Effect of Deficit Irrigation and Mulch on Onion Growth and Yield Parameters in Semi-Arid Region of Nigeria

Abstract

Water insufficiency is one of the major challenges for irrigated agriculture, particularly in water-stressed regions, which prompted the need to promote water-saving irrigation methods such as deficit irrigation (DI) and mulch practices (MP). An experiment was conducted to assess the effect of DI and MP on the productivity of Onions at Dala Alhamderi Irrigation Site, Borno State, Nigeria, during the 2020/2021 irrigation season. The experiment consisted of 4 levels of irrigation (100, 85, 70, and 55% of weekly reference evapotranspiration and 4 levels of mulches (no mulch NM, synthetic plastic SM, wood shaving WM and rice straw RM). The treatments were replicated 3 times making 48 plots and laid using a split-plot design. The data on Onion height, canopy cover, number of leaves, bulb yield, and water use efficiency (WUE) were collected and analyzed using the Statistics 8.0 software package. The interaction effect of DI and MP has significantly (p<0.05) affected the Onion growth parameters, yield and WUE. The higher growth parameters were recorded at mulched compared to no-mulch plots. However, among the mulched, plots irrigated at 85% with SM mulch yielded high values of Onion height, canopy cover, and the number of leaves of 42cm, 72%, and 8 respectively, Whereas the lower mean values of the Onion growth parameters were recorded at plots irrigated at 70 and 55% under WM and RM mulch. Higher Onion yields of 15.10 t/ha were recorded at plots irrigated at 85% with SM mulch, which was 19.4% higher than plots irrigated at 100% with no mulch treatment. The highest crop water use efficiency value of 19.08 kg/m3 was observed at 85% irrigation with SM mulch. Meanwhile, the lowest crop WUE of 12.53 kg/m3 was obtained for treatment at 100% irrigation under no-mulch. The crop WUE increases as the irrigation decrease under the mulching order of NM, RM, WM, and SM mulch during the cropping season. It can be concluded that the Onion farmers in the study area should adopt the DI at 85% with SM mulch that increased Onion bulb yield production by 19.4% and saved water by 15% when compared to the conventional full irrigation with no mulch. The saved water could be used to expand more land for crop cultivation.