Method And Mechanisms For The Non-invasive Girdling In Peach

Girdling is mostly applied to fruit tree production.Girdling can promote the improvement of fruit quality by regulating the carbohydrate of distribution in fruit trees,but the disadvantage is that Girdling physically invades the phloem and reduces the viability of fruit trees.Therefore,there is a need for a research and application technology that can avoid excessive damage to fruit trees and improve fruit quality,which is of great significance for improving the sustainable productivity of orchards.At present,studies have shown that using some physical materials to non-invasive girdling the stem of fruit trees can play an important role in regulating tree growth and promoting fruit development.Therefore,non-invasive girdling has extensive potential and prospects.In this study,different non-invasive girdling materials such as iron wire,nylon straps,metal cable ties were compared with the girdling control and CK.We measured the fresh weight,dry weight,leaf area,specific leaf weight,longitudinal diameter,horizontal diameter,gas exchange parameters,leaf water potential,non-structural carbohydrates,titratable acids,nutrient elements of the leaf branches of different treatments in different post-treatment periods.This experiment uses 13 C isotope labeling to assist in the study of the amount of carbon transported to the fruit.Through systematic research on each treatment,it is shown that non-invasive girdling can regulate the carbon and water balance of fruit trees,coordinated transport of carbon and water,and promote fruit quality,providing a theoretical and practical basis for sustainable high production in the orchard.(1)The non-invasive girdling(W,NCT,MT)showed obvious indentation in the treatment area.Among them,the indentation of MT treatment is the most obvious,which can provide continuous high pressure and result in the formation of cylindrical protrusions,while the cylindrical protrusions of the girdling treatment(G)are smaller.In the following year,the growth of the base diameter of MT treatment branches increased by about 237.55%,and the fruit setting of MT treatment increased by about 46.52%,while the fruit setting of G treatment showed no significant difference.It shows that MT treatment is superior to G treatment in the sustainable production of fruit trees in the following year.(2)The leaf area,specific leaf weight,fresh leaf weight,and dry leaf weight of W,NCT,and MT treatments all increased to different degrees in measurement periods.The MTtreatment was significantly improved in different periods,and the value difference was the largest at 42 days after the treatment(second rapid development period).The four leaf indicators increased by approximately 33.85%,18.46%,40.1%,and 39.40%,respectively.However,56 days after the treatment(mature stage),the fresh and dry weights of the leaves were only the highest in the G and MT treatments.56 days after treatment,W,NCT,MT,and G treatments all improved fruit shape index,but only MT and G treatments increased the fruit's horizontal and vertical diameters by about 16.44%and 7.87,respectively.During the same period,the dry weight of MT treated fruit increased by 28.11% and 41.1%.(3)Both non-invasive girdling and girdling can cause photosynthetic inhibition in the leaves.Among them,non-invasive girdling treatment with MT had the most severe photosynthesis inhibition,but Pn was still higher than G treatment by 14.44% after 56 days of treatment.Among the gas exchange parameters(Pn,Gs,Tr),W,NCT,and MT treatments decreased in different measurement periods.Among them,the lowest values of Pn,Gs,and Tr in MT treatment decreased by about 64.36%,75.26%,and 50.84%,respectively.Among the chlorophyll fluorescence parameters,the photosynthetic activity parameters such as Fs,?PSII,Fm,ETR,q P,and Fv'/Fm' treated by MT and G were all reduced at 56 days after treatment.The parameters related to heat dissipation are increased by Fo and NPQ,while the values of MT and G treatment are similarly increased by approximately 6.12% and 12.1%.It showed that the same treatments of MT and G can inhibit the photosynthetic performance of the leaves..(4)Among the relevant indicators of leaf moisture,both MT and G treatments can cause the increase in the saturated water vapor pressure deficit(Vpd L)of the leaves.Moreover,the difference reached the maximum when the fruit moisture was the most sensitive 40 days after the treatment,and the MT treatment increased about 64.86%.However,the leaf water potential(?)of the MT treatment showed a decrease when measuring the day and night water potential four times,and the difference decreased by about 20.87% after38 days of treatment.In addition,the hydraulic and economic trait parameters show a significant correlation.Among them,? was significantly negatively correlated with parameters such as specific leaf weight(SLW)and fruit non-structural carbohydrate(NSCF).? is extremely positively correlated with photosynthetic physiological indicators(Pn,Gs,WUE),which indicates that there is a restrictive balance between the hydraulic and economic traits of the leaves.(5)The W,NCT,and MT treatments can reduce the titratable acid of the fruit in the three periods,and the MT treatment 42 days after the treatment is most obvious about 54.4%.At the same time,these treatments can increase NSCF and leaf non-structural carbohydrates(NSCL)to varying degrees.Among them,MT and G treatments have significantly increased NSCF by approximately 23.8% and 19.17% during fruit ripening.In the MT treatment,the sugar components(sorbitol,sucrose,fructose,glucose)of leaves and fruits increased to varying degrees at 56 days after the treatment.It shows that MT non-invasive girdling treatment can promote the sugar accumulation of the fruit,reduce the acidity of the fruit,and promote the quality improvement of the fruit..(6)Among the nutrients(N,P,K)of leaves and shoots,the W,NCT,MT non-invasive girdling treatments and G treatments all showed a downward trend,and the difference in the decline in branches was greater than that of leaves.Among them,the MT treatment had the lowest N,P,and K content in leaves and branches,and the largest differences in N and K in branches decreased by about 34.39% and 31.57%.However,the content of C elements in each branch was aggregated,and the MT treatment increased significantly by about 28.94%.(7)Using the13 C isotope labeling method to explore the distribution rule of leaves photosynthetic products to fruits,according to the degree of obstacles formed by the non-invasive girdling treatment,the distribution of 13 C in leaves to fruits is also different.In the amount of13 C in different organs in different treatments,the rule of leaf>fruit>branch appeared in the early and middle stages of fruit development,and the13 C content of fruit was higher than that of leaves during the fruit ripening period.The amount of13 C allocated to the fruit in the non-invasive girdling treatment:MT>NCT>W>CK,where the MT treatment allocated 13 C in the fruit increased significantly by about 165.07%.MT is about 11.35% higher than G processing.In summary,the MT treatment without injury ring peeling meets the above requirements and has the best effect on improving the quality of the fruit.It can be considered for further practical research.