Abstract: To explore the effect of interstock on the pear root growth and the fruit quality,Nanshuigou1,E7-28,Zhongai 3 and OH×F51 were used as interstock grafted on Douli,while Xueqing was used as scion.The indexes related to the root development and the fruit quality were evaluated and the expression level of genes involved in sugar metabolism （SOT2 and SUT1） were analyzed.Compared with other interstocks,E7-28 showed the best compatibility with scion and rootstock,with more roots and larger fruit size.The fruit has a higher level of soluble solids and lower total titratable acid.The content of fructose and sucrose was higher,and the content of malic acid and citric acid was lower.Nanshuigou 1 has the largest leaf,the second-largest fruit weight,and the highest sucrose content.When Zhongai 3 was used as interstock,the root amount was less and the fruit had a lower level of soluble solids and a higher level of malic acid and citric acid.When OH× F51 was used as interstock,noticeable incompatibility was found with small canopy width,weak growth vigor and small size of the fruit.E 7-28 is the most suitable interstock,followed by Nanshuigou 1.

Key words: Interstock, Pear, Root development, Fruit quality