Effects of Different Humic Acid Doses on Yield and Quality Properties of Corn (Zea mays L.) in Iraq-Sulaymaniyah Conditions

The research was carried out in the ecological conditions of the Ranya region of Sulaymaniyah province, Iraq in the summer growing season of 2020. The goal of the study was to investigate the impact of humic acid on the growth and yield of corn. The trial included two commercial cultivars (DKC6050 and DKC6664) and soil application of four rates of humic acid (HA1: 0 kg/ha, HA2: 60 kg/ha, HA3: 120 kg/ha and HA4: 180 kg/ha). The experiment was conducted according to the split-plot experimental design in randomized blocks. In the study, a trial pattern was designed so that varieties were placed in the main plots, and doses of humic acid were placed in the subplots for a more precise investigation of their effects on the cultivars. In the experiment, the characteristics of growth, yield, and yield components were examined. According to the results, it was determined that applying humic acid positively affected all vegetative and yield parameters except for the germination time, cob diameter, protein ratio, and oil ratio. As the result of the interaction between the cultivars and the humic acid doses, significant results were obtained for seed yield, 100 seeds weight, yield per plant, cob diameter, harvest index, leaf area index, stem diameter, and silk appearance time. The highest grain yield was obtained from the DKC6050 variety (9844.8 kg/ha). Responses of cultivars to humic acid were the same and therefore no appreciable differences were observed between cultivars for comparison. However, it has been determined that the DKC6050 variety is a promising variety in terms of many characteristics and can be cultivated in the ecology where the research is carried out.