Breeding for enhanced drought resistance in barley and wheat - drought-associated traits, genetic resources and their potential utilization in breeding programmes

Drought represents the most devastating abiotic stress factor worldwide. It severely limits plant growth and development as well as agricultural characteristics including the final yield. The aim of this review is to summarise recent results of the breeding of barley (Hordeum vulgare) and wheat (Triticum aestivum; T. durum) for improved resistance to drought stress. First, drought-associated terms and definitions are outlined and plant strategies to cope with drought are presented. A brief overview of plant physiological mechanisms involved in water uptake and release is provided. Photosynthesis-related parameters (CO2 availability and associated features such as ribulose-1,5-bisphosphate carboxylase/oxygenase activity, 13C discrimination activity, water use efficiency) are discussed due to the crucial role of plant leaf stomata in both photosynthesis and water management. The second part describes the present state of research on drought resistance-associated traits in barley and wheat. Different strategies of plant water management aimed at maximising the final yield under various types of drought stress are discussed. Possibilities of the detection, identification and characterization of quantitative trait loci (QTLs) in barley and wheat germplasm are discussed and the future approaches to breeding for enhanced drought resistance as a complex physiological and agronomical trait are outlined.