RESPONSE OF ONION (Allium cepa L.) TO DEFICIT IRRIGATION AND MULCH ON YIELD AND WATER PRODUCTIVITY UNDER HARAMAYA, ETHIOPIA

Abstract

Improving water productivity for sustainable crop production and water savings represents a major challenge for agricultural water management in water scarce areas. A field experiment was conducted at Haramaya University experimental site during 2019/2020 irrigation season to evaluate the response of onion yield and water productivity to deficit irrigation levels and mulch techniques. The treatments include 100, 85, 70 and 55% of ETc applications. The experimental design was a split plot in RCBD arrangement with three replications. Crop water requirement was estimated using actual daily climatic temperature data. The analysis of variance revealed that there was a highly significant (p<0.01) difference among growth parameters, yield and yield parameters. The interaction effect of mulch and irrigation has also shown a significant effect for bulb height and unmarketable bulb yield except for leaf number per plant and a highly significant (p<0.01) effect for the rest parameters considered. The maximum yield of 38.43 ton/ha was recorded from 100% ETc with plastic mulch whereas the minimum yield of 16.36 ton/ha was recorded from 55% ETc with no mulch. The highest water productivity (9.08 kg/m3) was obtained from the plots treated with 70% ETc application under plastic mulch and shows no significant differences with 85% ETc application under plastic mulch and 70% ETc application under straw mulch. The lowest water productivity (6.57 kg/m3) was recorded from 55% ETc application under no mulch treatments. Budget analysis revealed that the most economically feasible combination for small-scale grower farmers with lower cost of production and maximum net return was from the application of 70% ETc and 85% ETc treated with straw mulch. Therefore, in terms of marketable bulb yield and water productivity, irrigating with 70% ETc and straw mulch would be recommended for production of onion in the study area.