The Photosynthetic Physiological Response Of Dicranopteris Dichotoma Under Different Light Conditions

In order to explore the difference between the natural and controlled experiment potted Dicranopteris dichotoma under different light conditions,different layers of shade net greenhouse were simulated to four kinds of light environment(shading treatment of one,two and three layers)to mensurate and find the internal contact among the effects of photoresponse process,chlorophyll fluorescence,pigment content,soluble protein content,malondialdehyde content and enzyme activities.Moreover,from the point of view of sun flecks,each treatment's potted D.dichotoma were contrasted with the D.dichotoma which freely grew up in the natural,for finding the photosynthetic induction ability of them.The study were aimed at reveal the relationship between the growth and distribution of D.dichotoma and light,also,it provided a theoretical basis for the application of subtropical ground cover and the regeneration and succession of forest communities in the subtropical and Low Mountain hilly areas.The main research conclusion were as follow.(1)Light adaptability of potted D.dichotoma was very strong,it could endure not only high shade,but aslo intensity ligh.Shading made difficult to accumulate the photosynthetic products of potted D.dichotoma and full light could inhibite the maximum net photosynthetic rate.35.96% of full light treatment was a turning point from the stomatal factors to the non stomatal limiting factors,which aslo had suitable light environment for the growth of potted D.dichotoma.(2)Potted D.dichotoma thougt increasing the reaction density,dark reaction after maximal photochemical efficiency,electron transfer efficiency,electron transfer quantum yield and performance parameters and reducing the ratio of quantum electron transfer,quantum yield and heat dissipation and the active parameters to adapt to low light environment.(3)Shading was benifit to the synthesis of pigment of potted D.dichotoma and it could promote photosynthesis in weak light intensity.The relative content of chlorophyll value(SPAD)increased with the decrease of light intensity,and there is a linear function relation between SPAD and the content of the pigment.high degree of fitting regression equation indicating that SPAD could better reflect the changing trend of chlorophyll content and it's a effective tool for determining the content of pigments in living state.(4)The activities of antioxidant enzymes,such as SOD,POD and CAT under the 4.75% light transmittance,were higher than those under the full light treatment in the greenhouse.Besides,the increase of POD and CAT activity had some compensation and coordination for the decrease of SOD activity.The increasing of the light intensity is one of the important factors which caused the synthesis and accumulation of soluble protein.The effect on the membrane lipid peroxidation of potted D.dichotoma under full light intensity was more serious than the weak light.(5)Compared with the wild growth of natural D.dichotoma,the response of the artificial light intensity treatment to the sun flecks was relatively fast,but the ability to maintain the photosynthetic induction was smaller.Therefore,different environment may the reson for the difference in response to the sun flecks.Potted D.dichotoma had strong photosynthetic efficiency and induction maintenance ability when the transmittance at 35.96%.