Iron (Fe) is one of the most important element in mineral nutrition of higher plants. High concentration of bicarbonate (HCO - 3 ) in the soil solution is acknowledged as the major factor inducing Fe deficiency in plants grown in calcareous soils. The presence of high levels of bicarbonate buffers the circulating soil solution to pH values ranging between 7.5 and 8.5, drastically reducing Fe solubility and availability. Under these conditions fruit yield and fruit quality of tree is depressed. Many fruit trees cultivated on calcareous and alkaline soils develop symptoms of iron-deficiency and it is now well accepted that their susceptibility also depends on the rootstock genotype. Quince is the most used rootstock for pear. Iron chlorosis is an important problem in quince tree, but differences exist between quince rootstocks in their tolerance to Fe chlorosis in calcareous soils. So tolerance to Fe deficiency of seedling rootstocks of quince, pear, crataeguce and quince A clonal rootstock were evaluated by exposure to two levels of Fe (3 and 50 µM) in the presence or absence of bicarbonate (10 mM) in soilless culture in greenhouse condition. This experiment was designed as a factorial in completely randomized design with four replications and two plants per each replication. Plant height, leaf area, leaf number, chorophyll index, chlorophyll fluorescence, leaf iron content, root iron content and antioxidant enzymes activity (including catalase, guaiacol peroxidase, ascorbate peroxidase, superoxide dismutase) were measured at the end of the experiment. Result of analysis of variance showed that effect of rootstock, treatment and interaction of rootstock and treatment for all studied traits was significant, except for leaf number and chlorophyll fluorescence. Result of this experimeant showed that studied traits significantly reduced in 3 µM treatment relative to 50 µM treatment. According to result of this study different rootstocks had various responses to iron deficiency stress. In iron deficiency stress condition (low iron or presence of bicarbonate in nutrition solution), pear and crataeguce rootstocks showed the lowest severity of chlorosis symptom among the studied rootstocks and had the highest height, leaf area, leaf number, chorophyll index, chlorophyll fluorescence and leaf and root iron concentration. Activity of catalase, guaiacol peroxidase and superoxide dismutase enzymes in these two Fe-efficient rootstocks was less effected by Fe defieicny treatmeants. In contrast, seedling rootstock of quince showed the highest severity of chlorosis (lowest chorophyll index of leaf) along with the greatest decrease in activity of guaiacol peroxidase (-74.2%) and ascorbate peroxidase (-52.3%). Also in this rootstock other studied traits was more decreased relative to pear, crataeguce and quince A rootstocks, by Fe defieicny stress treatmeants compar with control condition. Quince A rootstock have better performance than seedling rootstocks of quince under Fe deficiency conditions. In spite of sufficient Fe level in the media (50 µM), seedling rootstocks exposed to bicarbonate showed Fe deficiency symptoms and among the rootstocks, seedling rootstock of quince was more effected. Based on the results it was found out that rootstocks of pear and crataeguce were more tolerance to Fe deficiency, seedling rootstock of quince was more susceptible to iron chlorosis and quince A rootstock was intermediate.