Response Of Physiological And Biochemical Characters Of Cercis Canadensis 'Forest Pansy' To Light

Cercis Canadensis 'Forest Pansy' (Leguminosae) is origin United States, a horticultural variety of Canada Bauhinia (Cercis canadensis). In this paper, we study on Cercis Canadensis 'Forest Pansy' population that grew in Shanghai Vocational and Technical College of Agriculture and Forestry, Based on the one-month shading test (shading rates were 0, 30%, 60%, 80%) some morphological, photosynthetic and physiological indexes were determined. Disscussed Physiological responsesand adaptability of Cercis Canadensis 'Forest Pansy' under different shading ratio, the results are as follows:(1) As the light shading ratio increased, the leaf area of Cercis Canadensis 'Forest Pansy' is increased, while dry matter amount is reduced, Above show that it adapts to low light environment by increasing leaf area, seriously shade hampered plant dry matter amount accumulation.(2) The leaves' color anniversary changes of in Shanghai: in mid-March, new leaves is bright purple, gradually turn dark red, then green, and finally dark green. The smartest shading ratio increases, the earlier leaves'color turn green, this is because low-light promotes chlorophyll formation and inhibit anthocyanin synthesis.(3) With the increase in the rate of shade, purple leaf chlorophyll content increased Chl.a/b lower anthocyanin content of reduced carbohydrate content were lower, correlation analysis showed that the soluble sugar content and chlorophyll content as very significant negative correlation with the anthocyanin content as a significant positive correlation with starch content have become a significant positive correlation.(4) PAL activity showed different trends under different shading rate, with increase of the shading rate, PAL activity in lower correlation analysis showed that, PAL activity and anthocyanin content into a highly significant positive correlation with soluble sugar, soluble protein showed a significant positive correlation.(5) With the shading ratio increasing, light saturation point, light compensation point, CO₂ saturation point and CO2 compensation point of Cercis Canadensis 'Forest Pansy' are followed by lower, indicating that Cercis Canadensis 'Forest Pansy' is able to take advantage of low photon density, the maximum extent possible to carry out photosynthesis in limited light conditions, thereby enhancing the accumulation of organic matter to meet its growing energy needs of survival. However, severe shading severely affected its photosynthesis.(6) The Pn date changes of leaves in four kinds of shading treats is single-peak curve, the peak values appear in around 14:00. With the shad ratio increasing, Pn max gradually decreased, but the "break" phenomenon does not appear after shading, which shows the shading can reduce or avoid photoinhibition of photosynthesis in radiation light. PS II the efficiency of primary conversion of light energy (Fv/Fm) and the potential activity (Fv/Fo) in shading are both higher than in full-light, indicating that the photosynthetic electron transport rate is increased after shading, this means that leaves of Cercis Canadensis 'Forest Pansy' have high efficiency to reflect excitation energy capture of center.