Differences and mechanisms of post-anthesis dry matter accumulation in rice varieties with different yield levels

Post-anthesis dry matter accumulation (PDMA) plays an important role in yield, but the differences and mechanisms of PDMA among rice varieties with different yield levels are still unclear. Field experiments were conducted using six rice varieties with medium, high, and super high yield levels selected to not only analyze the relationship between PDMA and yield but also compare the physiological indexes among different varieties. The effects of grain fertilizer on PDMA and yield were also observed. PDMA and apparent transferred mass of non-structural carbohydrate (NSC) in stems from heading to maturity were significantly positively correlated with yield. The physiological indexes (root oxidation activity, zeatin ​+ ​zeatin riboside contents in roots and leaves, and leaf photosynthetic rate) at 0–20 days after anthesis (DAA) of super high-yielding varieties were significantly higher than those of medium-yielding and high-yielding varieties. In addition, the α-amylase activity in stems at 30–50 DAA of super high-yielding varieties was significantly higher than other varieties. Compared with no grain fertilizer application rate (GFAR), the GFAR for maximum yield and yield increase of super high-yielding varieties were higher than other varieties. The above physiological indexes at 10–20 DAA were increased under GFAR at 54 ​kg ​ha⁻¹. The α-amylase activity at 30–50 DAA was inhibited under GFAR at 81 ​kg ​ha⁻¹ that hindered NSC translocation, resulting in decreased yield. Our results indicated that higher PDMA and NSC translocation were the crucial characteristics that benefited the yield formation of super high-yielding rice varieties.