Water deficit and heat stress are the major abiotic factors limiting cereal production worldwide. This productivity is finally defined by yield per area of land either as biomass for animal feed or grains for both humans and animal consumption. In dryland agro-systems, terminal drought and heat dictating shortening of crop growth season. Hence, under climate change predicted scenarios this productivity challenge becomes radical. An integrated breeding and agronomy research might provide a solution that will stabilize cereal productivity under dryland both at crop and agro-systems levels. Here we present two case studies from our recent field work which might illustrate some benefits of such an integrated research approach: (1) at crop level we investigate structural biomass investment in bread wheat and its association with grain size and yield under terminal drought and heat stress. We show that selecting for highly adapted wheat genotypes with stem water-soluble carbohydrates demonstrates a useful strategy to offset the grain weight and grain yield reduction under water deficit and high temperatures. (2) at agro-system level we perform comparative study of biomass productivity under arid environments. The comparison includes two small grain crops, wheat and barley each represented by modern verities and traditional tall landraces. Here we show barley superiority in biomass production under water deficit compared to wheat. We also show that tall landraces are more productive then their commercial semi-dwarf counterparts under severe drought. We will provide evidence to how varietal and crop selection might improve agro-system productivity and sustainability in dryland.
