Impact of Combined Glutathione and Zn Application for Seed Priming in Ameliorating the Adverse Effects of Water Stress on Maize Seed Germination Attributes, Metabolite Levels, and Seedling Vigor

Different techniques, including exogenous application of different chemicals as seed priming, are in practice to improve seed germination or seedling emergence for better crop production, especially under water-deficit conditions. The present study was conducted to compare the effects of seed priming with glutathione alone or in combination with Zn on seed germination behavior, seedling growth, photosynthetic pigments, and lipid peroxidation in relation to alterations in seed metabolites, seedling antioxidative potential, and biochemicals under polyethylene glycol (PEG)-induced water stress. Three levels of glutathione (1.5, 3.0, and 4.5 mM) were applied separately as well as in combination with 0.5% Zn as seed priming. Water deficit significantly adversely affected seed germination potential, seedling growth, and biosynthesis of photosynthetic pigments in association with disturbed metabolic activities in germinating seeds, and increased lipid peroxidation in terms of the contents of H2O2 and malondialdehyde (MDA). Seed priming with glutathione alone or in combination with Zn significantly reduced the adverse impacts of water stress on seed germination and seedling growth in association with positive boosting influences on seed metabolic activities and increased biosynthesis of photosynthetic pigments, activities of antioxidant enzymes, and contents of non-enzymatic antioxidants, with more accumulation of reducing sugars (RS), non-reducing sugars (NRS), total soluble sugars (TSS), and total soluble proteins (TSP). Overall, combined application of glutathione and Zn for seed priming was found to be better than separate applications. The 3 mM level of glutathione in combination with Zn was most effective in ameliorating the adverse impacts of water stress.