High seed zinc concentration assures high seedling vigor and biomass production in durum wheat under zinc deficiency and drought stress

Low seed Zn concentration resulted in decreased germination rate and seedling height, whereas increasing seed Zn concentration up to 50 mg kg-1 restored these traits under low soil Zn as well as drought or control treatments (Table 1). Germination rate was reduced to 66 % in seeds with 9 mg Zn kg-1 grown under low Zn and water availability whereas highest germination rates (i.e. up to 100 %) were recorded in seeds with 50 mg Zn kg-1 treated with adequate Zn and water (Table 1). Germination rate was gradually reduced by low seed Zn, particularly in the low soil Zn (i.e. 0 mg Zn kg-1 soil) and drought stress treatments (Table 1). In treatment with adequate soil Zn (i.e. 5 mg Zn kg-­‐1 soil) and water supply, seed Zn concentration had no effect on germination rate, however seedling height was significantly reduced by low Zn in the seed. Seedling height and also germination rate was reduced by drought as well as low Zn in the seed when plants were germinated and grown with adequate Zn in soil (Table 1). At the vegetative stage (i.e. stem elongation), high seed Zn concentration alleviated shoot biomass loss upon low Zn supply in soil irrespective of irrigation regimes (Table 2). Low Zn supply severely reduced shoot Zn concentration and increasing seed Zn concentration had little impact due to dilution of Zn in shoot. Increasing seed Zn concentration induced SOD activity (results not shown), dry matter production and Zn content (i.e. total Zn uptake per plant) of plants grown under low Zn supply (Table 2).