Effects On Leaf Colouring And Photosynthetic Ecophysiological Characteristics Of Purple-Leaf Plum' Young Seedlings Under Shading In Summer And Autumn

Along with fast urbanization advancement of our country,the quantity of big buildings and so on incessantly increased as well as the level matching of garden greenery gradually enriched,massively shade space appeared.Therefore,there are extremely important theory value and the practical significance to study the garden greenery plants' changes of morphological characteristics and photosynthesis physiology ecology characteristic under shading condition.By respectively making 100%light transmittance(full sunlight),43% light transmittance(medium shading) and 27%light transmittance(heavy shading) 3 kinds of shading treatments,1-year-old young seedlings of Green-leaf plum grown on the ground was taken as the comparison,the influences of the SLW,the pigment content,the photosynthesis and chlorophyll fluorescence characteristic of Purple-leaf plum young seedlings' leaves under shading treatments in summer and autumn were compared and analyzed systematically.The results showed:1.Effect on leaf colouring and photosynthetic ecophysiological characteristics of purple-leaf plum' young seedlings under summer shadingAfter shading treatments,in order to adapts to the weak light circumstances to maintain certain photosynthesis ability,young seedlings' Ch1 content,Car content,AQY,CE,G_s,F_v/F_m,Φ_PSâ…¡ and qp were obviously enhanced,SLW,LCP,LSP and qN were obviously decreased,while their DIV of P_n and DIV of WUE were obviously reduced,that indicated the above compatible physiological reactions were insufficient to compensate the injury caused by shading treatment.At the same time,the Chl content of Purple-leaf plum's leaf was obviously enhanced while its Ant content was obviously reduced,that explained summer shading treatment was disadvantageous to its leaf color's fully expression,therefore we should fully satisfy its photosynthesis and leaf colouring in the purple-leaf plum's seedling breeding.But summer shading treatments effectively weakened the purple-leaf plum's light suppression, moreover its DIV of P_n under moderate shading was still more than 87.8%of that under full sunlight,therefore the purple-leaf plum's young seedling was also could be transplanted in moderate shading(the light permeation is about 57%) environment.2.Effect on leaf colouring and photosynthetic ecophysiological characteristics of purple-leaf plum' young seedlings under autumn shadingDuring the autumn experiment,the Car content,Φ_PSâ…¡ and qp of Purple-leaf plum young seedling's leaf remarkable increased,while its SLW,LCP,LSP and qN obviously reduced, all that may regard as its compatible physiological reaction to the autumn continuously shading,and that may cause it to maintain certain photosynthesis ability in the long-term weak light environment,and all those can proved Purple-leaf plum young seedling's shade-resistant ability is very strong.But its DIV of P_n and DIV of WUE were remarkable reduced,and its Chl content,AQY and CE were reduced at later period under treatment,that indicated the above compatible physiological reactions were insufficient to compensate the injury caused by autumn continuously shading,therefore we might think the autumn continuously shading was disadvantageous to its growth.Moreover,the Ant content of its leaf remarkable reduced firstly and remarkable increased lastly,and its leaf color under shading treatments was light firstly and deep lastly in the actual observation,that can proved that long time shading treatment in summer and autumn was disadvantageous to its leaf color's sustainable fully expression.So,the purple-leafplum young seedling was not suit to transplant under the long time shading in summer and autumn.3.Comparative analysis to effects on variety difference and season difference of leaf coloring and photosynthesis ability of Purple-leaf plum and Green-leaf plum's young seedlings under summer and autumn shadingThe leaf color of Purple-leaf plum under sunlight and shading in summer was obviously lighly than that in autumn;The leaf color of Purple-leaf plum under summer shading was obviously lighly than that under sunlight,while its leaf color under autumn shading was obviously lighly than that under sunlight was obviously deeply than that under sunlight.The photosynthesis ability of Purple-leaf plum and Green-leaf plum were obviously reduced under summer and autumn shading treatments,which mainly manifested as their DIV of P_n and DIV of WUE were obviously reduced after shading treatments;The photosynthesis ability obviously reduced under shading treatments also manifested as two aspects-variety difference and season difference,that were the reduced scope of photosynthesis ability of Green-leaf plum＞the reduced scope of photosynthesis ability of Purple-leaf plum,and the reduced scope of photosynthesis ability under autumn continuously shading treatment＞the reduced scope of photosynthesis ability under summer shading treatment,that explained the adverse effect on photosynthesis ability of Purple-leaf plum under summer and autumn treatments was smaller than that of Green-leaf plum,the adverse effect on photosynthesis ability of Purple-leaf plum and Green-leaf plum under autumn continuously shading treatment was bigger than that under summer shading treatment,there were five possible reason:1.The plants' growth stage and shading treatment time difference;2.The plants' leaf Ch1 content difference;3.The plants' weak light use ability difference;4.The plants' light energy use efficiency and CO₂ assimilation ability difference;5.The plants' PSâ…¡photosynthesis efficiency difference.