Effects of different sowing times and plant densities on bolting, yield and bulb parameters in onion

Abstract

In this study, using short-day onion cultivars, effects of sowing times on total and marketable yield were examined. In research fields of Cukurova University, Adana, Turkey, seeds of onion cultivars Texas Early Grano, Aki and Contes were sown at three consecutive times, i.e., September 18, October 1, and October 15. To test the effect of varying plant densities, four different rates of seeds, i.e., 4 kg ha(-1), 6 kg ha(-1), 8 kg ha(-1), and 10 kg ha(-1), were sown for each date. Results showed that sowing time was statistically effective on yield and the highest average yield (67.6 tons ha(-1)) was from the first sowing time. Effect of plant density on yield was also statistically significant. While 6 and 8 kg ha(-1) seed rates produced the highest yields the lowest was from 4 kg ha(-1) The highest yield (81.2 t ha(-1)) was from cv. Aki with 8 kg ha(-1) seed rate and 1(st) October insowing time. Average bolting ratio reduced as the sowing time progressed, with bolting percentages of 77.21%, 53.61% and 19.33% from the first, second and the third sowing times, respectively. Bolting percentages in cv. Texas Early Grano were high in both September and October sowing times. However, cultivars Aki and Contes showed low rates of bolting in the sowing times mentioned, and both cultivars did not show any bolting in the third sowing time.