Effects of amount and frequency of precipitation and sand burial on seed germination, seedling emergence and survival of the dune grass Leymus secalinus in semiarid China

Seed germination and seedling emergence are vulnerable to water stress in arid environments. When precipitation is low and unpredictable during the early growing season, seeds near the sand surface often suffer from hydration/dehydration during germination. We investigated the responses of seedling emergence and survival of a sand dune grass with high sand stabilization value to amount and frequency of precipitation and depth of burial in sand. Effects of amount and frequency of precipitation, burial and hydration/dehydration on seedling emergence of Leymus secalinus, were examined using standard procedures. Seedling emergence was affected by amount and frequency of monthly precipitation and depth of burial, and it decreased as precipitation frequency decreased with same amount of precipitation. Highest emergence percentage was obtained with 100 or 150 mm precipitation at 1-4 cm depth. Hydration/dehydration treatments decreased germination and increased dormancy percentage. Young seedlings with root lengths of 0-1 mm desiccated up to 30 days revived after rehydration. Seedling emergence of L. secalinus is adapted to 150 mm monthly precipitation with frequency of 10-30 times per month, 1-4 cm burial depth and dehydration interval of 1-2 days. Alteration of amount and/or frequency of precipitation caused by climate change could markedly affect seedling emergence and population regeneration of this species.