Physiological and biochemical mechanisms of taste decrease in high tasting japonica rice under warming at growth...

Area of Science:

• Agricultural Science
• Plant Physiology
• Food Science

Background:

• Japonica rice is a staple crop valued for its taste.
• Cool regions are experiencing climate warming, potentially affecting rice quality.
• Understanding rice taste response to warming is crucial for food security.

Purpose of the Study:

• To investigate the effects of simulated climate warming on the taste quality of japonica rice.
• To identify critical growth stages sensitive to warming for taste alteration.
• To elucidate the underlying biochemical mechanisms influencing taste quality under warming.

Main Methods:

• Field warming treatments applied at six distinct rice growth stages over two years.
• Analysis of milled rice taste value, including correlations with physicochemical properties.
• Biochemical assays to assess carbon and nitrogen metabolism, enzyme activities (GOT, GPT, AGPP, SSS, SBE, DBE, GBSS), and content of starch, amylopectin, amylose, and protein.

Main Results:

• Warming treatments negatively affected rice taste value, with the most significant impacts observed during the whole growth stage (T2) and grain-filling stage (T3).
• Taste value positively correlated with amylopectin, total starch, peak viscosity (PV), and breakdown (BD); negatively correlated with protein, amylose, hot pasting viscosity (HPV), and setback (SB).
• Warming increased nitrogen metabolism, leading to higher protein and lower amylopectin content, thus reducing taste quality.

Conclusions:

• Climate warming poses a significant threat to the taste quality of japonica rice in cool regions.
• The grain-filling and whole growth stages are particularly vulnerable to warming-induced taste degradation.
• Altered carbon and nitrogen metabolism, specifically increased protein and decreased amylopectin, are key drivers of reduced rice taste under warming conditions.