[Objective]The influence of rootstock on the horticulture and pathology characteristics, especially on scion varieties, growth, yield, fruit size, fruit quality and resistance, which directly decides the economic benefit of orchard. The selection of suitable scion/rootstock combination is an important prerequisite for good quality and high yield of citrus. In the country of origin of sweet pomelo, Fujian, sour pomelo (Citrus Grandis Osbeck) is used extensively as rootstock in nursery stock production. Trifoliata orange (Poncirus trifoliata L.) is one of the most common rootstock in citrus seedling industry of our country, which showed no graft compatibility in the late age of seedling grafting. The traditional citrus industry is satsuma orange, ponkan and a local variety ‘Juhuaxinyou’ in Zhangjiajie area, Hunan province. Red-flesh sweet pomelo industry developed in great area by seedling field planting or budling top graft which was introduced from Fujian province. There for, trifoliate orange and sour pomelo as stock or trifoliate orange as the base stock and navel orange, pokan, satsuma orange, ‘Juhuaxinyou’ as the inter stock becoming the features new of the scion/rootstock combination. Graft incompatibility such as premature aging of tree vigor, abscission layer in graft union, big and small foot, etiolation of branches and leaves appear on different scion/rootstock combination, which has caused a severe economical loss. The screening out of scion/rootstock combination with good wide compatibility and growth vigor has become an extremely urgent duty. In this study, to explore the most suitable rootstock type of red-flesh sweet pomelo, the canopy, plant height, scion/rootstock coarseness of tree and the weight of single fruit, thickness of rind, newel size, vertical and transverse diameter, the soluble solid (TSS) and titratable acid (TA) content of the fruit were measured for evaluating the effect of different rootstock types on tree growth and fruit quality of red-flesh sweet pomelo. [Method]6-year-old red-flesh sweet pomelo trees with trifoliate orange and sour pomelo as stock and 4-year-old trees with trifoliate orange as the base stock and navel orange, pokan, satsuma orange, ‘Juhuaxinyou’ as the inter stock were used as material in this study. The row spacing is 4 m and plant spacing is 3 m. 10 test trees were measured for growth vigor and 10 test fruits were measured for fruit shape in each combination. The tree canopy and plant height were measured with a tape measure. The weight of single fruit was weighed by electronic scales. The thickness of rind, newel size, vertical and horizontal diameter was measured with vernier caliper. TSS and TA content of the fruit were measured by the method of national standard GB 8210-2011. Inner quality estimated by mixed juicing sample which was composed of 10 fruit and 20 g sarcocarp from each one. Data in the paper are all average value. Data analyses were performed by using SAS statistical package; statistically significant differences were identified using analysis of variance (ANOVA); multiple comparisons were compared using the method of least significant difference (LSD). [Result]Rootstocks and inter-stocks were found to have significant effects on plant growth, fruit internal and external quality. The red-flesh sweet pomelo grafted on sour pomelo and top grafted on ‘Juhuaxinyou’ showed higher plant height—at 3.05 and 3.70 m respectively, and which top grafted on Mandarin orange showed the lowest—at 2.23 m. The trees had stronger affinity with sour pomelo than trifoliate orange on which showed ‘Bigfoot’. The scion girth on ponkan showed obviously bigger than inter-stock which scion/stock girth ratio is 1.28, other combinations are all small than 1. To external quality, red-flesh sweet pomelo grafted on sour pomelo and top grafted on ponkan, ‘Juhuaxinyou’ had longer vertical and transverse diameter than 160 mm and high single fruit weight than 1400 g. There was significant relationship between fruit size and central axis. The types of scion/rootstock combination had little effect on fruit shape index. To internal quality, the fruits budded on ponkan inter-stocks had lower soluble solid contents—at 9.57 %, while the fruits budded on sour pomelo rootstocks and ‘Juhuaxinyou’ inter-stocks had apparently higher titratable acid contents than other combination—at 1.47 % and 1.48 % respectively. [Conclusion]Using sour pomelo as rootstock, it always shows strong and vigorous growth, big and heavy fruit, slightly high TA, not low TSS, at the same time there also graft compatible with scion. So, the comprehensive behavior of sour pomelo is relatively balanced which is the suitable rootstock style that can be used for red-flesh sweet pomelo. This research provides a reference for the industry of red-flesh sweet pomelo and improvement of yield and quality.
