The Effect of Biochar and Humic Acid Rates on some Phophysiological Characteristics and Grain Yield SC704 Corn (Zea mays L.) Hybrid Under Water Deficit stress

To evaluate the effect of different rates of biochar and humic acid applications on physiological characteristics and grain yield of single cross 704 hybrid corn under water deficit stress, a split split plot experiment based on a randomized complete block design with three replications, was conducted during two years (2017-19) at Ahvaz. The main plot devoted to water deficit stress, with three levels irrigation (after depleting 30, 40, and 50% of field capacity as optimum irrigation, moderate stress, and severe stress, respectively) and sub-plot to biochar with 2 levels, non-application of biochar (control) and application of 4 tons per hectare of biochar, and the sub-sub plots to humic acid with 4 levels non-application of humic acid (control), and application of 2, 4, and 6 liters per hectare of humic acid. The results showed that the interaction effect of water shortage by biochar stress and water shortage by humic acid stress on grain yield, 1000-grain weight, number of grains per ear, superoxide dismutase, chlorophyll index and catalase were significant at 1% probability level. Under severe stress conditions grain yield (36.54%), number of grain per ear (36%) and leaf area index (30.36%) decreased and activity of superoxide dismutase (37.7%) increased. Acidic acid had a significant effect on all traits under study. The highest grain yield (8995.18 kg.ha-1) was related to irrigation treatment after 40% depletion of field capacity and application of 4 tons per hectare of biochar. Based the results obtained application of 4 liters per hectare of humic acid under moderate moisture stress conditions, could be recommended in arid and semi-arid conditions to save water consumption and reduce the effects of water deficit stress.