超级稻上部叶片光合能力的研究

Study on the photosynthetic capacity in upper leaves of super rice

2003年,以超级杂交稻组合GD-1S/RB207为材料,研究了水稻上部叶片的光合能力。结果表明,水稻剑叶中部的净光合速率(Pn)最高,上部次之,基部最低,并且叶片不同区段的气孔导度(Gs)和羧化效率(CE)呈现同样的变化趋势。对于不同叶位的叶片而言,Pn,Gs和CE自上而下逐渐降低。相关分析表明,Pn与CE的相关性都远高于Pn与Gs的相关性,而且Pn与胞间CO2浓度(Ci)呈负相关。因此得出结论:水稻叶片光合能力高低的决定因素是Rubisco的羧化活性而不是气孔导度。另外,虽然不同分蘖剑叶的Pn与Gs呈正相关,但是与Ci呈负相关,也说明气孔导度不是叶片光合能力高低的决定因素。

Portable photosynthetic gas analysis system LI-COR 6400 was used to measure in situ of net photosynthetic rate (Pn), stomatal conductance (Gs), and RuBP carboxylation efficiency (CE) at the grain-filling stage. A correlation analysis was made to explore the determinant of the photosynthetic capacity in rice leaf. In flag leaf,Pn in middle region was higher than that in its upper region,and leaf basal region had a lowest Pn value. Also there were some similar differences in Gs and CE between these different regions. In different positiongs of those leaves, Pn,Gs,and CE were gradually declined from upper to basal showing a leaf position gradient.The results of correlation analysis of these data indicates that the correlation coefficient between Pn and CE was much higher than that between Pn and Gs in two cases, and Pn was negatively correlated with intercellular CO_2 concentration (Ci). It is concluded that the carboxylation activity or activated amount of Rubisco rather than stomatal conducatance is a determinant of photosynthetic capacity in rice leaves. In addition, while Pn in flag leaves of different tillers was positively correlated with Gs but negatively correlated with Ci demonstrates that stomatal conducatance is not a determinant of potosynthetic capacity in rice leaves.