Abstract: In order to compare the physiological characteristics of different species of North American begonia on saline land in Tianjin, the soluble protein, soluble sugar, free proline, malondialdehyde content, membrane permeability, SOD, POD enzyme activity and other physiological and biochemical indexes in leaves were determined, with eight species of North American begonia as test material in Jinghai. The results showed that the highest soluble protein content was in Kells（42.235 mg/g）, the lowest was in Donghong（14.763 mg/g）; the highest soluble sugar content was in Kells（0.163%）and Julie（0.151%）, the lowest was in Wumei（0.103%）; the highest free proline content was in Kells（7.285 μg/g）and Donghong（6.211 μg/g）, the lowest was in Royal（2.747 μg/g）. The highest malondialdehyde content was in Kells（0.133umol/g）, the lowest was in Adam（0.079 μmol/g）and Julie（0.075 μmol/g）; the highest membrane permeability（34.96%）was in Donghong, the lowest was in royal（8.22%）; the highest POD enzyme activities was in Xiyangyang（50.771 U/g·min）and Wumei（54.254 U/g·min）, the lowest was in Donghong（12.208 U/g·min）; and there was no difference in SOD activity among the eight species of North American Begonia, and the enzyme activity was between 0.512 U/g and 0.613 U/g. According to the comprehensive analysis of membership functions, their order of saline tolerance were Kells>Donghong>Ruby>Julie>Adam>Royal>Xiyangyang>Wumei.

Key words: saline land, salt-alkaline tolerance, North American begonia, physiological characteristics