Effect of Ascorbic Acid Concentration and Harvest Date on the Percentage Loss of Grain Yield in Corn (Zea mays L.)

To study the effect of ascorbic acid concentration and harvest date on the percentage of grain yield loss in corn, an experiment was conducted at the College of Agriculture Research Station, Tikrit University. The experiment included three local corn varieties (Baghdad, Sara, and Fajir), three concentrations of ascorbic acid (0, 100, and 200 mg L⁻¹), and three harvest dates (30, 40, and 50 days after pollination) during the fall season on 15/7/2023. The results showed no significant differences among the varieties for the traits studied. However, ascorbic acid had a significant effect on the percentage of broken grains and the weight of broken grains. Spraying with 200 mg L⁻¹ resulted in the highest values 2.587% for broken grain percentage and 180.09 kg ha⁻¹ for broken grain weight. This treatment also produced the highest net grain yield, reaching 6790.96 kg ha⁻¹. Harvest date significantly affected all measured traits. Moisture content decreased by 15% between the first and third harvest dates. The percentage of remaining grains on the cob after shelling, as well as their weight, increased with earlier harvests. Specifically, the remaining grain percentages were 0.5248%, 2.0922%, and 3.4085%, and their corresponding weights were 39.98, 149.33, and 222.2 kg ha⁻¹ at harvests taken 50, 40, and 30 days after pollination, respectively. The percentage of broken grains increased from 0.7719% to 3.563%, and their weight rose from 54.23 to 232.94 kg ha⁻¹ as harvest timing moved from 50 to 30 days after pollination. Total grain loss also increased from 1.301% to 6.972%, and from 94.21 to 457.02 kg ha⁻¹. Meanwhile, the net grain yield decreased from 7203.93 to 6080.55 kg ha⁻¹ between the same two harvest dates.