Seed Germination Traits Predict Seedling Emergence Rather Than Survival Of Stipa Breviflora In Populations Along A Latitude Gradient

Seed germination is a key stage for successful seedling establishment, and thus it should be considered when selecting the seed source for ecological restoration. However, how seed germination traits of wild species in the laboratory contribute to seedling emergence and establishment under natural conditions is not well known. In this study, seeds from 12 populations collected in 2017 and 14 additional populations collected in 2018 of Stipa breviflora were used for laboratory germination tests and field seedling establishment evaluation in the Alxa Desert and at Yuzhong on the Loess Plateau. Depending on germination conditions, seed germination percentage showed a positive, negative, or no correlation with the latitude of seed collection. Seedlings derived from seeds collected in southern populations had a higher establishment percentage in southern growing sites than those from northern populations, and vice versa, suggesting that populations are locally adapted at the seedling survival stage. Germination in laboratory was generally positively correlated with seedling emergence in the field. There was positive relationship between lab germination and field seedling survival at Yuzhong Station, while negative relationship was observed at Alxa Station. These results suggested that high germination percentages could be adaptive or maladaptive depending on offspring growth conditions. Thus, seed source selection based on germination traits should take offspring growing conditions into consideration.