Drought resistance of native and introduced perennial grasses of south-eastern Australia

2005 ◽  
Vol 56 (11) ◽  
pp. 1261 ◽  
Author(s):  
T. P. Bolger ◽  
A. R. Rivelli ◽  
D. L. Garden

Perennial grasses are the key to the economic and environmental sustainability of pastures for livestock grazing in south-eastern Australia. Mortality of perennial grasses can occur during drought periods and there is anecdotal evidence of differences in drought resistance among species, but information on the basic ecophysiological responses of these species to drought is lacking. An experiment was conducted to determine the responses of 7 native and 3 introduced perennial grass species to continuous drought. Leaf survival during severe drought varied among the species nearly 4-fold, from 11 to 40 days, and was considered a measure of their overall drought resistance. All of the species had good dehydration tolerance, so the differences in drought resistance were related more to their dehydration avoidance traits, specifically to the amount of water available to the plant at the point where plant transpiration became minimal. The native species had both the longest and shortest leaf survival periods, with the introduced species ranking intermediate. Species exhibited various morphological traits that contributed to dehydration avoidance during severe drought, including leaf folding or rolling, rapid leaf shedding, and large amounts of cuticular wax. The results are discussed in terms of their implications for perennial grass persistence in south-eastern and in south-western Australia.


2007 ◽  
Vol 47 (2) ◽  
pp. 136 ◽  
Author(s):  
R. A. Culvenor ◽  
S. P. Boschma ◽  
K. F. M. Reed

Three winter-active populations of phalaris (Phalaris aquatica L.), selected over two generations for improved persistence under grazing, were evaluated with commercial cultivars of phalaris and other temperate perennial grasses from 1999–2003 in three environments of south-eastern Australia as part of a program to develop a cultivar for more sustainable pastures and to assess genotype × environment interaction. Grazed sites were located at Bulart in western Victoria, and Rye Park on the Southern Tablelands and Tamworth on the North West Slopes of New South Wales. At the conclusion of the experiment, the frequency of live plant base was highest at Rye Park despite soil acidity and drought. Significant variance among half-sib families in each population was also observed most frequently at this site. Frequency was intermediate at Bulart but lower than expected considering high soil fertility, probably because of high grazing pressure. Frequency was lowest at Tamworth where severe drought occurred from 2001 onwards. There was significant genotype × environment interaction for frequency among half-sib families. Significant common family variance for frequency across the Bulart and Rye Park sites was demonstrated, but not between Tamworth and either of the other sites in later years. The relationship between winter herbage mass potential and persistence differed with population and site, and was negative for one population at Bulart but positive for another population at Tamworth. Mean persistence of all families was 30% higher than winter-active controls at Rye Park and at least 40% higher at Bulart. Phalaris generally persisted better than cultivars of tall fescue (Festuca arundinacea Schreb.), cocksfoot (Dactylis glomerata L.) and perennial ryegrass (Lolium perenne L.) with some exceptions, particularly at Bulart. Development of a winter-active phalaris cultivar with improved persistence under grazing was considered possible for the Southern Tablelands and western Victorian environments with these populations but a separate program using additional germplasm will be needed for the North West Slopes environment.



2001 ◽  
Vol 52 (3) ◽  
pp. 351 ◽  
Author(s):  
Meredith L. Mitchell ◽  
T. B. Koen ◽  
W. H. Johnston ◽  
D. B. Waterhouse

This paper reports the results of an initial evaluation of a large collection of Australian perennial native grasses. The overall aim of the research was to identify accessions that may be useful for pastoral purposes and for controlling land degradation on hill-lands in the high (>500 mm) rainfall zone of south-eastern Australia. Accessions (807) representing 37 target species were established in spaced plant nurseries at Rutherglen and Wagga Wagga. Dactylis glomerata L. cv. Porto and Eragrostis curvula (Schrad) Nees. Complex cv. Consol were established as comparator (control) species. A range of attributes was observed over a 2-year period (19900—1992), including persistence, vigour, productivity, palatability, morphology, and characteristics related to seed production. Accessions were initially culled on the basis of their persistence. Data for a range of attributes were separately analysed using pattern analysis to provide a broad overview of the performance and characteristics of the remaining accessions. A number of selection criteria were applied which resulted in selection of a promising group of 20 accessions (12 species from 8 genera). The promising group of accessions will be evaluated further at field sites typical of hilly landscapes in the 500mp;mdash;600 mm rainfall zone of south-eastern Australia.



2001 ◽  
Vol 52 (3) ◽  
pp. 329 ◽  
Author(s):  
G. D. Li ◽  
K. R. Helyar ◽  
M. K. Conyers ◽  
B. R. Cullis ◽  
P. D. Cregan ◽  
...  

A long-term trial, known as ‘managing acid soils through efficient rotations’ (MASTER), commenced in 1992 to develop and demonstrate a cropping system that is economically viable on the highly acid soils of the traditional permanent pasture region in south-eastern Australia, so that their fertility is sustained or improved. There were 2 permanent pasture systems and 2 pasture–crop rotations, each with and without lime. This paper reports the effect of lime on crop production over the first cycle (6 years). On annual pasture–crop rotations, lime significantly increased the dry matter production at anthesis and grain yields of wheat (cv. Dollarbird) compared with the unlimed treatments. Averaged across years from 1992 to 1997 (excluding the severe drought year 1994), wheat crops produced 1.6 t/ha more grain on the limed treatments than on the unlimed treatments (3.6 v. 2.0 t/ha). On perennial pasture–crop rotations, the lime effects varied with crops grown at each phase and year. For example, despite being tolerant of acidity, oats (cv. Yarran) responded to lime in 1996. Likewise, triticale (cv. Abacus) responded to lime in 1997. Wheat (cv. Dollarbird) that is moderately tolerant to acidity responded to lime in phase 6 from 1992 to 1997 excluding 1994 (3.5 v. 1.7 t/ha). Acid-tolerant wheat varieties, triticale, and narrow-leaf lupins are considered the most viable crops for the soil and climatic conditions encountered in this high rainfall (5000—800 mm per annum) area of south-eastern Australia.



2007 ◽  
Vol 58 (12) ◽  
pp. 1167 ◽  
Author(s):  
R. J. Eckard ◽  
D. F. Chapman ◽  
R. E. White

Nitrogen (N) fertiliser use on dairy pastures in south-eastern Australia has increased exponentially over the past 15 years. Concurrently, imports of supplementary feed onto dairy farms have increased, adding further nutrients to the system. These trends raise questions about the environmental effects of higher nutrient inputs to dairy farms. To gauge possible effects, annual N balances were calculated from an experiment where N inputs and losses were measured for 3 years from non-irrigated grass/clover pastures receiving either no N fertiliser (Control) or 200 kg N/ha applied annually as ammonium nitrate or urea. Estimated total N inputs, averaged over the 3 years, were 154, 314, and 321 kg N/ha.year for the control, ammonium nitrate, and urea treatments, respectively, while N outputs in meat and milk were 75, 99, and 103 kg N/ha.year, respectively. The corresponding calculated N surplus was 79, 215, and 218 kg N/ha.year for the 3 treatments, respectively, and the ratio of product N/total-N inputs for the 3 treatments ranged from 50% in the control to 32% for both N treatments. Total N losses averaged 56, 102, and 119 kg N/ha.year, leaving a positive N balance of 23, 112, and 99 kg N/ha.year for the control, ammonium nitrate, and urea treatments, respectively. The ratio of product N/total-N inputs or the N surplus may be useful in monitoring the efficiency of conversion of N into animal products and the potential environmental effect at a whole-farm scale. However, additional decision support or modelling tools are required to provide information on specific N losses for a given set of conditions and management inputs. Given the large range in N losses there is opportunity for improving N-use efficiency in dairy pastures through a range of management practices and more tactical use of grain and N fertiliser.



2014 ◽  
Vol 65 (8) ◽  
pp. 767 ◽  
Author(s):  
M. L. Mitchell ◽  
J. M. Virgona ◽  
J. L. Jacobs ◽  
D. R. Kemp

Microlaena (Microlaena stipoides var. stipoides (Labill.) R.Br.) is a C3 perennial grass that is native to areas of south-eastern Australia. In this region, perennial grasses are important for the grazing industries because of their extended growing season and persistence over several years. This series of experiments focused on the population biology of Microlaena by studying the phenology (when seed was set), seed rain (how much seed was produced and where it fell), seed germination, germinable seedbank, seed predation and seedling recruitment in a pasture. Experiments were conducted at Chiltern, in north-eastern Victoria, on an existing native grass pasture dominated by Microlaena. Seed yields were substantial (mean 800 seeds m–2), with seed rain occurring over December–May. Microlaena has two distinct periods of high seed rain, in early summer and in early autumn. Seed predation is high. Within a 24-h period during peak seed production, up to 30% of Microlaena seed was removed from a pasture, primarily by ants. Microlaena seedlings recruited throughout an open paddock; however, seedling density was low (5 seedlings m–2). Microlaena represented only low numbers in the seedbank (0.01–0.05% of total); hence, any seedlings of Microlaena that germinate from the seedbank would face immense competition from other species. Management strategies for Microlaena-dominant pastures need to focus on the maintenance of existing plants.



2001 ◽  
Vol 52 (3) ◽  
pp. 343 ◽  
Author(s):  
W. H. Johnston ◽  
Meredith L. Mitchell ◽  
T. B. Koen ◽  
W. E. Mulham ◽  
D. B. Waterhouse

This paper reports on the collection phase of a research program which aimed to identify Australian native grasses that may be useful for pastoral purposes and for controlling land degradation on hill-lands in the high (>500 mm) rainfall zone of south-eastern Australia. Live plants of 37 target species were collected along a number of transects, and at specific locations, in New South Wales and Victoria. The collection sites were generally along public roads, and were chosen for their vegetation diversity. Each collection site was marked on a 1: 250000 topographic map, and detailed notes were taken of the native vegetation, geology, soil types, land use, and other features. Surface (00—10 cm) soil samples were collected at most sites and analysed for phosphorus, pH CaCl 2 , electrical conductivity, and particle size distribution. A total of 807 accessions were collected from 210 locations. At most collection sites, soils were acidic (median pH 5.6); soil phosphorus (Olsen) was in the low range (<8.5 mg/kg); and the target genera occurred with a low frequency (half of the sites yielded 3 accessions or less). Although genera collected in the study could be ranked on the basis of the mean pH of their collection sites, they all tolerated a considerable soil pH range (of about 2mp;mdash;5 pH units). Allowing root and shoot growth to recommence by growing collected plants for a short period in coarse sand considerably improved establishment success. Accessions collected in this study will be further evaluated.



2012 ◽  
Vol 63 (4) ◽  
pp. 389 ◽  
Author(s):  
R. Thapa ◽  
D. R. Kemp ◽  
M. L. Mitchell

Recruitment of new perennial grass plants within existing grassland ecosystems is determined by seed availability, suitable microsites, nutrients and climatic conditions, water and temperatures. This paper reports on the development of criteria to predict recruitment events using modelled soil moisture conditions associated with recruitment of species in five field experiments at Orange (Phalaris aquatica), Trunkey Creek (Austrodanthonia spp.), and Wellington (Bothriochloa macra) in central New South Wales, Australia, and the frequency of those conditions during the past 30 years. Recruitment events were recorded when a rainfall event (median 68 mm across the three sites) kept the surface volumetric soil moisture (0–50 mm) above the permanent wilting point for at least 15 continuous days, allowing for, at most, two ‘dry days’ in between. A key finding from our study is that rainfall events creating favourable soil moisture conditions for seedling emergence typically occurred in the second half of February, sometimes extending to early March. Previously it was thought that recruitment would more likely occur through autumn, winter, and spring when rainfall in southern Australia is more reliable. The 30 years’ data (1975–2004) showed that the P. aquatica site had a median of 20 continuous moist days each year in February–March, whereas, there were 16 and 10 days for the Austrodanthonia and B. macra sites, respectively. The probabilities of exceeding seven or 15 continuous days of moist surface soil were 98% and 78% at the P. aquatica site, 91% and 49% at the Austrodanthonia site, and 73% and 30% at the B. macra site, and indicated that some recruitment is possible in most years. These analyses were extended to several sites across New South Wales, Victoria, and Tasmania to estimate the frequency with which recruitment could occur within natural swards. Across these sites, the probabilities of exceeding seven continuous days of soil moisture were >55% and of exceeding 15 continuous days were lower, which showed that suitable climatic conditions exist during late summer–early autumn across south-eastern Australia for a recruitment event to occur. Future research may show that the criteria developed in this paper could have wider regional application.



2010 ◽  
Vol 61 (7) ◽  
pp. 554 ◽  
Author(s):  
Guangdi D. Li ◽  
Zhongnan Nie ◽  
Amanda Bonython ◽  
Suzanne P. Boschma ◽  
Richard C. Hayes ◽  
...  

The comparative herbage production and persistence of 7 chicory cultivars and 14 accessions collected from diverse regions of the world were evaluated over 3 years in 5 agro-ecological environments across New South Wales (NSW), Victoria (Vic.) and South Australia (SA). Results showed that all cultivars had higher herbage yields than the accessions, but varied greatly among sites. Averaged across all cultivars, total herbage yields were up to 24.6 t DM/ha over 3 years at the Hamilton, Vic. site, but as low as 6.9 and 5.7 t DM/ha at the Wagga Wagga and Bookham, NSW sites, respectively, where chicory only persisted for 2 years. In contrast, the average herbage yield of all accessions was only one-half of that produced by the cultivars at the Hamilton site and about one-third of that at the other 4 sites. All cultivars and accessions persisted well under the favourable climate conditions experienced at the Hamilton site. In contrast, severe drought in 2006 resulted in the death of chicory swards at the Wagga Wagga and Bookham sites, and substantial declines in persistence at the Manilla, NSW and Willalooka, SA sites. Nevertheless, accessions collected from Australia and Asia were more persistent than some of the cultivars and may provide opportunities to select genotypes better adapted to intermittently dry mixed farming systems in south-eastern Australia. Our findings indicated that the current cultivars were best suited to sites similar to the Hamilton site in the winter-dominant, higher rainfall zone of south-eastern Australia. Under these conditions chicory was likely to be productive and persistent for 4 years or longer. In the drier mixed farming zone, chicory may be more suitable in shorter (2–3-year) pasture phases. Further research is required to identify those factors contributing to poor persistence.



2003 ◽  
Vol 43 (10) ◽  
pp. 1211 ◽  
Author(s):  
S. G. Clark ◽  
E. A. Austen ◽  
T. Prance ◽  
P. D. Ball

Climate variability is a major constraint to farming in south-eastern Australia and one that is out of the farmers' control. However, a better understanding of long-term climate variability would be beneficial for on-farm management decisions. A series of long-term simulations were undertaken with the GrassGro decision support tool to determine the effect of climate variability on pasture and animal production at 6 locations in south-eastern Australia. The simulations ran from 89 to 119 years using daily weather records from each location. All simulations were for spring-lambing flocks of medium sized Merino ewes stocked at above-average district stocking rates, grazing well-fertilised, perennial grass–subterranean clover pastures. Annual rainfall total and, in particular, the distribution of rainfall during the year, were found to be more important than other weather variables in determining the amount of pasture grown in a year. The timing of the season opening rains (autumn break) was most important. The localities varied in their responses to climate variability, particularly in the timing of the autumn break; the pasture growth response to winter rainfall; and the relationship between rainfall and animal production.



2003 ◽  
Vol 54 (6) ◽  
pp. 561 ◽  
Author(s):  
R. J. Eckard ◽  
D. Chen ◽  
R. E. White ◽  
D. F. Chapman

The use of nitrogen (N) fertiliser on dairy pastures in south-eastern Australia has increased exponentially over the past 15 years. Concerns have been raised about the economic and environmental impact of N loss through volatilisation and denitrification. Emissions of NH3, N2, and N2O were measured for 3 years in the 4 different seasons from a grazed grass/clover pasture, with or without 200 kg N fertiliser/ha, applied as ammonium nitrate and urea.Nitrogen-fertilised treatments lost significantly more N than the control treatments in all cases. More NH3 was lost from urea-fertilised treatments than from either the control or ammonium nitrate treatments, whereas ammonium nitrate treatments lost significantly more N through denitrification than the control or urea treatments in all seasons, except for summer. More NH3 was lost in summer than in the other seasons, whereas denitrification and N2O losses were highest in winter and lowest in summer. The total annual NH3 loss from the control, ammonium nitrate, and urea treatments averaged 17, 32, and 57 kg N/ha.year, respectively. Annual denitrification losses were estimated at around 6, 15, and 13 kg N/ha.year for the control, ammonium nitrate, and urea treatments, respectively. Total gaseous N losses were estimated to be 23, 47, and 70 kg N/ha.year from the control, ammonium nitrate, and urea treatments respectively.Although the use of ammonium nitrate fertiliser would significantly reduce NH3 volatilisation losses in summer, this fertiliser costs 45% more per unit N than urea, so there is no economic justification for recommending its use over urea for the other seasons. However, the use of urea during the cooler, wetter months may result in significantly less denitrification loss. The results are discussed in terms of potential management strategies to improve fertiliser efficiency and reduce adverse effects on the environment.



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