The Influence Of Light Stress On The China Gold Leafelm Leaf Color And Photosynthetic Characteristics

Ulmus pumila cv.jinye is a new variety of color-leafed plants cultivated by Forestry Research Institute of Hebei Province,its leaf is golden and has a strong adaptability on the cold, arid climate,it is also a good color-leafed species for tree and shrub.The view color of Ulmus pumila cv.jinye in northern China is mainly from June to September in the summer.It is found in applications,on the inappropriate lighting conditions,the leaves of Ulmus pumila cv.jinye will recover, but with the severity of the green, its ornamental value continues to reduce. This paper recorded and analyzed more systematically the differences and changes of Ulmus pumila cv.jinye leaf color under four different light stress treatment,and compared with the full gloss growth of Ulmus pumila under the same habitat, tracking and determining the chlorophyll content, carotenoid content, anthocyanin content, phenylalanine ammonia lyase (PAL) activity, leaf cell sap pH, organic matter content and other physiological indicators of Ulmus pumila cv.jinye and Ulmus pumila in the color tracking period (6 to 9 months) with different light stress treatment,and preliminary analized the relationship between the changes in leaf color and these physiological indicators.Measured the photosynthesis of Ulmus pumila cv.jinye and Ulmus pumila under different light stress treatment, and preliminary analized the relationship between leaf color physiology and the photosynthesis. The results show that,(1) The changes in leaf color of Ulmus pumila cv.jinye is the result of the interaction of chlorophyll a, chlorophyll b, carotenoids, anthocyanin content, cell sap pH, PAL activity, organic matter content, and we also should consider the combined effects of various physiological indicators in the analysis.(2) Shading affects the photosynthetic characteristics of plants. Both the diurnal change of photosynthetic rate and the diurnal variation of transpiration rate of Ulmus pumila cv.jinye and the full gloss Ulmus pumila under different light stress treatment are.unimodal curve.There is no "midday depression", the peak occurred at around 13:00. With the increase of stress gradient, the net photosynthetic rate and transpiration rate of Ulmus pumila cv.jinye were gradually reduced and lower than that of Ulmus pumila. And the light saturation point and light compensation point, maximum net photosynthetic rate and apparent quantum yield gradually decreased and significantly lower than that of Ulmus pumila,it showed that the tolerance to strong light and the utilization ability to low light of Ulmus pumila cv.jinye were gradually weakened, Ulmus pumila sounded as strong endurance on both the high and low lights.(3) On the light shade conditions, Ulmus pumila cv.jinye leaves still have a relatively high carotenoid content and certain carotenoid content/chlorophyll content,it is slight pan-green in the basis of yellow and the leaves are more tender, lovely. It still can be regarded as the colored-leaf category, this largely enriched the color landscape of garden. When the shade density reaches a certain degree such as more than 50%, Colored-leaf of Ulmus pumila cv.jinye has been completely transformed into green leaf,it basically lost the ornamental value of colored-leaf from the perspective of color landscape. But at this time, the light,the physiology and the growth of plant have not been seriously affected,the growth condition is good. While when the shade density continues to increase to 75%,the leaf color of Ulmus pumila cv.jinye was close to that of Ulmus pumila, the growth physiology and photosynthetic of plants have been severely affected, the growth condition is bad. Therefore, in the application of Ulmus pumila cv.jinye for the landscaping,we should notice the influence law of the light made to its leaf color and growth physiology. We select the appropriate location of light environment to plant according to people's different preferences and requirements to color and its own growth habit. In addition to the full light planting,we also make proper underplanting.In order to enrich the application forms of plants and the color landscape of garden. But try to select the shade density in the environment of lower than 50% to ensure the ornamental effect and good growth of Ulmus pumila cv.jinye colored-leaf, and then create a colorful plant landscape.