Rootstocks have been used for propagating temperate fruit crops for more than 2000 years. Rootstocks have been selected to impart other benefits to the scion cultivar such as improving uniformity of growth and cropping, controlling tree size, inducing early and aboundant cropping, adaptation to unfavorable soil and climatic conditions. The present investigation was carried out to evaluate the influence of four clonal rootstocks (Quince A, Quince B, Quince C and PQBA29), and two seedling rootstocks (Kownjony and pear) on growth and performance of two pear scion cultivars namely Shahmiveh and Natanzi. During performing the experiments, vegetative growth indicies including, Current’s season shoot length, hieght of scion cultivars, trunk diameters (20 cm above the graft union, at graft union, and 10 cm below the graft union), leaf relative chlorophyll content, leaf stomatal conductance (Gs), and the substomatal carbon dioxide concentration (Ci) were measured and evaluated. The results indicated that the influence of all tested rootstocks on the most vegetative parameters measured in two scion cultivars (Shahmiveh and Natanzi) were significant. In Shahmiveh scion cultivar, the trunk diameter at 20 cm above the graft union was significantly higher than the Natanzi pear cultivar. Among the clonal and seedling rootstocks, The most rootstock impact on the trunk diameter was observed in PQBA29 and Kownjony rootstocks respectively and The highest influence of rootstocks (34.32%) on the trunk diameter at 20 cm above the graft union was related to Kownjony seedling rootstock as compared to Quince C rootstock with the least trunk diameter. The results also showed that among the tested rootstocks, the diameter of the trunk at the graft union, ranked the highest in Kownjony, and the lowest was recorded in the pear seedling rootstock. The seedling rootstock of Kownjony had the most influence on trunk diameter at 10 cm below graft union as compared to Quince C which had the least effect (42.51% reduction) on the same way and also showed highly significant difference with the rest of tested rootstocks. No significant differnces was observed between PQBA29 and the other two clonal rootstocks Quince A and Quince B. The PQBA29 rootstock also showed greater trunk diameter at 10 cm below the graft union significantly as compared to Quince C. There was no significant difference among the all clonal rootstocks in terms of current’s season shoot length. The maximum (more than twice) and the least current’s season growth was observed in PQBA29 clonal rootstock and pear seedling rootstock respectively. Both scion cultivars performed the least current’s season shoot length on the Quince C rootstock (
