ABSTRACT

Controlled-release fertilizers (CRFs) are known to improve grain yield and N-use efficiency (NUE) without intensive labor input in crop production. Here, we report field experiments conducted to investigate the effects of different CRFs [polymer coated complex fertilizer (PCCF), polymer-coated urea (PCU), and sulfur-coated urea (SCU)] on leaf characteristics, biomass, N uptake, grain yield, and NUE of machine-transplanted rice in Sichuan, China, from 2016 to 2017. Grain yield, N recovery efficiency (NRE), N agronomic efficiency (NAE), and N partial factor productivity (PFP) were positively correlated with improved leaf characteristics, dry matter accumulation, and N uptake. Total leaf area, leaf area, chlorophyll content, and net photosynthetic rate of the top three leaves, maximum accumulation rate of dry matter, and N accumulation, as well as panicles per m² and spikelets per panicle were increased by CRFs, thereby increasing both grain yield and NUE. Furthermore, compared to PCCF and SCU, PCU promoted relatively higher leaf photosynthetic potential of the top three leaves, which is closely related to increased biomass and N uptake. These effects ultimately improved grain yield, NRE, NAE, and PFP under the PCU treatment. Thus, PCU is effective in enhancing grain yield and NUE in machine-transplanted rice.