Drought Priming at Vegetative Growth Stage Enhances Nitrogen-Use Efficiency Under Post-Anthesis Drought and Heat Stress in Wheat

To study the effects of early drought priming at 5th-leaf stage on grain yield and nitrogen-use efficiency in wheat (Triticum aestivum L.) under post-anthesis drought and heat stress, wheat plants were first exposed to moderate drought stress (drought priming; that is, the leaf water potential reached ca. -0.9 MPa) at the 5th-leaf stage for 11days, and leaf water relations and gas exchange rates, grain yield and yield components, and agronomic nitrogen-use efficiency (ANUE) of the primed and non-primed plants under post-anthesis drought and heat stress were investigated. Compared with the non-primed plants, the drought-primed plants possessed higher leaf water potential and chlorophyll content, and consequently a higher photosynthetic rate during post-anthesis drought and heat stress. Drought priming also resulted in higher grain yield and ANUE in wheat under post-anthesis drought and heat stress. Drought priming at vegetative stage improves carbon assimilation and ANUE under post-anthesis drought and heat stress and their combination in wheat, which might be used as a field management tool to enhance stress tolerance of wheat crops to multiple abiotic stresses in a future drier and warmer climate.