弱光逆境对番茄幼苗形态、生理特征及叶片超微结构的影响

以两个不同生态型的番茄变种为试材,分别在对照(400～450 μmol/(m~2·s))和弱光逆境下(75～100 μmol/(m~2·s))研究番茄形态、生理指标及叶绿体超微结构的变化.结果表明:弱光显著抑制了番茄的生长,普通大果番茄(美粉二号)和樱桃番茄(红圣果)总的干物质含量分别下降了22.43%和28.87%,二者的壮苗指数分别比对照下降33.53%和51.48%,说明弱光条件下的植株发生了徒长.弱光下叶片光合色素含量显著增加,Chla/b则显著下降,有利于叶片捕获有限的光能.弱光逆境下番茄叶片净光合速率(Pn)下降,气孔导度也随Pn降低,但胞间CO_2浓度增高,表明弱光下番茄光合作用的限制因素是非气孔因素.弱光使番茄叶片厚度薄,栅栏组织与海绵组织比值减小.电镜观察结果表明,番茄叶片栅栏细胞内叶绿体数目及淀粉粒数目成比例减少,叶绿体和淀粉粒减小,叶绿体内基粒数和单个基粒中的片层数增加,这是弱光逆境对番茄叶绿体超微结构影响的首次报道.揭示了弱光与番茄生长及其光合系统结构性能之间的关系,为番茄耐弱光品种的选育提供理论参考.

Effects of Low Light Stress on Morphological Trait,Physiological Characters and Leaf Ultrastructure of Tomato(Lycopersicon esculentum L.) Seedlings

Two tomato cultivars were selected for the study, the whole-plant morphology, physiological characters as well as leaf ultrastructure of two tomato cultivars to differential light availabilities were examined in controlled environ-ment . The results showed that, under the low light stress, the growth of the plants was inhibited. The total plant dry weight declined significantly and the reduction was 22.43% of the common tomato(Meifen-2) and 28.87% of the cherry tomato (Hongsheng) ,and the healthy index decreased 33.53% of Meifen-2 and 51.48% of Hongsheng,respectively.Chl and Car content of the two cultivars grown under low light condition increased significantly, the Chi a/b ratio decreased during acclimation. Compared with control plants, the amount of soluble proteins and soluble sugars were drastically decreased by low light treatment.As the light intensity was lower,the net photosynthesis rate(Pn) and stomatal conductance(Gs) de-creased, but intercellular CO_2 concentration (Ci) increased. The decrease of net photosynthetic rate was considered as a re-sult of non-stomatal restriction. The blade thickness became thinner under low light stress, and the thickness rate of pal-isade and sponge tissue declined. The number of chloroplast and starch grain decreased as a result of low light intensity, the number of grana and lamella increased, the size of chloroplast and starch grain minished. The objective of this study revealed the relationship between photosynthetic system characters and low light stress, which could tolerate low light stress.