Abstract:

To investigate the effects of side-deep fertilization on rice biomass production, yield formation, and grain quality, in this experiment, no nitrogen fertilizer (0N) was set as the blank control, and the split application of 300 kg/hm² conventional fertilizer was set as the conventional control (CK). Two main plots were established: side-deep application of slow-release blended fertilizer and side-deep application of conventional compound fertilizer. Within these main plots, three nitrogen application gradients (240, 270 and 300 kg/hm²) were set as subplots. Additionally, two modes with a 10% nitrogen reduction were included: a one-time side-deep application of slow-release blended fertilizer (ODS18), and a one-base-one-topdressing side-deep application of conventional fertilizer (DSC18), resulting in a total of eight treatments. The results showed that compared with the control, side-deep fertilization did not reduce the number of tillers even when nitrogen application was reduced by 10%-20%; instead, it promoted tillering, with tiller numbers increased by 4.5% to 56.5% and effective panicles increased by 7.5% to 22.1%. Under side-deep fertilization, plant height increased across all nitrogen application levels, and the leaf area index significantly improved, favoring early-stage rice growth. It also significantly enhanced the photosynthetic potential, agronomic nitrogen use efficiency, and partial factor productivity of nitrogen fertilizer, with side-deep application of slow-release blended fertilizer outperforming side-deep application of conventional compound fertilizer. The highest photosynthetic potential and nitrogen use efficiency were achieved with slow-release blended fertilizer at a nitrogen application rate of 270 kg/hm². Under reduced nitrogen application and fewer fertilization events, side-deep fertilization effectively increased the number of effective panicles without reducing the seed-setting rate or 1000-grain weight, which were the main reasons for the yield increase. The yield of side-deep application of slow-release blended fertilizer with a 20% nitrogen reduction was close to that of the control, while a 10% nitrogen reduction increased yield by 14.5%, demonstrating significant potential for yield enhancement and efficiency improvement. The effects of side-deep fertilization on rice quality were complex, which could increase protein content but had minimal impact on processing and appearance quality. The head rice rate under side-deep application of compound fertilizer was higher than that of the control, and one-time deep side application of slow-release blended fertilizer significantly improved the head rice rate and reduced amylose content. In summary, side deep fertilization is an efficient fertilization method, which can stabilize or even increase the yield under the condition of reducing the amount of nitrogen fertilizer by 10% -20% and reducing the number of fertilization times by 2-3 times. In particular, the treatment of side deep application of slow-release blended fertilizer with 20% nitrogen reduction can stabilize the processing quality and appearance quality without reducing the yield, and has the value of large-scale promotion.

Key words: side-deep fertilization, reduced and simplified, biomass production, yield, quality