Improving grain yield and nitrogen use efficiency of direct-seeded rice with simplified and nitrogen-reduced...

Enhancing grain yield and nitrogen use efficiency (NUE) of rice is of great importance for sustainable agricultural development. Little effort has been made to increase grain yield and NUE of direct-seeded rice under the double-cropping system in South China. Field trials were conducted during 2018-2020 with four treatments, including nitrogen-free, farmers' fertilization practice (FP), 'three controls' nutrient management (TC), and simplified and nitrogen-reduced practice (SNRP).

Grain yield under SNRP averaged 6.46 t ha^-1 during the three years and was 23.0% higher than that of FP but comparable to that of TC. Recovery efficiency (RE_N ), agronomic efficiency (AE_N ), and partial factor productivity (PFP_N ) of nitrogen under SNRP increased by 12.0-22.7%, 159.3-295.0% and 94.6-112.5% respectively compared with FP. Harvest index and sink capacity increased by 7.3-10.8% and 14.9-21.3% respectively. Percentage of productive tillers (PPT) and biomass after heading increased by 24.0% and 104.5% respectively. Leaf nitrogen concentration at heading and nitrogen accumulation after heading increased by 16.3% and 842.0% respectively. Grain yield was positively correlated with PPT, sink capacity, harvest index, biomass and nitrogen accumulation after heading, RE_N , AE_N , and PFP_N .

Grain yield and NUE under SNRP were superior to those under FP and comparable to those under TC. Increase in sink capacity, higher PPT, more biomass and nitrogen accumulation after heading, and greater harvest index were responsible for high grain yield and NUE in SNRP with reduced nitrogen fertilizer and labor input. SNRP is a feasible approach for direct-seeded rice under a double-cropping system in South China. © 2023 Society of Chemical Industry.