Sub-theme 3c - Defining mechanisms and diagnostic tools to quantify soil N delivery from chickpea
Residual soil N from legume N2-fixation plays an important role in boosting the productivity of following crops (Peoples et al., 2009) by providing N (Kirkegaard et al., 2008). N delivery to the soil is poorly quantified and our ability to predict N release from legume residues in soils and uptake by following crops remains poor. Furthermore, the effects of soil conditions, especially soil nutrients and soil biology, on N2-fixation performance, plant growth and yield is poorly understood.
Using chickpea, quantitative studies of N in legume residues (roots and tops) and their contributions to follow on crops will be investigated. This will be tested against physiological constraints imposed by abiotic stresses and we will investigate N deposition patterns across diverse chickpea lines in the field and in the glasshouse. The development of advanced soil-based signatures that describe past and future N2-fixation capacity, will be developed to support management decisions by growers. This will involve extensive use of field surveys of chickpea performance (growth, N content, N isotope signatures) combined with stable isotope and molecular analysis of soils. Field studies will be backed by glasshouse trials to test the effects of soil conditions on performance under controlled conditions, to calibrate data from the field. Glasshouse studies will also be used to test the epigenetic effects of soil nutrients and biology on nodulation and N2-fixation across known chickpea genotypes.
Identification of agronomic practises that assist in optimising N2-fixation. Also, identification of key plant traits (e.g. rooting depth, patterns of root development w.r.t. soil conditions) that will inform breeding programs.