Wang Danying, Chen Song, Wang Zaiman, Ji Chenglin, Xu Chunmei, Zhang Xiufu, Chauhan Bhagirath Singh
State Key Laboratory of Rice Biology, China National Rice Research Institute, Hangzhou, Zhejiang, China.
Key Laboratory of Key Technology on Agricultural Machine and Equipment, South China Agricultural University, Guangzhou, Guangdong, China.
PLoS One. 2014 Oct 7;9(10):e109417. doi: 10.1371/journal.pone.0109417. eCollection 2014.
Mechanical hill direct seeding of hybrid rice could be the way to solve the problems of high seeding rates and uneven plant establishment now faced in direct seeded rice; however, it is not clear what the optimum hill seeding density should be for high-yielding hybrid rice in the single-season rice production system. Experiments were conducted in 2010 and 2011 to determine the effects of hill seeding density (25 cm×15 cm, 25 cm×17 cm, 25 cm×19 cm, 25 cm×21 cm, and 25 cm×23 cm; three to five seeds per hill) on plant growth and grain yield of a hybrid variety, Nei2you6, in two fields with different fertility (soil fertility 1 and 2). In addition, in 2012 and 2013, comparisons among mechanical hill seeding, broadcasting, and transplanting were conducted with three hybrid varieties to evaluate the optimum seeding density. With increases in seeding spacing from 25 cm×15 cm to 25 cm×23 cm, productive tillers per hill increased by 34.2% and 50.0% in soil fertility 1 and 2. Panicles per m2 declined with increases in seeding spacing in soil fertility 1. In soil fertility 2, no difference in panicles per m2 was found at spacing ranging from 25 cm×17 cm to 25 cm×23 cm, while decreases in the area of the top three leaves and aboveground dry weight per shoot at flowering were observed. Grain yield was the maximum at 25 cm×17 cm spacing in both soil fertility fields. Our results suggest that a seeding density of 25 cm×17 cm was suitable for high-yielding hybrid rice. These results were verified through on-farm demonstration experiments, in which mechanical hill-seeded rice at this density had equal or higher grain yield than transplanted rice.
杂交水稻机械穴直播可能是解决当前直播水稻面临的播种量高和秧苗立苗不均问题的途径；然而，在单季稻生产系统中，高产杂交水稻的最佳穴播密度尚不清楚。2010年和2011年进行了试验，以确定穴播密度（25厘米×15厘米、25厘米×17厘米、25厘米×19厘米、25厘米×21厘米和25厘米×23厘米；每穴3至5粒种子）对两个不同肥力田块（土壤肥力1和2）中杂交品种内2优6的植株生长和籽粒产量的影响。此外，在2012年和2013年，对三个杂交品种进行了机械穴播、撒播和移栽的比较，以评估最佳播种密度。随着播种间距从25厘米×15厘米增加到25厘米×23厘米，土壤肥力1和2中每穴有效分蘖分别增加了34.2%和50.0%。在土壤肥力1中，每平方米穗数随播种间距增加而下降。在土壤肥力2中，播种间距在25厘米×17厘米至25厘米×23厘米范围内时，每平方米穗数没有差异，但在开花期观察到顶部三叶面积和单茎地上部干重下降。在两个土壤肥力田块中，播种间距为25厘米×17厘米时籽粒产量最高。我们的结果表明，25厘米×17厘米的播种密度适合高产杂交水稻。这些结果通过田间示范试验得到了验证，在该试验中，这种密度的机械穴播水稻的籽粒产量与移栽水稻相当或更高。
