Response of Aegilops Species to Drought Stress During Reproductive Stages of Development.

Drought is an important abiotic factor limiting productivity of wheat. We screened 31 accessions of Aegilops belonging to five species with the objectives of identifying wild relatives of wheat with tolerance to an extended period of drought at the reproductive stage, and to identify physiological, growth and yield traits associated with tolerance. Plants were grown at full irrigation until anthesis (Feekes 10.5.1). Drought was then imposed by withholding water for 16 d. Controls were continuously irrigated. Across species, drought significantly decreased leaf chlorophyll by 31%, grain number spike-1 by 25%, individual grain weight by 68%, and grain yield plant-1 by 76%. Among the species, Ae. geniculata had greater tolerance to drought for yield (48% decline from control) compared to the others (> 73% decline from control). The tolerance was associated with greater grain number spike-1 and/or individual grain weight. Among Ae. geniculata accessions, TA 10437 and TA 1802 were identified as the most drought tolerant genotypes with 7% and 24% decline in grain yield, and a drought susceptibility index (DSI) ≤ 0.5. Highly susceptible Ae. geniculata accessions, such as TA 10009, TA 1813 and TA 1808, had >56% decline in grain yield and a DSI >1.0. The results suggest the presence of genetic variability among Aegilops species/accessions for drought tolerance. This variability can be utilized for improving drought tolerance in wheat during reproductive stages of crop development.