Yagihashi Tsutomu, Hayashida Mitsuhiro, Miyamoto Toshizumi
Department of Forest Science, Faculty of Agriculture, Laboratory of Silviculture, Hokkaido University, Sapporo 060-8589, Japan, , , , , , JP.
Department of Bioenvironment, Faculty of Agriculture, Yamagata University, Tsuruoka 997-8555, Japan Fax: +81-235-28-2928; e-mail:
Oecologia. 1998 Apr;114(2):209-212. doi: 10.1007/s004420050438.
To determine the effects of ingestion by birds on seed germination, we performed germination experiments in the field and laboratory with Sorbus commixta. The germination of four groups of seeds was compared: ingested seeds, seeds defecated in feces after feeding of fruits to birds; extracted seeds, seeds deliberately extracted from the fruit pulp; juiced seeds, seeds plus the juice of the pulp after seeds had been deliberately extracted from the pulp; intact seeds, seeds in untreated intact fruits. In the laboratory, intact and juiced seeds hardly germinated, but ingested and extracted seeds germinated. Thus, the pulp and its juice appeared to inhibit germination, but seeds could germinate without ingestion by birds once the seeds had been manually extracted from the pulp. In the field, intact fruits did not germinate in the first spring, because the seed was still covered with pulp. The pulp of intact seeds decomposed during the first summer, and thus, the seeds had the potential to germinate during the second spring. In fact, most intact seeds do not germinate during the second spring either, since they lose their viability during the first summer. Thus, under natural conditions, most seeds of Sorbus commixta cannot germinate without bird ingestion.
为了确定鸟类取食对种子萌发的影响，我们用杂交花楸在田间和实验室进行了萌发实验。比较了四组种子的萌发情况：被鸟类取食的种子；在给鸟类投喂果实后随粪便排出的种子；人工从果肉中取出的种子；完整果实中的种子（未处理的完整果实中的种子）。在实验室中，完整种子和榨取果汁后的种子几乎不萌发，但被鸟类取食的种子和人工取出的种子能够萌发。因此，果肉及其汁液似乎会抑制种子萌发，但一旦种子被人工从果肉中取出，即使没有被鸟类取食也能够萌发。在田间，完整果实中的种子在第一个春天不会萌发，因为种子仍被果肉包裹。完整种子的果肉在第一个夏天分解，因此，种子有可能在第二个春天萌发。实际上，大多数完整种子在第二个春天也不萌发，因为它们在第一个夏天失去了活力。因此，在自然条件下，大多数杂交花楸种子如果不被鸟类取食就无法萌发。
