Comprehensive evaluation of grafting compatibility of rootstock-scion combinations of pear in the region of Hexi Corridor

【Objective】 This study aimed to investigate and comprehensively evaluate the graft compatibility of diffe-rent dwarf rootstock-scion combinations of pear， in order to screen suitable combinations for the Hexi Corridor region and provide a reference for promoting the application and extension of dwarf interstocks in local pear cultivation. 【Method】 Using Pyrus betulifolia as the rootstock， and Zhongai 1 as the dwarf interstock， grafting experiments were conducted with seven rootstock-scion combinations of pear cultivars： Zaosu， Zaosu Red， Xinli 7， Hongnanguo， Jingbai， Changba， and Xiangshui， forming seven rootstock-scion combinations （T1-T7）. Indexes such as survival rate， rootstock-scion growth， and leaf photosynthetic parameters of the grafted pear seedlings of different rootstock-scion combinations were measured. Principal component analysis （PCA）， cluster analysis， and membership function method were employed for a comprehensive evaluation of graft compatibility. 【Result】 The graft survival rates of all combinations exceeded 90.00%， ranked as T1>T3>T6>T2>T4>T7>T5. The T1 combination had the highest survival rate at 97.34%， while T5 had the lo-west at 94.78%. The circumference ratio of interstock/scion across different combinations ranged from 1.03 to 1.30， and new shoot length ranged from 76.37 to 133.87 cm. The T1 combination showed the best healing status with an interstock-scion circumference ratio of 1.03. The T7 combination had the most leaves， the longest new shoots， and the net growth of interstock and scion diameter was higher than in other combinations. Among the different combinations， the T7 grafted seedlings had the lowest daily average intercellular CO₂ concentration （189.972 μmol/mol）； the highest daily average net photosynthetic rate 5.460 nmol/（m²·s）， which was significantly higher than other combinations （P<0.05， the same below）； T7 also had the highest daily average stomatal limitation value （0.531） and the lowest daily average water use efficiency 1.739 μmol/mol. The daily variation of leaf net photosynthetic rate in all seven combinations generally exhibited a bimodal “M” curve. Correlation analysis revealed positive correlations between the net growth of scion diameter and leaf number， between net growth of interstock diameter and net growth of base stock diameter， and between net growth of base stock diameter and net photosynthetic rate， with their correlation coefficients of 0.79， 0.84， and 0.85. The cumulative variance contribution rate of the three principal components reached 85.391%. Membership function analysis showed that the graft compatibility of the combinations ranked as： T7>T6>T5>T3>T1>T2>T4. Cluster analysis grouped the seven combinations into two categories， with T1 and T7 as one category. 【Conclusion】 The graft combination suitable for high-density dwarf cultivation in the Hexi Corridor region was identified as using the pear cultivar Xiangshui as the scion， and Zhongai 1 as the dwarf interstock.