中文摘要：

通过盆栽控制试验，研究了沙米、大果虫实和长穗虫实3种一年生沙生植物在4个模拟降水水平（A、B、C和D）和6种埋深水平（0，10，20，30，40和50mm）的出苗情况。结果表明，3种植物种子均没有休眠现象。沙米和长穗虫实均在10mm埋深处的出茁率最大，而大果虫实在30mm埋深处的出苗率最大，沙米、大果虫实和长穗虫实，各降水处理的平均出苗率分别为50．63％，77．29％和75．21％。在沙土表面的种子，沙米萌发受强烈抑制，而其余2种植物在降水较多的A、B和D处理下萌发较多但成苗较少。这3种植物耐埋深的大小依次为：大果虫实〉沙米〉长穗虫实。降水晕越大，其出苗率越高，沙米和大果虫实单次强降水下其种子出苗率大于等量的多次少量降水的积累，但是长穗虫实相反。这表明在十旱半干旱沙地，降水是调节季节性种子出苗最重要的决定冈素，种子在沙土中的垂直分布决定了降水后种子萌发的比例并有助于维持土壤种子库。

英文摘要：

The interactive effects of irrigation and seed burial depth in sand on seedling emergence and seedling survival in 3 annuals （Agriophyllum squarrosum, Corispermum macrocarpum and C. elongatum） which commonly grow on sand dunes in the experimental region of Inner Mongolia were investigated. Seedling emergence was examined for seeds sown on the surface, or at depths of 10, 20, 30, 40 and 50 mm in sand-filled pots. There were 4 different watering regimes in pots was： Treatments A （30 mm, initial irrigation）, B （10 mm）, C （10 mm）, and D （30 mm）. Subsequently, water equivalent to 5 mm of irrigation at 1, 2, or 6-d intervals was added to treatments A, B, and C, respectively, but no further irrigation was applied to treatment D. No seed dormancy was found in any species. A. squarrosum and C. elongatum seedling emergence was most favoured when seeds were buried at a depth of 10 mm, but for C. macrocarpum 30 mm was the most favourable depth. The average of the 4 different irrigation regimes for the 3 species was 50. 63% （A. squarrosum）, 77.29% （C. macrocarpum）, and 75.21% （C. elongatum）. When seeds sown on the sand surface were irrigated, seed ger- mination of A. squarrosum, was considerably suppressed, but many seeds of C. macrocarpum and C. elongatum, germinated though few seedlings survived due to water deficiency. The effectiveness of sand burial depth was decreased in the order C. macrocarpum, A. squarrosum and C. elongatum. The more irrigation, the greater the seedling emergence in all species but it was more after one heavy irrigation than after an accumulation of several light irrigations for A. squarrosum and C. macrocarJum , but was vice versa for C. elongatum. It is suggested that precipitation is the most crucial factor in determining the seasonal emergence of seedlings of the three species tested in the field. The vertical distribution of seeds in sand determines the proportion of seeds that germinate after precipitation and acts to maintain seed banks over multiple years.