Warming night-time temperatures reduce rice quality in East Asia

Researchers from China's Shaanxi Normal University led by Dr Xianfeng Liu have published a new study highlighting a decline in rice quality in East Asia, particularly in China and Japan, brought about by changing temperatures.

Dr Xianfeng Liu and colleagues used data collected over 35 years to explore the patterns in rice quality from Japan and China based on head rice rate (HRR). HRR is a portion of milled rice kernels that retain 75 per cent of their length after milling, during which the husk and bran are removed.

The team explored different climate variables to ascertain which had the greatest effect on HRR, including night-time temperature, daytime temperature, diurnal temperature, daily average temperature, hot days (above 30/35°C), precipitation, precipitation frequency, soil moisture, solar radiation, cloud cover, relative humidity, daytime vapour pressure deficit, transpiration and carbon dioxide concentration.

The scientists found that night-time temperatures affect rice quality. As night-time temperatures rise, a critical threshold for decline begins at 12° Celsius and 18° Celsius for Japan and China, respectively. When flowering and grain growth occur in such conditions, rates of photosynthesis and starch accumulation in the grain decrease, leading to lower rice quality as more grains are susceptible to breakage. The researchers have also revealed that the negative impact of climate change on rice quality is going to be harsher in China than in Japan.

(ISAAA/wi)

Reference:

Xianfeng Liu, Philippe Ciais, David Makowski, Juan Liang: Warming Leads to Lower Rice Quality in East Asia; First published: 03^rd November 2024; Geophysical Research Letters, November 2024. https://doi.org/10.1029/2024GL110557