Radiation utilization efficiency, latent heat flux and crop growth simulation in irrigated rice during post-flood period in east coast of India

Abstract

To study the radiation utilization efficiency, latent heat flux, and simulate growth of rice during post-flood period in eastern coast of India, on-farm trial was conducted with three water regimes in main plots (W1 = continuous flooding of 5 cm, W2 = irrigation after 2 days of water disappearance, and W3 = irrigation after 5 days of water disappearance) and five nitrogen levels in subplots (N1 = 0 kg N ha-1 , N2 = 60 kg N ha-1 , N3 = 90 kg N ha-1 , N4 = 120 kg N ha-1 , and N5 = 150 kg N ha-1 ) on a rice cultivar, ‘Lalat’. Average maximum radiation utilization efficiency (RUE) in terms of above ground dry biomass of 2.09 (±0.05), 2.10 (±0.02), and 1.9 (±0.08) g MJ-1 were computed under W1, W2, and W3, respectively. Nitrogen increased the RUE significantly, mean RUE values were computed as 1.60 (±0.07), 1.78 (±0.02), 2.060 (±0.08), 2.30 (±0.07), and 2.34 (±0.08) g MJ-1 when the crop was grown with 0, 60, 90, 120, and 150 kg ha-1 nitrogen, respectively. Midday average latent heat flux (on clear days) varied from 7.4 to 14.9 and 8 to 13.6 MJ m-2 day-1 under W2 and W3 treatments, respectively, at different growth stages of the crop in different seasons. The DSSAT 4.5 model was used to simulate phenology, growth, and yield which predicted fairly well under higher dose of nitrogen (90 kg and above), but the model performance was found to be poor under low-nitrogen dose