Paulsen Torbjørn R, Lindtjørn Ommund, Gjerdet Nils Roar, Högstedt Göran
Department of Biology, University of Bergen, Postboks 7800, N-5020 Bergen, Norway.
Department of Oral Sciences - Biomaterials, University of Bergen, Årstadveien 17, N-5009 Bergen, Norway.
Funct Plant Biol. 2006 May;33(4):401-406. doi: 10.1071/FP05279.
Reduced seed exit costs have been suggested to explain advanced seedling emergence and increased seedling growth in Sorbus aucuparia L. (Rosaceae; rowan) following Turdus spp. (Turdidae; thrush) gut passage. In the present study, seed coat tension strength of Turdus merula L. (Turdidae; blackbird) gut-passed and non-ingested control seeds were tested with a diametral compression test. Both maximum load (N) and work (mJ) required for opening the seeds were reduced in gut-passed seeds, although scanning electron microscopy showed no visible differences in seed coat surface structure between treatments. In addition, gut passage increased dry seed weight by 0.64 mg (22%), weight of hydrated seeds by 0.62 mg (16%) and width of hydrated seeds by 0.1 mm (9%). Absorption causing the seed coat to yield more easily to the germinating seedling is proposed as an explanation for the reduction in seed exit costs. For the emerging seedling, the time and force needed to open the seed coat was reduced, thus lowering dispersal and germination costs of S. aucuparia.
有人提出，种子排出成本的降低可以解释在槲鸫肠道通过后，欧洲花楸（蔷薇科；花楸）幼苗出苗提前和幼苗生长加快的现象。在本研究中，通过直径压缩试验测试了经乌鸫肠道通过和未摄取的对照种子的种皮抗张强度。虽然扫描电子显微镜显示处理之间种皮表面结构没有明显差异，但经肠道通过的种子打开所需的最大载荷（N）和功（mJ）均降低。此外，肠道通过使干种子重量增加了0.64毫克（22%），水合种子重量增加了0.62毫克（16%），水合种子宽度增加了0.1毫米（9%）。种皮因吸收作用而更容易让发芽的幼苗突破，这被认为是种子排出成本降低的一个解释。对于出土的幼苗来说，打开种皮所需的时间和力量减少了，从而降低了欧洲花楸的传播和发芽成本。
