Effects Of Loropetalum Chinense Var. Rubrum Under Shade

The leaves of Loropetalum chinense var. rubrum’Mizhi Maihong’were used as the research object in this study. The series of illumination treatments were set at different levels including,full light,25% shade,50% shade and 75% shade, to investigate the growth and physical condition under shading, exploring the relationship between leaf color changing under shaded conditions and the pigment content.It was aimed to carify the law of growing development and physiological condition, to improve the environment, to increase the productivity, and to enhance the ornamental. The research not noly provided a theory evidence and reference for scientific, but also effective management and industrialization production of Loropetalum chinense var. rubrum.Main research results of this investigation were as followed:(1)The Loropetalum chinense var. rubrum grow quicker under 25%, and 50% shade than full light conditions.However,it slowed down under 75% shade.It descripted that Loropetalum chinense var. rubrum must have active adapability in a certain level of weak light. Under the proper illumination, the higher degree shade degree Loropetalum chinense var. rubrum in, the more fast it growth. So,50% shade light condition was selected as the best light conditions of vegetative growth.(2)The leaves color of Loropetalum chinense var. rubrum was turned amaranth to green with the increasing of shade degree and the extension of shade time.The shade treatment also caused the flowering time delay, even not flowering, and damaged the blossom quantity,while the inflorescence were usually flowerets on ornamental hurt. In thus, full light condition was choosed as the optimal light conditions of ornamental Loropetalum chinense var. rubrum.(3)The contents of anthocyanins in Loropetalum chinense var. rubrum falled rapidly, the contents of chlorophyll and carotenoid increased under shading, while chlorophyll a/b, carotenoids/chlorophyll ratio minish,which could be considered as an adaptation mechanism of pigments.On the other side, shade caused significantly peroxidase and superoxide dismutase activity higher than in full condition,and renders increased firstly and then decreased.The content of malondialdehyde, soluble sugar continued declining.It indicated that shade had a positive effect on metabolism, cellular activity on Loropetalum chinense var. rubrum, authenticated its high shade tolerance capacity. (4) The photosynthetic and physiological parameters of Loropetalum chinense var. rubrum net photosynthetic rate, stomatal conductance and transpiration rate performance as " ∧ " trends with the shade degree increasing.The intercellular CO2 concentration and stomatal limiting value expressed by the "V" trends.It showed that the net photosynthetic rate was limited by the nonstomatal factors. Shade also caused the daily variation of net photosynthesis and transpiration chaged from "bimodal curve" to "unimodal curve", and delayed the peak arrival instant.It revealed that shady environment, to a certain extent, ease the glare suppression, eradication of photosynthetic "lunch break" to enhance solar energy utilization. Which indicate the Loropetalum chinense var. rubrum had a good shade tolerance.(5) The correlation coefficient between the parameters of leaf color and pigment showed that the pigments determines size of the color parameter value a, but had nothing to do with leaf colour parameter value L and b. The F-test showed a extremely significant of regression models between anthocyanins, carotenoids, chlorophyll, respectively as a factor, and leaf parameters value a. And it indicated that each of pigments provided a great impact on Loropetalum chinense var. rubrum leaves color.Drawing all the three different types of pigments as factors, the correlation coefficients and adjusted R2 value of the regression model increased.The results telled that it was the three types of pigments combined action for the leaf color, and the greatest contribution was provided by anthocyanins.