Photosynthetic Characteristics And Physiological Properties Of Ancient Sophora Japonica

The ancient tree of Sophora japonica has not only scientific research value,but also precious cultural resources.Most of the existing old trees grow in decline or even death,which has attracted the attention of the society and the management department.However,most of the studies on the ancient tree of Sophora japonica are focused on the establishment of the ancient tree health evaluation system and rejuvenation,and there are few studies on the activity of antioxidant enzymes and photosynthetic characteristics.This study intended to take the different age of Sophora japonica in Zhou Gong Temple as the research object,discussedthe relationship between tree age and physiological characteristics by comparing the physiological characteristics,so as to provide a basis for determining the aging degree of ancient trees and the protection of rejuvenation.The results are as follows:1.Old trees with bad health ratings have poor photosynthetic performance:Through photosynthetic determination of first-class ancient trees with different health status,it was found that the old trees had poor health assessment grades,and their photosynthetic related parameters were also low.The lower the light energy utilization rate was,the worse the photosynthetic ability was.2.The analysis of healthy old trees of different ages shows that the differences between the national conditions of the country in the year 800 and those in the 20-year period are significant:?1?From May to October,the net photosynthetic rate of 20 years old Sophora japonica was higher than that of 120 years old and 800 years old trees.The diurnal variation curve of net photosynthetic rate of 20 years old and 120 years old trees were always double peaks between May and October.However,the diurnal variation curve of net photosynthetic rate of800 years old tree was double peaks from May to August,but single peak between September and October which the other two ages appeared in October.The first peak of double-peaks curve appeared mostly at 11:00 a.m.,and the second mostly at 15:00.Besides,the peak value of single-peak curve appeared mainly at 12:00.What's more,the diurnal variation of stomatal conductance was basically the same as the diurnal variation of net photosynthetic rate except September and October when the curve of three ages appeared single peak and the peak was in 11:00 and 12:00 a.m.We also found the concentration of intercellular CO₂ in the whole experiment showed a trend of first decrease and then increase.?2?From May to October,the photosynthetic ability of Sophora japonica in three age groups was first increased and then decreased.According to the data obtained from fitting the light response curve every month,the growth of tree age was accompanied by the decline of physiological function of trees,resulting in a decrease in photosynthetic capacity.Sophora japonica from different ages began to accumulate organic matter through photosynthesis from May,but the parameters of the 800 years old tree decreased from August,which indicated that the adaptability to the environment was weakening with age and its normal physiological activities showed an aging weakening trend owing to the effects of environment.3.We measured the activity of antioxidant enzymes,soluble sugar and protein as well as the content of soluble sugar and protein of Sophora japonica at different ages.The results showed that both of the120 years old and 800 years old tree,the activity of CAT,the content soluble sugar and soluble protein decreased,the activity of POD decreased and then increased,the content of MDA increased gradually,and the activity of SOD in 20 years was the highest.During the whole aging process,the cell membrane lipid peroxidation level was increasing,and the content of MDA was rising.It could be seen the main way to scavenging reactive oxygen was enhancing the activity of antioxidant enzymes when the senescence was not very deep.However,with the further intensification of aging,their effects were becoming less and less obvious,and the content of soluble sugar and protein also decreased,which eventually led to the accumulation of active oxygen,the increased level of membrane lipid peroxidation and the decline of the physiological function of the whole plant.