"Double Late" Cultivation Model for Rice and Wheat and Its Comprehensive Evaluation on Annual Productivity

Effects of "double late"(late-maturity rice and late-sowing wheat) cultivation model on annual productivity of rice and wheat were systematically studied in a field experiment with four cultivation model treatments.Results showed that with the crop rotation being delayed,annual grain yield of rice and wheat increased.Grain yield of rice increased,whereas the grain yield of wheat increased firstly and then decreased with the highest yield under late-maturity medium japonica rice+wheat model(LMW).Moreover,prolonging rice growth duration and developing large panicles improved annual grain yield of rice and wheat.With maturity being prolonged,productivity with respect to the key inputs of rice increased.But for wheat,productivity per unit of seed decreased and others increased firstly and then decreased with the best performance under LMW model.Appropriate sowing date helped improve productivity with respect to key inputs,while appropriately delayed crop rotation was awarding to annual economic productivity of rice and wheat.Additionally,the concept of "double late" cultivation model and its regulation approaches were discussed.