Influence of nitrogen doses and plant population on yield and quality of green bunch onion

Field experiment was conducted over two growing seasons to evaluate the response of the green onion to nitrogen fertilizer and plant population effects. Six nitrogen doses (65, 80, 95, 110, 125 and 140 kg N/ha) were applied to three onion cultivars that belong to Texas Grano variety and planted at two plant populations of 66.7 and 83.3 plants/m². Yield showed significant increment with increasing nitrogen doses. Results of environmental impact revealed that the compensation point, at which high yield meets good nitrogen recovery % and distinguished saving in quantity of nitrogen loss, is at 83 plants/m², 125 kg N/ha, regardless of used cultivar. The rate of 125 kg N/ha showed greater nitrogen recovery % and lower nitrogen loss than 140 kg N/ha. Additionally, the absorbing capacity at that dose (125 kg N/ha) was not statistically differing from what realized by the higher dose (140 kg N/ha) in the second season.