Lalith Suriyagoda

Response of perennial pasture legume Cullen australasicum, to low water and phosphorus availability and the use of modelling to predict adaptation to the southern Australian wheatbelt

Growth of Cullen australasicum has not been widely studied. Plant performance indicators, such as biomass production and partitioning, light, water, and nutrient use under field conditions, adverse or favourable, cannot currently be predicted or modelled. The lack of research on this species, as well as lack of models for predicting growth of perennial legumes, especially semi-shrubs, in a mediterranean climate, is a major draw-back in popularising this species.

Thus, Lalith is investigating plant performance indicators, especially in relation to low availability of water and phosphorus and then develop a process-based simple Cullen australasicum growth model.

Lalith’s research falls into the CRC’s Program 2 research area and is related to the Perennial Legume Forages For a Dry Mediterranean Climate Project.

Objectives:

Investigate whether drought and phosphorus nutrition interact in their impact on growth and assimilation of nitrogen and phosphorus of Cullen australasicum in a manner that differs from their impact on Medicago sativa L
Investigate whether native perennial legume roots enhance the acquisition of water and phosphorus by neighbouring grass roots under varying soil moisture and phosphorus levels
Investigate whether Cullen australasicum modifies canopy architecture, leaf and canopy photosynthesis, respiration and dry matter partitioning when grown under conditions of high or low water and phosphorus availability
Produce an individual plant model to predict survival, canopy growth, radiation interception, photosynthesis, biomass production, water and nutrient (nitrogen, phosphorus) utilisation of the native perennial legume Cullen australasicum under the conditions it could experience in the southern Australian wheatbelt
Adapt the lucerne (Medicago sativa L.) module of the crop simulation model APSIM to represent Cullen australasicum; use APSIM to predict productivity of lucerne and Cullen australasicum for a range of soil type, climate change scenarios, and locations across the southern Australian wheatbelt, and thus compare the potential area of adaptation of Cullen australasicum to that of lucerne.