水稻白叶枯病对自然发病水稻光合作用的影响

利用LI-6400便携式光合仪研究了水稻发生白叶枯病以后叶片光合作用的日变化特征.结果表明:发病植株和对照的净光合速率(Pn)日变化曲线均为“单峰”型,没有明显的光合“午休”现象,这可能与水稻的生育期以及地理环境条件有关.发病植株和对照的Pn以及蒸腾速率(Tr)总量差异不显著,但日变化进程存在明显的差异.相关性分析表明,发病植株的光合作用除了受到光合有效辐射(PAR)的影响外,气孔导度(Gs)也是其主要限制因子.与对照相比,发病植株的气孔特征发生了显著的改变,气孔长度和宽度增加,密度降低,且气孔的分布极不均匀.同时,发病植株与对照的叶绿素总量和类胡萝卜素含量差异显著.发病植株叶绿素a和类胡萝卜素的含量显著低于对照,而叶绿素b的含量显著高于对照.水稻在受到病害胁迫的逆境中,表现出了较强的适应和抵抗能力,植物通过改变结构、性能及代谢方式以满足其生长发育的需求.

Effects of Rice Bacterial Blight on Photosynthesis in Naturally Infected Rice

Daily dynamics of photosynthetic characteristics in rice leaves infected by Xanthomonas oryzae pv. oryzae were analyzed by using the LI-6400 portable photosynthesis system. The results showed that diurnal changes of photosynthesis (Pn) in rice flag leaves had one peak, and there was no obvious midday depression in daytime. The phenomenon was possibly related to rice growth period and geographical environment conditions. Although no significant difference was observed in Pn and Tr between infected plants and the control, they were very different in the curves of diurnal variation. Correlation analysis showed that the main factors affecting Pn of infected plants were Gs and PAR. Compared with the control, stomatal characteristics changed more significantly in the infected plants. Length and width of the stoma increased, whereas the density decreased. Stoma distribution in flag leaves was not homogeneous in diseased plants. There were significant differences between infected plants and the control in chlorophyll and carotenoid. Chl a and carotenoid were higher in the control but Chl b was higher in infected plants by significance analysis. Rice showed strong adaptability and resistant ability when it was influenced by the pathogen. Rice growed under the stress of plant disease by changing structure, performance and metabolicway.