The effect of nitrogen and water management on the yield and endogenous hormone levels of drip‐irrigated rice.

Improving the management of water and fertilizers is an effective method for enhancing the seed‐setting performance of rice. This study aimed to explore the regulation of optimized water and nitrogen management on the root–leaf hormone balance and seed‐setting performance of drip‐irrigated rice. In a 2‐year field experiment, T‐43 (a drought‐resistant cultivar) and LX‐3 (a drought‐sensitive cultivar) were cultivated under two drip irrigation treatments (W1, limited, and W2, deficit) and three nitrogen fertilization treatments (N1, seedling:tillering:panicle:grain‐filling, 30%:50%:13%:7%; N2, 20%:40%:30%:10%; and N3, 10%:30%:40%:20%). Compared with other treatments, the W1N2 treatment increased the seed‐setting rate and grain biomass accumulation (2.7%–9.2% and 4.5%–69.8%) of the two cultivars on the basis of producing a higher effective panicle number, and T‐43 had a much higher seed‐setting rate and yield than LX‐3 (6.8%–14.6%). Increased fertilizer applications at the panicle and grain‐filling stages (N2) enhanced the root oxidation activity (ROA) and the zeatin+zeatin riboside (Z + ZR) and gibberellic acid (GA3) contents in the roots in the 0–10 cm layer and in the leaves from the heading stage to 20 days after heading. The grain biomass accumulation of T‐43 was significantly positively correlated with abscisic acid (ABA) and Z + ZR in the roots and leaves, while the grain biomass accumulation of LX‐3 was significantly positively correlated with auxin, ABA, Z + ZR/ABA, and GA3/ABA in the roots in the 10–20 cm layer. Overall, W1N2 promoted grain biomass accumulation by modulating the Z + ZR and ABA balance in roots and leaves, improved the root–shoot ratio, and enhanced ROA, thereby improving the seed‐setting performance of drip‐irrigated T‐43 rice. Core Ideas: Optimized water and nitrogen management improved seed‐setting rate on the basis of higher effective panicles.Increasing panicle and grain fertilizer enhanced the hormone content and root activity in 0–10 cm.The balance of the hormone content in roots and leaves promoted the transport of assimilates to grain. [ABSTRACT FROM AUTHOR]