The effects of different nitrogen doses and application times on yield and yield components of sunflower (Helianthus annuus L.)

This study was conducted to determine the effects of nitrogen doses (0, 3, 6, 9, 12 and 15 kg da-1) and application periods of nitrogen (100% sowing, 50% sowing-50% hoe period and 100% hoe period) on yield and yield components of sunflower under Kırşehir arid conditions in 2020. Experiment was carried out in randomized blocks design in split plot arrangement with three replications, and emergence, flowering and maturity time (day), plant height (cm), stem thickness (mm), head diameter (cm), leaf number (piece plant-1), 1000 grain weight (g), seed kernel ratio (%), crude oil ratio (%), total, full and empty grain number in table, empty grain ratio (%), plant seed yield (table g-1), seed yield (kg da-1), oil yield (kg da-1) and harvest index (%) were determined. According to the results, the effect of nitrogen doses and application periods on all parameters examined except the number of leaves were found to be statistically significant. In addition, emergence period, plant stem thickness, 1000 grain weight, grain oil ratio, empty grain number, full-empty grain ratio in the table, plant grain yield, grain and oil yield were statistically affected by nitrogen application periods × nitrogen doses interaction. Although nitrogen dose increase has a positive effect on yield parameters, the earliest emergence (19.33 days), flowering (85.33 days), ripening period (141.22 days), the highest seed kernel ratio (73.00%), the highest seed oil ratio (48.74%) control (0 kg da-1 N) application. According to nitrogen application periods and nitrogen doses applications, the highest seed (256.42 kg da-1) and oil yield (122.84 kg da-1) were obtained from 9 kg da-1 nitrogen application in 50% sowing-50% hoe period.