Study On The Relationship Between Leaf Color Expression And Pigment Content Of Four Color-Leafed Plants During The Growing Season

Color-leafed species are favored in garden landscape because of their different leaf color from general green leafed plants.In recent years,the variety of color-leafed plants has been increasing,gradually meeting the needs of urban landscape construction and matching.Different species of color-leafed plants have different adaptations to their environment and may have different leaf colors.Most of the domestic and international research on the colouring of foliage plants has focused on one plant or another within the same family.Therefore,this study compares different families and different colors of color-leafed plants to analyse their internal coloring mechanisms and to provide a reference for exploring the variation of color in different color-leafed plants.The environmental influence factor of light intensity is added to provide a certain theoretical basis for the further study of the color rendering mechanism of color-leafed plants and the rational application in landscape design.Taking Acer negundo’Aurea’,Amygdalus triloba(Linbl.)Ricker,Ulmus pumila’Jinye’and Prunus cerasifera Ehrhar f.atropurpurea(Jacq.)Rehd as experimental materials,the color-leafed parameters,photosynthetic pigment content,anthocyanin content soluble sugar content and p H value of cell fluid were determined and analyzed.In order to provide technical support and theoretical basis for prolonging the ornamental period of color-leafed plants and enhancing the color richness in plant configuration.The results show that:(1)The brightness L~*value of the four color-leafed plants decreased slowly.In the process of leaf color change of tree species with golden leaf,the yellow degree decreases gradually and the b~*value representing the Ulmus pumila’Jinye’decreases gradually.And the yellow degree of golden leaf elm leaves is more obvious,and the b~*value is higher accordingly.During the change of leaf color of tree species with red leaf,the degree of purplish red gradually weakens,and the a~*value representing the red parameter changes from high to low.The purplish red of Prunus cerasifera Ehrhar f.atropurpurea(Jacq.)Rehd leaves is more significant,and the higher the a~*value.(2)In terms of physiological indicators:the content of carotenoids in the early growth stage of tree species with golden leaf is high,the content of chlorophyll is low,and the leaves show golden yellow.The increase of soluble sugar content gradually weakened the yellow degree of tree species with golden leaf,but its increase made the leaves of tree species with red leaf show purplish red in the initial stage,and then the anthocyanin synthesis ability decreased and purplish red weakened.The increase of soluble sugar content can inhibit the content of carotenoids and gradually weaken the yellow degree of tree species with golden leaf,but its increase promotes anthocyanin synthesis,and makes the leaves of tree species with golden leaf show purple red in the early stage,and then the ability of anthocyanin synthesis decreases and purple red weakens.The increase of p H value of cell fluid in the acidic range can inhibit the yellow color of leaves,and the increase of p H value is conducive to the formation of purplish red of leaves.(3)Correlation analysis showed that the higher carotenoid content of tree species with golden leaf will make the leaves appear yellow,and the L~*and b~*values are higher.The purplish red color of tree species with red leaf is related to the content of anthocyanin,soluble sugar and chlorophyll,which affect the change of a~*value.The p H value of cell fluid indirectly affects the color of leaves.(4)In the direction of strong light,the L~*value,b~*value and carotenoid content of tree species with golden leaf are higher,while the contents of chlorophyll,anthocyanin,soluble sugar and p H value of cell fluid are lower,so the ornamental effect is better.tree species with golden leafs have better color in the direction of strong light,higher anthocyanin content,lower chlorophyll,carotenoid content and p H value of cell fluid,and more soluble sugar in the direction of weak light.The Amygdalus triloba(Linbl.)Ricker in the south is more bright,and the a~*value is significantly higher than that in other directions;The East a~*value of Prunus cerasifera Ehrhar f.atropurpurea(Jacq.)Rehd is significantly higher than that in other directions,and the color is better.