根外喷施硫酸镁对水稻淀粉品质的影响

选用寒地穗重型超级稻品种松粳9号、穗数型高产品种龙稻11号与优质品种龙稻18号为试验材料,盆栽条件下通过灌浆成熟期喷施硫酸镁和齐穗期增施氮肥处理及对照处理,系统比较根外喷施硫酸镁对水稻淀粉品质性状、叶片碳氮代谢相关酶活性和基因转录表达量及根系活力变化等的影响。结果表明,灌浆成熟期喷施硫酸镁显著降低稻米蛋白质含量,提高稻米蒸煮食味品质,而齐穗期增施氮肥处理使稻米蛋白质含量提高而降低蒸煮食味品质,硫酸镁处理通过降低稻米蛋白质含量提高稻米黏性和食味品质;灌浆成熟期喷施硫酸镁或齐穗期增施氮肥均显著提高灌浆成熟期叶片全氮含量和叶绿素含量以及灌浆各时期叶片Rubisco亚基基因转录表达量,增强水稻根系活力,促进根系氮素吸收,调控灌浆不同时期叶片和籽粒GS活性,但喷施硫酸镁效果显著优于增施氮肥;叶片全氮含量与GS活性间呈极显著负相关,与叶绿素含量、伤流液含氮化合物总量及Rubisco各亚基基因mRNA表达量呈极显著正相关。减氮同时在灌浆成熟期根外喷施硫酸镁是提高水稻产量和蒸煮食味品质的有效途径,研究为阐明根外喷施硫酸镁对水稻淀粉品质形成的影响和提高优质绿色水稻栽培技术水平提供理论依据。

Effect of applying magnesium sulfate on rice starch quality

Heavy panicle type and super high-yield japonica cultivar Songjing9 and multi-panicle type and high yield cultivar Longdao11 and Longdao 18 in cold region were used in this pot experiment.The treatments of magnesium sulfate at filling stage, nitrogen application at full heading stage and control were conducted to systematically study the effect of magnesium sulfate on rice starch quality,activities of nitrogen-carbon metabolism key enzymes and related gene expression in leaf, and root system activities. The results showed that application of magnesium sulfate at filling stage significantly decreased protein content in grain and increased cooking and eating quality, while nitrogen application at full heading stage increased protein content in grain and decrease cooking and eating quality which indicated that magnesium sulfate improves rice viscosity and eating quality through decreasing protein content in grain. Both application of magnesium sulfate at filling stage and nitrogen application at full heading stage significantly enhanced leaf total nitrogen content, chlorophyll content and expression level of Rubisco subunit genes, increased root system activities, promoted nitrogen accumulation in root system, thus regulated the activities of leaf and grain glutamine synthetase(GS), during different filling stages, however, application of magnesium sulfate was better than that of nitrogen fertilizer.Moreover, leaf total nitrogen content was extremely significant negative correlation with GS activities,extremely significant positive correlation with chlorophyll content, the total nitrogen compounds in bleeding fluid and expression level of Rubisco subunit genes. Therefore, reducing nitrogen and applying magnesium sulfate at filling stage was a effective path to improve rice yield and cooking and eating quality, so as to fulfill green-quality rice production. This research built the theoretical basis for elucidation of magnesium sulfate on rice starch quality formation and construction of rice green-quality cultivation technology.