Rice grain-filling characteristics under elevated air temperature in a temperate region

Abstract

Future climate change accompanied by global warming is expected to change rice growth environments and causes detrimental effects on yield formation processes, leading to reduction of rice yield and quality in many regions. This study was performed to evaluate the grain-filling responses to elevated air temperature above ambient during the grain-filling period after heading in a temperate region (37.27 °N, 126.99 °E; Suwon, South Korea). Six rice cultivars differing in maturity were grown under ambient air temperature conditions before being transferred at the initial heading stage to the plastic houses which were temperature controlled to the targets of ambient temperature (AT), AT + 1.5 °C, AT + 3.0 °C, and AT + 5.0°C. Grain-filling duration and maximum grain weight were estimated by fitting the time course change of grain weight to a logistic function. Grain-filling duration was not statistically different among temperature elevation treatments in all the tested varieties, while maximum grain weight was decreased with the increase in air temperature above ambient during the grain-filling stage. These results imply that the decreased grain-filling duration would not be the major factor for the grain weight decrease under higher temperatures than the current ambient temperature, whereas it would be attributed to the reduced supply of assimilates to the grain.