钵苗机插密度对不同类型水稻产量及光合物质生产特性的影响

在南方稻区大面积应用的常规粳稻、杂交粳稻、杂交籼稻中各选2个代表性品种为材料,根据钵苗机插不同穴距设置高、中、低3种密度处理,并以常规塑盘毯状育苗机插为对照,比较研究钵苗机插不同密度对水稻光合物质生产及产量的影响。结果表明,钵苗机插水稻各生育期茎蘖数随栽插密度的降低而减小,剑叶叶绿素含量及光合特征参数变化则呈相反趋势。单茎干物重、茎叶转运及净同化率均以低密度最大,中密度次之,高密度最低。常规粳稻抽穗后干物质积累量、群体生长率和光合势等指标随密度的降低极显著减小,成熟期群体干物重高密度平均较中、低密度分别高3.0%和7.6%,高、中密度的最终产量分别较对照增产11.8%和8.9%,低密度与CK无显著差异。杂交稻各群体生长指标以中密度最大,高密度实产介于中、低密度之间,杂交籼稻高密度处理与低密度相当,显著低于中密度。

Effect of Planting Density on Yield and Photosynthate Production Characteristics in Different Types of Rice with Bowl Mechanical-Transplanting Method

In order to study the impacts of planting density of nutrition bowl seedling mechanical-transplanting rice on photosynthate production and yield, a field experiment was conducted using conventional japonica rice Nanjing 44, Wuyunjing 24, japonica hybrid rice Yongyou 8, Changyou 5, and indica hybrid rice Liangyoupeijiu, II you 084 which have been widely grown in the southern China with high, medium and low density treatments of the different hill spacings in nutrition bowl mechanical-transplanting (12 cm, 14 cm, and 16 cm), and the conventional blanket seedling mechanical- transplanting as control. The results showed that, the tiller number of nutrition bowl mechanical-transplanting rice in the critical period and the declining rate of leaf area after heading decreased with the reduction of planting density, the productive tiller percentage increased significantly, while the chlorophyll content of flag leaf and the photosynthetic parameters presented the opposite trend. The dry matter weight of single stem, the matter transportation amount in stem and leaf, and the net assimilation rate were all the highest in the low density treatment, the medium in medium density treatment, and the lowest in high density treatment. After heading, the dry matter accumulation, population growth rate, photosynthetic potential and other indicators of conventional japonica rice decreased significantly with the reduction of planting density. The average dry matter weight of population in high density treatment at maturity stage was 11.8% and 8.9% higher than that in medium density treatment and low density treatment respectively, and without significant difference between the low density treatment and control. For the population growth indexes of hybrid rice, medium density treatment was the highest, and there was no significant difference between high density treatment and low density treatments. The actual yield in high density treatment was between that in medium and low density treatments, besides, that in high density treatment of indica hybrid rice was equal to that in low density treatment, but significantly lower than that in medium density treatment by 3.0%. Consequently, for conventional japonica rice and varieties with big panicle and numerous grain in agricultural production, the hill spacing of 12 centimeters could reach high yield, while for hybrid rice and big heavy panicle varieties, increasing the hill spacing appropriately was helpful to improve the percentage of spike-forming tillers and develop the advantage of panicle type, resalting in high yielding and high efficiency production.