Beneficial Effects of Silicon on Water Stress Tolerance in Maize (Zea mays L.) Grown in Calcareous Soil

The growth of maize (Zea mays L. cv hybrid 2031) plants were evaluated under water stress induced by decreasing soil moisture from 80% of field capacity as optimal value (control )to 40%, 50%, 60% and 70% of FC treatments, being considered as water stress for maize as affected by Si application at five rates (0. 50. 100, 150 and 200mg Si kg-1 soil). This evaluation was carried out in a pot experiment using calcareous soil in a split plot design. The soil moisture levels were applied to the main plots and the silicon levels were assigned to the sub-plots. The results obtained showed that water stress depressed the growth of shoot, relative water content and chlorophyll index values. Addition of Si up to 200 mg kg-1 soil partially improve the growth of shoot and increase the relative water content, chlorophyll index and proline content. The proline content in the leaves was markedly increased under water stress or with silicon application especially under high water stress conditions. The negative relationship between proline content and shoot dry weight, supporting the view that proline accumulation is a symptom of stress damage. Addition of Si increased Si accumulation in the shoot. Analyses of N, P, K, Cu and Zn showed no accumulation of these elements in the shoot under water stress, and added Si even increased their concentrations under water stress. These results suggest that under water stress conditions, silicon nutrition can improves maize plant growth.