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Accueil du site → Doctorat → Australie → Response of the perennial legume Cullen australasicum to low water and phosphorus availability and the use of modelling to predict adaptation to the southern Australian wheatbelt

University of Western Australia (2011)

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

Suriyagoda, Lalith D. B.

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

Auteur : Suriyagoda, Lalith D. B.

Université de soutenance : University of Western Australia

Grade : Doctor of Philosophy (PhD) 2011

Résumé
Truncated abstract] Arable lands across Australia are often affected by phosphorus (P) and moisture limitations, and most exotic pasture species are not well adapted to these marginal soils. Under such scenarios, Australian native species may perform better since they evolved in nutrient-impoverished and dry landscapes. However, information on Australian native species is very limited, and thus it is difficult to predict the growth of native pasture species and make comparisons with exotic pasture species. However, once basic morphological and physiological characteristics of a prospective pasture species are known, those can subsequently be used as inputs for the development of pasture growth models. Plant growth models integrate the understanding of plant physiological processes within a mathematical framework that allows dynamic simulation of plant growth and development to estimate plant responses to genetic, environmental and management factors. Therefore, this PhD project aimed to study the growth and physiology of the Australian native perennial legume species Cullen australasicum when grown in moisture- and P-limited conditions. Since C. australasicum is considered to have potential as a pasture species, the aim was to develop a growth model for C. australasicum to estimate its performance under the conditions of the wheatbelt of Western Australia. First, an experiment was conducted under glasshouse conditions to understand the mechanisms and adaptations of C. australasicum and C. pallidum to grow at low-P and low-moisture availability (Chapter 2). The changes in shoot and root growth, root architecture, rhizosphere carboxylate dynamics, leaf photosynthesis, water use-efficiency and phenological development were studied. The results were compared with a widely cultivated exotic perennial pasture legume, Medicago sativa (lucerne). Both C. australasicum and C. pallidum exhibited multiple adaptive responses to grow in P- and moisture-limited environments and show potential to be developed as pasture species. In the second experiment, I studied the interactive effect of drought and species combination (C. australasicum and M. sativa when grown with the exotic annual ryegrass (Lolium rigidum)) on growth, nutrition, hydraulic lift and photosynthesis in the presence of poorly soluble FePO4 as the source of P (Chapter 3). L. rigidum out-competed the legumes, producing more dry weight in both shoots and roots...

Mots Clés : Endemic plants — Western Australia — Wheatbelt. — Endemic plants — Drought tolerance — Cullen australasicum. — Drought. — Growth. — Legumes. — Modelling. — Phosphorus. — Survival.

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Page publiée le 29 novembre 2012, mise à jour le 10 juillet 2017