## 1 Introduction  
Rootstocks are resistant to various pests and diseases, and are tolerant to different abiotic stress. Therefore, grafting is a technique widely used in viticulture. Many researchers have evaluated the effects of rootstocks on vine growth and fruit composition. However, up to now, no agreements were reached due to the complex interactions among rootstocks, scion cultivars, soil, and climatic conditions. With respect to vine vigor, several previous studies reported significant differences among different grafted vines [1; 2; 3; 4; 5; 6]. For example, own-rooted 'Thompson Seedless' vines produced the lowest pruning weight in comparison with five grafted vines [7]. [PERSON] et al. [8] revealed that many genes regulating carbohydrate metabolism and sugar transportation were up-regulated by rootstocks. Therefore, the vigorous growth of vines may be affected by rootstocks through modifying the effectiveness of carbon transportation. Nevertheless, [PERSON] et al. [9] found that the differences in the pruning weight of 'Pinot Noir' between 110R and 125 AA were not significant. Besides, [PERSON] et al. [10] found that rootstocks did not affect leaf area. Several factors may modify the influence of rootstocks on vine vigor. A previous study reported that rootstock effects on pruning weight varied across different scion cultivars [11]. In addition, the influence of rootstocks on pruning weight and canopy size was closely associated with soil water supply, acidity, nitrogen level, and potassium availability [4; 12; 13; 14]. Sufficient nutrient and water in soil may mask the effect of rootstocks on vine growth. There is a close relationship between vine vigor and yield, which determine vine balance together. Rootstocks can affect the biomass allocation between the root system and the shoot, and then modify the biomass distribution between the fruit and the rest of the vine [7]. Several studies documented that rootstocks imparted significant effects on vine yields [2; 4; 6; 15; 16]. Variations in shoot length and vine vigor may affect the sunlight exposure during fruit bud differentiation, thus modifying vine yields [14]. By contrast, [PERSON] et al. [5] found that yields of 'Chardonnay' and 'Pinot Noir' grafted on four rootstocks, respectively, did not statistically differ in six consecutive seasons. Rootstock effects on yield formation may depend on scion cultivars and seasons. In addition, soil type is correlated with the influence of rootstocks on vine yields. Yields of 'Merlot' grafted on 110R and 101-14 only significantly differed in shale soil when compared to granite soil [13]. Grape compositions may be affected by rootstocks through several mechanisms. It is widely accepted that rootstocks affect berry composition through modifying the vine growth, which may alter the microclimate of grape clusters. [PERSON] et al. [10] attributed the differences in anthocyanins between two grafted vines to the variations in the canopy size, which can mediate the sunlight exposure accepted by grape clusters. Besides, several researchers have suggested that rootstocks may alter the fruit ripening rate, and then modify grape compositions, such as sugar, acidity, and so on [3; 4; 10]. It has been demonstrated that the period between budburst and flowering is much longer in _Vitis berlandieri_ compared to _Vitis riparian_ and _Vitis rupestris_[17]. In addition, [PERSON] et al. [18] revealed that the differences in the ripening rate between two grafted vines of 'Cabernet Sauvignon' were associated with the expression of genes controlling auxin action (ARF and Aux/IAA). Furthermore, different root system architectures can result in variations in the water and/or nutrient capability of different rootstocks [19]. It was reported that rootstocks with _Vitis rupestris_ and _Vitis berlandieri_ genetic makeup showed a good ability for nutrient uptake [7]. The variations in the nutrient element use efficiency of vines induced by rootstocks also affect grape compositions.