Determining nitrogen topdressing rates in accordance with actual seedling density and crop nitrogen status in direct-seeded rice

Authors：Peng, Bilin; Wang, Xinyu; Hu, Xiangyu; Liu, Yanzhuo; Liang, Kaiming; Fu, Youqiang; Hu, Rui; Li, Meijuan; Ye, Qunhuan; Yin, Yuanhong; Pan, Junfeng^*; Zhong, Xuhua^*

Source：Journal of the Science of Food and Agriculture, 2024, 104(4): 2294-2302.

DOI：10.1002/jsfa.13117

• direct-seeded rice
• maximum tiller number
• nitrogen management
• plant nitrogen status
• actual seedling density

BACKGROUND: Adjusting nitrogen (N) input based on actual seedling density (ASD) and plant N status is a practical approach for improving the yield stability of direct-seeded rice. However, the adjustment of topdressing N rates has been empirical in the past. This study aimed to establish a quantitative approach for determining N topdressing rates during tillering (N-til) and panicle development (N-PI) based on ASD and crop N status in direct-seeded rice. Field experiments were conducted involving 12 treatments, consisting of four N-til and three seeding rates in 2017, and eight treatments combining seeding rate, N-til, and N-PI in 2020. @@@ RESULTS: Linear regression analysis revealed that the tiller number at panicle initiation (TILPI) was predominantly influenced by ASD and N-til. The determination coefficients (R-2) of the regression models ranged from 0.887 to 0.936 across the four-season experiments. The results indicated that N-til could be determined accurately using ASD and the target maximum tiller number. Similarly, grain yield was influenced significantly by the N uptake at panicle initiation (NUPPI) and N-PI, with R-2 of 0.814 and 0.783 in the early and late seasons of 2020, respectively. This suggested that N-PI could be calculated based on NUPPI and the target grain yield. @@@ CONCLUSION: The findings offer a quantitative method for establishing N topdressing rates for tillering and panicle development, relying on the monitoring of actual seedling density and plant N status in direct-seeded rice production.

• Institution
  广东省农业科学院