Optimum Cultivation Model Increased the Grain Yield of Ratoon Rice and Nitrogen Agronomic Efficiency by Improving Root Morphological Traits and Stubble Character of the Main Rice

The present study investigated the effects of different integrated cultivation treatments on the yield, nitrogen agronomic efficiency (AE(N)), and growth performance of a ratoon rice system. A two-year field experiment was carried out during 2021-2022 using a randomized block design. Cultivation treatments included the farmers' practice model (control, CK), high-yield and high-efficiency model (T1), enhanced-high-yield and high-efficiency model (T2), and the no-N model (N0). The grain yield, yield components, root traits, and stubble characteristics were determined. The results showed that T2 treatment significantly increased the grain yield and AE(N) by 53% and 236%, respectively, compared with CK. Similarly, the stubble weight, non-structure carbohydrate contents, and the root attributes were significantly improved under T2 treatment. The correlation analysis suggested that ratoon rice yield and AE(N) was significantly and positively correlated with root weight (p < 0.01) and the stubble parameters including stubble weight (p < 0.01), starch content (p < 0.01), and soluble sugar content (p < 0.01). Additionally, a significant and positive correlation between root weight and stubble weight (p < 0.05) was determined in our study. Consequently, our work highlights the benefits of integrating planting density, nitrogen/water management, and other practices to achieve high AE(N) and grain yield of the ratoon rice by improving root trait and stubble characteristics of the main rice.