热胁迫下萝卜不同耐热性品种细胞组织结构比较

CELLULAR STRUCTURAL COMPARISON BETWEEN DIFFERENT THERMO-RESISTANT CULTIVARS OF RAPHANUS SATIVUS L. UNDER HEAT STRESS

利用显微及扫描电镜方法，研究热胁迫下萝卜不同耐热性品种外部形态、叶片及叶柄组织细胞结构的差异。耐热性品种比感热性品种叶表皮气孔密度大、体积小和开度小，部分呈关闭状态；叶片厚、叶肉细胞排列紧密，叶肉细胞很少出现质壁分离；耐热性品种叶柄内维管束总面积是感热性品种的1．5倍以上，具发达的形成层及厚壁组织。讨论了耐、感性品种结构差异与保持水分、免受高温失水伤害的关系。

The objective of this study was to investigate the effects of heat stress on leaf and petiole's microscopical structure of different thermo-resistant cultivars of Raphanus sativus L. the results obtained are summarized as follows: Under heat stress, the studied thermo-tolerant cultivars showed higher stomatal density, smaller volume and smaller stomatal opening area on abaxial epidermis than that of thermo-sensitive cultivars. Moreover, we observed those thermo-tolerant cultivars have thicker leaf, denser palisade tissue and smaller stomatic chamber, With more developed vein and much less occurred plasmolysis. Compared to thermo-sensitive cultivar, the petioles of thermo-tolerant cultivar were more study along with more quantity and larger transportation area of vascular stand as well as more active cambium. Based on these phenomena,the relation between the different structure of thermotolerant and thermo-sensitive cultivars were discussed, function of keeping water to avoid injuring under heat stress being discussed as well.