结实期动态温度对软米粳稻产量和品质的影响

以软米粳稻南粳46和苏香粳100为供试材料,通过人工气候室设置梯度温度模拟水稻灌浆结实期温度动态递减变化,设置结实期动态高温、常温和低温3个处理,以室外温度作为对照(CK),研究结实期动态温度对软米粳稻产量及其构成、干物质生产和稻米品质的影响。结果表明,与常温处理相比,结实期低温处理显著降低水稻产量,而高温处理并未减产。结实期温度主要通过影响结实率和千粒重而影响产量,高温处理下千粒重呈减少趋势;低温处理显著降低了结实率,但千粒重显著增加。对物质生产而言,结实期低温处理显著提高茎鞘干物质重及其比例,降低穗部干物质重及其比例,减少总干物质积累量。对稻米品质而言,结实期高温和低温处理均降低精米率和整精米率,导致加工品质变劣;高温处理增加垩白粒率和垩白度,而低温处理减少垩白粒率和垩白度,但品种间变化不一;随着结实期温度升高,稻米蛋白质含量增加,直链淀粉含量降低;高温和低温处理下稻米胶稠度均变短和米饭食味值下降。因此,结实期温度过高或过低都不利于软米粳稻加工和食味品质改善。

Effects of Nitrogen Fertilizer on Grain Quality of Different Cultivars of Japonica Rice

Three cultivars of Japonica rice:hybrid Japonica rice,inbred Japonica rice and soft Japonica rice,were used to study the effects of recommended nitrogen fertilizer on grain quality including milling,appearance,nutrition,cooking and eating quality,pasting property and their relationships in direct seeding rice.Recommended nitrogen fertilizer improved the brown rice rate,the milled rice rate,and the protein content;increased the chalky grain rate and the chalkiness,and reduced the amylose content,palatability and pasting viscosity.The nitrogen fertilizer caused the appearance,the cooking and the eating quality to deteriorate.Lower amylose content and protein content were found in soft Japonica rice compared to those in hybrid Japonica or inbred Japonica rice under the condition of the recommended rate of nitrogen fertilizer,contributing to high cooking and eating quality.Correlation analysis indicated that palatability was negatively correlated with amylose content,protein content,hardness and gelatinization temperature,and was positively correlated with stickiness,peak viscosity and breakdown.Therefore,the decreased amylose and protein content of the soft Japonica rice cultivar planted under the condition of the recommended rate of nitrogen fertilizer is beneficial to achieving high taste quality.