Optimized nitrogen fertilizer application strategy improves grain yield and quality of high-quality late indica rice under field ambient warming

Abstract

Post-heading high temperatures occurred frequently in late indica rice regions in southern China recently, but the effects of high post-heading temperature on rice yield and quality under nitrogen application including nitrogen management (NM) and panicle fertilizer (NPF) were still unclear. Therefore, the grain yield and quality of late indica rice cultivars were compared in 2020 (ambient temperature) to 2019 (warming 2.3 °C) and 2021 (warming 3.5 °C). The results showed that moderate NPF can increase the yield, protein content (PC) and brown rice rate, and reduce the chalkiness and amylose content (AC) under naturally high temperatures. The proportion and application of NPF values higher than 22.5%, 36 kg·ha−1 effectively improved grain yield, processing and appearance qualities, and PC, while reducing AC of late indica rice under natural warming. The temperature parameters, AC and PC during the total growth period could explain 81.7%, 90.7% and 89.6% of the variation in rice processing qualities, appearance qualities and gel consistency, respectively. The finding demonstrated that the optimum Tmean of improving rice yield and quality was 29.0 °C before heading and 21.1 °C after heading under NM, and 28.6 °C before heading, and 22.9 °C after heading under NPF. This study suggested that optimizing nitrogen management strategies under future climate warming conditions can synergistically increase indica rice yield and quality.