Effect of silicon application on wheat seedlings growth under water-deficit stress induced by polyethylene glycol

Silicon (Si) is known to ameliorate the deleterious effects of drought on plant growth. We evaluated growth of wheat (Triticum aestivum L. cv. Chamran) under water deficit stress induced by polyethylene golycol (PEG 20% w/v) as effected by Si application.Water deficit stress depressed the growth of shoot, relative water content (RWC) and chlorophyll concentration. Addition of 1.0 mM Si could partially improve the growth of shoot and increase the chlorophyll concentrations of stressed plants. The proline concentration in the leaves was markedly increased under water deficit stress, whereas added Si partially reversed this. Water deficit stress decreased the leaf soluble sugar concentration. There were significant negative regressions between proline concentration and shoot dry weight, supporting the view that proline accumulation is a symptom of stress damage rather than stress tolerance. Addition of Si obviously increased Si accumulation in the shoot. Analyses of K, and Ca showed no accumulation of these ions in the shoot under water stress, and added Si even increased their concentrations under water deficit stress. These results suggest that under PEG-induced water stress conditions, increase soluble sugar and decrease electrolyte leakage, contributed to the improved wheat growth by Si.