The Effects Of Three Tending Measures On The Physiology Of Rhus Typhina During Senescence

Rhus typhina is an excellent ornamental tree species with colored leaves,but its short life affects its ornamental value.In order to find out the aging mechanism of Rhus typhina,diagnose its vigor and take appropriate maintenance and management measures to delay its aging,4 Rhus typhina of 2,4,8 and12 years old were selected in Shijiazhuang expressway slope protection,Baoding botanical garden,Jianguo Road highway and railway The differences of plant morphology,leaf color,leaf pigment content,contents,antioxidant enzyme activity,endogenous hormone content and mineral element content in stems and leaves of 12-year-old Rhus typhina were studied:(1)The annual leaf growth decreased with the increase of tree age.The results showed that the annual leaf growth of 2-year-old Rhus typhina was the largest and the growth was vigorous;the annual leaf growth of 4-year-old Rhus typhina was slower than that of 2-year-old Rhus typhina;the annual leaf growth of 12-year-old Rhus typhina was the smallest and the growth was sluggish;the annual leaf growth of different ages was significantly different(P<0.05),and the average leaf area volume of 12-year-old Rhus typhina was only 38.26%of that of 2-year-old Rhus typhina.(2)The results showed that the chlorophyll and carotenoid contents of 2-year-old Rhus typhina were low,and the photosynthetic system was not perfect and the photosynthetic capacity was weak;The contents of chlorophyll and carotenoids were higher in 4a and 8a,and the photosynthetic capacity was the strongest in this stage;the photosynthetic system of 12a was damaged,the photosynthetic capacity was weakened,the number of chloroplast damaged was reduced,and the chlorophyll content was the lowest.The leaves of 2a and 12a were brighter and more yellow green,while the leaves of 4a and 8a were darker and greener.(3)The results showed that with the increase of tree age,the activities of SOD,POD,CAT and other antioxidant enzymes in leaves increased first and then decreased,the contents of free proline,soluble protein,soluble sugar increased first and then decreased,and the contents of MDA decreased first and then increased;the contents of mineral nutrients C,N,P,K,Ca,Mg,Na,Zn in branches and leaves showed a general trend The contents of endogenous hormones ZR,GA3,KT and IAA in Rhus typhina leaves increased first and then decreased,and ABA content showed a trend of "increase decrease increase".The contents of endogenous hormones ZR,GA3,KT and IAA in Rhus typhina leaves reached the lowest and ABA content reached the highest in 12a.(4)According to the comprehensive evaluation of the growth status of different age Rhus typhina by principal component analysis,the order of growth status of different age Rhus typhina is 4a>8a>2a>12a.According to the evaluation results,2-year-old Rhus typhina is in the young stage;4-8-year-old Rhus typhina is in the peak stage;12-year-old Rhus typhina is in the senescence stage.(5)The results showed that the chlorophyll content,SOD activity,POD activity,CAT activity and soluble protein content of Rhus typhina leaves increased significantly under the three tending measures except sprouting,pruning and root cutting The highest value increased by 44.78%,22.10%,73.27%,141.31%and 39.05%respectively compared with CK.The content of soluble sugar increased,and the content of MDA decreased first and then increased.The lowest value was significantly lower than CK by 25.20%.The comprehensive evaluation results showed that except sprouting and tillering treatment had the best effect on the physiology of aging Rhus typhina leaves,followed by root cutting treatment,and pruning treatment had the worst effect.