ABSTRACT Super rice has the potential of high yield with rational nitrogen fertilizer management, and South China region is one of the most important planting areas for super rice. However, limited information is available of the adaptability of super rice and its physiological mechanism with high‐yield cultivation mode in South China. Here, two associated field experiments were conducted in both early and late seasons in 2023, that is, Exp. 1, seven representative super rice varieties ( Huahang 31 , Jingliangyouhuazhan , Jingnusimiao , Y liangyou 1173 , Hemeizhan , Yuxiangyouzhan , and Wufengyou 615 , written as HH31, JLY, JNSM, YLY, HMZ, YXYZ, and WFY in order) were introduced to plant under four N fertilizer application methods no N application (T0), compound fertilizer deep application (T1), farmers' traditional fertilization (T2) and compound fertilizer surface broadcast (T3); Exp. 2, both YXYZ and WFY were planted under T1 and T2 to elucidate their physiological mechanisms of high grain yield and nitrogen use efficiency. The results showed that mean grain yields of YXYZ and WFY for T1 were 7.90 and 8.15 t ha −1 , which was significantly 10.03% and 8.81% higher than T2, respectively. This can be attributed to the increase in spikelets per panicle, filled grain percentage and 1000‐grain‐weight. The nitrogen agronomic efficiencies of YXYZ and WFY for T1 were 25.33 and 25.75 kg kg −1 , which were 31.04% and 27.16% higher than those of T2, respectively. The T1 treatment led to higher nitrogen recovery efficiencies for YXYZ (43.24%) and WFY (41.45%), which were 45.44% and 25.99% higher than those of T2, respectively. Besides, the larger total above‐ground biomass, leaf area index and the stronger NR and GS activities of YXYZ and WFY were observed for T1. Structural equation model (SEM) showed that yield components had significantly positive and direct regulating effects on grain yield (R2C = 0.72). There were remarkably positive correlations between NUE and N metabolizing enzyme activities, indirect affecting the formation of grain yield.
Guo et al. (Sun,) studied this question.