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

Yajuan Zhu Xuejun Yang Carol C. Baskin Jerry M. Baskin Ming Dong Zhenying Huang

1State Key Laboratory of Vegetation and Environmental Change, Institute of Botany, Chinese Academy of Sciences, Beijing 100093, China, 2Graduate School of Chinese Academy of Sciences, Beijing, 100039, China, 3Department of Biology and 4Department of Plant and Soil Sciences, University of Kentucky, Lexington, KY 40546, USA
* For correspondence. E-mail zhenying@ibcas.ac.cn

降水数量、频度和沙埋对赖草种子萌发、幼苗出土和存活的影响

在干旱环境中,种子萌发和幼苗出土对水分胁迫极为敏感。当生长季早期降水数量少且不可预测时,在沙子表面的种子通常经历水合-失水的循环。我们研究了一种具有固沙价值的沙丘植物幼苗出土与存活对降水数量、频度和沙埋的响应。赖草幼苗出土受到月降水数量和频度以及沙埋的显著影响,在同一降水数量下,幼苗出土数量随降水频度的下降而减少。最高幼苗出土数量出现在100和150mm降水、1-4cm沙埋深度中。水合-失水处理降低了种子萌发率,增加种子休眠率。根长为0-1mm幼苗脱水30天后可重新水合。因此,赖草的幼苗出土适应了月降水150mm、降水频度10-30次、沙埋1-4mm、失水1-2天间隔的环境条件。全球变化引起的降水数量和频度变化将对赖草幼苗出土和种群更新产生重要影响。

Abstract

Aims 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.
Methods Effects of amount and frequency of precipitation, burial and hydration/dehydration on seedling emergence of Leymus secalinus, were examined using standard procedures.
Results 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.
Conclusions 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.