| Salix chaenomelodies ‘Variegata' is a variant of the Salix chaenomeloides,which belongs to Salicaceae Salix.During the majority of the growing season,the top leaves of Salix chaenomelodies‘Variegata' are the bright red,the middle leaves are yellowish green,the lower mature leaves show green,and the whole tree shows red,yellow and green colors.Salix chaenomelodies ‘Variegata' is a new color leafed tree species of high ornamental value.Understanding the color regularity of color plants and effect of environmental cond-itions especially the light intensity on the coloring effect,is very important to the introduction and application of colored leaf trees and reasonable allocation.At present the study on Salix chaenomelodies ‘Variegata' is mainly focused on cutting propagation and introduction domestication,lacking reseaches on the color regularity and the influencin g factors.In my paper,the color regularity and photosynthesis of Salix chaenomelodies‘Variegata' were investigated,and the effects of light intensity on the coloring of the Salix chaenomelodies ‘Variegata' were studied by shading.The main results are as follows:1.Salix chaenomelodies ‘Variegata' grew well in Beijing area,the ground diameter could reach 1.26 cm and the plant height could reach 194.36 cm.Mature leaf width c an reach 4.01 cm,the average length can reach 12.26 cm,compared with other Salix s pecies,Salix chaenomelodies ‘Variegata' grows faster,wider leaf.The leaves at the top are bright red in the growing season.It can be introduced and cultivated in Beijing area as a new color leafed tree of high ornamental value.2.The red leaves of Salix chaenomelodies ‘Variegata' began in middle April,red leaves proportion reached the maximum in late April,but the red leaf number is only 2~3.In 5~7months,the number of leaves was about 5 pieces,the number of red leaves in August reached the maximum,about 7 pieces.In early September,the number of red leaves decreased,and redleaves disappeared in late September.Ornamental period could lasts 6 months,the best viewing effect was in August.3.The color pigment of red leaves on the top of the Salix chaenomelodies ‘Variegata' is anthocyanin,which was mainly distributed in palisade tissue under the epidermis of the blade near the axial surface,but also a little amount in the palisade tissue under the distal surface epidermis.In 5~8 months,the content of anthocyanin in the top leaves reached about 30mg/g or above,3~4 times of the other leaves.4.Salix chaenomelodies ‘Variegata' has higher compensation point and light saturation point showed the characteristics of the sun plants,Shading had a significant effect on the leaf color of the top leaves of Salix chaenomelodies ‘Variegata'.Under the condition of full illumination,the leaves were bright red,but with the increase of shading degree,the content of anthocyanin decreased,the number of red leaves decreased,and the red became lighter.When the light intensity was lower than a minimum light intensity,the colored leaf fade into green,and the new leaves were no longer red.5.Shading significantly reduced the content of anthocyanin and the activity of phe nylalanine ammonia lyase in the top leaves,after restored the light the content of anthocyanin increased and the activity of phenylalanine ammonia lyase increased,so the intensity of illumination have positively correlated with anthocyanin content and the acti-vity of phenylalanine ammonia lyase.However,the change rate and amplitude of anth ocyanin were much higher than the PAL activity.Therefore,the change of anthocyanin content after shading is related to the change of PAL activity,but there should be more rapid reaction path way to increase or degrade anthocyanin.These results have important reference for the introduction of the Salix chaenomelo dies ‘Variegata' in the Beijing area and the rational allocation in Landscape architecture... |
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