[Effects of seed soaking with humic acid on wheat seedlings antioxidant system under salt-alkali stress]

The seeds of two spring wheat genotypes Longmai 26 and Kehan 16 were soaked with humic acid to study the effects of seed soaking with humic acid on the seedlings antioxidant system of the two genotypes under NaCl and Na2CO3 stresses. Under the salt and alkali stresses, the seedlings leaf proline (Pro) content increased, membrane permeability enhanced, and aboveground fresh mass decreased. Under NaCl stress, the leaf catalase (CAT) activity increased, peroxidase (POD) activity decreased, and superoxide dismutase (SOD) decreased after an initial increase; under Na2CO3 stress, the CAT and POD activities increased while the SOD activity was in adverse. The activities of the test antioxidant enzymes were higher under Na2CO3 than under NaCl stress. When the seeds were soaked with humic acid, the seedlings leaf glutathione (GSH) content increased, and the SOD and CAT activities improved, which effectively relieved the damage of salt-alkali stress on the seedlings growth. Some differences were observed in the resistance level and related mechanisms against the salt-alkali stress between the two wheat genotypes, possibly due to their different interactions with the salt ion components and concentrations and the ways of seed soaking.