短期环割对塔克拉玛干沙漠南缘两种荒漠植物的生理影响

随着气候条件的改变, 人口和载畜量的日益增加, 塔克拉玛干沙漠南缘策勒绿洲主要植物种群花花柴(Karelinia caspia)和骆驼刺(Alhagi sparsifolia)正遭受日益严重的虫噬、放牧等机械损伤的影响, 干扰因子对花花柴和骆驼刺的影响日趋明显。以塔克拉玛干南缘沙漠策勒绿洲主要建群种花花柴和骆驼刺为材料, 测量了韧皮部环割处理10天后, 光合色素含量和光系统II (PSII)叶绿素荧光的变化。结果表明: (1)在韧皮部半割处理下, 花花柴、骆驼刺的光合色素含量和叶绿素荧光变化都不明显。(2)在韧皮部全割处理下, 花花柴、骆驼刺的光合色素含量和叶绿素荧光各参数变化较大, 在该处理下, 两种植物光合原初反应被抑制, 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被抑制。(3)韧皮部全割对花花柴和骆驼刺各生理状况产生较大影响, 相比而言, 环割对花花柴的影响更为持久。对于单个植株而言, 机械损伤对花花柴的破坏损伤更为显著。(4)在环割对花花柴和骆驼刺光合速率的影响中, 存在着依赖于碳水化合物(carbohydrate-dependent)的机制。

Effects of short-term phloem girdling on physiology in two desert plants in the southern edge of the Taklimakan Desert

Aims Our general objective was to understand the effects of short-term phloem girdling on physiological performance in Karelinia caspia and Alhagi sparsifolia, concerning not only the impacts of degrees of girdling but also the differences in damage between the two plants under girdling treatment. Specifically, we want to know the mechanisms of the decline in photosynthesis under girdling treatment.
Methods We imposed three different types of girdling treatments, normal branch, semi-girdling, and full-girdling, and studied the reaction of photosynthetic pigments, chlorophyll fluorescence parameters in K. caspia and A. sparsifolia under the conditions of girdling after about 10 days.
Important findings The effects varied with the type of girdling treatments and differed between K. caspia and A. sparsifolia. There was no apparent effect on physiological parameters in K. caspia with semi-girdling treatment; whereas full-girdling significantly reduced chlorophyll content and carotenoids content in both K. caspia and A. sparsifolia. The full-girdling also constrained the primary photosynthetic reaction in K. caspica and A. sparsifolia, and damaged the structure and function of photosystem II (PSII), leading to reduction in the activity of PSII. The processes of absorption, transmission, conversion, and electron capture of light energy in photosynthetic organs were also constrained, and the energy used for dissipate significantly increased. We believe the degree of damage in K. caspia under full-girdling is more severe than in A. sparsifolia. As the disturbance in Cele Oasis is further exacerbated, whether the population of A. sparsifolia could adapt to this change better than K. caspia is still inclusive, because the resilience of plants is also an essential factor. There exist a carbohydrate-dependent mechanism in the effects on photosynthetic rate in K. caspia and A. sparsifolia subjected to girdling.