Genetic Engineering) | Pollution and contamination | Aboriginal and Torres Strait Islander Environmental Knowledge | Anthropology | Applied Economics | Environmental Management | Conservation and Biodiversity | Enzymes | Landscape Ecology | Palaeoecology | Business Information Management (incl. Records, Knowledge and Information Management, and Intelligence) | Engineering Systems Design | Photogrammetry and Remote Sensing | Waste management reduction reuse and recycling | Food packaging preservation and processing | Agricultural Biotechnology not elsewhere classified | Geomatic Engineering | Land And Parks Management | Agricultural Economics | Building Science And Techniques | Gene Expression | Environmental biogeochemistry | Sustainable Agricultural Development | Crop and Pasture Nutrition | Social And Cultural Anthropology
ANZSRC Socio-Economic Objective (SEO)
Native vegetation | Forestry | Field crops | Global climate change adaptation measures | Environmentally Sustainable Plant Production not elsewhere classified | Primary products from plants | Plant Production and Plant Primary Products not elsewhere classified | Economic Growth | Horticultural crops | Land and water management | Horticultural Crops not elsewhere classified | Land and water management | Forestry not elsewhere classified | Flora, Fauna and Biodiversity at Regional or Larger Scales | Aboriginal and Torres Strait Islander development and welfare | Ecosystem Assessment and Management of Farmland, Arable Cropland and Permanent Cropland Environments | Other | Conserving Aboriginal and Torres Strait Islander Heritage | Land and water management | Living resources (flora and fauna) | Management of Solid Waste from Plant Production | Atmospheric composition | Land and water management | Expanding Knowledge in the Environmental Sciences |
Related Links
Publications
Nitrogen relations of natural and disturbed plant communities in tropical Australia
Publisher: Springer Science and Business Media LLC
Date: 17-11-1998
Abstract: Nitrogen relations of natural and disturbed tropical plant communities in northern Australia (Kakadu National Park) were studied. Plant and soil N characteristics suggested that differences in N source utilisation occur at community and species level. Leaf and xylem sap N concentrations of plants in different communities were correlated with the availability of inorganic soil N (NH
Turning the Table: Plants Consume Microbes as a Source of Nutrients
Publisher: Public Library of Science (PLoS)
Date: 30-07-2010
Effect of fire and tree-grass patches on soil nitrogen in Australian tropical savannas
Publisher: Wiley
Date: 06-01-2012
Invasive Andropogon gayanus (Gamba grass) alters litter decomposition and nitrogen fluxes in an Australian tropical savanna
Publisher: Springer Science and Business Media LLC
Date: 15-09-2017
DOI: 10.1038/S41598-017-08893-Z
Abstract: The African grass Andropogon gayanus Kunth. is invading Australian savannas, altering their ecological and biogeochemical function. To assess impacts on nitrogen (N) cycling, we quantified litter decomposition and N dynamics of grass litter in native grass and A . gayanus invaded savanna using destructive in situ grass litter harvests and litterbag incubations (soil surface and aerial position). Only 30% of the A . gayanus in situ litter decomposed, compared to 61% of the native grass litter, due to the former being largely comprised of highly resistant A . gayanus stem. In contrast to the stem, A . gayanus leaf decomposition was approximately 3- and 2 - times higher than the dominant native grass, Alloteropsis semilata at the surface and aerial position, respectively. Lower initial lignin concentrations, and higher consumption by termites, accounted for the greater surface decomposition rate of A . gayanus . N flux estimates suggest the N release of A . gayanus litter is insufficient to compensate for increased N uptake and N loss via fire in invaded plots. Annually burnt invaded savanna may lose up to 8.2% of the upper soil N pool over a decade. Without additional inputs via biological N fixation, A . gayanus invasion is likely to diminish the N capital of Australia’s frequently burnt savannas.
Key innovation or adaptive change? A test of leaf traits using Triodiinae in Australia
Publisher: Springer Science and Business Media LLC
Date: 28-07-2015
DOI: 10.1038/SREP12398
Abstract: The evolution of novel traits (“key innovations”) allows some lineages to move into new environments or adapt to changing climates, whereas other lineages may track suitable habitat or go extinct. We test whether and how, trait shifts are linked to environmental change using Triodiinae, C 4 grasses that form the dominant understory over about 30% of Australia. Using phylogenetic and relaxed molecular clock estimates, we assess the Australian biogeographic origins of Triodiinae and reconstruct the evolution of stomatal and vascular bundle positioning. Triodiinae ersified from the mid-Miocene, coincident with the aridification of Australia. Subsequent niche shifts have been mostly from the Eremaean biome to the savannah, coincident with the expansion of the latter. Biome shifts are correlated with changes in leaf anatomy and radiations within Triodiinae are largely regional. Symplectrodia and Monodia are nested within Triodia . Rather than enabling biome shifts, convergent changes in leaf anatomy have probably occurred after taxa moved into the savannah biome—they are likely to have been subsequent adaptions rather than key innovations. Our study highlights the importance of testing the timing and origin of traits assumed to be phenotypic innovations that enabled ecological shifts.
Water availability – a physiological constraint on nitrate utilization in plants of Australian semi‐arid muiga woodlands
Publisher: Wiley
Date: 10-1996
Natural abundance (δ15N) indicates shifts in nitrogen relations of woody taxa along a savanna–woodland continental rainfall gradient
Publisher: Springer Science and Business Media LLC
Date: 13-12-2014
DOI: 10.1007/S00442-014-3176-3
Abstract: Water and nitrogen (N) interact to influence soil N cycling and plant N acquisition. We studied indices of soil N availability and acquisition by woody plant taxa with distinct nutritional specialisations along a north Australian rainfall gradient from monsoonal savanna (1,600-1,300 mm annual rainfall) to semi-arid woodland (600-250 mm). Aridity resulted in increased 'openness' of N cycling, indicated by increasing δ(15)N(soil) and nitrate:ammonium ratios, as plant communities transitioned from N to water limitation. In this context, we tested the hypothesis that δ(15)N(root) xylem sap provides a more direct measure of plant N acquisition than δ(15)N(foliage). We found highly variable offsets between δ(15)N(foliage) and δ(15)N(root) xylem sap, both between taxa at a single site (1.3-3.4 ‰) and within taxa across sites (0.8-3.4 ‰). As a result, δ(15)N(foliage) overlapped between N-fixing Acacia and non-fixing Eucalyptus/Corymbia and could not be used to reliably identify biological N fixation (BNF). However, Acacia δ(15)N(root) xylem sap indicated a decline in BNF with aridity corroborated by absence of root nodules and increasing xylem sap nitrate concentrations and consistent with shifting resource limitation. Acacia dominance at arid sites may be attributed to flexibility in N acquisition rather than BNF capacity. δ(15)N(root) xylem sap showed no evidence of shifting N acquisition in non-mycorrhizal Hakea/Grevillea and indicated only minor shifts in Eucalyptus/Corymbia consistent with enrichment of δ(15)N(soil) and/or decreasing mycorrhizal colonisation with aridity. We propose that δ(15)N(root) xylem sap is a more direct indicator of N source than δ(15)N(foliage), with calibration required before it could be applied to quantify BNF.
Do cluster roots of Hakea actities (Proteaceae) acquire complex organic nitrogen?
Publisher: Springer Science and Business Media LLC
Date: 2003
Safeguarding human and planetary health demands a fertilizer sector transformation
Publisher: Wiley
Date: 17-02-2020
DOI: 10.1002/PPP3.10098
Effects of externally supplied protein on root morphology and biomass allocation in Arabidopsis.
Publisher: Springer Science and Business Media LLC
Date: 23-05-2014
DOI: 10.1038/SREP05055
Species-site matching in mixed species plantations of native trees in tropical Australia
Publisher: Springer Science and Business Media LLC
Date: 29-06-2012
Effect of woody vegetation clearing on nutrient and carbon relations of semi-arid dystrophic savanna
Publisher: Springer Science and Business Media LLC
Date: 25-11-2009
Carbon sequestration and soil fertility of tropical tree plantations and secondary forest established on degraded land
Publisher: Springer Science and Business Media LLC
Date: 16-05-2012
Responses of communities of soil organisms and plants to soil aging at two contrasting long-term chronosequences
Publisher: Elsevier BV
Date: 03-2017
Subtropical giant podzol chronosequence reveals that soil carbon stabilisation is not governed by litter quality
Publisher: Springer Science and Business Media LLC
Date: 05-04-2015
Effects of commercial microbial biostimulants on soil and root microbial communities and sugarcane yield
Publisher: Springer Science and Business Media LLC
Date: 18-11-2019
Early emergence and resource availability can competitively favour natives over a functionally similar invader
Publisher: Springer Science and Business Media LLC
Date: 24-02-2010
DOI: 10.1007/S00442-010-1583-7
Abstract: Invasive plant species can form dense populations across large tracts of land. Based on these observations of dominance, invaders are often described as competitively superior, despite little direct evidence of competitive interactions with natives. The few studies that have measured competitive interactions have tended to compare an invader to natives that are unlikely to be strong competitors because they are functionally different. In this study, we measured competitive interactions among an invasive grass and two Australian native grasses that are functionally similar and widely distributed. We conducted a pair-wise glasshouse experiment, where we manipulated both biotic factors (timing of establishment, neighbour identity and density) and abiotic factors (nutrients and timing of water supply). We found that the invader significantly suppressed the performance of the natives but its suppression ability was contingent on resource levels, with pulsed water/low nutrients or continuous watering reducing its competitive effects. The native grasses were able to suppress the performance of the invader when given a 3-week head-start, suggesting the invader may be incapable of establishing unless it emerges first, including in its own understorey. These findings provide insight for restoration, as the competitive effect of a functionally similar invader may be reduced by altering abiotic and biotic conditions in favour of natives.
Subantarctic Macquarie Island - A model ecosystem for studying animal-derived nitrogen sources using15N natural abundance
Publisher: Springer Science and Business Media LLC
Date: 17-11-1998
Abstract: Plants collected from erse sites on subantarctic Macquarie Island varied by up to 30‰ in their leaf δ
Metal-binding hydrogel particles alleviate soil toxicity and facilitate healthy plant establishment of the native metallophyte grass Astrebla lappacea in mine waste rock and tailings
Publisher: Elsevier BV
Date: 03-2013
DOI: 10.1016/J.JHAZMAT.2013.01.025
Abstract: Soil contaminants are potentially a major threat to human and ecosystem health and sustainable production of food and energy where mineral processing wastes are discharged into the environment. In extreme conditions, metal concentrations in wastes often exceed even the metal tolerance thresholds of metallophytes (metal-tolerant plants) and sites remain barren with high risks of contaminant leaching and dispersion into the environment via erosion. A novel soil amendment based on micron-size thiol functional cross-linked acrylamide polymer hydrogel particles (X3) binds toxic soluble metals irreversibly and significantly reduces their concentrations in the soil solution to below the phytotoxicity thresholds. X3 mixed into the top 50mm of phytotoxic mine waste materials in pots in glasshouse conditions reduced total soluble concentrations of toxic contaminants by 90.3-98.7% in waste rock, and 88.6-96.4% in tailings immediately after application. After 61 days, quality of unamended bottom layer of X3-treated pots was also significantly improved in both wastes. Combination of X3 and metallophytes was more efficient at improving soil solution quality than X3 alone. Addition of X3 to substrates increased substrate water retention and water availability to plants by up to 108% and 98% for waste rock and tailings respectively. Soil quality improvement by X3 allowed successful early establishment of the native metallophyte grass Astrebla lappacea on both wastes where plants failed to establish otherwise.
Invasive Andropogon gayanus (gamba grass) is an ecosystem transformer of nitrogen relations in Australian savanna
Publisher: Wiley
Date: 09-2009
DOI: 10.1890/08-0265.1
Abstract: Invasion by the African grass Andropogon gayanus is drastically altering the understory structure of oligotrophic savannas in tropical Australia. We compared nitrogen (N) relations and phenology of A. gayanus and native grasses to examine the impact of invasion on N cycling and to determine possible reasons for invasiveness of A. gayanus. Andropogon gayanus produced up to 10 and four times more shoot phytomass and root biomass, with up to seven and 2.5 times greater shoot and root N pools than native grass understory. These pronounced differences in phytomass and N pools between A. gayanus and native grasses were associated with an altered N cycle. Most growth occurs in the wet season when, compared with native grasses, dominance of A. gayanus was associated with significantly lower total soil N pools, lower nitrification rates, up to three times lower soil nitrate availability, and up to three times higher soil ammonium availability. Uptake kinetics for different N sources were studied with excised roots of three grass species ex situ. Excised roots of A. gayanus had an over six times higher-uptake rate of ammonium than roots of native grasses, while native grass Eriachne triseta had a three times higher uptake rate of nitrate than A. gayanus. We hypothesize that A. gayanus stimulates ammonification but inhibits nitrification, as was shown to occur in its native range in Africa, and that this modification of the soil N cycle is linked to the species' preference for ammonium as an N source. This mechanism could result in altered soil N relations and could enhance the competitive superiority and persistence of A. gayanus in Australian savannas.
Yeast as a Biofertilizer Alters Plant Growth and Morphology
Publisher: Wiley
Date: 03-2014
Transporters for uptake and allocation of organic nitrogen compounds in plants
Publisher: Wiley
Date: 18-04-2007
DOI: 10.1016/J.FEBSLET.2007.04.013
Abstract: Nitrogen is an essential macronutrient for plant growth. Following uptake from the soil or assimilation within the plant, organic nitrogen compounds are transported between organelles, from cell to cell and over long distances in support of plant metabolism and development. These translocation processes require the function of integral membrane transporters. The review summarizes our current understanding of the molecular mechanisms of organic nitrogen transport processes, with a focus on amino acid, ureide and peptide transporters.
Development of an environmental functional gene microarray for soil microbial communities
Publisher: American Society for Microbiology
Date: 11-2010
DOI: 10.1128/AEM.03108-09
Abstract: Functional attributes of microbial communities are difficult to study, and most current techniques rely on DNA- and rRNA-based profiling of taxa and genes, including microarrays containing sequences of known microorganisms. To quantify gene expression in environmental s les in a culture-independent manner, we constructed an environmental functional gene microarray (E-FGA) consisting of 13,056 mRNA-enriched anonymous microbial clones from erse microbial communities to profile microbial gene transcripts. A new normalization method using internal spot standards was devised to overcome spotting and hybridization bias, enabling direct comparisons of microarrays. To evaluate potential applications of this metatranscriptomic approach for studying microbes in environmental s les, we tested the E-FGA by profiling the microbial activity of agricultural soils with a low or high flux of N 2 O. A total of 109 genes displayed expression that differed significantly between soils with low and high N 2 O emissions. We conclude that mRNA-based approaches such as the one presented here may complement existing techniques for assessing functional attributes of microbial communities.
Identification of drought-response genes and a study of their expression during sucrose accumulation and water deficit in sugarcane culms
Publisher: Springer Science and Business Media LLC
Date: 13-01-2011
Abstract: The ability of sugarcane to accumulate high concentrations of sucrose in its culm requires adaptation to maintain cellular function under the high solute load. We have investigated the expression of 51 genes implicated in abiotic stress to determine their expression in the context of sucrose accumulation by studying mature and immature culm internodes of a high sucrose accumulating sugarcane cultivar. Using a sub-set of eight genes, expression was examined in mature internode tissues of sugarcane cultivars as well as ancestral and more widely related species with a range of sucrose contents. Expression of these genes was also analysed in internode tissue from a high sucrose cultivar undergoing water deficit stress to compare effects of sucrose accumulation and water deficit. A sub-set of stress-related genes that are potentially associated with sucrose accumulation in sugarcane culms was identified through correlation analysis, and these included genes encoding enzymes involved in amino acid metabolism, a sugar transporter and a transcription factor. Subsequent analysis of the expression of these stress-response genes in sugarcane plants that were under water deficit stress revealed a different transcriptional profile to that which correlated with sucrose accumulation. For ex le, genes with homology to late embryogenesis abundant-related proteins and dehydrin were strongly induced under water deficit but this did not correlate with sucrose content. The expression of genes encoding proline biosynthesis was associated with both sucrose accumulation and water deficit, but amino acid analysis indicated that proline was negatively correlated with sucrose concentration, and whilst total amino acid concentrations increased about seven-fold under water deficit, the relatively low concentration of proline suggested that it had no osmoprotectant role in sugarcane culms. The results show that while there was a change in stress-related gene expression associated with sucrose accumulation, different mechanisms are responding to the stress induced by water deficit, because different genes had altered expression under water deficit.
Organic nitrogen improves the water use of tropical tree seedlings cultivated for restoration plantings
Publisher: Wiley
Date: 17-02-2023
DOI: 10.1002/PPP3.10363
Abstract: Restoring degraded tropical lands is important for bio ersity protection and human livelihoods. Newly planted tree seedlings are often challenged by drought brought about by climate change. Here, we explored how nitrogen sources used for plant growth affected the water use of tropical tree seedlings under water limitation. We found that the application of the amino acid arginine reduced water use in the studied seedlings under water limitation, compared with the conventional ammonium nitrate fertiliser. Alternative sources of nitrogen should be considered for tree seedling production in nurseries as this could enhance drought resilience traits and improve the survival of seedlings in restoration plantings. Restoration via tree planting is impacted by climate change‐induced water scarcity. Nitrogen (N) supply modulates the morphology and physiology of plants and impacts water use. We compared the responses of rainforest tree seedlings Acacia mangium and Alphitonia petriei grown with inorganic N (Osmocote™, ammonium nitrate) or organic N (Argrow™, liquid arginine), hypothesising that organic N confers drought resilience by increasing water use efficiency (WUE). Seedlings were grown in a glasshouse for 12 weeks with organic or inorganic N in well‐watered conditions, and then half the seedlings were subjected to water limitation for a further 4 weeks. A. mangium grew equally well on all N sources, but water limitation reduced biomass production. In contrast, N sources but not water regimes influenced biomass production in A. petriei . Under water limitation, arginine‐supplied A. petriei had higher WUE and more depleted leaf δ 13 C than inorganic N‐supplied plants. Our results suggest that organic N in the form of arginine can regulate stomatal conductance in A. petriei to convey drought resilience in seedlings. The generality of these findings should be explored to evaluate if organic N is a feasible source for generating drought‐resilient seedlings for restoration plantings.
Microdialysis in soil environments: Current practice and future perspectives
Publisher: Elsevier BV
Date: 04-2020
Effects of grazing and fire management on rangeland soil and biocrust microbiomes
Publisher: Elsevier BV
Date: 04-2023
Seasonal variation in nitrous oxide and methane emissions from subtropical estuary and coastal mangrove sediments, Australia
Publisher: Wiley
Date: 10-12-2010
DOI: 10.1111/J.1438-8677.2010.00331.X
Abstract: Mangrove sediments can act as sources of the greenhouse trace gases, nitrous oxide (N(2) O) and methane (CH(4) ). Confident reporting of trace gas emissions from mangrove sediments at local levels is important for regional emissions inventories, since small changes in N(2) O and CH(4) fluxes greatly influence greenhouse gas budgets due to their high global warming potentials. It is also important to identify the drivers of trace gas emission, to prioritize management for minimising emissions. We measured N(2) O and CH(4) fluxes and abiotic sediment parameters at midday low tide in winter and summer seasons, at four sites (27°33'S, 152°59'E) ranging from estuary to ocean sub-tropical mangrove sediments, having varied anthropogenic impacts. At all sites, sediment N(2) O and CH(4) emissions were significantly lower during winter (7-26 μg N(2) O m(-2) · h(-1) 47-466 μg CH(4) m(-2) · h(-1)) compared to summer (28-202 μg N(2) Om(-2) · h(-1) 247-1570 μg CH(4) m(-2) · h(-1)). Sediment temperature, ranging from 18 to 33°C, strongly influenced N(2) O and CH(4) emissions. Highest emissions (202 μg N(2) O m(-2) · h(-1), 1570 μg CH(4) m(-2) · h(-1) ) were detected at human-impacted estuary sites, which generally had higher total carbon (<8%) and total nitrogen (<0.4%) in sediments and reduced salinity (<16 dS · m(-1)). Large between-site variation highlights the need for regular monitoring of sub-tropical mangroves to capture short-lived, episodic N(2) O and CH(4) flux events that are affected by sediment biophysico-chemical conditions at site level. This is important, particularly at sites receiving anthropogenic nutrients, and that have variable freshwater inputs and tidal hydrology.
Drying and rewetting effects on organic matter mineralisation of contrasting soils after 36 years of storage
Publisher: Elsevier BV
Date: 05-2019
Effects of nitrogen source and ectomycorrhizal association on growth and δ15N of two subtropical Eucalyptus species from contrasting ecosystems
Publisher: CSIRO Publishing
Date: 2006
DOI: 10.1071/FP05260
Abstract: Ectomycorrhizal (EM) associations facilitate plant nitrogen (N) acquisition, but the contribution of EM associations to tree N nutrition is difficult to ascertain in ecosystems. We studied the abilities of subtropical EM fungi and nutritionally contrasting Eucalyptus species, Eucalyptus grandis W.Hill ex Maiden and Eucalyptus racemosa Cav, to use N sources in axenic and soil cultures, and determined the effect of EM fungi on plant N use and plant 15N natural abundance (δ15N). As measured by seedling growth, both species showed little dependence on EM when growing in the N-rich minerotrophic soil from E. grandis rainforest habitat or in axenic culture with inorganic N sources. Both species were heavily dependent on EM associations when growing in the N-poor, organotrophic soil from the E. racemosa wallum habitat or in axenic culture with organic N sources. In axenic culture, EM associations enabled both species to use organic N when supplied with amide-, peptide- or protein-N. Grown axenically with glutamine- or protein-N, δ15N of almost all seedlings was lower than source N. The δ15N of all studied organisms was higher than the N source when grown on glutathione. This unexpected 15N enrichment was perhaps due to preferential uptake of an N moiety more 15N-enriched than the bulk molecular average. Grown with ammonium-N, the δ15N of non-EM seedlings was mostly higher than that of source N. In contrast, the δ15N of EM seedlings was mostly lower than that of source N, except at the lowest ammonium concentration. Discrimination against 15N was strongest when external ammonium concentration was high. We suggest that ammonium assimilation via EM fungi may be the cause of the often observed distinct foliar δ15N of EM and non-EM species, rather than use of different N sources by species with different root specialisations. In support of this notion, δ15N of soil and leaves in the rainforest were similar for E. grandis and co-occurring non-mycorrhizal Proteaceae. In contrast, in wallum forest, E. racemosa leaves and roots were strongly 15N-depleted relative to wallum soil and Proteaceae leaves. We conclude that foliar δ15N may be used in conjunction with other ecosystem information as a rapid indicator of plant dependency on EM associations for N acquisition.
A new species of Burkholderia isolated from sugarcane roots promotes plant growth
Publisher: Wiley
Date: 19-12-2014
Improving in situ recovery of soil nitrogen using the microdialysis technique
Publisher: Elsevier BV
Date: 11-2017
Patterns of rain forest plant endemism in subtropical Australia relate to stable mesic refugia and species dispersal limitations
Publisher: Wiley
Date: 11-12-2013
DOI: 10.1111/JBI.12219
Soil carbon turnover and sequestration in native subtropical tree plantations
Publisher: Elsevier BV
Date: 08-2007
A prominent role for precision composting in sustainable agriculture
Publisher: Research Square Platform LLC
Date: 10-08-2021
DOI: 10.21203/RS.3.RS-745873/V1
Abstract: Compost use in agriculture has the potential to increase the productivity and sustainability of food systems and to mitigate climate change. But the use of erse compost types in unsuitable biophysical conditions cause uncertain outcomes for crop yields, soil organic carbon (SOC) and nitrous oxide (N 2 O) emissions. Here, we performed a global meta-analysis with over 2000 observations to determine whether a Precision Composting Strategy (PCS) that aligns suitable composts and application methods with target crop and environment can advance sustainable food production. Eleven key predictors of compost (carbon-to-nutrient ratios, pH, salt content), management (nitrogen supply) and biophysical settings (crop type, soil texture, SOC, pH, temperature, rainfall) determined 80% of the effect on crop yield, SOC, and N 2 O emissions. We estimate that a PCS could increase global cereal production by 354.5 Tg annually, approximately 1.7-times Africa’s current cereal yield. We further estimate that annual Carbon sequestration could increase by 170.4 Tg Carbon, approximately 20% of the global potential of croplands. This points to a central role of PCS in current and emerging agriculture consistent with the United Nations’ Sustainable Development Goals.
Post-anthesis nitrate uptake is critical to yield and grain protein content in Sorghum bicolor
Publisher: Elsevier BV
Date: 09-2017
DOI: 10.1016/J.JPLPH.2017.05.026
Abstract: Crops only use ∼50% of applied nitrogen (N) fertilizer creating N losses and pollution. Plants need to efficiently uptake and utilize N to meet growing global food demands. Here we investigate how the supply and timing of nitrate affects N status and yield in Sorghum bicolor (sorghum). Sorghum was grown in pots with either 10mM (High) or 1mM (Low) nitrate supply. Shortly before anthesis the nitrate supply was either maintained, increased 10-fold or eliminated. Leaf sheaths of sorghum grown with High nitrate accumulated nitrate in concentrations >3-times higher than leaves. Removal of nitrate supply pre-anthesis resulted in the rapid reduction of stored nitrate in all organs. Plants receiving a 10-fold increase in nitrate supply pre-anthesis achieved similar grain yield and protein content and 29% larger grains than those maintained on High nitrate, despite receiving 24% less nitrate over the whole growth period. In sorghum, plant available N is important throughout development, particularly anthesis and grain filling, for grain yield and grain protein content. Nitrate accumulation in leaf sheaths presents opportunities for the genetic analysis of mechanisms behind nitrate storage and remobilization in sorghum to improve N use efficiency.
Atmospheric concentrations of ammonia and nitrogen dioxide at a tropical coral cay with high seabird density
Publisher: Royal Society of Chemistry (RSC)
Date: 2010
DOI: 10.1039/B910922F
Abstract: Ecosystems with high seabird densities can receive extremely high inputs of nitrogen (N) from bird guano. Seabirds deposit up to 1000 kg N ha(-1) y(-1) on Heron Island, a tropical coral cay of the Great Barrier Reef. We quantified atmospheric concentrations of ammonia (NH(3)) and nitrogen dioxide (NO(2)) with passive air s lers at beach, woodland and forest along a gradient of low, intermediate and high bird densities, respectively. NO(2) concentrations at all studied sites were generally low (average 0.2-2.3 microg NO(2) m(-3)) and similar to other ecosystems. An exception was the main traffic zone of helicopter and barge traffic which had elevated concentrations (average 6.2, maximum 25 microg NO(2) m(-3)) comparable to traffic-intense urban areas elsewhere. Increasing average NH(3) concentrations from 0.7 to 17 microg NH(3) m(-3) was associated with greater seabird nesting density. In areas of intermediate and high bird density, NH(3) concentrations were substantially higher than those typically detected in natural and agricultural systems, supporting the notion that seabird guano is a major source of NH(3). The steep decline of NH(3) concentrations in areas with low bird density indicates that trans-island transport of NH(3) is low. NH(3) may not only be re-deposited in close vicinity of the source but is also transported vertically as concentrations above the tree canopy averaged 7.5 microg NH(3) m(-3). How much guano-derived NH(3) contributes to reefal waters via the possible transfer path water --> land --> water remains to be established. We discuss atmospheric concentrations of NH(3) and NO(2) in context of N-based gaseous pollutants and effects on vegetation.
The effect of heterogeneous soil bulk density on root growth of field-grown mangrove species
Publisher: Springer Science and Business Media LLC
Date: 20-08-2018
Descriptive Table of Contents
Publisher: CSIRO Publishing
Date: 2004
DOI: 10.1071/FPV31N5TOC
Reclaiming Degraded Rainforest: A Spatial Evaluation of Gains and Losses in Subtropical Eastern Australia to Inform Future Investment in Restoration
Publisher: Wiley
Date: 27-09-2012
The effect of protein supplied in the growth medium on plant pathogen resistance.
Publisher: Informa UK Limited
Date: 03-10-2014
A comparative study on student perceptions of their learning outcomes in undergraduate science degree programmes with differing curriculum models
Publisher: Informa UK Limited
Date: 24-03-2017
Complementary resource use by tree species in a rain forest tree plantation
Publisher: Wiley
Date: 07-2010
DOI: 10.1890/09-1180.1
Abstract: Mixed-species tree plantations, composed of high-value native rain forest timbers, are potential forestry systems for the subtropics and tropics that can provide ecological and production benefits. Choices of rain forest tree species for mixtures are generally based on the concept that assemblages of fast-growing and light-demanding species are less productive than assemblages of species with different shade tolerances. We examined the hypothesis that mixtures of two fast-growing species compete for resources, while mixtures of shade-tolerant and shade-intolerant species are complementary. Ecophysiological characteristics of young trees were determined and analyzed with a physiology-based canopy model (MAESTRA) to test species interactions. Contrary to predictions, there was evidence for complementary interactions between two fast-growing species with respect to nutrient uptake, nutrient use efficiency, and nutrient cycling. Fast-growing Elaeocarpus angustifolius had maximum demand for soil nutrients in summer, the most efficient internal recycling of N, and low P use efficiency at the leaf and whole-plant level and produced a large amount of nutrient-rich litter. In contrast, fast-growing Grevillea robusta had maximum demand for soil nutrients in spring and highest leaf nutrient use efficiency for N and P and produced low-nutrient litter. Thus, mixtures of fast-growing G. robusta and E. angustifolius or G. robusta and slow-growing, shade-tolerant Castanospermum australe may have similar or even greater productivity than monocultures, as light requirement is just one of several factors affecting performance of mixed-species plantations. We conclude that the knowledge gained here will be useful for designing large-scale experimental mixtures and commercial forestry systems in subtropical Australia and elsewhere.
Microdialysis as an in situ technique for sampling soil enzymes
Publisher: Elsevier BV
Date: 08-2019
The core root microbiome of sugarcanes cultivated under varying nitrogen fertilizer application
Publisher: Wiley
Date: 30-07-2016
Abstract: Diazotrophic bacteria potentially supply substantial amounts of biologically fixed nitrogen to crops, but their occurrence may be suppressed by high nitrogen fertilizer application. Here, we explored the impact of high nitrogen fertilizer rates on the presence of diazotrophs in field-grown sugarcane with industry-standard or reduced nitrogen fertilizer application. Despite large differences in soil microbial communities between test sites, a core sugarcane root microbiome was identified. The sugarcane root-enriched core taxa overlap with those of Arabidopsis thaliana raising the possibility that certain bacterial families have had long association with plants. Reduced nitrogen fertilizer application had remarkably little effect on the core root microbiome and did not increase the relative abundance of root-associated diazotrophs or nif gene counts. Correspondingly, low nitrogen fertilizer crops had lower biomass and nitrogen content, reflecting a lack of major input of biologically fixed nitrogen, indicating that manipulating nitrogen fertilizer rates does not improve sugarcane yields by enriching diazotrophic populations under the test conditions. Standard nitrogen fertilizer crops had improved biomass and nitrogen content, and corresponding soils had higher abundances of nitrification and denitrification genes. These findings highlight that achieving a balance in maximizing crop yields and minimizing nutrient pollution associated with nitrogen fertilizer application requires understanding of how microbial communities respond to fertilizer use.
Dominance of legume trees alters nutrient relations in mixed species forest restoration plantings within seven years
Publisher: Springer Science and Business Media LLC
Date: 03-2008
A meta-analytical global comparison of aboveground biomass accumulation between tropical secondary forests and monoculture plantations
Publisher: Elsevier BV
Date: 03-2013
Nitrogen partitioning in orchard-grown Macadamia integrifolia
Publisher: Oxford University Press (OUP)
Date: 11-12-2009
Abstract: Nut yield is highly variable in commercial macadamia production, and to ensure that nitrogen (N) supply does not limit yield, high rates of N fertilizer are generally applied. To elucidate N source and sink relations in mature Macadamia integrifolia Maiden et Betche trees, we traced (15)N label after injection into in idual branches and, after soil application, analysed xylem sap and examined the effects of hedging on tree N relations. Xylem sap N and sugar composition and concentration changed in relation to phenology and tree management. Canopy position did not affect xylem sap N concentration but s ling date had a significant effect. Hedging in spring was associated with a rapid and dramatic reduction of the concentration of xylem sap N until the following autumn, but unhedged trees were not available to unequivocally assess the significance of the results. Following (15)N-branch injection in winter, most (15)N label was incorporated into flushing leaves and into bark. After (15)N injection in spring, flushing leaves and flowers were most strongly (15)N-labelled. In late spring, (15)N label was equally incorporated by developing nuts that were retained or later abscised. Soil (15)N application in summer resulted in (15)N-labelling of outer and mid-canopy leaves. In the following spring, (15)N label was translocated to flushing leaves, flowers and developing nuts. The results indicate that outer and mid-canopy leaves are the main N sink for soil-derived N during the vegetative phase and a N source for developing tissues during the reproductive phase. Our study provides evidence that N supply to developing nuts is not a primary cause for nut abscission, supporting the notion that high N fertilizer application rates do not improve nut retention. We propose that current orchard design and hedging practices should be reviewed in context of the role of outer canopy leaves as a source of N for reproductive tissues.
Editorial: Plant Competition in a Changing World
Publisher: Frontiers Media SA
Date: 26-04-2017
Impacts of the biocontrol agentMalacorhinus irregularis(Coleoptera, Chrysomelidae) onMimosa pigraseedlings and the importance of root nodules
Publisher: Informa UK Limited
Date: 04-2007
Soil microbial responses to labile carbon input differ in adjacent sugarcane and forest soils
Publisher: CSIRO Publishing
Date: 2014
DOI: 10.1071/SR13276
Abstract: Soil microbial activity can be constrained by availability of energy because soil carbon (C) occurs mostly as complex soil organic matter (SOM), with relatively small quantities of high-energy, labile C. Decomposition of SOM is mediated by energy-requiring processes that need extracellular enzymes produced by soil microbial communities. We examined how an increase in energy status via sucrose supplementation affects the production of SOM-degrading enzymes, comparing matched soils under forest and sugarcane agriculture with histories of contrasting inputs of complex and labile C. Activities of SOM-degrading enzymes increased in both soils after sucrose addition, but CO2 production increased more rapidly in the sugarcane soil. The forest soil had greater increases in phosphatase and glucosidase activities, whereas the sugarcane soil had greater increases in protease and urease activity. The contrasting microbial community-level physiological profiles of the soils further erged at 30 and 61 days after sucrose amendment, before returning to near pre-treatment profiles by 150 days. We interpreted the increasing soil enzyme production as indicative that enzyme production was limited by energy availability in both soils, despite contrasting histories of labile v. recalcitrant C supply. Quicker responses in sugarcane soil suggest pre-selection towards populations that exploit labile inputs.
The 15N natural abundance (δ15N) of ecosystem samples reflects measures of water availability
Publisher: CSIRO Publishing
Date: 1999
DOI: 10.1071/PP98146
Abstract: We assembled a globally-derived data set for site-averaged foliar δ15N, the δ15N of whole surface mineral soil and corresponding site factors (mean annual rainfall and temperature, latitude, altitude and soil pH). The δ15N of whole soil was related to all of the site variables (including foliar δ15 N) except altitude and, when regressed on latitude and rainfall, provided the best model of these data, accounting for 49% of the variation in whole soil δ15N. As single linear regressions, site-averaged foliar δ15N was more strongly related to rainfall than was whole soil δ15N. A smaller data set showed similar, negative correlations between whole soil δ15N, site-averaged foliar δ15N and soil moisture variations during a single growing season. The negative correlation between water availability (measured here by rainfall and temperature) and soil or plant δ15N fails at the landscape scale, where wet spots are δ15N-enriched relative to their drier surroundings. Here we present global and seasonal data, postulate a proximate mechanism for the overall relationship between water availability and ecosystem δ15N and, newly, a mechanism accounting for the highly δ15N-depleted values found in the foliage and soils of many wet/cold ecosystems. These hypotheses are complemented by documentation of the present gaps in knowledge, suggesting lines of research which will provide new insights into terrestrial N-cycling. Our conclusions are consistent with those of Austin and Vitousek (1998) that foliar (and soil) δ15N appear to be related to the residence time of whole ecosystem N.
Sorbents can tailor nitrogen release from organic wastes to match the uptake capacity of crops
Publisher: Elsevier BV
Date: 12-2018
DOI: 10.1016/J.SCITOTENV.2018.07.135
Abstract: Delivering nutrients from mineral or organic fertilizers out of synchrony with crop uptake causes inefficiencies and pollution. We explore methodologies for evaluating sorbents as additives to organic agricultural wastes to retain nitrogen in an exchangeable form and deliver at rates that approximate the uptake capacity of roots. Focussing on ammonium (NH
Managing nitrogen environmental impacts to improve green technical efficiency in Philippines rice cultivation
Publisher: Elsevier BV
Date: 2023
DOI: 10.1016/J.JENVMAN.2022.116529
Abstract: The efficient use of nitrogen fertilisers is a global priority to optimise the economic and environmental outcomes of farming. This paper is the first to consider pollution in the form of nitrous oxide emissions and excess nitrogen to analyse technical efficiency (TE) in farming. This is done by extending the two-stage double bootstrap Data Envelopment Analysis to explicitly model nitrogen pollutants as undesirable outputs. We compared green TE (when undesirable pollutants are considered) and conventional TE (without pollutants) using a case study of 33 rice-producing provinces in the Philippines. Provinces in Mindanao, Luzon, and Visayas islands experienced improvements in green TE but stagnant conventional TE from 2006 to 2017. Although transplanting rice seedlings (rather than direct sowing of seeds) improved both green and conventional TE, seed quality was also identified as an important factor for green TE but not for conventional TE. Our analysis has implications for sustainable rice production and such analysis can be extended to other crops. To advance the effective green transformation of rice production, future research should analyse farm-level data to understand farmers' decisions regarding seed quality, crop establishment method and nitrogen fertiliser application to devise comprehensive farm integrated management plans.
Realising the Circular Phosphorus Economy delivers for Sustainable Development Goals
Publisher: Wiley
Date: 18-03-2022
Foreword to 'Plant and Ecosystem Physiology: Research and Methodology'
Publisher: CSIRO Publishing
Date: 2006
DOI: 10.1071/FPV33N5_FO
Nitrogen use strategies of neotropical rainforest trees in threatened Atlantic Forest
Publisher: Wiley
Date: 03-2003
Amino acid transporter mutants of Arabidopsis provides evidence that a non‐mycorrhizal plant acquires organic nitrogen from agricultural soil
Publisher: Wiley
Date: 11-02-2017
DOI: 10.1111/PCE.12881
Abstract: Although organic nitrogen (N) compounds are ubiquitous in soil solutions, their potential role in plant N nutrition has been questioned. We performed a range of experiments on Arabidopsis thaliana genetically modified to enhance or reduce root uptake of amino acids. Plants lacking expression of the Lysine Histidine Transporter 1 (LHT1) displayed significantly lower contents of
Growth of subtropical ECM fungi with different nitrogen sources using a new floating culture technique
Publisher: Elsevier BV
Date: 2002
Introducing BASE: The Biomes of Australian Soil Environments soil microbial diversity database
Publisher: Oxford University Press (OUP)
Date: 28-09-2021
Using digital photography to monitor changes in biocrusts and ground cover in a savanna rangeland
Publisher: CSIRO Publishing
Date: 09-03-2023
DOI: 10.1071/RJ22019
Abstract: Biocrusts form a living soil cover in Australia’s northern savannas, delivering essential ecosystem services. More accessible tools are needed to quantify and monitor ground cover, including biocrusts, as current methodologies are time-consuming, expensive, or specialised. At Victoria River Research Station (Northern Territory, Australia), long-term fire research plots were used to monitor the response of low vegetative ground and soil covers for different burning intervals and seasons. Mobile phone photographs were analysed using machine-learning software and a derived decision tree-based segmentation model (DTSM). The resulting data were compared to visual in-field assessment by trained researchers. Visual assessments and photographs were taken at two time points during the post-fire recovery period, mid-wet and dry seasons, at three burning intervals (2, 4, and 6 years) and for two different burning times, early or late dry season. DTSM-derived grass and litter cover were statistically similar to field observations in the burnt and unburnt plots. Biocrust cover derived from DTSM also matched field observations in fire treatments and unburnt control plots in the dry season, except when obscured by grass or litter. In the wet season, DTSM underestimated biocrust cover in some treatments, and DTSM did not detect biocrust obscured under dense grass cover. Nevertheless, biocrust pigment analysis confirmed a significant presence of biocrusts both on seemingly bare soil and under the grass canopy. We concluded that mobile phone photographs are suitable for monitoring dry-season ground cover. When similar colours of grass and litter cover were combined, the modelled accuracy reached 95–97%. With some refinements, DTSM analysis of photographs could accurately quantify the impact of fire disturbance on biocrusts and grass cover. However, it would be advantageous to improve the model by additional field records to determine how much biocrust occurs under the grass. This study provides land managers with an efficient method of recording ground cover over time to aid land-condition assessments.
Rhizophagy—A New Dimension of Plant–Microbe Interactions
Publisher: Wiley
Date: 18-03-2013
Effect of nitrogen fertilizer management and waterlogging on nitrous oxide emission from subtropical sugarcane soils
Publisher: Elsevier BV
Date: 15-03-2010
Macroalgal species richness and assemblage composition of the Great Barrier Reef seabed
Publisher: Inter-Research Science Center
Date: 31-10-2013
DOI: 10.3354/MEPS10366
The OJIP fast fluorescence rise characterizes Graptophyllum species and their stress responses
Publisher: Springer Science and Business Media LLC
Date: 07-08-2007
DOI: 10.1007/S11120-007-9207-8
Abstract: Causes for rarity in plants are poorly understood. Graptophyllum reticulatum is an endangered endemic species, and it has three close relatives with different conservation status: the vulnerable G. ilicifolium, the rare G. excelsum, and the common G. spinigerum. Applied to the chlorophyll a fluorescence transient of leaves, the JIP test provides a Performance Index (PI) which quantifies the main steps in photosystem II (PSII) photochemistry including light energy absorption, excitation energy trapping, and conversion of excitation energy into electron flow. The PI is calculated from three components which depend on the reaction center density, the trapping efficiency, and the electron transport efficiency. PI was measured in the natural habitats of the four species and under artificially imposed environmental stresses in the glasshouse to determine whether conservation status was related to stress resilience. The results showed that soil type is unlikely to restrict the endangered G. reticulatum, vulnerable G. ilicifolium, or rare G. excelsum because PI was similar in plants grown in erse soils in the glasshouse. Photoinhibition is likely to restrict the endangered G. reticulatum to shade habitats because PI was significantly reduced when plants were exposed to more than 15% ambient light in controlled experiments. Water availability may determine the location and distribution of the vulnerable G. ilicifolium and common G. spinigerum because PI was reduced more than 60% when plants were exposed to water stress. While the characteristics of their natural habitats correspond to and explain the physiological responses, there was no obvious relationship between conservation status and environmental resilience. PI can be used to monitor vigor and health of populations of plants in the natural habitat. In cultivation experiments PI responds to key environmental variables that affect the distribution of species with conservation significance.
Metal-binding particles alleviate lead and zinc toxicity during seed germination of metallophyte grass Astrebla lappacea
Publisher: Elsevier BV
Date: 06-2011
DOI: 10.1016/J.JHAZMAT.2011.03.116
Abstract: Combining metal-binding particles and metal-tolerant plants (metallophytes) offers a promising new approach for rehabilitation of heavy metal contaminated sites. Three types of hydrogel metal-binding polymer particles were synthesized and their effects on metal concentrations tested in vitro using metal ion solutions. The most effective of the tested polymers was a micron-sized thiol functional cross-linked acrylamide polymer which reduced the available solution concentrations of Pb(2+) (9.65 mM), Cu(2+) (4mM) and Zn(2+) (10mM) by 86.5%, 75.5% and 63.8%, respectively, and was able to store water up to 608% of its dry mass. This polymer was not toxic to seed germination. In deionised water, it enhanced seed germination, and at otherwise phytotoxic Pb(2+) (9.65 mM) and Zn(2+) (10mM) concentrations, it allowed normal germination and root elongation of the metallophyte grass Astrebla lappacea. We conclude that the polymer has the potential to facilitate restoration of heavy metal contaminated lands by reducing the concentration of metal cations in the soil solution and improving germination rates through reduced toxicity and enhanced plant water relations.
Without management interventions, endemic wet‐sclerophyll forest is transitioning to rainforest in World Heritage listed K’gari (Fraser Island), Australia
Publisher: Wiley
Date: 15-01-2019
DOI: 10.1002/ECE3.4853
Micron-size metal-binding hydrogel particles improve germination and radicle elongation of Australian metallophyte grasses in mine waste rock and tailings
Publisher: Elsevier BV
Date: 03-2013
DOI: 10.1016/J.JHAZMAT.2013.01.049
Abstract: Metal contamination of landscapes as a result of mining and other industrial activities is a pervasive problem worldwide. Metal contaminated soils often lack effective vegetation cover and are prone to contaminant leaching and dispersion through erosion, leading to contamination of the environment. Metal-binding hydrogel particle amendments could ameliorate mine wastes prior to planting and enhance seedling emergence. In this study, micron-size thiol functional cross-linked acrylamide polymer hydrogel particles (X3) were synthesised and tested in laboratory-scale experiments on phytotoxic mine wastes to determine their capacity to: (i) increase substrate water holding capacity (WHC) (ii) reduce metal availability to plants to below the phytotoxicity threshold and (iii) enhance germination characteristics and early radicle development of two Australian metallophyte grasses under limiting and non-limiting water conditions. Addition of X3 to mine wastes significantly increased their WHC and lowered toxic soluble metal concentrations in mine waste leachates. Germination percentages and radicle elongation of both grasses in wastes were significantly increased. Highest germination percentages and greater radicle development recorded in X3 amended wastes under water limited conditions suggests that X3 was able to ameliorate metal toxicity to radicles, and provide moisture, which improved the imbibition and consequent germination of the seeds.
Nitrogen fertilizer dose alters fungal communities in sugarcane soil and rhizosphere
Publisher: Springer Science and Business Media LLC
Date: 02-03-2015
DOI: 10.1038/SREP08678
Abstract: Fungi play important roles as decomposers, plant symbionts and pathogens in soils. The structure of fungal communities in the rhizosphere is the result of complex interactions among selection factors that may favour beneficial or detrimental relationships. Using culture-independent fungal community profiling, we have investigated the effects of nitrogen fertilizer dosage on fungal communities in soil and rhizosphere of field-grown sugarcane. The results show that the concentration of nitrogen fertilizer strongly modifies the composition but not the taxon richness of fungal communities in soil and rhizosphere. Increased nitrogen fertilizer dosage has a potential negative impact on carbon cycling in soil and promotes fungal genera with known pathogenic traits, uncovering a negative effect of intensive fertilization.
Ecosystem Services at the Farm Level—Overview, Synergies, Trade‐Offs, and Stakeholder Analysis
Publisher: Wiley
Date: 27-04-2023
Abstract: The current geological epoch is characterized by anthropogenic activity that greatly impacts on natural ecosystems and their integrity. The complex networks of ecosystem services (ESs) are often ignored because the provision of natural resources, such as food and industrial crops, is mistakenly viewed as an independent process separate from ecosystems and ignoring the impacts on ecosystems. Recently, research has intensified on how to evaluate and manage ES to minimize environmental impacts, but it remains unclear how to balance anthropogenic activity and ecosystem integrity. This paper reviews the main ESs at farm level including provisioning, regulating, habitat, and cultural services. For these ESs, synergies are outlined and evaluated along with the respective practices (e.g., cover‐ and intercropping) and ES suppliers (e.g., pollinators and biocontrol agents). Further, several farm‐level ES trade‐offs are discussed along with a proposal for their evaluation. Finally, a framework for stakeholder approaches specific to farm‐level ES is put forward, along with an outlook on how existing precision agriculture technologies can be adapted for improved assessment of ES bundles. This is believed to provide a useful framework for both decision makers and stakeholders to facilitate the development of more sustainable and resilient farming systems.
Amino acids are a nitrogen source for sugarcane
Publisher: CSIRO Publishing
Date: 2012
DOI: 10.1071/FP12042
Abstract: Organic forms of nitrogen (ON) represent potential N sources for crops and an alternative to inorganic N (IN, ammonium nitrate). Sugarcane soils receive organic harvest residues (~40–100 kg ON ha–1), but it is unknown whether ON is a direct N source for crops. We investigated whether sugarcane can use organic monomers in the form of amino acids and whether the use of amino acids as a N source results in distinct metabolic or morphological change when compared with use of inorganic N (IN). Plantlets cultivated in sterile culture and young plants grown in non-sterile soil culture were supplied with IN, ON (five amino acids present in sugarcane soils), or combined IN and ON. All treatments resulted in similar biomass and N content indicating that sugarcane has a well developed capacity to use ON and confirms findings in other species. ON-supplied plants in axenic culture had increased total branch root length per unit primary root axis which has not been reported previously. In both experimental systems, ON supplied plants had increased asparagine concentrations suggesting altered N metabolism. Root of ON-supplied soil-grown plants had significantly reduced nitrate concentrations. We interpret the shift from nitrate to asparagine as indicative of N form use other than or in addition to nitrate by sugarcane. N metabolite profiling could advance knowledge of crop N sources and this will aid in development of N efficient cropping systems with a reduced N pollution footprint.
Early Response of Soil Properties and Function to Riparian Rainforest Restoration
Publisher: Public Library of Science (PLoS)
Date: 12-08-2014
Arabidopsis and Lobelia anceps access small peptides as a nitrogen source for growth
Publisher: CSIRO Publishing
Date: 2011
DOI: 10.1071/FP11077
Abstract: While importance of amino acids as a nitrogen source for plants is increasingly recognised, other organic N sources including small peptides have received less attention. We assessed the capacity of functionally different species, annual and nonmycorrhizal Arabidopsis thaliana (L.) Heynh. (Brassicaceae) and perennial Lobelia anceps L.f. (C anulaceae), to acquire, metabolise and use small peptides as a N source independent of symbionts. Plants were grown axenically on media supplemented with small peptides (2–4 amino acids), amino acids or inorganic N. In A. thaliana, peptides of up to four amino acid residues sustained growth and supported up to 74% of the maximum biomass accumulation achieved with inorganic N. Peptides also supported growth of L. anceps, but to a lesser extent. Using metabolite analysis, a proportion of the peptides supplied in the medium were detected intact in root and shoot tissue together with their metabolic products. Nitrogen source preferences, growth responses and shoot–root biomass allocation were species-specific and suggest caution in the use of Arabidopsis as the sole plant model. In particular, glycine peptides of increasing length induced effects ranging from complete inhibition to marked stimulation of root growth. This study contributes to emerging evidence that plants can acquire and metabolise organic N beyond amino acids.
Nitrate Paradigm Does Not Hold Up for Sugarcane
Publisher: Public Library of Science (PLoS)
Date: 28-04-2011
Soluble inorganic and organic nitrogen in two Australian soils under sugarcane cultivation
Publisher: Elsevier BV
Date: 07-2012
Impact of point source pollution on nitrogen isotope signatures (δ15N) of vegetation in SE Brazil
Publisher: Springer Science and Business Media LLC
Date: 05-2002
DOI: 10.1007/S00442-002-0906-8
Abstract: This study presents novel evidence that
Spatial and temporal variation of nitrous oxide and methane flux between subtropical mangrove sediments and the atmosphere
Publisher: Elsevier BV
Date: 02-2007
Moving beyond the conceptual: Specificity in regional climate change adaptation actions for biodiversity in South East Queensland, Australia
Publisher: Springer Science and Business Media LLC
Date: 12-12-2014
A precision compost strategy aligning composts and application methods with target crops and growth environments can increase global food production
Publisher: Springer Science and Business Media LLC
Date: 05-09-2022
13C Natural Abundance in Plant Communities Along a Rainfall Gradient: a Biological Integrator of Water Availability
Publisher: CSIRO Publishing
Date: 1995
DOI: 10.1071/PP9950051
Abstract: Carbon isotope natural abundance (δ13C) has been previously used as a powerful tool in the study of water-using processes at the leaf, in idual and within-community levels. We analysed 348 species from 12 plant communities along a 900 km-long rainfall gradient in southern Queensland. Although the range of δ13C values found in a given community was large, variability in the δ13C signature of plants within a community was relatively small given the large numbers of species s led (mean n per site of 29) and the taxonomic ersity in each. The community-averaged δ13C signature ranged from -25.60 in a brigalow (Acacia harpophylla) dominated community in western Queensland to - 31.20 in subtropical rainforest in eastern Queensland. A strong relationship was found between the δ13C value averaged for each site and rainfall within the range 350-1700 mm per annum. Foliar δ13C was also related to the number of rain days per annum and moisture balance (rainfall - evaporation). The strength of these relationships varied only slightly according to the rainfall parameter used, with values for r2 of 0.78, 0.70, 0.70 and 0.74 for the relationship between δ13C and long-term rainfall average, 5-year rainfall average, number of rain days and moisture balance, respectively. Despite considerable taxonomic variability within a given plant community, the averaged δ13C signature for that community gives a strong indication of moisture availability.
Nitrogen ecophysiology of Heron Island, a subtropical coral cay of the Great Barrier Reef, Australia
Publisher: CSIRO Publishing
Date: 2004
DOI: 10.1071/FP04024
Abstract: Coral cays form part of the Australian Great Barrier Reef. Coral cays with high densities of seabirds are areas of extreme nitrogen (N) enrichment with deposition rates of up to 1000 kg N ha–1 y–1. The ways in which N sources are utilised by coral cay plants, N is distributed within the cay, and whether or not seabird-derived N moves from cay to surrounding marine environments were investigated. We used N metabolite analysis, 15N labelling and 15N natural abundance (δ15N) techniques. Deposited guano-derived uric acid is hydrolysed to ammonium (NH4+) and gaseous ammonia (NH3). Ammonium undergoes nitrification, and nitrate (NO3–) and NH4+ were the main forms of soluble N in the soil. Plants from seabird rookeries have a high capacity to take up and assimilate NH4+, are able to metabolise uric acid, but have low rates of NO3– uptake and assimilation. We concluded that NH4+ is the principal source of N for plants growing at seabird rookeries, and that the presence of NH4+ in soil and gaseous NH3 in the atmosphere inhibits assimilation of NO3–, although NO3– is taken up and stored. Seabird guano, Pisonia forest soil and vegetation were similarly enriched in 15N suggesting that the isotopic enrichment of guano (δ15N 9.9‰) carries through the forest ecosystem. Soil and plants from woodland and beach environments had lower δ15N (average 6.5‰) indicating a lower contribution of bird-derived N to the N nutrition of plants at these sites. The aquifer under the cay receives seabird-derived N leached from the cay and has high concentrations of 15N-enriched NO3– (δ15N�7.9‰). Macroalgae from reefs with and without seabirds had similar δ15N values of 2.0–3.9‰ suggesting that reef macroalgae do not utilise 15N-enriched seabird-derived N as a main source of N. At a site beyond the Heron Reef Crest, macroalgae had elevated δ15N of 5.2‰, possibly indicating that there are locations where macroalgae access isotopically enriched aquifer-derived N. Nitrogen relations of Heron Island vegetation are compared with other reef islands and a conceptual model is presented.
The vegetative nitrogen response of sorghum lines containing different alleles for nitrate reductase and glutamate synthase
Publisher: Springer Science and Business Media LLC
Date: 25-10-2017
Waterlogging and fire impacts on nitrogen availability and utilization in a subtropical wet heathland (wallum)
Publisher: Wiley
Date: 10-1997
Easily deconstructed, high aspect ratio cellulose nanofibres from Triodia pungens; An abundant grass of Australia's arid zone
Publisher: Royal Society of Chemistry (RSC)
Date: 2015
DOI: 10.1039/C5RA02936H
Abstract: The production of high aspect ratio cellulose nanofibres without resorting to very harsh mechanical and/or chemical processing steps remains a challenge that hinders progress in the fast-moving nanocellulose field.
First report of Glomerella cingulata (Colletotrichum gloeosporioides) causing anthracnose and tip dieback of Lygodium microphyllum and L. japonicum in Australia
Publisher: Scientific Societies
Date: 09-2008
Abstract: The Old World climbing fern, Lygodium microphyllum (Cav.) R. Br., and Japanese climbing fern, L. japonicum (Thunb.) Sw., are invasive noxious weeds in Florida (1). Exploratory surveys for classical biological control agents of L. microphyllum in the fern's native range of Australia and Asia have focused on aboveground herbivores (1). From February to August 2006, fungi were isolated from symptomatic foliage, including lesions associated with leaf curls caused by the mite Flocarus perrepae Knihinicki & Boczek., obtained from L. microphyllum at sites across southeast Queensland, Australia and from both fern species grown at the CSIRO Long Pocket Laboratories in Brisbane, Australia. Anthracnose symptoms with chlorotic margins, initiating at the tip or base of the in idual pinnules, were observed on fronds. Dieback symptoms affected growing tips, with sunken lesions and a gradual necrotic wilt as far as the next growth junction of pinnae. Sections from diseased margins were surface sterilized, placed onto water agar, and incubated at 23°C with a 16-h photoperiod. Variable colonies of white-to-gray mycelia, felted or tufted with complete margins, grew well on oatmeal agar and potato dextrose agar. Conidia were hyaline to light salmon, aseptate, straight, and cylindrical (10.4 to 18.2 × 2.6 to 5.2 μm), borne in salmon-to-bright orange masses at 25°C, and consistent with previous descriptions of Colletotrichum gloeosporioides (Penz.) Penz. & Sacc. (3), anamorph of Glomerella cingulata (2). Asci that formed after 3 to 4 weeks in culture were eight-spored, clavate to cylindrical (46.8 to 62.4 × 9.1 to 11.7 μm), and thickened at the apex, and ascospores were cylindrical (11.7 to 18.2 × 3.9 to 5.2 μm), slightly curved, unicellular and hyaline, which is consistent with descriptions of G. cingulata (2). No fruiting bodies were observed in planta acervuli, setae, and perethecia were not observed. Identification was further confirmed by molecular analysis using the primer pair ITS1/ITS4 (4) (GenBank Accession No. EU697014), indicating 100% similarity to isolates of G. cingulata. To confirm pathogenicity, Koch's postulates were performed on three plants of L. japonicum and 12 plants of L. microphyllum, with an equal number of controls. Conidial suspensions were made to 1.7 × 10 6 conidia ml –1 . During the experiments in the glasshouse, temperatures ranged from 12.6 to 40°C and relative humidity from 39 to 85%. Tips and fronds were collected after 2 to 8 weeks and isolation and identification performed. G. cingulata was consistently reisolated from diseased tissue. No symptoms appeared on controls and isolations did not yield the pathogen. To our knowledge, this is the first report of G. cingulata infecting L. microphyllum and L. japonicum in Australia. Its potential as a biological control agent in the ferns' introduced range remains to be tested. References: (1) J. A. Goolsby et al. Biol. Control. 28:33, 2003. (2) J. E. M. Mordue. Glomerella cingulata. No. 315 in: CMI Descriptions of Pathogenic Fungi and Bacteria. CAB, Kew, UK, 1971. (3) B. C. Sutton. The Genus Glomerella and its Anamorph Colletotrichum. In: Colletotrichum: Biology, Pathology and Control. J. A. Bailey and M. J. Jeger, eds. CAB International, Wallingford, UK, 1992. (4) T. M. White et al. Amplification and Direct Sequencing of Fungal Ribosomal RNA for Phylogenetics. Page 315 in: PCR Protocols: A Guide to Methods and Applications. M. A. Innis et al., eds. Academic Press, San Diego, 1990.
Indigenous and modern biomaterials derived from Triodia (‘spinifex’) grasslands in Australia
Publisher: CSIRO Publishing
Date: 2012
DOI: 10.1071/BT11285
Abstract: Plant-derived fibres and resins can provide biomaterials with environmental, health and financial benefits. Australian arid zone grasses have not been explored as sources of modern biomaterials including building materials. Triodia grasslands are a dominant vegetation type in the arid and semiarid regions of Australia covering a third of the continent. Of the 69 identified Triodia species, 26 produce resin from specialised cells in the outer leaf epidermis. In Aboriginal culture, Triodia biomass and resin were valued for their usefulness in cladding shelters and as a hafting agent. Since European settlement, Triodia grasslands have been used for cattle grazing and burning is a common occurrence to improve pasture value and prevent large-scale fires. Although Triodia grasslands are relatively stable to fires, more frequent and large-scale fires impact on other fire sensitive woody and herbaceous species associated with Triodia and invasion of exotic weeds resulting in localised changes in vegetation structure and composition. The extent and change occurring in Triodia grasslands as a result of altered land-use practices, fire regimes, and changing climate warrant careful consideration of their future management. Localised harvesting of Triodia grasslands could have environmental benefits and provide much needed biomaterials for desert living. Research is underway to evaluate the material properties of Triodia biomass and resin in the context of Indigenous and western scientific knowledge. Here, we review uses of Triodia and highlight research needs if sustainable harvesting is to be considered.
A quantitative genetics approach to nitrogen use efficiency in sugarcane
Publisher: CSIRO Publishing
Date: 2010
DOI: 10.1071/FP09260
Abstract: The economic and environmental consequences of inefficient use of nitrogen (N) fertiliser in agricultural crops is of concern worldwide, so new crop varieties with improved nitrogen use efficiency (NUE) are sought. Here, we report the first study of mapping quantitative trait loci (QTL) for nitrogen physiology traits in sugarcane. QTL analysis was undertaken for each parent of a segregating bi-parental sugarcane mapping population. We grew 168 progeny under limiting (0.2 mM NH4NO3) and non-limiting (5.0 mM NH4NO3) N supplies in two glasshouse experiments. Significant marker-trait associations (MTA) were detected in each treatment for shoot dry weight, root dry weight, total shoot N, shoot internal NUE (iNUE measured as units shoot dry weight per unit N), leaf protein content and glutamine synthetase (GS) activity. MTA for GS activity did not co-locate with other traits except leaf protein content, indicating that variation in GS activity is not linked to plant size or iNUE during early growth. Under high N, there were no significant MTA for iNUE among markers from the male parent, Q165, an Australian commercial cultivar, but six MTA were found for markers inherited from the female parent, IJ76–514, a Saccharum officinarum ancestral variety. The results indicate that variation for iNUE under high N may be lower in commercial varieties than unimproved genotypes. Further, four MTA were consistent with previous field-based research on sugar and biomass production. Our study provides initial evidence that QTL may be incorporated in sugarcane breeding programs targeting improved NUE.
Diversifying students-as-partners participants and practices
Publisher: McMaster University Library
Date: 07-05-2021
Nitrogen affects cluster root formation and expression of putative peptide transporters
Publisher: Oxford University Press (OUP)
Date: 20-04-2009
DOI: 10.1093/JXB/ERP111
Crosstalk between sugarcane and a plant-growth promoting Burkholderia species
Publisher: Springer Science and Business Media LLC
Date: 21-11-2016
DOI: 10.1038/SREP37389
Abstract: Bacterial species in the plant-beneficial-environmental clade of Burkholderia represent a substantial component of rhizosphere microbes in many plant species. To better understand the molecular mechanisms of the interaction, we combined functional studies with high-resolution dual transcriptome analysis of sugarcane and root-associated diazotrophic Burkholderia strain Q208. We show that Burkholderia Q208 forms a biofilm at the root surface and suppresses the virulence factors that typically trigger immune response in plants. Up-regulation of bd -type cytochromes in Burkholderia Q208 suggests an increased energy production and creates the microaerobic conditions suitable for BNF. In this environment, a series of metabolic pathways are activated in Burkholderia Q208 implicated in oxalotrophy, microaerobic respiration, and formation of PHB granules, enabling energy production under microaerobic conditions. In the plant, genes involved in hypoxia survival are up-regulated and through increased ethylene production, larger aerenchyma is produced in roots which in turn facilitates diffusion of oxygen within the cortex. The detected changes in gene expression, physiology and morphology in the partnership are evidence of a sophisticated interplay between sugarcane and a plant-growth promoting Burkholderia species that advance our understanding of the mutually beneficial processes occurring in the rhizosphere.
Effects of Seabirds on Plant Communities
Publisher: Oxford University Press
Date: 08-09-2011
Impacts of Seabirds on Plant and Soil Properties
Publisher: Oxford University Press
Date: 08-09-2011
Climate and soils together regulate photosynthetic carbon isotope discrimination within C3 plants worldwide
Publisher: Wiley
Date: 09-2018
DOI: 10.1111/GEB.12764
Effects of the growth environment on the yield and material properties of nanocellulose derived from the Australian desert grass Triodia
Publisher: Elsevier BV
Date: 12-2018
Nitrogen and phosphorus additions negatively affect tree species diversity in tropical forest regrowth trajectories
Publisher: Wiley
Date: 07-2010
DOI: 10.1890/09-0636.1
Abstract: Nutrient enrichment is increasingly affecting many tropical ecosystems, but there is no information on how this affects tree bio ersity. To examine dynamics in vegetation structure and tree species biomass and ersity, we annually remeasured tree species before and for six years after repeated additions of nitrogen (N) and phosphorus (P) in permanent plots of abandoned pasture in Amazonia. Nitrogen and, to a lesser extent, phosphorus addition shifted growth among woody species. Nitrogen stimulated growth of two common pioneer tree species and one common tree species adaptable to both high- and low-light environments, while P stimulated growth only of the dominant pioneer tree Rollinia exsucca (Annonaceae). Overall, N or P addition reduced tree assemblage evenness and delayed tree species accrual over time, likely due to competitive monopolization of other resources by the few tree species responding to nutrient enrichment with enhanced establishment and/or growth rates. Absolute tree growth rates were elevated for two years after nutrient addition. However, nutrient-induced shifts in relative tree species growth and reduced assemblage evenness persisted for more than three years after nutrient addition, favoring two nutrient-responsive pioneers and one early-secondary tree species. Surprisingly, N + P effects on tree biomass and species ersity were consistently weaker than N-only and P-only effects, because grass biomass increased dramatically in response to N + P addition. The resulting intensified competition probably prevented an expected positive N + P synergy in the tree assemblage. Thus, N or P enrichment may favor unknown tree functional response types, reduce the ersity of coexisting species, and delay species accrual during structurally and functionally complex tropical rainforest secondary succession.
Assessing the vulnerability of an assemblage of subtropical rainforest vertebrate species to climate change in south-east Queensland
Publisher: Wiley
Date: 20-08-2012
Assessing refrigerating and freezing effects on the biological/chemical composition of two livestock manures
Publisher: Elsevier BV
Date: 12-2014
Carbon storage in a Ferrosol under subtropical rainforest, tree plantations, and pasture is linked to soil aggregation
Publisher: CSIRO Publishing
Date: 2009
DOI: 10.1071/SR08162
Abstract: Soil is a large sink for carbon (C), with the potential to significantly reduce the net increase in atmospheric CO2 concentration. However, we previously showed that subtropical tree plantations store less C into long-term soil pools than rainforest or pasture. To explore reasons for differences in C storage between different land-use systems, we examined the relationships between soil aggregation, iron and aluminium oxide and hydroxide content, and soil organic C (SOC) under exotic C4 pasture (Pennisetum clandestinum), native hoop pine (Araucaria cunninghamii) plantations, and rainforest. We measured SOC concentrations of water-stable and fully dispersed aggregates to assess the location of soil C. Concentrations of dithionite- and oxalate-extractable iron and aluminium were also determined to assess their role in SOC sequestration. Soil under rainforest and pasture contained more C in intra-aggregate particulate organic matter (iPOM, μm) than hoop pine plantations, indicating that in rainforest and pasture, greater stabilisation of SOC occurred via soil aggregation. SOC was not significantly correlated with dithionite- and oxalate-extractable Fe and Al in these systems, indicating that sorption sites of Fe and Al oxides and hydroxides were saturated. We concluded that soil C under rainforest and pasture is stabilised by incorporation within soil aggregates, which results in greater storage of C in soil under pasture than plantations following land-use change. The reduced storage of C as iPOM in plantation soil contributes to the negative soil C budget of plantations compared with rainforest and pasture, even 63 years after establishment. The results have relevance for CO2 mitigation schemes based on tree plantations.
Relationship between microbial composition and substrate use efficiency in a tropical soil
Publisher: Elsevier BV
Date: 04-2018
Nitrogen Deposition Effects on Ecosystem Services and Interactions with other Pollutants and Climate Change
Publisher: Springer Netherlands
Date: 2014
Monitoring plant physiological characteristics to evaluate mine site revegetation: A case study from the wet-dry tropics of northern Australia
Publisher: Springer Science and Business Media LLC
Date: 1999
Short Communication. A robust method for chromosome quantification and ploidy determination in woody species
Publisher: CSIRO Publishing
Date: 2009
DOI: 10.1071/BT09006
Abstract: Accurate determination of ploidy level of putative polyploid plants is essential for tree breeding and other applications. Methods for ploidy determination include quantification of chromosome numbers in root-tip cells via light microscopy and indirect assessment via anatomical and morphological traits. Flow cytometry is potentially a high-throughput method to quantify nuclear DNA content however, it does not allow determining chromosome numbers and interfering compounds often prevent its use. Microscopy-based quantification of chromosomes in active root-tip cells remains the most unambiguous method for ploidy determination, although root tips are difficult to obtain from field-grown plants, and light microscopy can result in insufficient resolution in species with many and small chromosomes. Here, we present a robust technique that uses 2, 4-diamidino-2-phenylindole (DAPI) dye and 1000-fold magnification fluorescence microscopy for quantification of chromosomes in root and shoot tips of woody angiosperms and gymnosperms, and overcomes the reported difficulties. Rather than the conventional tip squashing, spreading tips on glass slides resulted in very good chromosome separation in erse species, with up to 56 chromosomes and a chromosome size of 2–20 μm. Chromosome counts were performed in diploid Agathis robusta, Elaeocarpus angustifolius, Eucalyptus robusta, Paulownia tomentosa, Pongamia pinnata and Toona ciliata, and di- and tetraploid Acacia crassicarpa and Citrus species.
Uptake of non-pathogenicE. coliby Arabidopsis induces down-regulation of heat shock proteins
Publisher: Informa UK Limited
Date: 12-2010
Isolation and analysis of mRNA from environmental microbial communities
Publisher: Elsevier BV
Date: 10-2008
DOI: 10.1016/J.MIMET.2008.05.019
Abstract: The advent of metagenomics has revealed that our planet harbors millions of previously undiscovered microbial species. However, functional insights into the activities of microbial communities cannot easily be obtained using metagenomics. Using transcriptional analyses to study microbial gene functions is currently problematic due to difficulties working with unstable microbial mRNA as a small fraction of total cellular RNA. Current techniques can be expensive and time consuming, and still result in significant levels of rRNA contamination. We have adapted techniques to rapidly isolate high high-quality RNA from environmental s les and developed a simple method for specific isolation of mRNA by size separation. This new technique was evaluated by constructing cDNA libraries directly from uncultured environmental microbial communities, including agricultural soil s les, aquatic flocculants, organic composts, mammalian oral and faecal s les, and wastewater sludge. The sequencing of a fraction of these cDNA clones revealed a high degree of novelty, demonstrating the potential of this approach to capture a large number of unique transcripts directly from the environment. To our knowledge, this is the first study that uses gel electrophoresis to isolate mRNA from microbial communities. We conclude that this method could be used to provide insights into the microbial 'metatranscriptome' of entire microbial communities. Coupled with high-throughput sequencing or the construction of cDNA microarrays, this approach will provide a useful tool to study the transcriptional activities of microorganisms, including those of entire microbial communities and of non-culturable microorganisms.
DNA is taken up by root hairs and pollen, and stimulates root and pollen tube growth
Publisher: Oxford University Press (OUP)
Date: 13-04-2010
Abstract: Phosphorus (P) enters roots as inorganic phosphate (Pi) derived from organic and inorganic P compounds in the soil. Nucleic acids can support plant growth as the sole source of P in axenic culture but are thought to be converted into Pi by plant-derived nucleases and phosphatases prior to uptake. Here, we show that a nuclease-resistant analog of DNA is taken up by plant cells. Fluorescently labeled S-DNA of 25 bp, which is protected against enzymatic breakdown by its phosphorothioate backbone, was taken up and detected in root cells including root hairs and pollen tubes. These results indicate that current views of plant P acquisition may have to be revised to include uptake of DNA into cells. We further show that addition of DNA to Pi-containing growth medium enhanced the growth of lateral roots and root hairs even though plants were P replete and had similar biomass as plants supplied with Pi only. Exogenously supplied DNA increased length growth of pollen tubes, which were studied because they have similar elongated and polarized growth as root hairs. Our results indicate that DNA is not only taken up and used as a P source by plants, but ironically and independent of Pi supply, DNA also induces morphological changes in roots similar to those observed with P limitation. This study provides, to our knowledge, first evidence that exogenous DNA could act nonspecifically as signaling molecules for root development.
DNA uptake by Arabidopsis induces changes in the expression of CLE peptides which control root morphology
Publisher: Informa UK Limited
Date: 09-2010
Physiological profiles of restricted endemic plants and their widespread congenors in the North Queensland wet tropics, Australia
Publisher: Elsevier BV
Date: 05-2003
Optimising methods for the recovery and quantification of di- and tripeptides in soil
Publisher: CSIRO Publishing
Date: 2018
DOI: 10.1071/SR17279
Abstract: Di- and tripeptides are intermediaries in the nitrogen cycle and are likely to have roles in the soil–microbe–plant continuum, but they have hitherto been difficult to measure in soils. To lay the base for future studies of oligopeptides in soil, we added 10 known di- and tripeptides with erse chemical properties to forest and agricultural soils and then recovered the peptides by means of induced diffusive fluxes using microdialysis, a minimally-intrusive soil s ling technique. The concentration of the peptides recovered with the probes was 25–39% (relative recovery) of the concentration in the external solution, and followed the same trend as previously observed for amino acids, with smaller peptides (e.g. Gly-Gly) recovered at a higher rate than larger ones (e.g. Tyr-Phe). After derivatisation with AccQ-Tag™, a standard method for amino acids, peptides were analysed by ultra-high-pressure liquid chromatography-triple quadrupole mass spectrometry. Multiple reaction monitoring mass spectrometry was used to quantify specific peptides with a short run time of 15 min and a detection limit of 0.01–0.02 pmol injected (0.005–0.01 pmol µL–1) for the different peptides. This methodology allowed successful analysis of all standard di- and tripeptides tested here. We conclude that microdialysis in combination with UHPLC-MS will allow measurement of plant-relevant fluxes of di- and tripeptides in undisturbed soil.
Nitrogen fluxes at the root-soil interface show a mismatch of nitrogen fertilizer supply and sugarcane root uptake capacity
Publisher: Springer Science and Business Media LLC
Date: 26-10-2015
DOI: 10.1038/SREP15727
Abstract: Globally only ≈50% of applied nitrogen (N) fertilizer is captured by crops and the remainder can cause pollution via runoff and gaseous emissions. Synchronizing soil N supply and crop demand will address this problem, however current soil analysis methods provide little insight into delivery and acquisition of N forms by roots. We used microdialysis, a novel technique for in situ quantification of soil nutrient fluxes, to measure N fluxes in sugarcane cropping soils receiving different fertilizer regimes and compare these with N uptake capacities of sugarcane roots. We show that in fertilized sugarcane soils, fluxes of inorganic N exceed the uptake capacities of sugarcane roots by several orders of magnitude. Contrary, fluxes of organic N closely matched roots’ uptake capacity. These results indicate root uptake capacity constrains plant acquisition of inorganic N. This mismatch between soil N supply and root N uptake capacity is a likely key driver for low N efficiency in the studied crop system. Our results also suggest that (i) the relative contribution of inorganic N for plant nutrition may be overestimated when relying on soil extracts as indicators for root-available N and (ii) organic N may contribute more to crop N supply than is currently assumed.
Microbial function in adjacent subtropical forest and agricultural soil
Publisher: Elsevier BV
Date: 02-2013
Evolutionary conservation of a core root microbiome across plant phyla along a tropical soil chronosequence
Publisher: Springer Science and Business Media LLC
Date: 09-08-2017
DOI: 10.1038/S41467-017-00262-8
Abstract: Culture-independent molecular surveys of plant root microbiomes indicate that soil type generally has a stronger influence on microbial communities than host phylogeny. However, these studies have mostly focussed on model plants and crops. Here, we examine the root microbiomes of multiple plant phyla including lycopods, ferns, gymnosperms, and angiosperms across a soil chronosequence using 16S rRNA gene licon profiling. We confirm that soil type is the primary determinant of root-associated bacterial community composition, but also observe a significant correlation with plant phylogeny. A total of 47 bacterial genera are associated with roots relative to bulk soil microbial communities, including well-recognized plant-associated genera such as Bradyrhizobium, Rhizobium , and Burkholderia , and major uncharacterized lineages such as WPS-2, Ellin329, and FW68. We suggest that these taxa collectively constitute an evolutionarily conserved core root microbiome at this site. This lends support to the inference that a core root microbiome has evolved with terrestrial plants over their 400 million year history.
Perennial lifestyle--an adaptation to nutrient limitation?
Publisher: Oxford University Press (OUP)
Date: 09-08-2010
Plants can use protein as a nitrogen source without assistance from other organisms
Publisher: Proceedings of the National Academy of Sciences
Date: 18-03-2008
Abstract: Nitrogen is quantitatively the most important nutrient that plants acquire from the soil. It is well established that plant roots take up nitrogen compounds of low molecular mass, including ammonium, nitrate, and amino acids. However, in the soil of natural ecosystems, nitrogen occurs predominantly as proteins. This complex organic form of nitrogen is considered to be not directly available to plants. We examined the long-held view that plants depend on specialized symbioses with fungi (mycorrhizas) to access soil protein and studied the woody heathland plant Hakea actites and the herbaceous model plant Arabidopsis thaliana , which do not form mycorrhizas. We show that both species can use protein as a nitrogen source for growth without assistance from other organisms. We identified two mechanisms by which roots access protein. Roots exude proteolytic enzymes that digest protein at the root surface and possibly in the apoplast of the root cortex. Intact protein also was taken up into root cells most likely via endocytosis. These findings change our view of the spectrum of nitrogen sources that plants can access and challenge the current paradigm that plants rely on microbes and soil fauna for the breakdown of organic matter.
Towards the circular nitrogen economy – A global meta-analysis of composting technologies reveals much potential for mitigating nitrogen losses
Publisher: Elsevier BV
Date: 02-2020
DOI: 10.1016/J.SCITOTENV.2019.135401
Abstract: Composting is an important technology to treat biowastes and recycle nutrients, but incurs nitrogen (N) losses that lower the value of the final products and cause pollution. Technologies aimed at reducing N losses during composting have inconsistent outcomes. To deepen insight into mitigation options, we conducted a global meta-analysis based on 932 observations from 121 peer-reviewed published studies. Overall, N losses averaged 31.4% total N (TN), 17.2% NH
Soil organic carbon recovery in tropical tree plantations may depend on restoration of soil microbial composition and function
Publisher: Elsevier BV
Date: 11-2019
Glycine metabolism by plant roots and its occurrence in Australian plant communities
Publisher: CSIRO Publishing
Date: 1999
DOI: 10.1071/PP98116
Abstract: Soluble organic nitrogen, including protein and amino acids, was found to be a ubiquitous form of soil N in erse Australian environments. Fine roots of species representative of these environments were found to be active in the metabolism of glycine. The ability to incorporate [15N]glycine was widespread among plant species from subantarctic to tropical communities. In species from subantarctic herbfield, subtropical coral cay, subtropical rainforest and wet heathland, [15N]glycine incorporation ranged from 26 to 45 % of 15NH4+ incorporation and was 2- to 3-fold greater than 15NO3- incorporation. Most semiarid mulga and tropical savanna woodland species incorporated [15N]glycine and 15NO3- in similar amounts, 18–26 % of 15NH4+ incorporation. We conclude that the potential to utilise amino acids as N sources is of widespread occurrence in plant communities and is not restricted to those from low temperature regimes or where N mineralisation is limited. Seedlings of Hakea (Proteaceae) were shown to metabolise glycine, with a rapid transfer of 15N from glycine to serine and other amino compounds. The ability to take up and metabolise glycine was unaffected by the presence of equimolar concentrations of NO3- and NH4+. Isonicotinic acid hydrazide (INH) did not inhibit the transfer of 15N- label from glycine to serine indicating that serine hydroxymethyltransferase was not active in glycine catabolism. In contrast aminooxyacetate (AOA) strongly inhibited transfer of 15N from glycine to serine and labelling of other amino compounds, suggesting that glycine is metabolised in roots and cluster roots of Hakea via an aminotransferase.
Nitrogen-fixing legume tree species for the reclamation of severely degraded lands in Brazil
Publisher: Oxford University Press (OUP)
Date: 02-2011
Abstract: The main challenges faced in the reclamation of severely degraded lands are in the management of the systems and finding plant species that will grow under the harsh conditions common in degraded soils. This is especially important in extremely adverse situations found in some substrates from mining activities or soils that have lost their upper horizons. Under these conditions, recolonization of the area by native vegetation through natural succession processes may be extremely limited. Once the main physical and chemical factors restrictive to plant growth are corrected or attenuated, the introduction of leguminous trees able to form symbioses with nodulating N₂-fixing bacteria and arbuscular mycorrhizal fungi constitutes an efficient strategy to accelerate soil reclamation and initiate natural succession. These symbioses give the legume species a superior capacity to grow quickly in poor substrates and to withstand the harsh conditions presented in degraded soils. In this article we describe several successful results in Brazil using N₂-fixing legume tree species for reclamation of areas degraded by soil erosion, construction and mining activities, emphasizing the potential of the technique to recover soil organic matter levels and restore ecosystem bio ersity and other environmental functions.
Tropical Rainforest Restoration Plantations Are Slow to Restore the Soil Biological and Organic Carbon Characteristics of Old Growth Rainforest
Publisher: Springer Science and Business Media LLC
Date: 08-2019
Sugarcane genotypes differ in internal nitrogen use efficiency
Publisher: CSIRO Publishing
Date: 2007
DOI: 10.1071/FP07183
Abstract: The large amounts of nitrogen (N) fertiliser applied to most cropping systems support high yields but cause N pollution. More efficient use of N in cropping systems can be achieved through improved N management practices combined with genetic improvement of the crop. The magnitude of genetic variation in sugarcane (Saccharum officinarum L.) for internal nitrogen use efficiency (iNUE, biomass produced per unit tissue N) was investigated as this could provide a basis for breeding varieties with reduced N demand. Genotypes of a mapping population were examined for biomass production and physiological variables under low or high N supply in controlled conditions. Key findings were: (i) genotypic variation for biomass production and iNUE was up to 3-fold greater under low than high N supply, (ii) elite parent Q165 was among the best performing genotypes for biomass and iNUE at high N but not at low N supply, and (iii) several genotypes had high iNUE at both N supplies. While glutamine synthetase (GS EC 6.3.1.2) activity has been linked with grain yield in other crops, no direct relationship was observed between whole tissue GS activity and vegetative biomass or iNUE in sugarcane genotypes. Soluble protein content was negatively correlated with iNUE and biomass production. This study demonstrates that there is considerable genetic variation for iNUE in sugarcane, which can be exploited for breeding. It is proposed that breeding programs should assess genotypes not only at high N, but also at low N supply rates to select genotypes that produce high biomass with low and high N supply.
The mixotrophic nature of photosynthetic plants
Publisher: CSIRO Publishing
Date: 2013
DOI: 10.1071/FP13061
Abstract: Plants typically have photosynthetically competent green shoots. To complement resources derived from the atmospheric environment, plants also acquire essential elements from soil. Inorganic ions and molecules are generally considered to be the sources of soil-derived nutrients, and plants tested in this respect can grow with only inorganic nutrients and so can live as autotrophs. However, mycorrhizal symbionts are known to access nutrients from organic matter. Furthermore, specialist lineages of terrestrial photosynthetically competent plants are mixotrophic, including species that obtain organic nutrition from animal prey (carnivores), fungal partners (mycoheterotrophs) or plant hosts (hemi-parasites). Although mixotrophy is deemed the exception in terrestrial plants, it is a common mode of nutrition in aquatic algae. There is mounting evidence that non-specialist plants acquire organic compounds as sources of nutrients, taking up and metabolising a range of organic monomers, oligomers, polymers and even microbes as sources of nitrogen and phosphorus. Plasma-membrane located transporter proteins facilitate the uptake of low-molecular mass organic compounds, endo- and phagocytosis may enable the acquisition of larger compounds, although this has not been confirmed. Identifying the mechanisms involved in the acquisition of organic nutrients will provide understanding of the ecological significance of mixotrophy. Here, we discuss mixotrophy in the context of nitrogen and phosphorus nutrition drawing parallels between algae and plants.
Modelling predicts positive and negative interactions between three Australian tropical tree species in monoculture and binary mixture
Publisher: Elsevier BV
Date: 09-2006
Nitrification and denitrification as sources of sediment nitrous oxide production: A microsensor approach
Publisher: Elsevier BV
Date: 05-2008
Past, present and future of organic nutrients
Publisher: Springer Science and Business Media LLC
Date: 20-07-2012
Organic Wastes Amended with Sorbents Reduce N2O Emissions from Sugarcane Cropping
Publisher: MDPI AG
Date: 10-08-2021
DOI: 10.3390/ENVIRONMENTS8080078
Abstract: Nutrient-rich organic wastes and soil ameliorants can benefit crop performance and soil health but can also prevent crop nutrient sufficiency or increase greenhouse gas emissions. We hypothesised that nitrogen (N)-rich agricultural waste (poultry litter) amended with sorbents (bentonite clay or biochar) or compost (high C/N ratio) attenuates the concentration of inorganic nitrogen (N) in soil and reduces emissions of nitrous oxide (N2O). We tested this hypothesis with a field experiment conducted on a commercial sugarcane farm, using in vitro incubations. Treatments received 160 kg N ha−1, either from mineral fertiliser or poultry litter, with additional N (2–60 kg N ha−1) supplied by the sorbents and compost. Crop yield was similar in all N treatments, indicating N sufficiency, with the poultry litter + biochar treatment statistically matching the yield of the no-N control. Confirming our hypothesis, mineral N fertiliser resulted in the highest concentrations of soil inorganic N, followed by poultry litter and the amended poultry formulations. Reflecting the soil inorganic N concentrations, the average N2O emission factors ranked as per the following: mineral fertiliser 8.02% poultry litter 6.77% poultry litter + compost 6.75% poultry litter + bentonite 5.5% poultry litter + biochar 3.4%. All emission factors exceeded the IPCC Tier 1 default for managed soils (1%) and the Australian Government default for sugarcane soil (1.25%). Our findings reinforce concerns that current default emissions factors underestimate N2O emissions. The laboratory incubations broadly matched the field N2O emissions, indicating that in vitro testing is a cost-effective first step to guide the blending of organic wastes in a way that ensures N sufficiency for crops but minimises N losses. We conclude that suitable sorbent-waste formulations that attenuate N release will advance N efficiency and the circular nutrient economy.
15N natural abundance of vascular rainforest epiphytes: implications for nitrogen source and acquisition
Publisher: Wiley
Date: 1995
Adaptations of strangler figs to life in the rainforest canopy
Publisher: CSIRO Publishing
Date: 2006
DOI: 10.1071/FP06014
Abstract: Figs are rainforest keystone species. Non-strangler figs establish on the forest floor strangler figs establish epiphytically, followed by a dramatic transition from epiphyte to free-standing tree that kills its hosts. Free-standing figs display vigorous growth and resource demand suggesting that epiphytic strangler figs require special adaptations to deal with resource limitations imposed by the epiphytic environment. We studied epiphytic and free-standing strangler figs, and non-strangler figs in tropical rainforest and in cultivation, as well as strangler figs in controlled conditions. We investigated whether the transition from epiphyte to free-standing tree is characterised by morphological and physiological plasticity. Epiphyte substrate had higher levels of plant-available ammonium and phosphate, and similar levels of nitrate compared with rainforest soil, suggesting that N and P are initially not limiting resources. A relationship was found between taxonomic groups and plant N physiology strangler figs, all members of subgenus Urostigma, had mostly low foliar nitrate assimilation rates whereas non-strangler figs, in subgenera Pharmacocycea, Sycidium, Sycomorus or Synoecia, had moderate to high rates. Nitrate is an energetically expensive N source, and low nitrate use may be an adaptation of strangler figs for conserving energy during epiphytic growth. Interestingly, significant amounts of nitrate were stored in fleshy taproot tubers of epiphytic stranglers. Supporting the concept of plasticity, leaves of epiphytic Ficus benjamina L. had lower N and C content per unit leaf area, lower stomatal density and 80% greater specific leaf area than leaves of conspecific free-standing trees. Similarly, glasshouse-grown stranglers strongly increased biomass allocation to roots under water limitation. Epiphytic and free-standing F. benjamina had similar average foliar δ13C, but epiphytes had more extreme values this indicates that both groups of plants use the C3 pathway of CO2 fixation but that water availability is highly variable for epiphytes. We hypothesise that epiphytic figs use fleshy stem tubers to avoid water stress, and that nitrate acts as an osmotic compound in tubers. We conclude that strangler figs are a unique experimental system for studying the transition from rainforest epiphyte to tree, and the genetic and environmental triggers involved.
Species turnover of corticolous bryophyte assemblages over 15 years in an Australian subtropical cloud forest
Publisher: Wiley
Date: 19-05-2015
DOI: 10.1111/AEC.12268
Does soil acidity reduce subsoil rooting in norway spruce (picea abies)?
Publisher: Springer Science and Business Media LLC
Date: 2001
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