Weather relation of rice-grass pea crop sequence in Indian Sundarbans

In order to develop weather-based yield prediction models for rice and grass pea in coastal saline zone of West Bengal, the experiments were conducted with rice (cv. CR 1017) and grass pea (cv. Bio L 212) in the rainy and winter seasons, respectively of 2016-17 and 2017-18. Rice was sown in nursery bed on six different dates starting from June 15 to July 19 at weekly interval in both rainy seasons in two different land situations viz. medium upland and medium lowland. Likewise, grass pea was sown on six different dates just before harvesting of rice. It was observed that both early sown rice and grass pea resulted in higher grain yield and took more time to mature under medium lowland situation irrespective of sowing dates. Correlation study revealed that air temperature during sowing to transplanting phase exhibited significant positive correlation with grain of rice in medium upland (Tmax = 0.76**, Tmin = 0.69*) and medium lowland (Tmax = 0.93**, Tmin = 0.81**) situations. On the other hand, maximum temperature and total solar radiation during 100% emergence to 100% flowering stage were negatively associated with the grain yield of grass pea in both medium upland (Tmax = -0.69*, Accumulated solar radiation = -0.73**) and medium lowland (Tmax = -0.74**, Acc. solar radiation = -0.77**) situations. Grain yield of rice and grass pea could be predicted with 94.4% and 87.4% predictability. Pre-harvest forecasting of grain yield was possible with 77.3% for rice and 83.8% for grass pea.