Abstract

                                Jaya and B.C. 5 varieties of rice were grown in field under 90, 120 and 150 kg N/ha. and saturation to field capacity. 5 cm submergence to saturation and 10 cm sub- mergence to cracking levels of soil moisture in summer seasons of 1971 and 1972, to study their yield response and water need and to quantify various components of water loss. Results revealed that between two varities, Jaya yielded significantly higher (49.2 Q/ha) than B.C. 5 (34.8 Q/ha). Varieties responsed upto 120 kg N and yielded. on an average, 45.4 Q grain/ha levels. Yield of 44.8 Q was recorded at soil moisture level of 5 cm submergence to saturation as against 44.5 Q at 10 cm submergence to soil cracking or 36.7 0 at saturation to field capacity. On an average the total amount of water applied in 10 cm submergence to cracking treatment (2828 mm) was 17.4 and 9 per cent higher than in saturation to field capacity and submergence to satura- tion treatments respectively. Loss through percolation amounted to nearly 61 per cent which decreased with decrease in moisture levels of the soil. On the contrary. ET loss in case of 10 cm submergence to cracking was only 31 per cent and increased with decrease in the moisture levels. Highest loss 38 per cent was recorded in saturation to field capacity treatment. A total of five to seven per cent of the losses could not be accounted for. Water use efficiency was higher in 5 cm submergence to saturation treatment compared to others.

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