Study On Photosynthetic Characteristics,Fruit Quality, Ornamental And Application With Different Tree Shapes Of Prunus Salicina

Plum（Prunus salicina）is a species of drupes woody plant of the genus Prunus in family Rosaceae.With its advantage in high yield and economic profit.plum has benn cultivated in large quantities as fruit tree.It has also been widely used in leisure agriculture and landscaping for its ornamental characteristics in organs,such as flowers,leaves and tree shapes.Using4-year-old plum variety’Gongzhuhong’in spindle shape,Y-shape and natural open center shape as experimental materials,several indicators have been determined,such as tree structure,canopy structure,photosynthetic characteristics,fruit quality and fruit yield.The research findings will provide a theoretical reference for the ornamental and application of different canopy structures of Prunus salicina.The main results are as follows:1.During the various periods of fruit development,the diurnal variation of net photosynthetic rate of three tree shapes all showed a double-peak curve.The first peak appeared at 8:00 or 10:00 am and the second peak appeared at 14:00 pm.There was an obvious’midday depression’phenomenon at noon.The net photosynthetic rate among three trees shapes have been compared.The natural open center shape and the Y-shape were higher than spindle shape.There was no significant difference in the net photosynthetic rate between natural open center shape and Y-shape.Order of the content of photosynthetic pigment among three trees shapes was,natural open center shap>Y-shap>spindle.The net photosynthetic rate of various periods of fruit development among three tree shapes have been compared.The results showed fruit maturing stage>fruit color-changed stage>fruit hardening stage>fruit expanding stage.The strongest photosynthetic capability appeared at fruit maturing stage,so did the chlorophyll a+b content.2.The net photosynthetic rate（Pn）,transpiration rate（Tr）,stomatal conductance（Gs）,water use efficiency（WUE）of bearing branchs among three tree shapes have been compared.The results showed natural open center shape>Y-shape>spindle.vegetative branchs among three tree shapes showed the same trend in terms of photosynthesis parameters.Comparation in the intercellular CO2 concentration among three tree shapes have been carried out.The results showed spindle shape>Y-shape>natural open center shape.Comparation in the chlorophyll fluorescence parameters such as actual photochemical efficiency(Φ_PSⅡ),foxtail millet maximum photochemical efficiency（F_v/F_m）,electron transport rate（ETR）,photochemical quenching coefficient（q_P）,non-photochemical quenching coefficient（q_N）of bearing branch among three tree shapes,showed natural open center shape>Y-shape>spindle.The same trend were observed in vegetative branchs among three tree shapes.The photosynthetic capacity of the bearing branch was higher than that of vegetative branch.3.Comparation of LCP among three tree shapes have been studied.Natural open center shape is the highest,followed by spindle shape,and LSP of Y-shaped the lowest.They were1718.02μmol·m^-2·s^-1,1387.55μmol·m^-2·s^-1 and 1153.12μmol·m^-2·s^-1,respectively.All the LSP of three tree shapes were higher than 1100μmol^-2·s^-1,which indicated a strong adaptability to strong light.Comparation of LCP among three tree shapes showed that the Y-shape was the highest,followed by the nature open center shape,and the spindle shape the lowest.The values were 80.29μmol·m^-2·s^-1,53.77μmol·m^-2·s^-1 and 45.61μmol·m^-2·s^-1,respectively.As for AQY among three tree shapes,the results showed that the spindle shape was the highest,followed by the nature open center shape,and the Y-shape the lowest.The values were 0.0399,0.0305 and0.0279 respectively.The spindle shape showed the lowest LCP but the highest AQY,which indicated a strong adaptability to weak light.4.The fruit quality indexes among three tree shapes have been compared.The results showed that spindle shape had the largest single fruit weight,followed by the nature open center shape,and the smallest the Y-shape.Soluble solids,soluble sugar,SS/TA,and anthocyanin of spindle shape were significantly higher than those of other two tree shapes.The nature open center shape had the largest Vitamin C,followed by Y-shape,and the lowest the spindle shape.There was no significant difference in the fruit shape index,fruit hardness and flavonoids among three tree shape.As for the yield of a single plant among three tree shape,the natural open center shape was the highest,reaching 22.52 kg,followed by the Y-shape with 14.39 kg.The spindle shape had the lowest yield with only 8.58 kg.The three tree structures,flowers and fruits are ornamental.5.There were significant differences in the amount of branches and branch composition among three tree shapes.The branche number of the spindle shape was significantly more than that of natural open center shape and Y-shape.The canopy of Y-shape was relatively the shortest,with the crown stretched and the smallest branch number.Among three tree shapes,the cluster branches and short branches all accounted for a large proportion,which were 39%-64%and13%-37%respectively.The number of the cluster branches and short branches of the natural open center shape and Y-shape were significantly higher than the spindle shape.The average stem length of annual branche of the natural open center shape was significantly longer than spindle shape and Y-shape.There was no significant difference in the average stem diameter between spindle shape and natural open center shape.But both were significantly larger than the Y-shape.6.The canopy characteristics among three tree shapes have been compared.The leaf area index（LAI）of spindle shape was the largest,which was 1.32.The canopy light transmittance（CLT）of spindle shape was the smallest,which was 0.23.Both the ellipsoidal leaf angle distribution parameter（ELADP）and the total radiation under the canopy of spindle shape were the lowest.The Y-shape had the highest CLT and ELADP.The natural open center shape had relatively higher LAI and CLT.Compared with spindle shape,the natural open center shape had higher ELADP.The total radiation under the canopy of the natural open center shape and Y-shape were significantly higher than that of the spindle shape.7.Natural open center shape was full,open canopy,good ventilation and light transmission conditions,distinct main and lateral branches,many flowers,compact clusters,large number of fruits,colorful,multi-dimensional viewing,and most fruits concentrated in the lower part of the tree,easy to pick;Y-shape was a"flat"tree,with horizontal crown spread out,extending beautifully,good ventilation and light transmission conditions,low canopy,easy to pick,convenient management;The spindle tree has the highest crown,steeple shape,compact,tidy and beautiful,with numerous flowers,compact flower clusters,large fruits and attractive colors.