关键词: 水稻, 乙烯, 1-氨基环丙烷-1-羧酸, 淀粉体结构, 外观品质, 干湿交替灌溉

Abstract: To elucidate the relationship between ethylene evolution from the grains and the appearance quality of rice, ten rice genotypes were used to deterimine the ethylene evolution rate, 1-aminocylopropane-1-carboxylic acid (ACC) concentration and appearance quality of rice, and the effects of chemical regulators on concentrations of ethylene and ACC were also investigated to verify the roles of ethylene in rice quality. The ethylene evolution rates and ACC concentrations in grains during the mid and late grain filling stages were very significantly and positively correlated with chalky kernel percentage and chalkiness of rice. The varieties with a low ACC concentration in grains exhibited a close amyloplast arrangement and small gap between starch granules, whereas those with a high ACC concentration in the grains showed a loose arrangement and wide gap between the granules. Application of 1 μmol/L ACC to panicles at mid and late grain filling stages significantly loosened amyloplast arrangement and increased chalky kernel percentage, chalky area and chalkiness of rice, and the results were reversed when 1 μmol/L amino-ethoxyvinylglycine, an inhibitor of ACC synthetic enzyme, was applied to panicles. A practice of moderate dry-wet alternate irrigation reduced ethylene evolution and ACC concentration in grains and thereby reduced chalkiness. The results suggested that ethylene and ACC in grains played an important role in the endosperm structure and appearance quality of rice, and the appearance quality would be improved by reducing ethylene and ACC concentrations in grains either through variety breeding, or chemical regulations or cultivation techniques.

Key words: rice, ethylene, 1-aminocylopropane-1-carboxylic acid, amyloplast structure, appearance quality, dry-wet alternate irrigation