Chinese Journal of Plant Ecology (植物生态学报) 2013/37:12 PP.1101-1113
Aims Our general objective was to understand the effects of short-term phloem girdling on physiological per-formance 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. cas-pia 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 inclu-sive, 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.