不同供水条件下小麦不同绿色器官的气孔特性研究

Stomatal Characteristics of Different Green Organs in Wheat under Different Irrigation Regimes

为了考察小麦叶片与非叶器官气孔结构特性的差异及其对供水条件的反应,设置不同灌水处理,利用电镜观察小麦灌浆期不同绿色器官的气孔分布和结构特征,并分析其与气孔特性指标间的关系。结果表明,在不同灌水处理下看到各非叶器官(穗、旗叶鞘和穗下节间)均分布着气孔,但其数目少于旗叶叶片。护颖仅在远轴面存在气孔;外稃在多水条件下(4水处理)近轴面出现较多气孔,而远轴面看不到气孔,但在水分胁迫(无水处理)条件下,气孔却出现在远轴面而不在近轴面;在不同水分处理下均观察到芒上明显的气孔分布。从气孔大小看,穗各部分(护颖、外稃、内稃和芒)略小于其他器官。随着灌水次数的减少,各器官气孔密度呈增大趋势,气孔器及气孔孔径表现出长度增加、宽度减小的特征。限水灌溉下非叶器官(穗、旗叶鞘和穗下节间)在籽粒灌浆期气孔导度、蒸腾速率和光合速率的稳定性高于叶片。相关分析表明,不同器官的气孔导度与蒸腾速率均呈显著正相关,非叶器官气孔导度与光合速率的相关程度明显低于叶片。说明在干旱少水条件下,叶与非叶器官蒸腾作用均会减弱,叶片光合速率亦相应降低,而非叶器官光合速率可能保持相对稳定,可相对提高其水分利用效率。

Stomata are the channel of CO2 and water vapour exchange between the plant and atmosphere, and contributing to photosynthesis, transpiration and temperature fitness of plant. There have been many reports about the stomatal structure and characteristics focused on the leaf blades, the major photosynthetic organs, in wheat but only a few reports about stomatal distribution on the ear（especially on the awn）, whereas, no any report on stomatal structure characteristics and their relations to photosynthetic rate and transpiration rate of various non-leaf green organs in wheat under different water condition. In current study, a field experiment was conducted with two cultivars （Lumai 21 and SJZ 8） and three irrigation treatments[ No irrigation, Two irrigations （1 500 m^3·hm^-2） and Four irrigations （3 000 m^3· hm^-2） in the growing period of wheat], in order to asses differences in stomatal structure characteristics and their response to irrigation between flag leaf blade and non-leaf green organs （flag leaf sheath, peduncle, glume, lemma, palea and awn） . Stomatal structure and distribution on leaf blade and non-leaf green organs in winter wheat were observed, and the stomatal conductance, transpiration rate and photosynthetic rate were also measured in response to different supplemental irrigation treatments. It was showed that under different irrigation treatments, stomata was found on all surfaces of flag leaf blade , sheath and peduncle, and also on the surface of awn and abaxial surface of glume in ear. However, for lemma, stomata appeared only on the adaxial （not on the abaxial ）side under both two and four irrigation treatments, and only on the abaxial side under water stress（no irrigation）. In size, stomat apparatus on the ear（glume, lemma, palea and awn）was smaller than that on other organs. With the decrease of water supply, the width of stomatal aperture was also decreased, while both stomat frequency and stomatal aperture length of various organs increased. Compared with flag leaf blade, non-leaf green organs （flag leaf sheath, peduncle and ear） was less sensitive to supplemental irrigation, and showed higher stability in stomatal conductance, transpiration rate and photosynthetic rate during the later filling period. There was a positive correlation between stomatal conductance and transpiration rate in various organs, while the coefficient of correlation in non-leaf green organs was lower than that in leaf blade. The results suggested that with the decrease of water supply, transpiration rates were declined for both the leaf blades and non-leaf green organs, then, photosynthetic rates might be remarkably decreased in leaf blades, however, relatively stable in non-leaf green organs, which may lead to higher water use efficiency （WUE） in non-leaf green organs than in leaf blades.