Effects of Different Cultivation Patterns on the Yield and Physiological Characteristics in Mid-Season Japonica Rice

Rice is one of the most important food crops in China. The realization of continuously high yield has great significance in ensuring food security and society stability. Meanwhile, low nitrogen (N) use efficiency is a serious problem in rice production in China. The objective of this study was to investigate if a cultivation technique could coordinately increase both grain yield and N use efficiency in rice. Mid-season japonica rice cultivars were used with the treatments of local high-yielding cultivation (con-trol), super high-yielding cultivation, and high-yielding and high N use efficiency cultivation (HHC). The characteristics of grain yield formation under different cultivation systems and their physiological basis were analyzed. The results showed that, com-pared with the control, the HHC significantly increased biomass of root and shoot, root cytokinin concentration and root oxidation activity, grain-leaf ratio, leaf photosynthetic rate during the mid and late grain filling periods, nonstructural carbohydrate accumu-lation in stems and sheaths at the heading time, remobilization of carbon accumulated from heading to mature stage, and harvest index. The HHC increased grain yield by 31% and agronomic N use efficiency (increased grain yield per unit N application) by 57% when compared with the control. The results suggest that root and shoot growth could be improved and high grain yield and high N use efficiency could be achieved through integrating and optimizing cultivation techniques in rice production.