表皮环割对花花柴(Kareliniacaspica)水势及光合参数的短期影响

生长在塔克拉玛干沙漠南缘的植物在生长季常遭受虫害和放牧的影响,频繁的干扰在很大程度上限制了该地区植物的生存和生长.以塔克拉玛干沙漠南缘策勒绿洲外围花花柴(Karelinia caspica)为试验材料,模拟干扰对于花花柴生理状况的短期影响,设置了对照(正常枝条)、中度环割(表皮环割50%)、重度环割(表皮环割100%),观测了环割后10 d内花花柴气孔导度、水势、光合色素、叶绿素荧光等在不同环割条件下的变化特征.结果显示:(1)除了类胡萝卜素(Car)含量外,中度环割对花花柴各项生理参数的影响不明显;(2)重度环割能够明显降低花花柴气孔导度、清晨水势和正午水势、叶绿素(Cal)含量和类胡萝卜素(Car)含量;(3)重度环割使得花花柴的光合原初反应遭到抑制,光系统Ⅱ(PSⅡ)结构和功能遭到损害,活性降低,光合器官对光能的吸收、传递、转化和电子捕获等过程也遭到抑制,用于耗散的能量显著增多.整体来看,重度环割下的花花柴短期内各项生理参数均出现显著降低,而中度环割下花花柴各项生理参数短期内变化不大.当人为或者昆虫、野兔等对花花柴表皮产生机械损伤时,表皮部分损伤的植物也许可以通过自身修复,使得各项生理机能恢复正常,而表皮遭受重度破坏的植物会随着时间的推移趋向于死亡.在荒漠化防治过程中,我们应该尽量避免花花柴的表皮被全部剥蚀.

Short-term Effect of Phloem Girdling on Water Potential and Photosynthetic Characteristics in Karelinia caspica

Plants grow in the southern edge of Taklimakan Desert in the growing season often suffer impact of pests and grazing. Our general objective was to know the effects of short-term phloem girdling disturbance on physiological parameters in Karelinia caspica. Specifically, we want to know the effect of different degrees of girdling on physiological parameters in K.caspica and provide the basic data for revealing the possible mechanisms of photosynthetic changes in K.caspica caused by girdling. So we set three different types of girdling: normal branch, moderate girdling, severe girdling, and observed responses of stomatal conductance, water potential, photosynthetic pigments, chlorophyll fluorescence parameters in K. caspica under the conditions of girdling after about 10 days. We found effect of different-degree-girdling on K.caspica were different. That is to say, the change of physiological parameters in K.caspica under moderate girdling is not obvious. However, severe girdling can significantly reduce stomatal conductance, predawn water potential and midday water potential, chlorophyll content and carotenoids content in K.caspica. The severe girdling also restrained the original photosynthetic reaction of K.caspica, and damaged the structure and function of PSⅡ under such conditions. The activity of PSⅡ declined after girdling. The processes of absorption, transmission, conversion and electron capture of light energy in photosynthetic organs ware also restrained. The energy used for dissipate will significantly increase. When faced with mechanical damage of phloem caused by insect and people, if the phloem is not completely damaged, plants may be able to make the function of physiological returned to normal through self-repair of tissue. While plant suffered severe damage may die. We should better avoid the phloem be completely eroded. There may a carbohydrate-independent mechanism in the effect of photosynthetic rate on K. caspica under the condition of girdling exist.