STM Article Repository

Despite the fact that water is the most limiting factor for irrigated crop production in the semi-arid areas of northern Ethiopia, limited scientific information has been reported on a more productive and responsible use of the limited irrigation water in agricultural systems. Hence, a field experiment was conducted at Axum area to investigate the influence of deficit irrigation on onion yield and its water use efficiency (WUE) under drip irrigation system. Eleven different water applications at different growth stages were evaluated using randomized complete block design replicated 3 times. The results revealed that the yield and yield components of onion increased significantly with increasing the amount of water application; whereas WUE significantly decreased with increasing water application. The maximum bulb yield (28.0 t ha-1) was obtained in the full-irrigation application. Onion crop subjected to 40% deficit of crop water requirement (ETc) decreased its yield by about 3 -10 t ha-1. However, the maximum WUE (7.60 kg m-3) was obtained in the 40% deficit throughout the growing season, with water saving of 15.88 cm which is sufficient to irrigate 0.67 hectare of additional area of onion in which this earns better economic returns as compared to that of full irrigation application. The result also showed that onion is very sensitive to water stress during the development (2nd) and mid (3rd) stage of the crop. However, water stress on the 1st and 4th stage did not reduce the onion yield significantly. Hence, deficit irrigation should be applied during the less sensitive crop growing stages so as to improve water use efficiency with little or no impact on yield of onion in the semi-arid conditions like Tigray region.