Short term stomatal responses to light intensity changes and osmotic stress in sorghum seedlings raised with and without silicon

Effects of silicon application on stomatal conductance in sorghum were investigated. Sorghum seedlings were grown in culture solution containing 0 or 1.67 mM silicon. On ninth day after giving silicon treatment, when there were no differences in shoot and root growth between the silicon-supplied and silicon-deficient treatments, seedlings were exposed to gradually increasing light intensity, combination of sudden increase and decrease in light intensity, and water stress induced by mixing sorbitol with the culture solution. There was increased stomatal conductance with increasing light intensity and no significant difference was observed between the two silicon treatments. Under water stress, the stomatal conductance of silicon-supplied seedlings was higher than that of silicon-deficient seedlings. The higher stomatal conductance in silicon-supplied seedlings under water stress was attributed to increased leaf water potential due to silicon-induced enhancement of hydraulic conductance. The results indicated that silicon application could affect stomatal conductance in sorghum seedlings through the modification of plant water relations.