弱光条件下桃叶片结构及光合特性与叶绿体超微结构变化

 【目的】探讨弱光条件下设施桃树叶片光合器官结构特征变化及品种间差异，为设施桃品质改良提供理论依据。【方法】以设施栽培的庆丰和麦香桃树为试材，设置全光照(CK)、60%～70%光照(T1)和30%～40%光照(T2)3种处理，测定了弱光条件下桃树功能叶片净光合速率(Pn)，观察了气孔形态；分析了桃树新梢的不同部位叶片的叶绿素含量（chl）、叶片结构特征；采用透射电镜观察了弱光条件下桃树新梢不同部位叶片的叶绿体超微结构；比较了品种间差异。【结果】随着光照强度的减弱，桃叶片Pn 降低；而T1提高了麦香叶片10：00和14：00的Pn；叶片气孔密度、气孔开张度和气孔导度(Cs)下降；叶片Chl总量、Chl a、Chl b的含量显著增加。叶片的叶面积、叶比重、上下表皮厚度、海绵组织厚度降低，而栅栏组织厚度和栅/海比升高；叶肉细胞内的叶绿体数增多，叶绿体基粒明显变厚，基粒数和基粒片层数增加，新梢上位叶片栅栏组织叶绿体内的淀粉粒数降低，下位叶片栅栏组织的淀粉粒数增加。【结论】弱光条件下新梢不同部位叶片间和不同品种间的叶片Chl、Pn、气孔行为、叶片结构特征、叶绿体结构特征表现显著差异。

Characteristics of Photosynthesis Machinism in Different Peach Species Under Low Light Intensity

The leaf characteristics and microstructure of chloroplast of peach in solar greenhouse were studied. The result showed that as the light is weaker, the total chlorophyll content，chlorophyll a and chlorophyll b content increased; at the same time, the ratio of chlorophyll a and chlorophyll b decreased. The chlorophyll content of the young leaves is higher than those younger and older ones whether that is under shade condition or under natural condition. The chlorophyll content of NJN is highest among those different peach breed. With the shade degree aggravated, the number of chloroplast per cell in palisesade tissue increased, and the grana lamella is thicker; the amyloid number of younger leaves augmented, while it is reversed in young leaves. As for NJN, the grana number of younger leaves in sponge tissue was cut down when shaded, but there is little difference of the grana number of younger leaves in sponge tissue between Maixiang and Qingfeng. When shaded, the length of the cell in palisesade tissue was shorter compare with those under nature light.