Prediction of evapotranspiration and grain yield of rice (Oryza sativa L. cv Thriveni) in a humid tropical climate
In a humid tropical climate at Pattambi (10° 48′ N, 76° 12′ E), the evapotranspiration (ET) rates of rice (Oryza sativa L. cv. Thriveni) were 2.8–5.7 mm/day during the first crop season (May–September) and 6.2–9.1 mm/day during the second crop season (September–January). The crop was grown at the Station in the irrigated lowlands on sandy soils with average yields of 3025 and 2925 kg/ha in the first and second cropping seasons, respectively. The seasonal ET, water requirements, water use efficiency and field water use efficiency of the crop were 400 mm, 1150 mm, 7.56 and 2.63 kg/ha per mm in the first crop season and 650 mm, 1500 mm, 4.50 and 1.95 kg/ha per millimetre in the second crop season. Using the reference crop ET computed by Blaney-Criddle, Radiation, and Penman methods and measured evaporation from class A pan, Colorado and GGI 3000 pans, the crop coefficients were worked out. Correlations between weather parameters and the biomass of rice were obtained. The grain yield (Y, in kg/ha) of the crop was predicted using the equationY=1.71Y0−56S+85F−2430 (N=8,r=0.920), whereY0 is the sample of biomass of the rice at flowering in kg/ha,S andF are the duration of sunshine hours and maximum air temperatures (°C) between the 46th day of transplanting and maturity.
Key wordsPaddy rice yield Evapotranspiration Correlation model-Kerala
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