Effect of Different Rootstocks on Vegetative Growth and Photosynthetic Parameters of Pear ‘Shahmiveh’ and ‘Natanz’ Cultivars

The present investigation was carried out to evaluate the influence of four clonal rootstocks (Quince A, Quince B, Quince C, PQBA29), and two seedling rootstocks (Gownjony and pear) on growth and performance of two pear scion cultivars namely Shahmiveh and Natanz. In the course of the experiment, vegetative growth indices including, current’s season shoot length, height 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 internal carbon dioxide concentration (Ci) were measured. The results indicated that, in Shahmiveh scion cultivar, the trunk diameter at 20 cm above the graft ::::::union:::::: and at the graft ::::::union:::::: was significantly higher than the Natanz pear cultivar. Among the clonal and seedling rootstocks, the greatest trunk diameter was observed in Gownjony rootstock. The maximum current’s season growth was related to PQBA29 rootstock, which was two times greater than pear seedling rootstock. The greatest and smallest height of trees were obtained in Gownjony and Quince A, respectively. Among the rootstocks, no significant differences was observed in terms of net photosynthesis and leaf stomatal conductance, but the results showed that, the net photosynthetic rate and leaf stomatal conductance in Shahmiveh scion cultivar was significantly higher than the Natanz pear cultivar. The leaf relative chlorophyll content in Gownjony rootstock was significantly greater than the Quince B rootstock. Therefore, based on the above results, Quince C seems to have a slower vegetative growth than the other rootstocks and is potentially more suitable for dense orchards.