干旱区生态环境知识资源中心(Arid): 沙埋和种子大小对固沙禾草沙鞭的种子萌发与幼苗出土的影响

Arid

	沙埋和种子大小对固沙禾草沙鞭的种子萌发与幼苗出土的影响
其他题名	EFFECTS OF SAND BURIAL AND SEED SIZE ON SEED GERMINATION AND SEEDLING EMERGENCE OF PSAMMOCHLOA VILLOSA
	朱雅娟; 董鸣; 黄振英
来源期刊	植物生态学报
ISSN	1005-264X
出版年	2005
卷号	29 期号:5 页码:730-739
中文摘要	该文研究了野外条件下不同深度的沙埋对沙鞭(Psammochloa villosa)种子萌发和幼苗出土的影响,以及温室条件下种子大小对不同深度沙埋后的种子萌发和幼苗出土的影响.结果表明,沙埋深度显著影响沙鞭的种子萌发率、幼苗出土率和种子休眠率.沙子表面的种子不能萌发.2 cm的浅层沙埋时的种子萌发率和幼苗出土率最高,1 cm沙埋的种子萌发率和幼苗出土率次之.沙埋深度超过2 cm之后,沙鞭的种子萌发率和幼苗出土率与沙埋深度呈负相关.2 cm的种子休眠率最低.从2～12 cm,种子休眠率随着沙埋深度的增加而增加.在幼苗能够出土的深度(1～6 cm),幼苗首次出土所需的时间随着沙埋深度的增加而延长.种子大小对沙鞭的种子萌发率没有显著影响.但是在深层沙埋(6 cm)时,与小种子相比,大种子产生的幼苗的出土率较高.从2～6 cm,大种子形成的幼苗的茎长度都较长.
英文摘要	Sand burial is a common phenomenon in sand dune ecosystems all over die world. Although many sLudies concerning the effects of sand burial on seed germination and seedling emergence have been conducted in many parts of the world, such studies are rare in China. In the summer of 2003, we studied the effects of sand burial depth (0, 1, 2, 4, 6, 8, 10 and 12 cm) and seed size on seed germination and seedling emer-gence of Psammochloa villosa, an important.psammophyte that establishes on mobile sand dunes in deserts and sandy lands of North China. Seeds were collected in their natural habitat in Mu-Us Sandland, Ordos Plateau, in 2002 and stored at - 18 °C ■ The average seed mass of P. villosa was (5.51 0.05) mg. Seeds were sort-ed into 3 groups based on their mass: small (4 - 4.9 mg, mean = (4.489 0.012) mg), medium (5 -5.9 mg, mean = (5.457 0.012) mg), and large (6 - 6.9 mg, mean = (6.415 0.011) mg). We conducted two experiments, one in the field and the other in a non-heated greenhouse. In the second experi-ment, burial depth was 1, 2, 4, 6 and 8 cm. Before burial experiments, all seeds were treated with cold stratification in 5 °C for 4 weeks in order to break dormancy. We found that sand buiial depth had significant effects on seed germination and seedling emergence of P. villosa. Experiments revealed diat the highest percentage of seeds that germinated and seedlings that emerged occurred at 2 cm burial depth. Few seeds lying on the surface of the sand germinated, and, those that did ger-minate , could not anchor their roots into the soil and seedlings did not establish successfully. The next greatest germination and emergence percentage occurred at the 1 cm burial depth. The timing of emergence was delayed with deeper burial depth. As burial depth increased from 2 to 12 cm, the percentage of seeds that germinated and emerged declined , a higher number of seeds remained dormant, and the number of days before first emer-gence increased. As sand burial depth increased, some seeds were able to germinate but the seedlings were not able to emerge possibly because the seeds did not have enough energy. Seedlings that could not emerge, etio-lated , died and decomposed in the sand. At all depths, the seeds that could not germinate remained dormant. Possible reasons for sustained dormancy include poor aeration, high sand moisture, low soil temperature, poor O2 content, higher CO2 levels in soil and low light intensity. The dormant seeds, which form soil seed banks, are very important for the long-term survival of this species. The dormant seeds can germinate when sand ero-sion decreases the burial depth and the seeds are exposed to optimal environmental conditions, such as sand depth. However, our experiment revealed that seeds buried at deeper depths had higher mortality rates (15 -35%). The high mortality might be due to fungal infection, water-soluble germination inhibitors in the seed coat, and an unfavorable microenvironment and low O2 concentrations. Seed size did not affect the percentage of seeds that germinated or remained dormant, but had a remark-able effect on the percentage of seedlings that emerged at different sand burial depths. At greater depths ( > 6 cm), large seeds had higher rates of seedling emergence than medium and small seeds. From 1 to 6 cm depth, the seedling shoots that originated from large seeds were longer than those from small seeds; also, at 2 to 6 cm depth, seedling shoots that originated from medium sized seeds were longer than those from small seeds. Therefore, we suggest larger seeds have ecological advantages in sand dune ecosystems. Larger seeds have a larger endosperm, contain more energy, and thus can emerge from deeper burial depths. This will benefit seedling growth in early stages and help them to successfully establish under extreme desert conditions. Sand burial might be a selective pressure on seed size; therefore, seed polymorphism as an evolutionary strategy can benefit the renewal of P. villosa populations. In sand dune habitats, P. villosa produced different sizes of seeds that could emerge from different depths of sand burial. The diversity of seed size could enhance opportu-nities for seedling establishment in this heterogeneous environment allowing plants to respond to different sand burial depths, enhance their ability to adapt to the changing environment, and increase survival.
中文关键词	沙鞭 ; 沙埋深度 ; 种子大小 ; 种子萌发 ; 幼苗出土 ; 种子生态学
英文关键词	Psammochloa villosa Sand burial depth Seed size Seed germination Seedling emergence Seed ecology
语种	中文
国家	中国
收录类别	CSCD
WOS类目	PLANT SCIENCES
WOS研究方向	Plant Sciences
CSCD记录号	CSCD:2036275
来源机构	中国科学院植物研究所
资源类型	期刊论文
条目标识符	http://119.78.100.177/qdio/handle/2XILL650/206881
作者单位	中国科学院植物研究所, 中科院植被数量生态学重点实验室, 北京 100093, 中国
推荐引用方式 GB/T 7714	朱雅娟,董鸣,黄振英. 沙埋和种子大小对固沙禾草沙鞭的种子萌发与幼苗出土的影响[J]. 中国科学院植物研究所,2005,29(5):730-739.
APA	朱雅娟,董鸣,&黄振英.(2005).沙埋和种子大小对固沙禾草沙鞭的种子萌发与幼苗出土的影响.植物生态学报,29(5),730-739.
MLA	朱雅娟,et al."沙埋和种子大小对固沙禾草沙鞭的种子萌发与幼苗出土的影响".植物生态学报 29.5(2005):730-739.