Effect of nitrogen priming on the seed germination characteristics of Puccinellia distans

In this study, we examined the influence of different concentrations (0, 0.01%, 0.04%, 0.08%, 0.16%, 0.32%, 0.64%, and 1.28%; w/w) of ammonium nitrate solution and priming time (0, 3, 6, and 12 h) on the seed germination characteristics of Puccinellia distans, in order to provide a reference for gaining a better understanding of the effects of nitrogen deposition on the seed reproduction of grassland plants. The results showed that the germination percentage, germination index, and seedling vigor index of P. distans seeds were significantly (P < 0.05) related to nitrogen concentration, priming time, and their interaction. The germination ability of P. distans seeds increased after priming with 0～0.08% ammonium nitrate, but declined in seeds primed with 0.16%～1.28% ammonium nitrate, and reached the highest level in seeds primed with 0.08% ammonium nitrate for 3 h. This indicated that moderate priming with nitrogen can promote the germination of P. distans seeds, whereas excessive nitrogen priming appeared to have an inhibitory effect. Therefore, whereas a moderate deposition of nitrogen might promote the germination of P. distans seeds in saline-alkali grassland, excess deposition could inhibit germination.