中文摘要：

为阐明超级稻产量形成机制，以4个超级稻品种【两优培九和II优084（杂交籼稻）、淮稻9号和武粳15（粳稻）】为材料，2个高产品种【汕优63（杂交籼稻）和扬辐粳8号（粳稻）】为对照，观测了不同生育时期叶片光合性状和根系生理性状的变化特点。结果表明，4个超级稻品种的平均总颖花量和产量较两个对照品种分别高出43．5％和16．1％，但超级稻的结实率较对照品种低15．3个百分点。超级稻品种在生育前期叶片中叶绿素a含量、叶绿素b含量、总叶绿素含量、类胡萝卜素含量、光合速率、蒸腾速率、气孔导度和根系中单位干重根系活力、每株根系活力、总根系吸收面积、活跃吸收面积和比表面积均高于对照品种，而在生育后期以上性状指标下降速率大于各自对照品种，直至齐穗后20d前以上性状指标均小于各自对照品种。说明超级稻强大的产量库容与其生育前中期较强的叶片光合能力和较好的根系生理性状密切相关，生育后期叶片光合能力和根系生理活性下降快导致其结实率下降，从而限制了其产量潜力的发挥。提高生育后期特别是结实后期根系生理活性是进一步提高超级稻产量的重要途径。

英文摘要：

The success in super rice breeding has been considered as a great progress in rice production in China. This study aimed to understand the mechanism underlying the yield formation of super rice. Four super rice cultivars, Liangyoupeijiu and IIyou 084 （indica hybrids）, Huaidao 9 and Wujing 15 （japonica）, and two elite check cultivars, Shanyou 63 （indica hybrids） and Yangfujing 8 （japonica）, were grown in field. Leaf photosynthetic characteristics and root physiological traits were investigated at different growth stages. The results showed that average total spikelet number and grain yield of the four super rice cultivars were 43.5% and 16.1%, respectively, more than those of two elite check cultivars, but the seed-setting rate of the four super rice culti- vars was low 15.3% than that of the two elite check cultivars. The contents of chlorophyll a and b, total chlorophyll （a＋b） and carotenoid, photosynthetic rate, transpiration rate, stomatal conductance of leaves, and specific root oxidation activity, root oxida- tion activity per plant, total root absorption area per plant, root active absorption area, specific surface area were higher in super rice than in elite check cultivars at earlier growth stages, while those traits decreased more quickly in super rice cultivars than in check cultivars at latter growth stages, and lower in super rice than in check cultivars up to 20 days after full heading. The results suggest that stronger leaf photosynthetic capacity and root activity during the early and mid-growth periods contribute to greater yield sink capacity of super rice, while the rapid decline of leaf photosynthetic capacity and root physiological activity at the late growth stage results in poor grain filling, and consequently, limits yield potential of super rice. Enhancing root physiological ac- tivity at late growth stage, especially during the grain filling period would be an important approach for super rice to further in- crease grain yield.