Figure 1. Conceptual models for (a) traits associated with adaptation to moisture-stressed environments grouped according to main drivers of yield under drought (yield = water uptake [WU] x water use efficiency [WUE] x harvest index [HI] as defined by Passioura, 1977); (b) generic traits associated with adaptation to moisture-stressed and/or hot, irrigated environments (adapted from Reynolds and Trethowan, 2007) grouped according to main drivers of yield without water limitation (yield = light interception [LI] x radiation use efficiency [RUE] x harvest index [HI]).