Effects of different rootstocks on the growth and berry quality in ‘Ruidu Hongyu’ grapevines

Abstract：【Objective】The objective of this study was to evaluate the effects of rootstocks on the phenophase, growth, fruiting characteristics and fruit quality of‘Ruidu Hongyu’grapevines, so as to provide a scientific basis for selecting suitable rootstocks and improve the berry coloration in Southern China. 【Methods】‘Ruidu Hongyu’grapevines were grafted onto 11 different rootstocks and self-rooted seedlings were used as the control. In the experiment, the steel pipe connected building greenhouses was adopted for cultivation, and grape frame shape was trained as single cross‘bird’frame, with a spacing of 2.5 m×1 m, north-south line in the row. The experiment was designed as a random block arrangement with single row plot, 3 plots for each treatment, 5 grapevines for each plot. The experimental materials were 3-year-old‘Ruidu Hongyu’grapevine graftings that were not treated with flower and fruit thinning. The experiment was undertaken in 2017—2018. The phenophase dates, percentages of bud break and fruiting branches were investigated. The thickness of main vine, stock vine and vine internode of different plants were randomly measured by a vernier calipe, vine internode length was randomly measured by a tapeline. Each treatment was repeated for 10 times. Different treatments were sampled at the same time of fruit ripening. Thirty clusters were randomly selected from different plants for measuring cluster weight, length and width. Fifty berries were randomly collected from different plants, cluster and azimuth for evaluating berry weight as well as longitudinal and transverse diameters. The hardnesswas measured by texture analysis and soluble solids was measured by hand- held refractometer. The samples were ground into freeze-dried powder with liquid nitrogen and stored in a refrigerator at -80 ℃ for evaluating on titratable acids, anthocyanin, total phenols, soluble sugar and organic acid. Each treatment was repeated for 3 times. The experiment was carried out in the experimental base of the Scientific Research and Innovation, Zhejiang Academy of Agricultural Sciences in Haining, where it belongs to north subtropical monsoon climate zone, with an annual temperature of 15.9 ℃, a rainfall of 1 187 mm, sunshine hours of 2 002.9 h, a frost free period of 233.5 d, and sandy soil. The soil layer at 0-20 cm contained 18.1 g·kg^-1 of organic matter, 0.9 g·kg^-1 of total nitrogen, 84.5 mg·kg^-1 of available phosphorus, 133.0 mg · kg^-1 of available potassium, and the pH value was 6.7.【Results】The order for sake of better influence from high to low was:‘Huajia No.8’＞‘Kangzhen No.1’＞‘101- 14’＞‘Kangzhen No.3’＞‘Ruperstrisdulot’＞self- root seedlings＞‘110R’＞‘Riparia Gloire’＞‘SO4’＞‘Salt creek’＞‘225Ru’＞‘420A’. Considering the skin coloring factor, the anthocyanin contents in pericarp of vines grafted onto‘Kangzhen No.1’‘101- 14’and‘Ruperstrisdulot’were significantly less than the control (42.78%, 57.42% and 46.21%), so they showed the problem of uneven coloring. Grapevines grafted on‘Riparia Gloire’had the highest anthocyanin content in pericarp (157.94% ), which was significantly higher than the control, but the comprehensive quality was worse than the control. Grapevines grafted onto‘Kangzhen No.3’could improve the anthocyanin content in pericarp (114.12%), which was significantly higher than the control, but the yield (43.07%) was lower than control and the comprehensive principal component value F was smaller than the‘Huajia No.8’.‘Ruidu Hongyu’grafted onto‘Huajia No.8’could improve the anthocyanin content in pericarp (112.67% ), which was significantly higher than the control and no significant difference existed with‘Kangzhen No.3’. Besides, it had the best overall performance.‘Huajia No.8’could enhance vine growth potential, increase the berry weight up to (5.92±0.13) g (25.16% ), which was significantly heavier than the control, the soluble solid content was up to（20.62±0.13）% that was the highest among the tested materials, the ratio of soluble solid to acid was 48.32, the total sugar content was (165.04±3.07) mg · g^-1 and the β value was 0.66, so that the berry was tasted fresh with long aftertaste.【Conclusion】Different rootstocks had different effects on scion’s phenophase dates, vine growth, fruit characteristics and berry quality. The comprehensive evaluation showed that‘Huajia No.8’was the most suitable rootstock for ‘Ruidu Hongyu’grapevine among the 11 stock-scion combinations. It could enhance the growth potential, fruit quality, the soluble solids, total sugar content and make berries color-setting better with excellent quality, taste and flavor.