The effect of foliar application of ascorbic acid on yield components and physiologic character of sweet corn under different irrigation regims

To investigate the effect of ascorbic acid foliar application on phenological and physiological characteristics of sweet corn under water deficits, an experiment was carried out as split plots in randomized complete block design with three replications at Hashtgerd in 2014. Three levels of drought stress (complete irrigation, moderate and severe drought stress) were considered as main plots and four levels of ascorbic acid foliar application (control, 40, 80 and 120 mg.lit-1) as sub-plots. The studied characteristics were plant height, number of grain per ear, 1000-grain weight, grain yield, total chlorophyll, relative water content (RWC), proline and superoxide dismutase (SOD) activity. The results showed that drought stress decreased plant height, number of grain per ear, 1000-grain weight, grain yield, total chlorophyll, RWC and increased proline accumulation and SOD and catalase activities so that severe drought stress conditions decreased number of grain per ear, 1000-grain weight and grain yield about 43.03, 23.11 and 49%, respectively. In contrast, ascorbic acid foliar application increased plant height, 1000-grain weight, grain yield, total chlorophyll and RWC and reduced proline accumulation and SOD and catalase activities so that the most positive effect of ascorbic acid was observed in 120 mg.lit-1. Also, ascorbic acid foliar application with 120 mg.lit-1 increased grain yield about 32.1%.