Effects Of Leaf Removal On Fruit Quality Of Cabernet Sauvignon And Cabernet Franc Grape

During the growth of grape,the exposure rate of the cluster has a significant impact on fruit growth and the final fruit quality.In recent years,leaf removal has been widely applied as an effective cultivation technique and has achieved good results.However,the results of research on the effects of leaf removal on grape fruit quality index are inconsistent,and there are few reports on the mechanism of anthocyanin synthesis pathway regulation by removing leaves,and the period and intensity of leaf removal in different regions due to climate differences are also different.In this study from 2017 to 2018,Cabernet Sauvignon and Cabernet Franc in Linfen region,Shanxi province were used as experiment materials.At the veraison beginning and veraison ending of grape,2 leaves,4 leaves and 6 leaves of the bearing shoot were removed to study the effects of different leaf removeal treatments on grape fruit quality,especially anthocyanins,in order to provide experimental basis for improving the quality of anthocyanins in Cabernet Sauvignon and Cabernet Franc in central south region,Shanxi province.The main findings are as follows:(1)The leaf removal treatments could effectively increase the content of reducing sugar,total anthocyanin,total phenol and tannin in grape fruit,and the best treatment was removed6 leaves of the bearing shoot at veraison ending of Cabernet Sauvignon,the reducing sugar,total anthocyanins,total phenol and tannin were increased by 9.35%,18.64%,11.36% and25.87%,respectively.The reducing sugar,total anthocyanins and total phenol of the removed6 leaves of the bearing shoot at veraison ending of Cabernet Franc increased by 4.95%,10.08% and 13.31%,respectively.(2)The leaf removal treatments could effectively increased the anthocyanins content of grape,and the removing 6 leaves at the veraison beginning and the veraison ending had the best effect on the total content of anthocyanins in Cabernet Sauvignon,compared with the control,the average increase was 30.65% and 42.30%,respectively.The removal 6 leaves at the veraison ending had the best effect on the total content of anthocyanins in Cabernet Franc,which was 62.87% higher than the control.(3)The leaf removal treatments can increase the content of non-anthocyanins phenolic compounds in grape.The total content of non-anthocyanins phenolic and flavonols of Cabernet Sauvignon were obviously improved on removing 6 leaves at the veraison beginning,compared with the control,the average increase was 113.13% and 123.89%,and the most enhanced component was kaempferol-3-O-glucoside,which was 168.68% higher than the control;It was best treatment to remove 6 leaves at the veraison ending for the total content of non-anthocyanins phenolic of Cabernet Franc,which was 71.63% higher than the control,and the most enhanced component was rhamnosin-3-O-glucoside,which was76.69% higher than the control.(4)The effect of leaf removal on the aroma component of grape was different between varieties and years.In 2017,the leaf removal treatment significantly reduced the aroma component of Cabernet Sauvignon,and in 2018,the removing 2 leaves at the veraison ending could increse the total content of aroma,linear fatty aldehydes and linear fatty lipids of Cabernet Sauvignon,compared with the control,the average increase was 18.48%,43.20% and 27.62%.6 leaves at the veraison beginning and at the veraison ending to increase the total content of aroma,linear fatty aldehydes,straight-chain fatty alcohols and aromatic aroma component had the best effects.(5)The removing 6 leaves during the development of Cabernet Sauvignon could induce the up-regulation of VvPAL,VvF3H2,VvDFR,VvLDOX,Vv4 CL,VvCHI1 and VvMYB5 b genes.The expression level of VvPAL was average increased by 227.43% compared to the control of removing 6 leaves at the veraison beginning.Considering comprehensively,the removing 6 leaves at the veraison beginning and the veraison ending are the best for the anthocyanins of Cabernet Sauvignon,and the removing 6leaves at the veraison ending is the best for the anthocyanins of Cabernet Franc.