Effect of long-term fertilization on the growth and yield formation of early rice

Abstract

Fertilization is crucial for rice growth and yield formation. We conducted a 42-year long-term fixed experiment in southeast China, examining nine treatments. This study focused on three treatments: a combination of chemical N, P, and K (NPK), a double dose of chemical N, P, and K (HNPK), and a combination of chemical fertilizer and organic fertilizers (NPKM). We assessed rice yield, yield components, tiller dynamics, dry matter accumulation, chlorophyll dynamics, and leaf transcriptome at the full heading stage. Results indicated that early rice yield followed the order of NPKM > HNPK > NPK. Compared to NPK, HNPK and NPKM significantly increased spikelet density, effective panicles, and 1000-grain weight, while also promoting tillering. NPKM and HNPK significantly enhanced dry matter accumulation from the full heading stage to the filling stage and facilitated the transport of dry matter from leaves and stems to spikes during the filling to mature stages. NPKM consistently maintained higher chlorophyll content than HNPK and NPK at all stages, significantly reducing chlorophyll decline from the full heading stage to the filling stage. Correlation analysis revealed a significant positive relationship between yield and both chlorophyll content and dry matter accumulation under long-term fertilization. There was also a significant negative correlation between yield and chlorophyll reduction from the full heading stage to the filling stage. Differential gene expression analysis at the full heading stage showed significant enrichment in photosynthesis and plant senescence metabolism pathways among different fertilization treatments. Overall, the combined application of chemical and organic fertilizers significantly increased early rice yield by enhancing tillering, regulating photosynthesis and senescence-related gene expression, boosting dry matter accumulation from the full heading stage to the filling stage, and improving dry matter transport to spikes from the filling to the mature stage.