## 4 Discussion  
Fruit bagging is a common practice used in the production of peach [2], apple [1], pear [25], and graprefruit [3], which has multiple effects on internal and external quality of fruit. Bagging can change the growth environment of fruits, and paper bags commonly used in production have a particularly obvious impact on light. Light can affect fruit coloring, and the effect of light on different fruit tissues varies [21]. The amount of light absorbed by different kiwri fruit tissues is inconsistent; the light exposure of the inner axial placenta is only \(1/30\) of that of the surface [26]. In this study, we found that bagging had different effects on the color of the epicarp and mesocarp. Bagging mainly affected the color of the mesocarp and the brightness in the epicarp, indicating that bagging can improve the brightness of the fruit surface and enhance the appearance of the inner fruit. Bagging followed by debugging produces fruit with a bright red color, which is more appealing to consumers [27]. In our study, debugging improves the brightness of the fruit surface, which is consistent with previous research [28]. Although bagging improves fruit's appearance quality, it also has some negative effects on fruit quality [27]. Studies on kiwifruit showed that bagging reduced the soluble solids of 'Jinkui' (_A. deliciousa_) and 'Jinyan' (_A. chinensis_) [29], but had no effect on the soluble solids, dry matter, soluble sugars, and tittatable acids of A. _eriantha_[4]. In this study, bagging reduced the accumulation of dry matter, tittatable acid, and starch during fruit development, which is consistent with previous findings [29]. Fructose, glucose, and sucrose are the main components of soluble sugars in fruits [30]. The proportion of soluble sugar components constantly changes with the development and maturity of the fruit. The content of fructose and glucose in mature kiwifruit is the highest, followed by sucrose [31]. Studies on pears have shown that bagging fruits reduces sugar content and the activities of enzymes related to sucrose metabolism [32]. The reason why bagging reduces the edible quality of fruits may be that after bagging, fruits are in shading condition for a long time, and photosynthesis of fruit skins is weakened or almost absent, which reduces the assimilates of fruits. Meanwhile, respiration in bags needs to consume certain assimilates [28]. Soluble sugar content plays an important role in fruit development and  
Figure 7: Effect of bagging on the expression levels of AsA synthesis-related genes during kiwifruit development. Each assay was performed in triplicate to ensure the validity of the experimental data and to reduce the variance. All results are presented as mean \(\pm\) standard error (SE). Bars with the same letter are not significantly different at \(p>0.05\) among three treatments, according to paired-samples \(t\)-test, ‘ns’ means not significant. ripening. Sucrose treatment can promote the accumulation of anthocyanin in strawberry fruit, thereby accelerating fruit ripening [33]. Fruit ripening was significantly delayed in low-sugar-content orange mutant [34]. Exogenous sucrose treatment accelerates color change of postharvest tomato fruit [35]. In this study, the contents of sucrose, fructose, and glucose gradually increased as the fruits matured, but the sugar content of bagged fruits decreased compared to that in the control. This implies that the changes of soluble sugar content and color are correlated during the development and ripening of kiwifruit. Most fleshy fruits are green during the early stage of development. With the maturation of the fruits, the contents of various components in the fruits change significantly. Chlorophyll and carotenoids are the main pigments involved in the development of yellow-fleshed fruits [6]. During fruit development and ripening, chlorophyll is degraded, and carotenoids are synthesized and accumulated [11].