Effect of Different Nitrogen Fertilizer Levels on Growth and Yield of Bombay Red Onion (Allium cepa L.) Variety in the Southern Zone of Tigray, Ethiopia

The primary objective of this study was to assess the impact of nitrogen fertilizer rates on the growth, yield, and yield components of Bombay red onion variety. The study was carried out using a randomized complete block design. The study was carried out at Alamata Agricultural Research Center in Kara Adishabo in 2019, testing various Nitrogen fertilizer rates (0, 23, 46, 69, and 92 kg N/ha) with three replications. Results indicated that the different rates of Nitrogen fertilizer significantly wavered most of the growth, yield and yield components of the onion where the highest leaf number (14.67) was obtained from 92 Kg N/ha while the lowest mean number of leaves per plant (4.33) was recorded at nill Kg N/ha while the highest marketable bulb yield was obtained in treatments that received 92 Kg N/ha (38.30 t/ha) and 69 Kg N/ha (40.01 t/ha) which was not statistically different while the lowest one was obtained in treatments that received nill Kg N/ha (17.93 t/ha) and 23 Kg N/ha (19.42 t/ha). Applying 69 kg of nitrogen per hectare in the study area can result in achieving the highest yield of Bombay red onion variety.