Seed germination and vitality of ungerminated seeds
The 21-day seed germination of GM soybean, wild soybean, and hybrids are shown in Fig. 1. In 2018, GM soybean had the highest total germination rate (93.05%), while wild soybean had the lowest germination rate (14.67%). The F1 hybrid germination rate was intermediate between that of wild and GM soybeans, and there were significant differences in seed germination between the F1 hybrid and parental lines.
The germination of GM and wild soybean was similar in different years, and the germination of F2 and F3 hybrids was 53.67% and 38.33%, respectively. Both F2 and F3 hybrids exhibited intermediate germination between wild and GM soybeans, and significant differences were observed in seed germination between F2 and F3 hybrids and the parental lines.
At the end of the germination test, all nongerminated GM seeds were found to be mildewed and rotten; in contrast, most ungerminated wild soybean, F1, F2, F3seeds seemed normal and did not change in shape, size or color. These seeds were evaluated for their ability to germinate after partial seed coat removal, and the results showed that the five-day seed germination of all observed wild soybean and hybrids was above 87.5% (Table 2).