穴基本苗对机插杂交中籼稻群体构建及产量的影响

Effects of seedling number per hole on population quality and yield of mechanical transplanting middle-season Indica hybrid rice

以两系杂交稻为对象,设置1、2、3和4苗·穴-1等4个处理,研究每穴栽插苗数对机插杂交中籼稻群体构建及产量的影响,探明杂交中籼稻机插秧适宜的每穴栽插苗数。结果表明,在拔节及抽穗期,随着每穴栽插苗数的增加,群体叶面积指数及干物质积累量随之增加,但抽穗期以后由于3、4苗·穴-1处理的群体叶面积衰减较快,致使成熟期的叶面积指数及干物质积累量显著减少,成熟期时以2苗·穴-1处理最高。随着每穴栽插苗数的增加,有效穗数随之增加,每穗粒数逐渐减少,但单穴超过2苗时,穗数的增加不再显著;结实率除4苗·穴-1处理显著降低外,其余各处理无显著差异;千粒重受每穴栽插苗数的影响较小,各处理差异不显著。群体颖花量及产量均随着每穴栽插苗数的增加呈现先增加后减少的趋势,均以2苗·穴-1最高。综合来看,机插杂交中籼稻以单穴2苗最为适宜,能使水稻在生育中后期形成高光效群体,保持较高LAI及较强的干物质积累能力,增大群体颖花量从而获得高产。每穴栽插苗数过多不利于群体颖花量的增加,反而易导致减产。

In order to research the effects of seedling number per hole on population quality and yield of me- chanical transplanting middle-season lndica hybrid rice and ascertain the suitable seedling number per hole for mechanical transplanting, a field experiment was conducted with different seedling number per hole （ 1, 2, 3 and 4 seedlings per hole） using a two-line hybrid rice, Liangyou 6236. The results showed that the population LAI and dry matter weight were increased with the increment of seedling number per hole at elongation and heading stage. In maturity stage, the population LAI and dry matter weight of 2 seedlings per hole was highest in all of treat- ments, but 3 and 4 seedlings per hole were decreased significantly because these two treatments population quality was deteriorated and LAI was decreased rapidly after heading stage. The effective panicles number was increased with the increment of seedling number per hole, but there was no significant difference when the seedling number per hole was more than two. There existed a decreasing trend in grain number per pancile. The seed setting rate of 4 seedlings per hole was decreased significantly, but there was no significant difference among other treatments. The difference of 1000-grain weight among the treatments with different seedling number per hole was not significant. The yield increased firstly and then decreased with the increment of seedling number per hole. The yield of 2 seedlings per hole was tiptop, and it was significantly higher than other treatments. The total amount of population spikelets existed the same trend as the yield. The increased of population spikelets was the major rea- son to promote yield. The results indicted that 2 seedlings per hole was suitable for mechanical transplanting middle-season lndica hybrid rice. It can helped rice population to keep higher LAI and stronger dry matter accumula-tion ablity, established a high photosynthetic efficiency population at middle and late stage of rice growth, and increased population spikelets, so the yield was increased significantly. Excessive seedling number per hole was not benefit to the increase of spikelet population, so the yield was decreased significantly.