Impact of different zinc application strategies on yield, yield component, and chlorophyll content of wheat under drought and zinc-deficiency stress conditions

Abstract

Drought and zinc (Zn) deficiency are serious biotic stress factors that restrict plant growth and agricultural production in arid and semi-arid regions, especially when they take place concurrently. Wheat is most commonly cultivated in these regions, where the topsoil often remains dry during the grain-filling stage, and this can result in wheat yield losses. Different Zn application strategies, including untreated seed (0 Zn), hydropriming (0 Z), seed priming (5 mM), seed coating (1.5 g Zn/kg seeds), soil application (10 kg Zn/ha), foliar spray 0.5%, and two combinations of soil application with foliar (10 kg Zn/ha + 0.5%) and seed coating with foliar (1.5 g Zn/kg seeds + 0.5%) were compared under controlled-growth chamber and greenhouse experiment (20–25 °C and 70% RH) conditions to evaluate the grain yield, chlorophyll content, and leaf area indices of two wheat varieties under drought and Zn-deficiency stresses. The results show that the losses of grain yield because of drought and Zn-deficiency stresses reached up to 8% in Imam and 15% in Altindane, compared to the well-watered yields for both test varieties. However, Zn application through seed coating and the combination of seed coating with foliar spray improved the yields under drought stress by 10.8% and 9.5% in Imam and by 14% and 17% in Altindane, respectively. Drought stress and Zn deficiency caused deleterious effects on the chlorophyll content and leaf area indices. Nevertheless, the application of seed coating and seed coating + foliar spray with Zn improved the chlorophyll content, compared to the untreated seed.