Abstract:

Hydrogen sulfide （H₂S） plays an important role in the germination of crop seeds. This research explored the role of an exogenous H₂S donor， NaHS， as a priming agent for increasing seed vigor and its physiological mechanism. Naked oat seeds were used as the test material， and primed with different concentrations of NaHS （0， 50， 100， 200， 400， 800 and 1600 μmol·L^-1） for 18 h and with 800 μmol·L^-1 NaHS for different times （6， 9， 12， 15， 18， and 21 h）. The germination potential （GP）， germination rate （GR）， germination index （GI）， vitality index （VI） and seedling dry weight （DW） were analyzed to determine the appropriate NaHS priming concentration and priming time. Compared with non-priming of seeds， the effects of 800 μmol·L^-1 NaHS priming for18 h on H₂S production， storage substance content and active oxygen metabolism of seeds were studied. The results showed that 800 μmol·L^-1 NaHS priming for 18 h could significantly increase the GP， GR， GI， and VI of naked oat seeds， but had no significant effect on DW. NaHS priming had no significant effect on the starch， soluble sugar， soluble protein， reduced ascorbic acid （ASA）， dehydroascorbic acid （DHA） contents， ASA/DHA， and ascorbic peroxidase activity of seeds， but significantly increased H₂S and oxidized glutathione （GSSG） contents， cytochrome oxidase （COX）， superoxide dismutase， catalase and peroxidase activities by 113.5%， 14.4%， 103.3%， 6.1%， 112.0% and 120.5%， respectively； Decreased α-amylase and β-amylase activities and superoxide anion， hydrogen peroxide， malondialdehyde， reduced glutathione （GSH） contents， GSH/GSSG and plasma membrane relative permeability by 39.8%， 53.6%， 34.7%， 36.1%， 37.6%， 29.2%， 38.1% and 11.9%， respectively. These results indicate that NaHS priming may increase the H₂S content of the seeds， thereby regulating the antioxidant system and activating COX activity， reducing the damage caused by reactive oxygen species to the plasma membrane， enhancing cell aerobic respiration metabolism， and improving the vitality of naked oat seeds.

Key words: seed priming, hydrogen sulfide, naked oat, seed vigor, physiological mechanism