8 Results
Filter Results
00000000VGLS-PUBLIC
Author(s) 
Trumble, H. C. (Hugh Christian), 1903- Donald, C. M. (Colin Malcolm) Council for Scientific and Industrial Research (Australia) Waite Agricultural Research Institute.
Format: 
Books
Publication Date(s) 
1938
Available:
Author(s) 
South Australia. Department of Agriculture. Flaxley Research Centre (S.A.)
Format: 
Journal
Publication Date(s) 
1990-2022
Available:
Author(s) 
British Farm Equipment.
Format: 
Books
Publication Date(s) 
1953
Available:
Author(s) 
Victoria. Department of Primary Industries Grains Research and Development Corporation (Australia)
Format: 
Books
Publication Date(s) 
2005
Available:
Author(s) 
Mitchell, Meredith Leigh.
Format: 
Books
Summary: 
Microlaena stipoides, a C3 perennial grass, is common within grazed native pastures in the high rainfall zone (> 550 mm average annual rainfall) of south-eastern Australia. Microlaena has the ability to survive and persist in environments within this zone that commonly experience soil water deficits during the summer months. Our knowledge of the summer drought survival mechanisms of Microlaena to sustain its populations is incomplete. Using field, glasshouse and laboratory studies and experiments, this thesis researched key components of the population biology of Microlaena. The thesis investigates the extent to which Microlaena populations in the summer-dry environment of south eastern Australia are maintained by adult plants and/or seeds and seedling recruitment.Microlaena has a unique morphology: its shoots arise from corm-like structures that are located approximately 20 mm below the ground surface. The location of the active buds and their depth of burial may provide Microlaena with the ability to withstand close grazing and protection from hot, dry summers. There was no evidence that Microlaena exhibited summer-dormancy, which is characteristic of Mediterranean species. When irrigation was applied, even with high soil temperatures, it responded by producing new buds and tillers. Microlaena was able to withstand short (up to 30 days) but not prolonged dry periods. The survival of Microlaena over protracted dry periods, typical of southern Australia, either requires deep roots or is related to the position in the landscape where Microlaena most commonly occurs, or both.Microlaena is not dormant, but quiescent, during summer droughts and has the ability to respond to summer rainfall events. Its underground structures (rhizomes and corms) allow it to respond rapidly to favourable soil moisture conditions. Management strategies for Microlaena-dominant pastures nee d to be based on the maintenance of existing plants.Seed yields were substantial (mean of 800 seeds mâ2), with seed rain occurring over the December to May period. Microlaena has two distinct periods of high seed rain: in early summer and then again early autumn. Seed predation is high. Within a 24-hour 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 (five seedlings mâ2). Microlaena only represented low numbers in the seed bank (0.01â0.05% of total); hence, any seedlings of Microlaena that germinate from the seed bank would face immense competition from other species.To determine the relative important of vegetative propagation in terms of population biology, a molecular technique was used. The amplified fragment length polymorphism (AFLP) technique could detect differences between Microlaena populations, indicating that the populations are likely to be undergoing some degree of outcrossing. This would indicate that even though seed recruitment is an uncommon event, it occurs frequently enough to ensure diversity within the population.The objective of the thesis was to investigate Microlaena population dynamics in the summer-dry environment of south-eastern Australia. This thesis has demonstrated that Microlaena relies on a combination of seedling recruitment and adult plants to maintain its populations in southern Australia.
Publication Date(s) 
2013
Available: