Abstract
We studied germination behaviors and persistence mechanism of wild Glehnia littoralis, a typical coastal species at temperate sandy coasts of the North Pacific Ocean, and tested the hypothesis that the coastal plants may have evolved special seeds adapting to the coasts, by which they recruit and persist easily, occupying the coasts as ideal habitats. In the Shandong Peninsula, China, we investigated temperature and moisture conditions of coast sand in relation to germination and evaluated effects of sand burial, seawater immersion and sowing time on germination. When germination began, daily dawn temperatures of sand were about 10 °C and daily noon temperatures were about 25 °C; the temperatures were not different in the sand <8 cm deep. The sand at these depths showed a significant difference in moisture contents. The seeds exhibited large germination rates if sand burial was at depths >= 3 cm and winter freezing was kept longer than 2.5 months. Seeds experiencing seawater immersion were able to germinate well. These evidences suggest that G. littoralis has evolved special seeds adapting to seawater dispersal and specific season rhythm. By the seeds, G. littoralis occupies temperate sandy coasts as ideal habitats to persist.
Highlights
Factor Sand layer Time changing Sand layer Time changing Sand layer Time changing Burial depth Seawater immersion Sowing time
The germination rates were significantly low at the depths = 3 cm. These results demonstrate that the depths favorable for germination were not less than 3 cm, perhaps because moisture contents were high and steady at these depths
After daily dawn and noon temperatures of sand rise to ca. 10 and 25 °C, G. littoralis seeds get ready for germination
Summary
Two-way ANOVA indicated that these temperatures were not different among the four layers, but varied significantly with time changing (Table 1). The results of two-way ANOVA indicated that moisture contents varied significantly with time, and nearly significantly among the four layers (Table 1). Seawater immersion might have no effects on final cumulative germination rates (Table 1), which could exceed 60%, but dynamics of the germination differed obviously among these immersion levels (Fig. 2). These results indicate that seawater immersion might not promote the maximum germination rates of G. littoralis seeds but could activate the seeds for a swift germination. Cumulative germination rates of G. littoralis seeds experiencing pre-germination seawater immersion for some days. The finding suggests that G. littoralis seeds have the property of winter-dormancy, and most of them remain dormant until winter provides them a freezing longer than 2.5 months
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