Agro Climatic Models for Prediction of Growth and Yield of Rice (Oryza sativa L.).

Among the varieties tested, the maximum number of productive tillers and test weight were recorded with NLR-145 while the maximum number of total and filled grains were with BPT 1768 when compared to BPT-5204. Significantly higher grain yield (5195 kg ha-1) was recorded with the variety NLR 145 which was on a par with that of BPT-1768 (4942 kg ha-1) and significantly superior to that of BPT-5204 (4771 kg ha-1). The maximum straw yield was obtained with NLR-145 (6842 kg ha-1) when compared to BPT-5204 (6371 kg ha-1) and BPT-1768 (6450 kg ha-1). The growing degree days (GDD), heliothermal units (HTU) and photothermal units (PTU) required to attain maturity worked out revealed that from planting to maturity the requirement of GDD was 1467 to 1818oC days with NLR-145, 1639 to 1977oC days with BPT-5204 and 1941 to 2257oC days with BPT-1768. The accumulation of HTU was 7498 to 8545oC day hours with NLR-145, 8395 to 9128oC day hours with BPT-5204 and 10241 to 10338oC day hours with BPT-1768. The photothermal units requirement ranged from 16806 to 21362oC day hours with NLR-145, 18751 to 23131oC day hours with BPT-5204 and 26313 to 22204oC day hours with BPT-1768. Among the varieties, the maximum heat use efficiency was recorded with NLR-145 compared to that of BPT-5204 and BPT-1768. The highest heat use efficiency of 7.68 kg ha-1oC-1 day-1 for dry matter and 3.36 kg ha-1oC-1 day-1 for grain yield was recorded with 23rd August and 7th October plantings, respectively. Significant linear relationships were observed for leaf area index and dry matter production with three agroclimatic indices viz., GDD, HTU and PTU. Similarly, linear relationship derived between grain yield and heat units revealed that GDD accounted for 51 and 55 per cent, HTU accounted for 52 per cent and PTU accounted for 52 and 55 per cent variation in grain yield of rice varieties NLR-145 and BPT-1768, respectively. However, for BPT-5204 no significant linear relationship was observed for grain yield with three agroclimatic indices studied. Based on results of present investigation it could be concluded that planting of rice varieties around 23rd August resulted in superior growth performance and grain yield compared to 7th, 23rd September and 7th October plantings. Significant linear relationships for leaf area index and dry matter production with three agroclimatic indices viz., GDD, HTU and PTU revealed that model equations can be applied to predict rice growth using daily information on temperature, photoperiod and sunshine hours during the crop season.