Effects of soil water conditions on seedling regeneration in Myricaria laxiflora remnant populations

Remnant populations of Myricaria laxiflora are degrading due to difficulties in regeneration. To uncover the critical factors that hinder the regeneration of M. laxiflora populations, the present study examined seed persistence, seed germination and seedling survival and growth under different soil water contents and groundwater levels. Results revealed that seed viability significantly decreased with prolonged storage time. The germination rate of seeds stored for 15 days was 10.9%, which was 79.8% lower than unstored seeds. The viability of seeds was also significantly influenced by soil water content. The germination rate under the 0 g g−1 soil water content treatment was 105.3% higher than 0.10 g g−1 soil water content. Groundwater level significantly affected seed germination and seedling growth. The suitable groundwater level for seed germination and seedling growth was between −10 and −15 cm, at which, the germination rate, seedling survival rate and seedling biomass reached their highest values. Compared to the 0 and −20 cm groundwater levels, the −10 cm level resulted in a 16.8% and 166.7% higher germination rate, 14.1% and 9.2% higher seedling survival rate and 116.7% and 82.0% higher aboveground biomass, respectively. The longest main roots were observed at the −15 cm groundwater level. Therefore, it was concluded that changes in soil water content and groundwater level affect the regeneration of remnant M. laxiflora populations. Remnant populations of Myricaria laxiflora are severely degrading due to difficulties in regeneration. We found that seed viability of M. laxiflora decreased as soil water contents increased. Seeds in the 0.00 g g−1 soil water content treatment exhibited the highest germination rate. Seed germination and seedling survival rate increased at first then decreased as groundwater level decreased. The suitable groundwater level for seed germination and seedling growth was between −10 and −15 cm. Our findings indicate that changes in soil water content and groundwater level arose by the construction of large scale water conservancy and hydropower projects affect the regeneration of remnant M. laxiflora populations.