EFFECT OF DEFICIT IRRIGATION REGIMES ON GROWTH, YIELD, AND WATER USE EFFICIENCY OF MAIZE (Zea mays) IN THE SEMIARID AREA OF KIBOKO, KENYA

Abstract

Background: Globally, more than 40% of annual food production comes from irrigated lands, and agriculture is the largest consumer of water, at 70% of all freshwater withdrawals. As water scarcity becomes more acute worldwide, increasing the effectiveness of agricultural water resources becomes a priority for enhanced food production. Methodology: A study was carried out for two seasons in Kiboko, Makindu Sub-County during 2018 and 2019 short and long rains, respectively to evaluate the response of maize growth, yield, and water use efficiency to deficit irrigation in the semi-arid area. The experiment was arranged in Randomized Complete Block Design with three replicates. The irrigation regimes were T1 (100 % field capacity), T2 (75 % field capacity, T3 (50% field capacity), T4 (25 % field capacity), and T5 (rain-fed) were evaluated. Results: In season I, there was a difference (P≤0.05) on Plant height, leaf area, and leaf area index, in T1 compared to T5. Plants in T1 were higher (308.1cm) than those in T5 (263cm) (control). Irrigation deficit showed an effect (P≤0.05) on maize growth in season II, with plant height of 270.3cm in T1 compared to 95.6cm in T5. The yield components showed a difference (P≤0.05) on cob-size, 100grains weight, aboveground biomass and harvest index in both seasons. The highest yield of 10.9 and 10.2 t ha-1 was obtained in T1in Season I and II, respectively and lowest in T5 (8.8 t ha-1 and 3.0 t ha-1) in the season I and season II, respectively. Higher aboveground biomass and yield were obtained under full irrigation, and declined under varied deficit irrigation regimes. Water use efficiency had no significant difference at the different treatments in the season I, since rains were moderately reliable, thus allowing pausing of irrigation with little water stress. However, in season II, a difference (P≤0.05) in water use efficiency (WUE) was observed. Generally, water use efficiency ranged from 19.6 to 22.kg ha-1 mm-1 in season I and 16.6 to 24.8 kg ha-1mm-1 in season II. Implication: Irrigating maize at 50% water deficit increases the WUE with minimal yield decline, hence a better deficit irrigation strategy in water conservation under scarcity situation. Conclusion: Growth and yield of maize increased with increased amount of irrigation water and decreased under reduced irrigation while WUE increased with reduced irrigation and decreased under sever water stress.