Growth and bulb yield of onion (Allium cepa L.) varieties as influenced by NPS fertilizer in Western Ethiopia

Abstract

Onion is main crops in Ethiopian regular nutrition, cultivated year round under rain-fed and irrigated conditions. The low productivity of onion crops in Ethiopia as compared to other onion producing countries was due to disease, insect pest, lack of improved varieties, lower use of improved varieties and improper agronomic practices. A field experiment was conducted at Dambi Dollo University, Ethiopia for two consecutive years (2020 and 2021) under rain-fed to evaluate effect of NPS fertilizer rates on performance of onion varieties. The experiment was laid out using Randomized Complete Block Design with three replications in factorial mixture of four levels of NPS fertilizer (0, 50, 100, 150 kg ha-1) and three varieties (Adam Red, Monarch and Nafis). Variance Analysis indicated that NPS fertilizer and varieties were expressively affected days to 90% physiological maturity, marketable and unmarketable yield and total bulb yield of onion crop but not significantly influenced by their interaction. The number of leaves per plant and plant height were significantly influenced by main effect of varieties, NPS fertilizer rates and their interaction. The highest values for number of leaves per plant (16.08) recorded at 150 kg ha-1 for Monarch variety. Moreover, days to 90% physiological maturity (134.8 days) and total bulb yield (29.35 t ha-1) were recorded from the highestNPS application rate of 200 kg ha-1. Similarly, the maximum plant height (16.08 cm) and marketable onion bulb yield (26.41 t ha-1) were obtained from 150 kg ha-1 NPS rate. Hence, based the highest marketable onion bulb yield gained, Nafis variety of onion and 150 kg ha-1 of NPS fertilizer should be advised for production in the western part of Oromia, Ethiopia and other areas with similar agro-ecological conditions.