A Comparative Study of Germination Characteristics in a Local Flora

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Abstract
A laboratory study was made of the germination characteristics of seeds collected from a wide range of habitats in the Sheffield region [England, UK]. Measurements were conducted on freshly-collected seeds and on samples subjected to dry storage, chilling and scarification. Responses to temperature and light flux were also examined. The germination biology of groups of species classified with respect to various criteria including life-form, family, geographical distribution, ecology and seed shape, weight and color was compared. Marked differences were observed in the capacity of freshly-collected seeds for immediate germination. Of the 403 spp. examined, 158 failed to exceed 10% germination but 128 attained values > 80%. Germination was high in the majority of grasses and low in many annual forbs and woody species. In the majority of species, germination percentage increased during dry storage; this effect was most marked in small-seeded species. Under the experimental conditions, all of the annual grasses showed the potential for rapid germination. High rates were also observed in many of the annual forbs and perennial grasses. Low rates of germination occurred in the majority of sedges, shrubs and trees, and were particularly common in species of northern distribution in Britain. Although germination in most species was promoted by light, some were inhibited under relatively high light flux. In 104 spp. a marked reduction in germination occurred if seeds were kept in the dark and in many species this inhibitory effect could be intensified by either or both excluding temperature fluctuations and abandoning the use of a green safety light. There were recurrent associations between features of seed morphology and of germination, several of which coincided with particular ecological characteristics. The functional significance of some of the germination characteristics observed in this study implies that certain regenerative mechanisms in the field may be predicted from the laboratory characteristics of the seed.