Response of rice quality to climate warming: a meta-analysis

Context

Global warming strongly influences rice quality, and despite numerous studies attempting to clarify its effects, individual experiments often demonstrate contradictory outcomes. A comprehensive evaluation of the impacts of global warming on rice quality has remained elusive.

Objective

This study aims at quantifying the changes in several important rice quality indicators under increasing temperatures and further elucidate the significant impacts on rice quality under global warming. We also analyze the key environmental factors determining the impacts of climate warming on rice quality.

Methods

A meta-analysis was conducted on a global rice quality database compiled from 58 published studies containing experimental observations from 901 sets of control and treatment means. These experimental records were used to qualify the effect of climate warming on rice quality, including four key aspects: appearance, milling, eating and cooking, and nutrition.

Results

Warming significantly increased indicators of deteriorated grain appearance (chalky rate by 84.24 %, chalkiness by 98.69 %), and decreased milling quality indicators (brown rice rate by −2.17 %, milled rice rate by −3.41 %, and head rice rate by −13.37 %), both contributing to a decline in rice quality under warming. Increased temperature also significantly reduced amylose content by −7.81 % and slightly increased protein content by 5.22 %. The difference between treatment and control temperature emerged as the most crucial factor explaining the effect of warming on brown rice rate, milled rice rate, and head rice rate. Soil types had important effects on chalky rate and chalkiness, while nitrogen content was the most important factor in controlling amylose content.

Conclusions

Global warming has a significant effect on rice quality, but the specific response degree of each quality indicator depends on the quality traits considered and the regulation of key environmental factors.

Significance

Our findings provide convincing global evidence of a warming impact on rice quality, underlining the importance of integrating grain quality when assessing the effect of climate change on global food security.