摘要
红砂 (Reaumuria soongorica)和霸王 (Zygophyllum xanthoxylum)分别是我国西北干旱荒漠区重要的超旱生小灌木和灌木。试验室条件下 ,研究了两种灌木种子萌发对干旱胁迫 (以 PEG模拟干旱条件 )和播深的响应。干旱胁迫设 0、 - 0 .3、- 0 .6、- 0 .9、- 1.2、- 1.5、- 1.8、- 2 .1、- 2 .4、- 2 .7MPa共 10个处理 ,播深设 0、0 .3,0 .5 ,1.0 ,1.5 ,2 .0 ,3.0 ,4 .0 cm共 8个处理。结果显示 :模拟干旱条件下 ,供试种的发芽势 (3d发芽率 )皆从 - 0 .3MPa起即开始显著下降 (P<0 .0 5 )。发芽率红砂从 - 0 .9MPa渗透势、霸王从 - 0 .6 MPa开始显著降低 ;种子萌发的最低渗透势阈值红砂和霸王分别为 - 1.8MPa和 - 1.5 MPa。干旱胁迫对种子胚芽生长有抑制作用 ,但轻度干旱可促进初生根生长 ,重度干旱胁迫抑制初生根生长。播深实验表明 ,红砂和霸王种子均为子叶出土发芽类型。一般情况下 ,供试种随播深增加胚芽长度呈增加而初生根呈下降趋势 ,但霸王在播于土表时初生根生长受到抑制。实验室条件下 ,达到最大出苗率的播深红砂为 0～ 0 .5 cm,霸王为 0～ 2 cm。在适宜条件下 ,红砂和霸王种子萌发的最低需水量分别为 110 %和 90 % ,初始萌发时间分别为 4 0 h和 4 8h。红砂种子发芽势低 (2 8% )、萌发持续而分散 ;霸?
Reaumuria soongorica and Zygophyllum xanthoxylum are very important ultra-xeromoph shrubs in the northwest arid desert region of China. Seeds of the two species were collected at maturity in the Alashan aria desert grassland of China in 2001 and kept at -5℃ until use. Responses of seed germination to simulated drought stress (germination paper moistened by PEG 6000 solution) and sowing depths were investigated in this study. The drought stress included 10 treatments ranging from 0 to -2.7MPa, and sowing depth comprised 8 treatments ranging from 0 to 4cm in sand soil medium. All tests were conducted at the Herbage Seed Testing Center, Ministry of Agriculture of China ( Lanzhou ) from December 2001 to May 2002. Each test was arranged in 4 replicates with 50 seeds for each replication. Results showed that germinative capacity (3d germination rate) of the test species declined significantly ( P<0.05 ) as the osmotic potential decreased. Compared to control ( 0MPa ), final germination percentages started reducing ( P<0.05 ) at (-0.9MPa) in R. soongorica and at -0.6MPa in Z. xanthoxylum. The lowest thresholds of osmotic potential for seed germination were -1.8MPa in R. soongorica and -1.5MPa in Z. xanthoxylum. Both plumule and radical length of the test species were significantly ( P<0.05 ) reduced as the osmotic potential decreased, except that the radical length increased between 0MPa and -0.3MPa. This result indicated that slight drought stress can promote radical growth in these species. The sowing depth experiment indicated that both test species belong to an epigeal germination type. The maximum seedling emergence percentages were obtained in 0～0.5cm sowing depths for R. soongorica and in 0～2cm for Z. xanthoxylum, showing that emergence of Z. xanthoxylum was more tolerant to the deeper sowing depth. Generally, the plumule length increased and radical length decreased as the sowing depth increased, except that the radical growth of Z. xanthoxylum was inhibited for surface sowing. This may have been because water uptake was limited on the surface for the large seed size of this species. The ratio of plumule and radical length showed a tendency to increase as the sowing depth increased, and this was more evident for Z. xanthoxylum at a sowing depth from 2 to 4cm. Under optimum conditions, germination characters for the test species showed that minimum water uptake rates for germination were 110% and 90%, and initial germination times were 40h and 48h for R. soongorica and Z. xanthoxylum, respectively. R. soongorica seeds showed a lower germination capacity and slower germination speed than those of Z. xanthoxylum. For instance, germination capacities were 28% for R. soongorica and 87% for Z. xanthoxylum. The ecological significance of the relationship between germination and germination conditions is discussed.
出处
《生态学报》
CAS
CSCD
北大核心
2004年第8期1629-1634,共6页
Acta Ecologica Sinica
基金
国家重点基础研究发展规划资助项目 ( G2 0 0 0 0 4870 4)
国家自然科学基金重点资助项目 ( 3 973 0 10 0 )~~
