Zinc-biofortified seeds improved seedling growth under zinc deficiency and drought stress in durum wheat

High zinc (Zn) concentration of seeds has beneficial effects both on seed vigor and human nutrition. This study investigated the effect of Zn biofortification on growth of young durum wheat (Triticum durum cv. Yelken) seedlings under varied Zn and water supply. The seeds differing in Zn concentrations were obtained by spraying ZnSO4 to durum wheat plants at different rates under field conditions. Three groups of seeds were obtained with the following Zn concentrations: 9, 20, and 50 mg Zn kg(-1). The seeds differing in Zn were tested for germination rate, seedling height, shoot dry matter production, and shoot Zn concentration under limited and well irrigated conditions in a Zn-deficient soil with and without Zn application. In an additional experiment carried out in solution culture, root and shoot growth and superoxide dismutase activity (SOD) of seedlings were studied under low and adequate Zn supply. Low seed Zn concentration resulted in significant decreases in seedling height both in Zn-deficient and sufficient soil, but more clearly under water-limited soil condition. Decrease in seed germination due to low seed Zn was also more evident under limited water supply. Increasing seed Zn concentration significantly restored impairments in seedling development. Drought-induced decrease in seedling growth at a given seed Zn concentration was much higher when soil was Zn-deficient. Increasing seed Zn concentration also significantly improved SOD activity in seedlings grown under low Zn supply, but not under adequate Zn supply. The results suggest that using Zn-biofortified seeds assures better seed vigor and seedling growth, particularly when Zn and water are limited in the growth medium. The role of a higher antioxidative potential (i.e., higher SOD activity) is discussed as a possible major factor in better germination and development of seedlings resulting from Zn-biofortified seeds.