Sub-theme 1b - Minimising the impact of extended drought
Managing drought requires a balance between traits controlling water use efficiency (WUE) and yield potential (Blum, 2009). Across multiple chickpea lines, the relationship between WUE and C allocation (yield) can be positive or negative (Gan et al., 2010; Leport et al., 1999), highlighting existing genetic diversity with respect to drought management. To explore this further, carbon allocation, temporal patterns of water use and plant hydraulics of candidate chickpea genotypes will be initially screened for drought and heat tolerance. Selected lines will be characterised in controlled environments and the field. Components of WUE (leaf water potential, net photosynthesis, carboxylation efficiency, stomatal conductance, nocturnal conductance, leaf internal CO2 conductance (Barbour et al., 2010), thermal photosystem damage (Cieraad et al., 2012), C allocation and harvest index), turgor maintenance and stomatal sensitivity to soil moisture content and vapour pressure deficits, will be measured under non-limiting conditions against treatments involving extended drought, with secondary treatments incorporating heat shock (45°C) and chilling events (0-5°C). These measurements will be correlated with C isotope discrimination (Farquhar & Richards, 1984), an integrative proxy for WUE, to reconcile previous conflicting results in chickpea for this trait (Turner et al., 2007; Kashiwagi et al., 2013).
Characterisation of traits that control the trade-off between C assimilation and water use to develop a model that predicts chickpea yields, WUE and nitrogen use efficiency (NUE) (Theme 2b) and enable targeted approaches for developing cultivars with better adaptation to specific environments.