抛秧立苗对水稻光合特性和物质生产的影响

Effect of Seedling Standing and Establishment on Photosynthetic Characteristics and Matter Production of Broadcasted Rice

以超级稻品种南粳44作为试验材料,设置带土直立苗、带土倾斜苗、带土平躺苗、无土平躺苗、无土手栽苗等不同苗姿,研究抛秧立苗及其对水稻光合特性和物质生产的影响。结果表明,1)立苗速度表现为带土倾斜苗>带土平躺苗>无土平躺苗;2)无土平躺苗立苗期叶面积一直下降,其他苗姿秧苗均上升。无土平躺苗、无土手栽苗黄叶比率分别在抛后8d、6d达到最大后开始下降,而带土秧苗均在第2天达到最大后下降,其黄叶比率显著小于无土秧苗。3)立苗期除无土平躺苗栽后2～4d地上干物质量下降外,其他苗姿秧苗栽后都上升,总体增速表现为带土直立苗>带土倾斜苗>带土平躺苗>无土手栽苗>无土平躺苗,立苗期各苗姿秧苗干物质积累量、光合势、净同化率均呈现此趋势;4)水稻各生育时期茎蘖数、群体叶面积指数、有效叶面积率、高效叶面积率、粒叶比、群体光合势、净同化率、阶段物质积累量和群体生长速率均表现为带土直立苗>带土倾斜苗、无土手栽苗>带土平躺苗>无土平躺苗,抽穗期和齐穗后20d剑叶的光合速率亦呈此趋势。带土秧苗活棵立苗比无土秧苗快,直立苗、倾斜苗比平躺苗快,且各生育期的群体生长均具优势。因此,带土秧苗抛栽并提高直立苗比率,能保持较好的光合特性和较高的物质生产能力,利于水稻生长和高产的形成。

The photosynthetic characteristics and matter production of broadcasted rice seedlings were studied to lay a theoretic basis for high-yielding and super-high-yielding cultivation of broadcasted rice with Nanjing 44 as material un- der five treatments including the upright seedlings with soil（USWS）, leaning seedlings with soil（LESWS）, lying seed lings with soil（LASWS）, lying seedlings without soil（LASWTS）, upright seedlings without soil（USWTS）. Results were as follows： 1） Seedling standing speed showed the trend of LESWS〉 LASWS〉 LASWTS; 2） LAI of LASWTS kept decreasing during seedling standing period, while LAI of others increased. The proportions of yellow leaf in LASWTS, USWTS, LESWS, LASWS and USWS reached their peaks at 8 d, 6 d, 2 d, 2 d, 2 d after broadcasting, respectively, and fell thereafter. 3） The dry weight of the above-ground parts all increased except LASWTS during the seedling standing period, with the general increasing rate of USWS^LESWS〉LASWS〉LESWTS〉USWTS. Moreo- ver, the dry matter accumulation, leaf area duration and net assimilation rate under various treatments showed the same trend. 4） Tiller number, population LAI, effective LAI rate, efficient LAI rate, ratio of grain to leaf area, pho- tosynthetic potential, net assimilation rate, dry matter accumulation and growth rate of broadcasted rice at different growth stages all exhibited the trend of USWS〉LESWS, USWTS〉LASWS〉LASWTS, and the net photosynthetic rate at heading stage and 20 d after heading showed the same trend as well. Given these observations, it could be con- cluded that the process of standing and establishment of seedlings with soil was faster than that without soil, and that of upright or leaning seedlings was faster than that of lying seedlings, which could be altributed to their stronger popu- lation growth during the whole period. Therefore, it is needed to choose seedlings with soil and to increase the propor- tion of the upright seedlings in order to obtain better photosynthetic characteristics and higher matter production capa- bility, thus making for preferable plant growth and higher yield formation.