Effect of Water Stress on Crop Coefficient of Irrigated Soybeans (Glycine max L merr.) under sub-humid Conditions

Authors : Omotayo ADEBOYE, Bart SCHULTZ, Oludolapo ADEKALU, Krishna PRASAD

Pages : 94-109

View : 19 | Download : 11

Publication Date : 2021-12-22

Article Type : Research Paper

Abstract :In order to manage irrigation systems effectively and sustainably for food production, it is important to estimate crop evapotranspiration with high precision and understand the relationship between functional parameters in the soil-water-plant-atmosphere system. Soybean was drip irrigated for two seasons in Ile-Ife, Nigeria. The experimental factor was the timing of irrigation. The treatments consisted of full irrigation insert ignore into journalissuearticles values(T1111);; skipping of irrigation every other week during flowering insert ignore into journalissuearticles values(T0111);; pod initiation insert ignore into journalissuearticles values(T1011);; seed filling insert ignore into journalissuearticles values(T1101); and maturity insert ignore into journalissuearticles values(T1110);. The treatments were arranged in a randomized complete block design with three replicates. Leaf area index insert ignore into journalissuearticles values(LAI);, canopy cover insert ignore into journalissuearticles values(CC); and crop coefficient insert ignore into journalissuearticles values(kc); were measured and the single crop coefficient approach was used to determine evapotranspiration insert ignore into journalissuearticles values(ETc);. The crop coefficient insert ignore into journalissuearticles values(kc); during flowering and maturity ranged from 1.14-1.29 and 0.49-1.19 respectively, while during pod initiation and seed filling, it was 1.29 in the seasons. The actual crop coefficient insert ignore into journalissuearticles values(kci); when irrigation was skipped during flowering, pod initiation, seed filling and maturity ranged from 1.04-1.46; 1.30-1.48; 0.82-1.48 and 0.77-1.17 respectively in the seasons. The kci when irrigation was skipped during flowering, pod initiation, seed filling and maturity reduced by 13.4, 11; 26 and 17% respectively compared with the fully irrigated soybeans. Exponential equations described excellently the relationship between kci and green leaf area index insert ignore into journalissuearticles values(LAI); insert ignore into journalissuearticles values(0.87 ≤ r2 ≤ 0.97; p < 0.0001);. There was strong linear correlation between kci and daily actual evapotranspiration insert ignore into journalissuearticles values(ETc); insert ignore into journalissuearticles values(0.73 ≤ r2 ≤ 0.84; p < 0.0001); in the seasons. The kci and canopy cover insert ignore into journalissuearticles values(CC); are highly and significantly linearly related insert ignore into journalissuearticles values(0.89 ≤ r2 ≤ 0.97; p < 0.0001); and intercept very close to zero. Skipping of irrigation during the reproductive stages of soybeans reduced the crop coefficient and evapotranspiration.
Keywords : Drip irrigation, soybeans, crop coefficient, full and deficit irrigation