Abstract

Onion (Allium cepa L) is one of the most popular vegetables in the world. It is a recently introduced bulb crop in the agriculture community of Ethiopia and it is rapidly becoming a popular vegetable among producers and consumers. Like in many other countries, temperature is noted to be as one of the most important environmental factors that affect onion dry bulb and seed production in Ethiopia. Timing of planting date is hence important so that every developmental phase may occur at times when temperature is favorable for crop performance and high yields can be obtained. Therefore, the current study was carried out in order to investigate effects of planting dates on onion bulb production under irrigation conditions in Wolaita Zone, Ethiopia. Field experiments were carried out in Wolaita Zone to investigate effects of planting dates on onion bulb production under irrigation condition using RCBD design replicated three times. Five different planting dates with fifteen days intervals, starting from mid September to mid November, were used as treatments. The major data collected were subjected to analysis of variance using SAS software by the command PROC GLM. The analyses of variances indicated that both growth and yield parameters measured were significantly affected by planting date in the study area. The highest plant height (54cm) and leaf number (9.3) were recorded from onion planted at mid October. Maturity of onion was more prolonged (154.3 days) when planted at mid-September and shortened (134.3 days) when planted at mid November. Higher number of marketable bulb (240,972), marketable yield (29.58 t ha-1) and total yield (35.83 t ha-1) were obtained from planting onion at mid October. In general, it can be concluded that onion yield tended to increase when planted under irrigation starting from mid-September to mid October in the study area. Hence, onion growing farmers in the study area should be advised to plant onion in between period of mid-September to mid-October so as to get more onion bulb.