Responses of rice yields in different rice-cropping systems to climate variables in the middle and lower reaches of the Yangtze River, China

The Middle and Lower reaches of the Yangtze River Basin (MLYRB) together constitute the most intensive rice-farming region of China and is one of the most important rice production regions in the world. Under the double rice-cropping and single rice-cropping systems in MLYRB, there are three rice crops: early rice, late rice and single rice. This study examined the relationship between climate variables and rice yields of the different rice-cropping systems and evaluated quantitatively the effects on yields of the three rice crops and their economic consequences. It also evaluated the contribution of technological factors in mitigating the adverse effect of climate change by building a yield model based on a gene expression programming (GEP) algorithm. The findings indicated that climate variation had the most important effect on yield of early rice among the three rice crops. No significant positive effect of abundant precipitation on yield was detected, but there was a significant negative effect on yield of early rice because the increased number of rainy days reduced solar radiation and the temperature required for optimal rice growth. The yield model showed that increase of the minimum rice purchase price provided an economic incentive to farmers to increase investment in inputs and therefore improve yields but the ability of farmers to use adaptive strategies to mitigate adverse effects of climate change has decreased.