不同水分供给对小麦叶与非叶器官叶绿体结构和功能的影响

Changes of Chloroplast Ultramicrostructure and Function of Different Green Organs in Wheat under Limited Irrigation

在田间不同灌水条件(春季不灌水、春季灌2水和春季灌4水,每次灌水750m3hm-2)下,于灌浆后期对小麦叶片与非叶器官(穗颖、穗下节和叶鞘)叶绿体结构进行了电镜观察,并对不同器官的净光合速率(Pn)和光化学效率(Fv/Fm)进行了测定,以期探明小麦叶与非叶器官光合结构和功能对水分变化的适应性差异。结果表明,在充足供水条件(春季灌4水)下,叶片的叶绿体数目明显多于各非叶器官,但护颖和外稃叶绿体含有较多的淀粉粒。在灌浆期上层土壤重度水分亏缺(春季不灌水)条件下,植株各器官叶绿体均出现明显的衰老特征,但衰老程度存在器官间显著差异,旗叶叶片叶绿体受损程度明显大于非叶器官。在所测非叶器官中,外稃叶绿体对干旱胁迫反应较为敏感,而护颖、穗下节间和旗叶鞘叶绿体结构具有较强的稳定性。水分胁迫下各器官Pn和Fv/Fm值均降低,叶片降低幅度最大,且随灌浆进程其光合下降最快,但穗下节间、旗叶鞘和穗器官较为稳定,可能与其叶绿体结构的稳定性有关。说明小麦非叶绿色器官光合结构与功能对水分亏缺具有较强的耐性。

The green organs in wheat （Triticum aestivum L.） consist of leaf and non-leaf organs including ear, culm, and sheath. Understanding the structures and functions of these non-leaf green organs under abiotic stresses will help to explore the potential of photosynthesis of the whole plant. In order to identify the photosynthetic adaptation of different green organs to drought stress in winter wheat, the changes of chloroplast ultra-microstructure and function of the organ above were studied in a field experiment in the 2002–2003 growth season （a medium rain fall growth season） using cultivar Shijiajuang 8 with water treatments of no irrigation （control）, irrigating twice at jointing and anthesis stages, and irrigating 4 times at pseudostem erecting, booting, anthesis, and grain-filling stages. Each irrigation received 750 m^3 ha^-1 water. Chloroplast ultramicrostructure of flag leaf blade and non-leaf organs （peduncle, flag leaf sheath, glume, and lemma） in response to different irrigation treatments were observed during late grain-filling period, and the net photosynthetic rate （Pn） and Fv/Fm values of different green organs were measured simultaneously. The results showed that the chloroplast number of non-leaf organs was less than that of leaf blade, and many starch grains were found in the chloroplasts of glume and lemma under sufficient water supplies （irrigating 4 times）. Obvious senescence characteristics and differences in chloroplast ultramicrostructure were found in different organs of control, and the senescence was significantly severer in flag leaf than in non-leaf green organs. The chloroplast structure of flag leaf blade and lemma was destroyed under drought stress, while that of peduncle, sheath, and glume showed relatively stable in the late developmental stage under different irrigation regimes. Post-anthesis drought stress decreased Pn and Fv/Fm values in different green organs, but much less affected them in non-leaf organs （peduncle, sheath, and ear）. The results indicated greater stability of chloroplast structure and photosynthetic activity in non-leaf green organs at the late grain-filling stage under water stress.