研究准噶尔无叶豆(Eremosparton songoricum) 6个居群间果实和种子特性及种子萌发差异, 以揭示异质生境下准噶尔无叶豆果实和种子的生态适应机制。结果显示: 居群间准噶尔无叶豆的植株距离(F = 2.34, p = 0.03)和植株冠幅(F = 8.49, p < 0.01)存在显著差异, 沙漠北缘E、F居群和沙漠腹地C居群(受人类干扰剧烈)的植株距离和植株冠幅高于沙漠腹地A、B、D居群; 居群间准噶尔无叶豆果实和种子的长度、宽度、厚度、重量存在显著差异, 居群E、F和C的大部分参数显著高于其他沙漠腹地居群; 居群间果实多子性(F = 6.96, p < 0.01)也存在显著差异, 居群C的果实多子性最高((32.50 ± 4.79)%); 萌发结果表明, 居群间新鲜的成熟种子萌发不存在显著差异, 且萌发率都低于15%; 所有居群的大部分种子都存在物理性休眠现象, 人为划破种皮能显著提高种子萌发率, 但在低温(15/5 ℃)条件下, 所有居群的种子萌发率都较低, 说明低温抑制了种子萌发; 经人为划破种皮解除物理休眠后, 种子的休眠没有完全释放, 居群C、E和F (大种子居群)的种子萌发率显著高于居群A、B和D (小种子居群) (F = 30.77, p < 0.01), 说明准噶尔无叶豆种子不仅存在物理性休眠现象, 也可能存在生理休眠现象。不同程度的种子复合休眠可能是准噶尔无叶豆不同居群适应古尔班通古特沙漠的重要生存策略。

Aims Eremosparton songoricum is a rare and endangered endemic species in Central Asia. In China, it occurs in severely wind-eroded mobile and semi-mobile sand dunes of the Gurbantünggüt Desert. It has low fruit set, low seed set and rare seedling establishment. Our objectives were to determine the characteristics of populations, i.e., the variation of fruit or seed traits and seed germination among populations, to explain mechanisms of ecological adaptations of E. songoricum in different heterogeneous environments.
Methods We determined the density and distance of plants and differences of shape, mass and proportion of multi-seed in six populations. Temperatures simulating those in the natural habitat of E. songoricum were used to determine the type of seed dormancy.
Important findings The distance (F = 2.34, p = 0.03) and crown size (F = 8.49, p < 0.01) of plants were significantly different among populations and were highest in site C that was severely disturbed by humans. The distance and crown size located in the northeastern Gurbantünggüt Desert with abundant soil moisture (E and F) were higher than populations located in the hinterland of desert (A, B, D) except population C. The characteristics of fruit and seed (length, width, thickness and mass of fruits and seeds) in the populations were significantly different but seed length and width were not. The majority of traits values were higher in populations E, F and C. The proportion of multi-seed per fruit was significantly different (F = 6.96, p < 0.01) and was highest in population C (32.50% ± 4.79%). Freshly matured E. songoricum seeds were dormant since germination percentages were <15% in all the tested temperature regimes in the populations. Scarified seeds germinated to a significantly higher percentage than non-scarified ones in all temperature regimes, indicating freshly matured E. songoricum seeds were physically dormant. A significantly lower germination percentage was recorded at 15/5 °C than at the higher-temperature regimes, indicating that low temperature inhibited seed germination. Large-seeded populations (C, E and F) had higher germination percentages (<70%) than small-seeded populations (A, B and D; <50%) after scarified treatments (F = 30.77, p < 0.01), indicating that seeds from all populations had physical and physiology dormancy (PY + PD). The varying degree of PY + PD of E. songoricum seeds in different populations may be an important survival strategy for E. songoricum in the heterogeneous environments in the Gurbantünggüt Desert.