Abstract:

In order to investigate the optimal staining conditions for soybean seed viability determination and the changes of important physiological indexes during seed germination stage,single factor and orthogonal tests were used to design and screen the optimal combination of Triphenyltetrazolium chloride(TTC)for soybean seed viability determination.The changes of germination rate and endogenous cell wall hydrolase of soybean seeds under different germination conditions were also analyzed.Univariate analysis showed that the presence or absence of imbibition treatment was critical for seed staining,and low concentration(0.1%)TTC solution significantly reduced the seed staining rate.The results of multi-factor orthogonal test showed that the optimal dyeing conditions of soybean seeds were as follows:imbibition time 6 h,TTC concentration 1%,dyeing temperature 35 ℃,dyeing time 60 min.The dyeing rate of seeds in this combination was 98.5%.Germination rate test showed that light and dark conditions had no significant effect on germination process.Seed germination was inhibited under more water and promoted under less water.In a certain temperature range,low temperature delayed the germination process of seeds,but increased the final germination percentage of seeds.The activities of cellulase,polygalacturonase and β-galactosidase did not change significantly when seeds germinated under light and dark conditions,while the activities of xyloglucan endoglycosylase under light were significantly higher than those under dark conditions.The activities of cellulase and polygalacturonase did not change significantly when seed were imbibed in various water content.The activity of β-galactosidase increased gradually with the increase of water,while the activity of xyloglucan endoglycosylase showed an opposite trend.It is noteworthy that the activities of four cell wall hydrolases in soybean embryos were significantly elevated with the increase of germination temperature.In conclusion,TTC staining results have important practical significance for the rapid determination of soybean seed viability and the improvement of soybean seed quality testing technical regulations.Exploring the activity of cell wall hydrolase in soybean seeds under different germination conditions will help to reveal the mechanism of seed germination in dicotyledons.

Key words: Soybean, Seed viability, Seed germination, Cell wall hydrolase, Reactive oxygen species