Effect Of Different Defoliation On Tree Nutrient?Yield And Fruit Quality Of Rosa Roxburghii Tratt

Rosa Roxburghii is a unique newly-developing fruit tree in China and most widely planted in Guizhou province.The fruits and leaves of Rosa Roxburghii are rich in active ingredients such as VC,flavonoids,polysaccharides,free amino acids,etc,which can be used to develop a variety of products.In the process of processing Rosa roxburghii leaves,the number of leaves picked will not adversely affect the fruit yield and quality,which is still inconclusive.In order to study the effects of different leaf loss on nutrient content,yield and quality of Rosa roxburghii Trattcv.'Guinong5',a4-year-old Rosa roxburghii Tratt cv.'Guinong5',was used as a test material.Four degrees?20%?40%?60%and 80%?of loss in leaves were designed to explore the efforts of different losses of spring of shoot leaves on the growth of new shoots,tree nutrients and fruit yield and quality of Rosa roxburghii,the leaves without loss of the plant were taken as the control.The following results were obtained.1.The loss of leaves in spring tips of Rosa roxburghii would delay the ripening period of fruit in the current year and the sprouting period in the following spring,but had no significant effects on flowering,leaf spreading and fruit ripening period in the following year.There was no effect on the ripening period of fruit in the current year and the sprouting period of spring shoot in the following year when the amount of loss in leaves were less than 20%.2.The summer shoots of Rosa roxburghii would be pulled out ahead after the loss of leaves,and the number of summer shoots was positively correlated with the loss of leaves(r=0.99^**).The length and diameter of spring and summer shoots were negatively correlated with leaf loss in different treatments.The number,length and diameter of autumn shoots were negatively correlated with leaf loss.In the following growing season,there was a significant linear negative correlation(r=0.84^**)between the spring shoot number of Rosa roxburghii and defoliation.3.The loss of leaves in spring shoot of Rosa roxburghii significantly decreased the nutrient content of Rosa roxburghii in the same year and the following year.During the nutritional diagnosis period in June,the contents of N,P,K,Ca,Mg,Fe,Mn,Cu,Zn and B in leaves decreased significantly after defoliation.In the treatment of leaf loss 80%,the content of these elements was the lowest.After defoliation in spring shoot,the degree of decreases in elements in leaves were Mg>B>P>Zn>Cu>K>N>Fe>Ca>Mn.The leaf loss was negatively correlated with the contents of N,P,K,Ca,Mg,Fe,Mn,Cu,Zn and B in leaves.4.The loss of leaves in spring shoot of Rosa roxburghii significantly reduced the fruit yield of Rosa roxburghii in the same year and next year.The weight of single fruit,yield per plant and fruit setting rate decreased significantly with the increase of leaf loss.Single fruit weight,yield per plant and fruit setting rate were significantly negatively correlated with leaf loss.5.The loss of leaves in spring shoot of Rosa roxburghii hads adverse effects on the quality of Rosa roxburghii fruit in the same year and next year.Defoliation significantly reduced juice yield,seed number,soluble solids,total soluble sugar,titratable acid,vitamin C,total flavonoids content,and increased fruit shape index.In the treatment of leaf loss of 80%,the above quality index decreased the most.The edible rate was not affected by defoliation.The juice yield,seed number,soluble solids,total soluble sugar,titratable acid,vitamin C and total flavonoids content were significantly and negatively correlated with leaf loss,while the fruit shape index was significantly and positively correlated with leaf loss,while the edible rate was not significantly correlated with leaf loss.6.Under non-artificial conditions,the loss of leaves caused by natural factors such as drought,diseases and pests will also adversely affect the fruit quality of Rosa roxburghii.With the increase of leaf loss,the single fruit weight,fruit setting rate,soluble solids,total soluble sugar,titratable acid,vitamin C and total flavonoids content decreased significantly.To sum up,the loss of leaves in spring shoot of Rosa roxburghii promoted the growth of summer shoots and increase the number of summer shoots.Under the condition of less than 20%loss in leaves,leaf loss at spring tip had no significant effect on nutrient,yield and quality of Rosa roxburghii.In production,orchards providing leaves and fruit of Rosa roxburghii as raw materials should control the amount of leaves picked less than 20%,and the interval between leaves picked was at least one year.Otherwise,the nutrients,yield and quality of Rosa roxburghii trees will be adversely affected.