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

Kar, Gouranga, Kumar, Ashwani, Sahoo, Narayan, Mohapatra, Sucharita
Paddy and water environment 2014 v.12 no.2 pp. 285-297
biomass, cultivars, developmental stages, heat transfer, irrigation, model validation, models, nitrogen, rice, India
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⁻¹were 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⁻¹when the crop was grown with 0, 60, 90, 120, and 150 kg ha⁻¹nitrogen, 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⁻¹under W₂and W₃treatments, 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.