The Experts below are selected from a list of 279 Experts worldwide ranked by ideXlab platform
Roger M. Gifford - One of the best experts on this subject based on the ideXlab platform.
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Productivity of Trifolium subterraneum and Phalaris aquatica under warmer, high CO2 conditions
New Phytologist, 2001Co-Authors: J. M. Lilley, T. P. Bolger, Roger M. GiffordAbstract:Summary • Despite the importance of grass-legume pastoral ecosystems worldwide, there is little known about the impacts of concurrent increase in temperature and atmospheric CO2 concentration on their productivity. • Pure and mixed swards of subterranean clover (Trifolium subterraneum) and Phalaris (Phalaris aquatica) were established under ambient and warmed (+3.4°C) air temperatures, at ambient and 690 µmol mol−1 CO2 concentrations in field tunnels in temperate south-eastern Australia. • Over one year, elevated CO2 increased clover foliage growth in the monoculture by 19%, and by 31% in the mixture. Warming reduced clover monoculture herbage production at ambient CO2 by 28% and reduced the growth enhancement by elevated CO2 to +8%. Forage growth of Phalaris monoculture was not affected significantly by either factor. Forage growth of the mixture was increased by 34% in response to higher CO2, but unaffected by warming. Elevated CO2 combined with warming increased forage growth of the mixed sward by 23%. • Concurrent rise in atmospheric CO2 concentration and temperature increased productivity of subterranean clover-Phalaris swards. However, longer term effects on species competition and persistence may modify this conclusion.
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Nutritive value and the nitrogen dynamics of Trifolium subterraneum and Phalaris aquatica under warmer, high CO2 conditions
New Phytologist, 2001Co-Authors: J. M. Lilley, T. P. Bolger, M. B. Peoples, Roger M. GiffordAbstract:Summary • Will changes in nutritive values and N-relations offset initial gains in forage productivity under potential climate change observed for grass–legume pastures of south-eastern Australia? • Herbage nutritive value and symbiotic nitrogen fixation were investigated for pure and mixed swards of subterranean clover (Trifolium subterraneum) and Phalaris (Phalaris aquatica) in field tunnels at ambient and 690 µmol mol−1 CO2 concentrations and at ambient and warmed (+3.4°C) air temperatures. • Elevated CO2 increased the nonstructural carbohydrate content of herbage whereas warming tended to decrease it. These effects were mainly on soluble carbohydrates in Phalaris and starch in clover herbage. The N concentration of both species was decreased by elevated CO2 but unaffected by warming. The proportion of clover-N derived from N2 fixation was increased by 12% under elevated CO2 but decreased by 6% under warming. • Concurrent warming and high-CO2 conditions are expected to lead to improved herbage nutritive value for ruminants due to increased nonstructural soluble carbohydrate content. Longer term effects on nutritive value and N-dynamics via species persistence and competition require further study.
J. M. Lilley - One of the best experts on this subject based on the ideXlab platform.
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Productivity of Trifolium subterraneum and Phalaris aquatica under warmer, high CO2 conditions
New Phytologist, 2001Co-Authors: J. M. Lilley, T. P. Bolger, Roger M. GiffordAbstract:Summary • Despite the importance of grass-legume pastoral ecosystems worldwide, there is little known about the impacts of concurrent increase in temperature and atmospheric CO2 concentration on their productivity. • Pure and mixed swards of subterranean clover (Trifolium subterraneum) and Phalaris (Phalaris aquatica) were established under ambient and warmed (+3.4°C) air temperatures, at ambient and 690 µmol mol−1 CO2 concentrations in field tunnels in temperate south-eastern Australia. • Over one year, elevated CO2 increased clover foliage growth in the monoculture by 19%, and by 31% in the mixture. Warming reduced clover monoculture herbage production at ambient CO2 by 28% and reduced the growth enhancement by elevated CO2 to +8%. Forage growth of Phalaris monoculture was not affected significantly by either factor. Forage growth of the mixture was increased by 34% in response to higher CO2, but unaffected by warming. Elevated CO2 combined with warming increased forage growth of the mixed sward by 23%. • Concurrent rise in atmospheric CO2 concentration and temperature increased productivity of subterranean clover-Phalaris swards. However, longer term effects on species competition and persistence may modify this conclusion.
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Nutritive value and the nitrogen dynamics of Trifolium subterraneum and Phalaris aquatica under warmer, high CO2 conditions
New Phytologist, 2001Co-Authors: J. M. Lilley, T. P. Bolger, M. B. Peoples, Roger M. GiffordAbstract:Summary • Will changes in nutritive values and N-relations offset initial gains in forage productivity under potential climate change observed for grass–legume pastures of south-eastern Australia? • Herbage nutritive value and symbiotic nitrogen fixation were investigated for pure and mixed swards of subterranean clover (Trifolium subterraneum) and Phalaris (Phalaris aquatica) in field tunnels at ambient and 690 µmol mol−1 CO2 concentrations and at ambient and warmed (+3.4°C) air temperatures. • Elevated CO2 increased the nonstructural carbohydrate content of herbage whereas warming tended to decrease it. These effects were mainly on soluble carbohydrates in Phalaris and starch in clover herbage. The N concentration of both species was decreased by elevated CO2 but unaffected by warming. The proportion of clover-N derived from N2 fixation was increased by 12% under elevated CO2 but decreased by 6% under warming. • Concurrent warming and high-CO2 conditions are expected to lead to improved herbage nutritive value for ruminants due to increased nonstructural soluble carbohydrate content. Longer term effects on nutritive value and N-dynamics via species persistence and competition require further study.
R A Culvenor - One of the best experts on this subject based on the ideXlab platform.
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Characterisation of Sardinian germplasm of the perennial pasture grass Phalaris aquatica
Crop and Pasture Science, 2020Co-Authors: R A Culvenor, Stuart Kemp, Kevin F. M. ReedAbstract:Germplasm of the perennial pasture grass Phalaris aquatica L., from Sardinia, Italy, is a potentially valuable source for grass breeders owing to climatic similarities to regions where P. aquatica is used, a relatively high incidence of acidic soils, and exposure to prolonged grazing pressure. At field sites in south-eastern Australia, Sardinian accessions were compared as spaced plants and drill-rows with accessions from southern Europe and north-western Africa and with commercial cultivars. They were also evaluated in grazed swards at three sites over 4 years under conditions that challenge persistence, including heavy grazing pressure, acid soils and drought. Morphologically, the accessions were comparatively dense, fine and short, with similarities to southern European accessions and cultivars of the cv. Australian type. However, they were earlier heading and more summer-dormant, particularly those from southern Sardinia. In drill-rows, Sardinian accessions were later heading and less productive in winter than accessions from Morocco. In swards, Sardinian accessions had lower seedling vigour and winter growth potential than modern winter-active cultivars. However, they were dense and persistent under high grazing pressure, and some accessions survived better than all cultivars on an acid, low-fertility soil. Developing cultivars that are superior to the cv. Australian type with acceptable seed production and alkaloid levels presents a challenge to breeders. However Sardinian germplasm offers a range of maturity times combined with higher levels of summer dormancy and a grazing-tolerant morphology, attributes that may expand the area of adaptation of the species into the hotter and more drought-prone margin.
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Generation and Characterisation of a Reference Transcriptome for Phalaris (Phalaris aquatica L.)
Agronomy, 2017Co-Authors: Rebecca C. Baillie, R A Culvenor, Michelle C. Drayton, Luke W. Pembleton, Sukhjiwan Kaur, Kevin F. Smith, German Spangenberg, John W. Forster, Noel O. I. CoganAbstract:Phalaris aquatica is a cool-season perennial grass species that is extensively cultivated in Australia, with additional usage in other areas of the world. Phalaris displays a number of desirable agronomic characteristics, although unfavourable traits include excessive seed shattering, sensitivity to aluminium toxicity, and several toxicosis syndromes. Varietal development has to date been based on traditional selection methods, but would benefit from the application of genomics-based approaches, which require the development of large-scale sequence resources. Due to a large nuclear DNA content, methods that target the expressed component of the genome and reduce the complexity of analysis are most amenable to current sequencing technologies. A reference unigene set has been developed by transcriptome sequencing of multiple tissues from a single plant belonging to the variety Landmaster. Comparisons have been made to gene complements from related species, as well as reference protein databases, and patterns of gene expression in different tissues have been evaluated. A number of candidate genes relevant to removal of undesirable attributes have been identified. The reference unigene set will provide the basis for detailed studies of differential gene expression and identification of candidate genes for potential transgenic deployment, as well as a critical resource for genotypic analysis to support future genomics-assisted breeding activities for Phalaris improvement.
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Persistence and productivity of Phalaris (Phalaris aquatica) germplasm in dry marginal rainfall environments of south-eastern Australia
Crop and Pasture Science, 2017Co-Authors: R A Culvenor, Mark Norton, J. De FaveriAbstract:Perennial grasses have production and environmental benefits in areas of southern Australia typified by the mixed farming zone of southern New South Wales (NSW). The perennial grass Phalaris (Phalaris aquatica L.) is widely used in southern Australia; however, it would find more use in the mixed farming zone if its persistence in marginal rainfall areas (450–500 mm average annual rainfall) were improved. We evaluated a range of germplasm (n = 29) including wild accessions, lines bred from these, and existing cultivars for persistence and production at three sites in a summer-dry area of southern NSW with 430–460-mm average annual rainfall. Two sites were used over 4 years and the third site over 5 years. Summer dormancy, maturity time and seedling growth were also assessed. Analysis of genotype × environment interaction employing factor analytic models and accounting for spatial and temporal correlations indicated that changes in persistence occurred mainly over time rather than between sites. Ranking changes occurred in the dry establishment phase of the experiment and during a severe final summer drought, with few changes occurring in the intervening high-rainfall years. Lines that survived the establishment phase best had vigorous seedlings and earlier maturity, whereas those surviving the final summer best were earlier maturing and higher in summer dormancy with high winter-growth activity. Some later maturing lines within the higher summer dormancy group were less persistent. Some accessions from North Africa were the most persistent; also, populations bred from these and other more persistent accessions generally persisted and produced better than cultivars used presently. However, present cultivars were capable of high yield in the higher rainfall years. We suggest that persistence of higher summer dormancy cultivars over very dry years could be improved by selecting for earlier maturity time.
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Response to selection for grazing tolerance in winter-active populations of Phalaris (Phalaris aquatica L.). 1. Persistence under grazing in three environments
Crop and Pasture Science, 2009Co-Authors: R A Culvenor, S. P. Boschma, K. F. M. ReedAbstract:Forage grass cultivars must have adequate grazing tolerance for use in the grazing systems for which they are intended. Response to 2 cycles of selection for persistence under heavy grazing pressure was examined in 3 winter-active breeding populations of the productive perennial grass, Phalaris (Phalaris aquatica L.), from 2000 to 2003, at Bulart in western Victoria and Rye Park on the Southern Tablelands and Tamworth on the North-West Slopes of New South Wales. There was one continuously grazed and one rotationally grazed set of plots at Bulart to examine the effect of grazing management. All sites were affected by drought in later years but drought stress was most severe at Tamworth. A strongly positive linear response to selection was observed in an analysis of persistence measured as frequency of Phalaris plant base across the 3 sites (excluding the rotational treatment at Bulart), but response interacted with site. By 2003, linear response averaged 14% frequency units or 34–40% proportional response per cycle at Rye Park and the continuously grazed plots at Bulart, sites that were environmentally suited to survival of Phalaris. In contrast, response to selection was absent or slightly negative at Tamworth where conditions were drier and hotter. Populations responded similarly in analyses across all 3 sites but 1 population was less responsive when analyses were restricted to Bulart and Rye Park. Herbage mass measurements in 2001 at Bulart and 2002 at Rye Park indicated positive responses to selection, which were increasingly linked to frequency over time. Rotationally grazed plots at Bulart displayed higher frequency than continuously grazed plots after 3 years of grazing. The experiment showed that grazing tolerance was a heritable trait in the populations tested when environmental constraints were not limiting and that useful improvements in persistence had been obtained compared with existing cultivars.
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Response to selection for grazing tolerance in winter-active populations of Phalaris (Phalaris aquatica L.). 2. Correlated response in yield potential, plant characteristics, and alkaloid levels
Crop and Pasture Science, 2009Co-Authors: R A Culvenor, S. P. Boschma, K. F. M. ReedAbstract:Phenotypic changes in populations of perennial grasses are known to occur in response to natural or deliberate selection under grazing. These changes may have agronomic significance. Associated changes in morphology and yield potential of young stands in response to 2 cycles of selection for grazing tolerance were examined in 3 winter-active breeding populations of the perennial grass, Phalaris (Phalaris aquatica L.). Levels of alkaloids which potentially could affect palatability were also examined. There was a decline in seedling growth and autumn and winter yield in spaced plants of 6.3–7.5% per cycle pooled across populations. Seedling growth measured in sown swards at 2 sites was not affected by selection. Visually estimated sward yield in the second year, ignoring large gaps, agreed with the spaced plant results but the decline was not significant at P ≤ 0.05 when herbage yield was measured by mowing, probably due to effects of plant density. On balance, it was concluded that a decline in individual plant yield of 6–7% per cycle had occurred but this could be compensated by higher density, particularly over time as differences in persistence under grazing developed. The most pronounced morphological response to selection under grazing was towards a more densely tillered growth habit, although one exception occurred. There was also a tendency towards a more prostrate growth habit and later heading, but this was significant only for the most erect and earliest maturing population. Two cycles of selection did not significantly affect summer activity or area of plant base in any population. Tryptamine alkaloids were below the level likely to affect palatability but tended to increase with selection, particularly in a very low tryptamine base population, which suggested that they may play a role in persistence. Because of potentially deleterious effects on yield, care is required in using this selection method. A balance of yield potential and grazing tolerance appropriate to the management system is needed.
T. P. Bolger - One of the best experts on this subject based on the ideXlab platform.
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Productivity of Trifolium subterraneum and Phalaris aquatica under warmer, high CO2 conditions
New Phytologist, 2001Co-Authors: J. M. Lilley, T. P. Bolger, Roger M. GiffordAbstract:Summary • Despite the importance of grass-legume pastoral ecosystems worldwide, there is little known about the impacts of concurrent increase in temperature and atmospheric CO2 concentration on their productivity. • Pure and mixed swards of subterranean clover (Trifolium subterraneum) and Phalaris (Phalaris aquatica) were established under ambient and warmed (+3.4°C) air temperatures, at ambient and 690 µmol mol−1 CO2 concentrations in field tunnels in temperate south-eastern Australia. • Over one year, elevated CO2 increased clover foliage growth in the monoculture by 19%, and by 31% in the mixture. Warming reduced clover monoculture herbage production at ambient CO2 by 28% and reduced the growth enhancement by elevated CO2 to +8%. Forage growth of Phalaris monoculture was not affected significantly by either factor. Forage growth of the mixture was increased by 34% in response to higher CO2, but unaffected by warming. Elevated CO2 combined with warming increased forage growth of the mixed sward by 23%. • Concurrent rise in atmospheric CO2 concentration and temperature increased productivity of subterranean clover-Phalaris swards. However, longer term effects on species competition and persistence may modify this conclusion.
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Nutritive value and the nitrogen dynamics of Trifolium subterraneum and Phalaris aquatica under warmer, high CO2 conditions
New Phytologist, 2001Co-Authors: J. M. Lilley, T. P. Bolger, M. B. Peoples, Roger M. GiffordAbstract:Summary • Will changes in nutritive values and N-relations offset initial gains in forage productivity under potential climate change observed for grass–legume pastures of south-eastern Australia? • Herbage nutritive value and symbiotic nitrogen fixation were investigated for pure and mixed swards of subterranean clover (Trifolium subterraneum) and Phalaris (Phalaris aquatica) in field tunnels at ambient and 690 µmol mol−1 CO2 concentrations and at ambient and warmed (+3.4°C) air temperatures. • Elevated CO2 increased the nonstructural carbohydrate content of herbage whereas warming tended to decrease it. These effects were mainly on soluble carbohydrates in Phalaris and starch in clover herbage. The N concentration of both species was decreased by elevated CO2 but unaffected by warming. The proportion of clover-N derived from N2 fixation was increased by 12% under elevated CO2 but decreased by 6% under warming. • Concurrent warming and high-CO2 conditions are expected to lead to improved herbage nutritive value for ruminants due to increased nonstructural soluble carbohydrate content. Longer term effects on nutritive value and N-dynamics via species persistence and competition require further study.
M. B. Peoples - One of the best experts on this subject based on the ideXlab platform.
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Nutritive value and the nitrogen dynamics of Trifolium subterraneum and Phalaris aquatica under warmer, high CO2 conditions
New Phytologist, 2001Co-Authors: J. M. Lilley, T. P. Bolger, M. B. Peoples, Roger M. GiffordAbstract:Summary • Will changes in nutritive values and N-relations offset initial gains in forage productivity under potential climate change observed for grass–legume pastures of south-eastern Australia? • Herbage nutritive value and symbiotic nitrogen fixation were investigated for pure and mixed swards of subterranean clover (Trifolium subterraneum) and Phalaris (Phalaris aquatica) in field tunnels at ambient and 690 µmol mol−1 CO2 concentrations and at ambient and warmed (+3.4°C) air temperatures. • Elevated CO2 increased the nonstructural carbohydrate content of herbage whereas warming tended to decrease it. These effects were mainly on soluble carbohydrates in Phalaris and starch in clover herbage. The N concentration of both species was decreased by elevated CO2 but unaffected by warming. The proportion of clover-N derived from N2 fixation was increased by 12% under elevated CO2 but decreased by 6% under warming. • Concurrent warming and high-CO2 conditions are expected to lead to improved herbage nutritive value for ruminants due to increased nonstructural soluble carbohydrate content. Longer term effects on nutritive value and N-dynamics via species persistence and competition require further study.