ORCID Profile
0000-0002-2987-724X
Current Organisation
University of Tasmania
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Publisher: CSIRO Publishing
Date: 05-08-2021
DOI: 10.1071/CP20336
Abstract: The introduction of exotic pasture germplasm has formed the foundation of many Australian grazing systems. Scientists have searched the world for plants to improve the feedbase, amassing collections of erse genetic material, creating genebanks that have made a large contribution to feedbase productivity. These genebanks contain a vast range of legumes, grasses, herbs and shrubs with growth habits ranging from small herbaceous plants to woody trees and life cycles from annuals to short- and long-term perennial plants. They have been collected from cool temperate to tropical climates and arid to high-rainfall zones. Hundreds of cultivars have been developed from material either collected by Australian plant breeders overseas or introduced from overseas genebanks. The collection of this germplasm has enabled plant breeders to extend the area of adaptation of species into climates, soils and systems previously considered marginal. The importance to Australian and world agriculture is increasing as plant breeders seek traits to meet the challenges of a changing climate and animal production systems. Furthermore, urbanisation, landscape degradation and political instability are making it increasingly difficult to collect pasture and forage germplasm from native grasslands in many countries. This emphasises the need to maintain and improve the capacity of the Australian Pastures Genebank (APG). The APG houses ~85 000 accessions and is a modern, online source of ersity for plant scientists around the world. This paper summarises the history of the founding genebank collections, their environment and farming systems focus, and the visionary and resourceful in iduals that built them.
Publisher: CSIRO Publishing
Date: 2012
DOI: 10.1071/WR11032
Abstract: Context Management of grazing wildlife on private land in Tasmania is a contentious issue for landowners, animal-welfare groups and the Tasmanian Government. Wildlife species known to graze pasture include Tasmanian pademelon (Thylogale billardierii), Bennett’s wallaby (Macropus rufogriseus rufogriseus), forester kangaroo (Macropus giganteus), brushtail possum (Trichosurus vulpecula) and fallow deer (Dama dama). Understanding the spatio-temporal patterns of wildlife grazing is important when considering wildlife-control options to mitigate pasture loss however, limited research has been undertaken. Aims To quantify the impact of wildlife grazing on pasture production and to assess the spatial and temporal pasture biomass loss from an established pasture to investigate the effect of protecting pastures from wildlife grazing on species composition of an existing perennial pasture to determine whether wildlife grazing contributes to a decline in the composition of improved pasture species over time and an increase in-ground cover of less desirable grasses and broadleaf weeds and to examine whether protecting pastures from wildlife grazing could increase ground cover. Methods Pasture biomass loss to wildlife grazing was determined by a paired exclusion-cage method over a 26-month period from February 2008 to April 2010. A quantitative pasture model was used to simulate pasture growth at the study site. Changes in the botanical composition of the sward in response to wildlife grazing were determined by hand-separation, drying and weighing of harvested material, and also by visual estimation of the ground cover of in idual plant species. A wildlife faecal-pellet survey was used to develop an index of wildlife feeding activity. Key results Pasture loss to wildlife grazing varied spatially and temporally. Pasture loss decreased with increasing distance from the edge of cover vegetation. The proportion of pasture lost increased during periods of slow pasture growth. Visual estimates of ground cover showed that grazing by wildlife resulted in an increase in bare ground in unprotected swards, whereas protection from grazing resulted in an increase in production of perennial and annual species, as determined by hand-separation of harvested material, and a decrease in bare ground as determined by visual estimate. Faecal-pellet surveys were found to be strongly correlated with pasture biomass losses. Conclusions The proportion of pasture loss to wildlife grazing was found to be influenced by distance from native vegetation and also by pasture availability, which was seasonal. Wildlife can alter the composition of pastures by reducing the ground cover and yield of improved grasses. Continual grazing of pastures by wildlife in addition to rotational sheep grazing may increase the amount of bare ground. Implications Wildlife-control methods need to be carefully chosen if the intended benefits of alleviating pasture biomass losses are to be achieved. Quantifying the loss of pasture is important because it enables the extent and significance of losses to be determined and may inform decisions about the most appropriate wildlife control measures to adopt. Controlling wildlife during periods of slow pasture growth may be important in preventing damage and yield loss of plant species actively growing during these times. Failure to control wildlife may result in a decrease in the composition of desirable plant species.
Publisher: CSIRO Publishing
Date: 07-03-2023
DOI: 10.1071/CP22301
Abstract: Strawberry clover (Trifolium fragiferum L.) is periodically raised as an alternative perennial pasture legume for temperate regions of Australia. Its tolerance of waterlogging is widely known, yet its ability to persist through periods of soil moisture deficit is often understated. Other desirable characteristics include its stoloniferous growth habit and tolerance of mildly saline conditions. Only four strawberry clover cultivars have been registered in Australia, and the most popular, cv. Palestine, is a direct introduction, released in 1938 and first certified in 1951. Furthermore, strawberry clover’s distribution has largely been confined to niche environments, particularly waterlogged and saline areas. This paper reviews the taxonomy and breeding system, morphology, distribution and ecology, and subsequent transfer of strawberry clover to Australia. It reviews and maps the suitability of strawberry clover for perennial pasture systems in the medium–-high rainfall and irrigated temperate zones of Australia, with reference to future climates. The paper also highlights the breeding focus, commercialisation and marketing required to supersede cv. Palestine and lists the germplasm available in the Australian Pastures Genebank, with origins. We conclude that, although strawberry clover is unlikely to become a dominant perennial pasture legume species in Australia, it could be used in a wider range of environments than just those affected by salinity and/or waterlogging stress.
Publisher: CSIRO Publishing
Date: 06-04-2023
DOI: 10.1071/CP22366
Abstract: Context Serradellas (Ornithopus spp.) are promising alternative annual legumes to subterranean clover (Trifolium subterraneum L.), for permanent, temperate pastures. However, many cultivars exhibit unstable flowering dates across years. This is a risk for seed production and persistence. Aim This study assessed how vernalisation and photoperiod cues determine maturity type and flowering date stability among serradella cultivars. Methods First flower appearance was recorded for early and late maturing cultivars of yellow serradella (Ornithopus compressus L.), French serradella (Ornithopus sativus Brot.) and subterranean clover after exposure to six vernalisation treatments (0, 1, 3, 5, 7 or 9 weeks at 5°C) with subsequent growth under four photoperiods (8, 12, 16 or 20 h). Key results ‘Intrinsic earliness’ differed by only zero to three nodes for cultivars within species, indicating that maturity type was determined primarily by a cultivar’s responses to vernalisation and photoperiod. An interaction between these responses was observed, with a precipitous decline in the requirement for vernalisation when photoperiods exceeded 12 h. Many cultivars also displayed a persistent component to their vernalisation response, whereby long photoperiods (20 h) did not completely negate the response to vernalisation. Conclusions Later maturity was associated particularly with need for long exposure to the vernalisation treatment to minimise the duration from sowing to first flower appearance. Stable flowering is more likely when a cultivar has components of its vernalisation requirement that are not satisfied before autumn ends to prevent premature flowering, and a photoperiod response in spring that overrides any unmet vernalisation requirement. Implications Persistence by serradella cultivars requires selection for suitable responsiveness to vernalisation and photoperiod.
Publisher: CSIRO Publishing
Date: 20-02-2023
DOI: 10.1071/CP22299
Abstract: In Australia, 71% of agricultural greenhouse gas (GHG) emissions are enteric methane (CH4), mostly produced by grazing sheep and cattle. Temperate low CH4 yielding legumes and herbs can mitigate enteric CH4 production, but system-level GHG emissions need to be considered. The aims of the study were to: (1) devise a framework to assess GHG reductions when introducing low CH4 yielding species (2) assess mechanisms of CH4 reduction in temperate legume and herb species for Australia (3) use a case study to demonstrate expected changes to system-level GHG emissions with the introduction of low CH4 yielding legumes and (4) identify knowledge gaps and research priorities. Results demonstrate lowering emissions intensity (kg CO2-equivalent/kg product) is crucial to mitigate GHG emissions, but livestock productivity is also important. Several pasture species have anti-methanogenic properties, but responses often vary considerably. Of the species investigated biserrula (Biserrula pelecinus) has great potential to reduce enteric CH4 emissions, but in a case study its emission intensity was similar to subterranean clover (Trifolium subterraneum) but higher than lucerne (Medicago sativa). We conclude that there are temperate legumes and herbs with anti-methanogenic properties, and/or high productivity that could reduce total CH4 emissions and emissions intensity of ruminant livestock production. There is also great ersity in some plant genotypes that can be exploited, and this will be aided by more detailed understanding of plant secondary compounds associated with CH4 reduction. This review suggests an opportunity to formulate pasture species mixtures to achieve reduced CH4 emissions with greater or equal livestock production.
Publisher: CSIRO Publishing
Date: 2019
DOI: 10.1071/CP18573
Abstract: Species composition is limiting production in & % of pastures in Tasmania, Australia—a situation not unique to Tasmania. There are many reasons for degradation and poor persistence of improved pastures, with species selection crucial. Selection currently relies on producers making an assessment based on experience, external advice from agronomists and seed merchants, and experimental trial data. This project sought to assess the benefit of using fine-scale soils data and long-term rainfall data to determine the suitability of pasture species at a farm level across & Mha of agricultural land in Tasmania. Suitability rules were developed for perennial ryegrass (Lolium perenne L.) and lucerne (Medicago sativa L.) involving growth responses to soil characteristics (pH, soil depth, electrical conductivity, drainage, and coarse fragments) and average annual rainfall. Suitability classes were defined as well suited, suitable, moderately suitable, and unsuitable, with additional subclasses to account for soil limitations that could be mitigated through management. Soil grids were generated using digital soil mapping techniques from ~6500 new and existing site data sources spread across Tasmania. Rainfall data from 539 Bureau of Meteorology rainfall-recording sites were modelled using regression kriging interpolation. Soil pH was found to be a major constraint on lucerne, with 61.3% of the land area having a pH & .7. Ameliorating the soil with lime could reduce this constraint to 33.5% of the land area. Drainage was another major constraint on lucerne suitability, with 37.8% of land constrained by imperfectly or poorly drained soils. Improving drainage by installing surface or underground drains could reduce the affected area to 22.1%. The mapping showed that perennial ryegrass was constrained by soil pH, with 38.2% of land having a pH & .5. However, liming could reduce this constraint to just 9.6%. Accurate identification of the likely constraints on pasture production and persistence before sowing and choice of appropriate species and management intervention will result in fewer failed sowings and greater productivity. The feasibility of expanding this approach is being assessed for a larger area of south-eastern Australia and across a wider range of pasture species.
Publisher: CSIRO Publishing
Date: 2019
DOI: 10.1071/CP19063
Abstract: This review examines the prospect of improving perennial legume adaptation to grazed mixed pasture swards across the higher-altitude regions of south-eastern Australia through improved management, particularly as it relates to soil fertility. The range of adapted perennial species available to farmers often remains limited to only one perennial forage legume species, white clover (Trifolium repens L.). Despite recent advances in cultivars for increased persistence in dryland environments, white clover remains sensitive to drought with its inherently shallow root system and limited capacity to restrict water loss from herbage. With few alternative species likely to become widely available in the foreseeable future, prospects for extending the boundaries of perennial legume adaptation likely rely on a dual approach of improving soil fertility and further genetic improvement in white clover. Improved soil fertility would focus on overcoming soil acidity and addressing nutrient deficiencies, particularly of phosphorus, potassium, boron and molybdenum, which tend to be more widespread in the target region. Addressing these soil constraints would alleviate periodic moisture stress by: (1) increased water availability through improved infiltration and soil hydraulic properties (2) increased root growth to maximise exploration of the soil volume and (3) better maintenance of plant cell structures to foster improved osmotic regulation. However, the extent to which white clover adaption may be extended remains an issue of further research. This review highlights an opportunity for further genetic improvement of white clover by focusing on improving the capacity to recover from periodic droughts through seedling regeneration. Further breeding efforts in white clover should examine the feasibility of selecting for hard seed characteristics more similar to the best-adapted subterranean clover (Trifolium subterraneum L.) cultivars across this region to promote ongoing seedling regeneration.
Publisher: MDPI AG
Date: 08-12-2021
Abstract: The formation of aerenchyma in adventitious roots is one of the most crucial adaptive traits for waterlogging tolerance in plants. Pasture grasses, like other crops, can be affected by waterlogging, and there is scope to improve tolerance through breeding. In this study, two summer-active cocksfoot (Dactylis glomerata L.) cultivars, Lazuly and Porto, and two summer-active tall fescue (Lolium arundinaceum Schreb., syn. Festuca arundinacea Schreb.) cultivars, Hummer and Quantum II MaxP, were selected to investigate the effects of waterlogging on root growth and morphological change. Cultivars were subjected to four periods of waterlogging treatments (7, 14, 21 and 28 days), while comparable plants were kept under free drained control conditions. The experiment was arranged as a split–split plot design, with waterlogging treatments (waterlogged, control) considered as main plots, time periods (days of waterlogging) as subplots and cultivars as sub-subplots. Plants began to show signs of waterlogging stress 14–21 days after the onset of waterlogging treatments. There were no significant differences in shoot biomass between the waterlogged and control plants of any cultivar. However, waterlogging significantly reduced root dry matter in all cultivars, with greater reduction in cocksfoot (56%) than in tall fescue (38%). Waterlogging also led to increased adventitious root and aerenchyma formation in both species. Cocksfoot cultivars showed a greater increase in adventitious roots, while tall fescue cultivars had a greater proportion of aerenchyma. Both cultivars within each species showed similar responses to waterlogging treatments. However, an extended screening program is needed to identify whether there are varietal differences within species, which could be used to discover genes related to aerenchyma or adventitious root formation (waterlogging tolerance) for use in breeding programs.
No related grants have been discovered for Rowan Smith.