Influence of eight rootstocks on fruit quality of Morus multicaulis cv. 'Zijing' and the comprehensive evaluation of fruit quality traits

Mulberry (Morus L.) has become an important crop throughout the world due to its fruits have been industrially exploited for various commercially valuable products. Many studies on mulberry related to genetic diversity, fruit quality, and breeding programs have been carried out, but little information on mulberry rootstocks is available, especially the possibility of applying grafting to improve the fruit quality. Here, we evaluated the effects of 8 different rootstocks on the fruit quality of 'Zijing' mulberry. Twelve fruit quality traits were extremely different except for the fruit shape index (FSI). 'Zijing' on 'Zheza 2' had the highest fruit weight (FW) and size, as well as titratable acidity (TA), but lower levels of other compounds content except the total soluble solids content (TSS) were detected. 'Yuesang 51' exhibited the highest soluble sugar content (SSC), reducing sugar content (RSC), SSC/TA ratio, anthocyanin content (AC) and the lower TA. In contrast, the lowest TSS, SSC and RSC were shown in 'Guisang 5'. Moreover, 'Guisang 12' exhibited the highest TSS and soluble protein content (SPC). The highest vitamin C content (VC) was observed in 'Guisang 6'. 'Tang 10 x Lun109', Zhenzhubai seedlings, 'Yuesang 11' together with 'Yuesang 51' had the lowest and similar levels of TA. Most importantly, these fruit quality traits were evaluated by principal component analysis (PCA), and 'Yuesang 51' with good comprehensive fruit quality was screened out, followed by 'Guisangyou 12'. Overall, these results contribute to evaluating the roles of different rootstocks on improving fruit quality of mulberry.