Effect of humic acid foliar application on growth and quantity of corn in irrigation withholding at different growth stages

In order to study effect of humic acid foliar application and limited irrigation on growth and quantitative character¬istics of corn an experiment was conducted in research field of Varamin in Iran during 2012 growing season. The experimental design was laid out in a randomized complete block with a split plots arrangement of treatments in three replications. Main plots included three different levels of irrigation (complete irrigation, irrigation withhold¬ing at 8-leaf stage and irrigation withholding at staminate inflorescence) and four different concentration of humic acid foliar application (0, 150,300 and 450 ppm) was allocated to subplots were. The results showed that irrigation withholding conditions in different growth stages significantly decreased plant height, yield components, seed yield, biological yield and harvest index. Humic acid foliar application in irrigation with holding in different growth stages had positive effect on all attributes in this experiment. In general, the results of the present study indicate that usage of humic acid reduces the harmful effects of water deficit stress and increases resistance to drought stress in corn plant