Effect of foliar application of ascorbic acid on quantitative and qualitative traits as well as some biochemical changes in leaves of grain corn (Zea maize L.) under water deficit stress

In order to study the effects of water deficit stress and foliar application of ascorbic acid on some agronomic, physiologic and biochemical traits of corn, an experiment was conducted in research field of Agriculture Faculty of Islamic Azad University, Varamin Branch in Iran during 2014 growing season. The experimental design was laid out in a randomized complete block arranged in split plots with three replicates. Irrigation at four levels (normal irrigation according to the region, irrigation withholding at eight leafy stage, irrigation withholding at silking stage and irrigation withholding at eight leaf stage and silking stages) as the main factor and ascorbic acid foliar application at three levels (0, 50 and 100 ppm) as the sub-factor were allocated to main and sub plots, respectively. The results showed that irrigation withholding at different growth stages significantly decreased seed yield and biological yield, harvest index, oil and protein percentage, oil and protein yield, total chlorophyll content, increased proline content and superoxide dismutase activity in the leaves. Foliar application of ascorbic acid could prevent quantitative and qualitative yield loss and chlorophyll degradation. In addition, ascorbic acid foliar application decreased proline accumulation and superoxide dismutase activity in the leaves. In general, considering the qualitative and quantitative improvement in studied traits, it can be concluded that ascorbic acid application can scavenge reactive oxygen species and reduce antioxidant enzyme activity and proline accumulation, which in turn, leads to increased seed yield and quality with improving growth conditions.