播期对水稻机械旱直播产量及稻米品质的影响

为探明机械旱直播水稻在长江中游地区较优的播种时期,本试验以广两优476(GLY476)和黄华占(HHZ)两个水稻品种为材料,采用机械旱整旱播模式,设置5个播期处理,即S1(5月10日)、S2(5月17日)、S3(5月24日)、S4(5月31日)、S5(6月7日),考察播期对水稻产量形成、光温资源利用率、稻米品质形成的影响。结果表明,广两优476和黄华占的产量均随着播期的延后呈先升高后降低的趋势,其中S4处理的产量最高,该处理下两水稻品种产量分别较S1高15.8%和27.4%。随着播期的延后,光能生产效率呈现逐渐增加的趋势,广两优476在S5处理下的光能生产效率最高,两年平均值为0.432 g·MJ^-1, 黄华占以S4处理最高,两年平均值为0.421 g·MJ^-1;且两品种积温利用率的变化趋势和光能生产效率类似,均以S4处理最高,两者平均值分别为3.72和3.61 kg·℃^-1·d^-1·hm^-2。两品种在S4和S5处理下的整精米率均高于其他播期处理;随着播期延后,两品种S5处理的垩白粒率和垩白度分别较各自的最高值下降14.1~17.1个百分点和4.6~7.8个百分点;营养品质变化趋势和外观品质一致,随播期延后呈显著下降趋势,两品种S5处理的平均直链淀粉含量较S1处理降低1.3~1.5个百分点,蛋白质含量降低2.0个百分点。综上所述,长江中游地区机械旱直播水稻5月中上旬播种期使水稻遭遇高温危害,产量和稻米外观品质降低。将播期延迟到5月底至6月上旬,可有效避免高温危害,对提高水稻稳产能力具有重要作用。本研究为明确水稻生产区高温发生规律,调整适宜播种期,提高机械旱直播水稻稳产能力提供了重要参考。

Effects of Sowing Dates on Grain Yield and Rice Quality Under Mechanical Dry Direct Seeding

In order to ascertain the optimal sowing time of mechanical dry direct seeding in the middle reaches of the Yangtze River, two varieties Guangliangyou476 (GLY476) and Huanghuazhan (HHZ) were used as experimental materials under mechanical drought direct seeding mode with five sowing date treatments to investigate the yield formation, utilization of light and temperature resources and rice quality formation. The five sowing date treatments were designed as S1(May 10), S2(May 17), S3(May 24), S4(May 31) and S5(June 7), respectively. Results showed as follows: The yield of GLY476 and HHZ increased gradually with the delay of sowing date, and the yield at S4 was the highest, which was 15.8% and 27.4% higher than S1, respectively. The light energy production efficiency of the two varieties increased gradually with the delay of sowing date. The light energy production efficiency of GLY476 was the highest at S5, and HHZ was the highest at S4, with two-year averages of 0.432 g·MJ^-1 and 0.421 g·MJ^-1, respectively. The accumulated temperature utilization rate of the two varieties was the highest at S4, and the average values of the two varieties were 3.72 and 3.61 kg·℃^-1·d^-1·hm^-2, respectively. Under S4 and S5 treatments, the head rice rate of the two varieties was higher than that of the other sowing dates. With the delay of sowing date, chalkiness grain percentage and chalkiness degree of S5 treatment of two varieties decreased by 14.1~17.1 percentage point and 4.6~7.8 percentage point than that of the highest value, respectively. The change trend of nutritional quality was consistent with that of appearance quality. Amylose content and protein content showed a significant decreasing trend with the delay of sowing date, the amylose content of S5 treatment of two varieties decreased by 1.3~1.5 percentage point than that of S1 treatment and the protein content decreased by 2.0 percentage point. In summary, mechanical dry direct seeding was influenced by high temperature during the sowing period of mid-early May, and the yield and appearance quality of rice decreased in the middle reaches of the Yangtze River. Delaying the sowing date in the end of May to the early June can effectively avoid the high temperature hazards. Therefore, to clarify the occurrence regularity of high temperature in rice production area and adjust the suitable sowing time could provide important reference for improving the ability of stable rice production under mechanical dry direct seeding.