Study On Physiological Characters Of Color Change On Leaves Of Plantycladus Orientalis Cv.nemperourescens

This research is to Plantycladus orientalis cv.nemperourescens as experimental material,through comparing different periods at the top of the topmost yellow leaf and the base green leaf photosynthetic characteristics,pigment content and related enzyme activity and leaf ultrastructure observation,analysis of pigment content and related enzyme activity and leaf color changes,for the causes of the formation of Plantycladus orientalis cv.nemperourescens in tip top yellow leaf and leaf color dynamic change rule carries on the preliminary physical exploration,the main conclusions are as follows:(1)The leaves at the top of Plantycladus orientalis cv.nemperourescens began to show yellow from the germination stage in March,and gradually changed to yellow-green with the growth color of the leaves,and then showed yellow in October.(2)It is speculated that stomatal conductance has more effect on photosynthesis in yellow leaves than in green leaves.The net photosynthetic rate(Pn)of the yellow leaves at the top of branch tip was lower than that of the green leaves at the base.Chlorophyll content in yellow leaves was positively correlated with stomatal conductance(Gs)and intercellular COO concentration.(3)The ratio of carotenoid content to chlorophyll content determines the change of leaf color at the top of Plantycladus orientalis cv.nemperourescens.As the ratio increases,leaf color gradually turns yellow,while the ratio decreases,leaf color gradually turns green.According to the physiological research,the dynamic change of leaf color of Plantycladus orientalis cv.nemperourescens was physiologically regular,which indicated that the change of leaf color was regulated by internal physiological mechanism.(4)Chlorophyll synthesis was influenced by the activity of original chlorophyll oxidoreductase and chlorophyll enzyme in the yellow leaves at the top of Plantycladus orientalis cv.nemperourescens.(5)According to the observation of chloroplast ultrastructure of leaves in different stages of Plantycladus orientalis cv.nemperourescens,in the chloroplast development stage,the chloroplasts in the yellow leaves at the top of the branch tips were less developed than those in the green leaves at the base.The chloroplast degradation in the yellow leaf at the top of the branch tip was earlier than that in the green leaf at the base.