Abstract:

The paper aims to study the effect of leaf picking on fruit quality of wine grape (‘Italian Riesling’ and ‘Cabernet Gernischet’) in different color-changed stages, and screen out the period of leaf picking which is suitable for improving the quality of the two varieties. The ‘Italian Riesling’ and ‘Cabernet Gernischet’ were treated by leaf picking in different stages, and the grape fruits without leaf picking were taking as control. The total soluble solid, total soluble sugar, titratable acid, tannin and total phenol content in the two varieties were measured and analyzed by principal component analysis. The total soluble sugar, total soluble solids, total phenol, and sugar/acid were improved, and the titratable acid content was reduced in middle and later stage of full color-changed stages. In the two stages, the soluble sugar content of ‘Italian Riesling’ and ‘Cabernet Gernischet’ of the treatment group were significantly higher than those of the control group by 13.07%, 22.03%, 6.40%, and 43.38%, respectively. In later stage of full color-changed stages, the titratable acid content of the ‘Cabernet Gernischet’ treatment group decreased most significantly, 48.94% lower than that of the control group. The total phenol content in the treatment group of ‘Cabernet Gernischet’ was the highest in the two stages, which was 3.05 and 3.02 mg/g. According to the comprehensive evaluation, the score of grape fruit quality improved by leaf picking from high to low was: C-9.7>I-9.7>I-8.17>C-8.17>I-CK>C-CK. In later stage of full color-changed stages, leaf picking had great influence on fruit quality of ‘Italian Riesling’ and ‘Cabernet Gernischet’.

Key words: wine grape, Hexi Corridor, ‘Italian Riesling’, ‘Cabernet Gernischet’, color-changed stage, leaf picking, fruit quality