Abstract
Hedysarum scoparium and Caragana korshinskii seedlings were used as the test materials to carry out the roots exposure stress model test. By comparing the physiological growth indexes in the leaves of the tested plants, the stress resistance ability was evaluated. The results showed (1) root exposure resulted in excessive oxygen free radicals, which resulted in membrane lipid peroxidation and increased MDA content in two plants. The increase of MDA content in H. scoparium was greater than that in C. korshinskii. (2) H. scoparium mainly regulate their own adaptation to the stress by regulating carotenoids. C. korshinskii adjusts itself to adapt to the stress by regulating chlorophyll. (3) H. scoparium resist this stress mainly by regulating their respiration rate. (4) H. scoparium mainly through the mobilization of proline, by adjusting the proline concentration to reduce their water potential; C. korshinskii reduced its water potential mainly by regulating the concentration of soluble sugar to adapt to the stress. (5) H. scoparium and C. korshinskii activated peroxidase (H. scoparium) and catalase (C. korshinskii) to clean up intracellular peroxides, respectively. To sum up, under the same root exposure ratio, there were significant differences in physiological regulation and morphological indexes between H. and C. korshinskii, but their stress resistance mechanisms were quite different.