杂交稻低播量精准条播育秧机插提高群体均匀度和产量的效应分析

【目的】明确杂交稻低播种量下精准条播（precision drill sowing,PS）育秧提高机插群体均匀度和产量的效应,创建杂交稻毯苗稀播少本机插理论与技术。【方法】选用籼粳杂交稻甬优1540为供试品种,在余杭区崇化村和富阳区中国水稻研究所试验基地开展试验。以传统撒播（broadcast sowing,BS）育秧机插为对照,设计标准9寸秧盘横向取秧18穴,纵向取秧40穴的精准条播育秧机插方式,机插每穴播种量为2.5粒（T₁,43.2 g/盘）,3.5粒（T₂,60.5 g/盘）,4.0粒（T₃,69.1 g/盘）,考察种子分布均匀度、秧苗素质、机插质量、机插群体干物质生产、有效穗数均匀度及产量结构的变化。【结果】（1）与BS相比,PS提高了种子分布均匀度。（2）PS显著提高了秧苗素质,增加了秧苗的干物质积累和秧苗均匀度。与BS相比,不同播量下PS的秧苗均匀度平均提高47.5%,播量越低,PS对秧苗均匀度的提高作用越明显。（3）与BS相比,PS的机插漏秧率平均降低了8.9个百分点。同时PS使机插苗数均匀度平均提高了87.8%,其中T₂处理PS机插每穴2—3苗比例最高,机插苗数均匀度最好。（4）PS通过提高机插群体的分蘖高峰苗数进而提高有效穗数,在不同播种量下,PS机插群体的有效穗数平均增加6.7%,同时使有效穗数均匀度提高40.2%,其中T₂处理下PS机插群体的有效穗数和有效穗数均匀度最高,同时PS提高了机插群体的叶面积指数和干物质积累。（5）不同播量下PS通过增加机插群体的有效穗数使产量平均增加9.0%,其中T₂处理产量最高,随着播量的增加,PS机插相对于BS机插的产量增加幅度下降,同时机插苗单株对产量的贡献率降低。（6）相关性分析表明,机插群体有效穗数均匀度和叶面积指数、干物质积累及水稻产量呈显著正相关。【结论】精准条播育秧机插通过提高种子分布均匀度,降低机插漏秧率,提高机插苗数均匀度,进而提升了杂交稻机插群体均匀度和产量,是在毯苗条件下实现杂交稻低播量丰产种植的有效方式。

Beneficial Effects of Precision Drill Sowing with Low Seeding Rates in Machine Transplanting for Hybrid Rice to Improve Population Uniformity and Yield

【Objective】 The aim of this study was to clarify the beneficial effect of precision drill sowing (PS) in machine transplanting for improving the population uniformity and yield of hybrid rice under low seeding rate, and to establish the theory and technology for machine transplanting with sparse sowing and fewer seedling in machine transplanting with flat seedling of hybrid rice. 【Method】 Indica-japonica hybrid rice ‘Yongyou 1540’ was used in this study, and the experiment was conducted at Chonghua country (Yuhang district) and experimental base of China National Rice Research Inistitute (Fuyang district) at the same time. PS was layout set at 18 horizontal hills×40 vertical hills in the standard seedling tray for machine transplanting. The sowing amount per hill in seedling tray was set as 2.5 seeds (43.2 g/tray, T₁), 3.5 seeds (60.5 g/tray, T₂), and 4.0 seeds (69.1 g/tray, T₃), and the same seeding rates in traditional broadcast sowing (BS) for machine transplanting were set as the control. Then, the seed distribution, seedling quality, machine planting quality, dry matter accumulation in rice population, the uniformity of the number of productive tillers and yield formation were investigated. 【Result】(1) Compared with BS, PS improved the uniformity of seed distribution in seedling tray. (2) PS significantly enhanced rice seedling quality, and increased the dry matter accumulation and uniformity of seedling. PS increased the seedling uniformity by 47.5% on average among different seeding rates than that under BS, which presented a more beneficial effect with low seeding rates. (3) Compared with BS, PS reduced the missing hill percent in machine transplanting by 8.9 percentage point on average, and PS enhanced the uniformity of seedling number transplanted per hill by 87.8% on average, meanwhile, the percentage of hills with 2-3 seedling transplanted was the highest at T₂ under PS. (4) PS increased the number of tillers at tillering peak stage to increase the number of productive panicles in rice population. Among the different seeding rate treatments, PS increased the number of productive tillers by 6.7% on average, meanwhile, which enhanced the uniformity of the number of productive tillers by 40.2%, in which T₂ presented the highest productive tillers and productive tillers uniformity, meanwhile PS enhanced the leaf area index and dry matter accumulation of rice population. (5) PS enhanced the rice yield by 9.0% on average compared with BS by increasing in the number of productive tillers, in which T₂ presented the highest yield. With the increasing of seeding rate, the increasing rate of yield under PS in contrast to BS presented a reduction tendency, while a decreasing was observed in the contribution rate of machine-transplanted seedlings to yield. (6) Correlation analysis showed that the population uniformity of the number of productive tillers positive correlated to leaf area index, dry matter accumulation and rice yield. 【Conclusion】Precision drill sowing in machine transplanting improved the uniformity of seed distribution, reduced the missing hill percent, increased the uniformity of seedling transplanted per hill, therefore contributed to enhance the rice population uniformity and yield. Precision drill sowing was an effective method to achieve higher yield with flat seedling in machine transplanting under low seeding rates of hybrid rice.