Objective: In order to get the method to improve the salt resistance of seeds and seedlings for Cassia obtusbifolia under NaCl stress, seed germination and physiological characteristics of C. obtusifolia seedlings were studied.
Method: Several physiological indexes of C. obtusifolia seeds treated with exogenous carbon monoxide donor hematin under NaCl stress like the germination vigor, germination rate, germination index and vigor index were measured. And other indexes like the relative water content, the contents of photosynthetic pigment, chlorophyll fluorescence parameters, the contents of soluble sugar, protein and proline, malondialdehyde (MDA), the activities of superoxide (SOD), peroxidase (POD) and catalase (CAT) were also measured.
Result: The germination indexes of C. obtusifolia seeds under NaCl stress had been inhibited obviously. But after the treatment of hematin, every germination indexes were all increased. The result showed that the treatment of exogenous CO donor hematin obviously improved the germination vigor, germination rate, germination index and vigor index, increased the content of chlorophyll a, chlorophyll b, total chlorophyll, improved the photochemical efficiency of photosystem II (Fv/Fm), photochemical efficiency (Fv'/Fm'), PS II actual photochemical efficiency (phiPS II), photochemical quench coefficient (qP), decreased non-photochemical quenching coefficient (NPQ) and the content of malondialdehyde (MDA) , increased the relative water content of leaves and the content of soluble surge, protein and proline. Meanwhile, the results also indicated that CO improved the activities of superoxide (SOD), peroxidase (POD) and catalase (CAT). The effects of CO could be reversed when CO scavenger Hb is added.
Conclusion: Exogenous CO donor hematin with appropriate concentration could significantly alleviate the damages to the seeds and seedlings of C. obtusifolia under NaCl stress and promote the salt resistance of the seeds and seedlings through improving the germination indexes, the photochemical efficiency and the antioxidase activities of the seedlings.