Effect Of Fruit Load And Exogenous Abscisic Acid Application On Tree Growth, Nutrition And Fruit Quality Of Grapevine

Two years of field experiment were conducted in Shanghai to evaluate the effect of fruit load on tree growth, nutrition of root, and fruit quality of 3-year-old'Jumeigui'(Vitis Vinifera×Vitis Labrusca)and'Summer black'(Vitis Vinifera×Vitis Labrusca)with 16 m2 of canopy area per vine. Further more, the effect of exogenous abscisic acid on the color and quality of'Jumeigui'grape berries was studied. The results show that:(1)With the increase of fruit load, the vegetative growth of grapevine(shoot length, shoot diameter, trunk circumference and leaf area) are restrained. The differences between all of treatments of'Jumeigui'grapevine are not significant. And it is the same to'Summer Black'grapevine except that its trunk circumference decreased significantly with the increase of fruit load.(2) The total nitrogen content in the root of grapevine was increased from abscission period to dormant period (FAPTDP) and it is susceptible to the fruit load. At the same period, the total nitrogen content increased significantly with increase of fruit load. And we also found that the content of starch in the root showed a downward trend FAPTDP, whereas the content of sugar, on the contrast, increased. The fact is that some starch converted into soluble sugar and the amount decreased with the increase of fruit load.(3)With the increase of fruit load, the content of anthocyanin in the skin and total soluble solids (TSS) in the must decreased significantly, whereas the cluster weight, berry weight, titratable acidity and pH changed a little. Besides, the content of soluble sugar and free amino acids decreased with the increase of fruit load and this, as a result, leaded to sweetness of grapes.(4)Considering several elements, such as tree growth, nutrition storage and berry quality, the maximum fruit load for kyoho grapevine series with with vigorous growth such as'Summer Black'is 1300kg/667m2 and for'Jumeigui'with middle-growth is 1100 kg/667m2.(5) Application of exogenous abscisic acid at veraison increased the content of anthocyanin in the skin—more than twice the control, but the content of TSS and individual berry weight were decreased. In addition, the content of total soluble solids surpassed the minimum quality standards under 500 mg/L ABA treatment, which also allowed grapes to be harvested 10 days earlier than the control.