Yield and quality responses of two indica rice hybrids to post-anthesis asymmetric day and night open-field warming in lower reaches of Yangtze River delta

Abstract

Rice production is challenged by asymmetric rise in day and night temperatures. Efforts are required to improve our understanding about the impact of climate change induced asymmetrical fluctuations in temperature extremes. This paper presents first effort to investigate effect of post-anthesis asymmetric daytime, nighttime and diel warming, as predicted under low emission scenario (B1) of Intergovernmental Panel on Climate Change (IPCC), on yield and milling quality of two indica rice hybrids, Teyou-559 (susceptible) and Shanyou-63 (resistant), differing in response to temperature. Four canopy warming regimes, ambient reference (AT), daytime warming (HDT, +1.3°C), nighttime warming (HNT, +2.7°C), and diel warming (HDNT, +1.3/2.7°C), were imposed through free-air temperature enhancement (FATE) facility using infrared heaters. Both hybrids responded differentially to daytime, nighttime and diel warming and shortened grain filling duration (1–2 days), reduced grain yield and 1000-grain weight were determined. Nighttime warming caused more deleterious impact than daytime or diel warming. These results indicate that the daytime (−4%), nighttime (−7%) and diel (−6%) warming under low emission scenario will have differential effects on rice production. This reduction is mainly due to differential decrease in grain weight. Resistant Shanyou-63 proved to be more susceptible to daytime warming, while susceptible Teyou-559 was affected more by nighttime and diel warming. Diel warming had significantly negative influence on head rice recovery of both cultivars, with slight inter-annual variation, followed by nighttime and daytime warming. Reduction in head rice recovery indicated the breakage of rice kernels. Daytime warming had greater effect on grain yield 1000-grain weight than nighttime warming considering per 1°C warming. Effect of warming on yield and quality can be attributed to reduction in translocation of photosynthates during grain filling, resulting in reduced grain filling, grain weight and development of chalky kernels. Further studies are required to elucidate mechanism underlying differential response to asymmetric warming and to suggest appropriate management practices to minimize yield loses.