Broadband crop rotation of cotton-grain-rape improved crop yield and light utilization efficiency

Cotton-grain-rape broadband crop rotation can efficiently utilize farmland resources; however, the utilization characteristics of the light energy resources of different crops in this planting system are still unclear. Three treatments were used in this study: cotton monoculture (T1), wheat-maize rotation (T2) and broadband crop rotation of cotton-grain crop-rape (T3). The yields of cotton, maize, and wheat, and dry matter weight, leaf area index, extinction coefficient, light energy interception, and other indicators were determined. Compared with T1, T3 increased the yields and dry weight of cotton by 15.20% and 10.35%, respectively. Compared with T2, T3 increased the yields of maize and wheat by 21.61% and 11.53%, respectively, and the dry weight of maize increased by 6.17%. From July 16th to September 13th, the leaf area index of T3 significantly increased by 7.21%−12.76%, compared to that of T1. In July 24th and August 4th, the light interception rate of cotton of T3 significantly decreased by 3.59% and 3.24%, respectively, compared to that of T1. The leaf area index, extinction coefficient, and PAR (photosynthetically active radiation) interception efficiencies of maize and wheat did not differ significantly under different treatments. Compared with T1 and T2, the light interception of the entire growth period of cotton was reduced by 3.14% in T3, while the light interception of the entire growth period of maize increased by 0.76% significantly. No significant difference was noted in light interception throughout the wheat growth period. The light-use efficiencies of cotton, maize, and wheat increased significantly by 18.81%, 6.76%, and 14.10%, respectively. In this experiment, the edge row advantage and rotation effect simultaneously increased the yield of cotton, maize, and wheat as well as the aboveground dry matter weight of cotton and maize, improved the accumulation and distribution of crop dry matter, and thereby enhanced the light energy utilization efficiency of cotton, maize, and wheat. This study clarified the effects of cotton-grain-rape broadband crop rotation on the yield and canopy light energy utilization of cotton, maize, and wheat, providing a theoretical basis for the promotion and application of this model.