Germination responses of diploid Butomus umbellatus to light, temperature and flooding

Abstract

Summary The germination of seeds of diploid Butomus umbellatus was studied to determine the favourable conditions for germination and whether seed germination may represent a limitation within the sexual reproductive cycle of this cytotype. The need to stratify the seeds and the response of the seeds to environmental conditions during germination were studied. The influence of light/darkness, temperature, day length, and flooding/aerobic conditions was tested. Seed germination was enhanced in the winter by cold wet stratification, which indicates prevailing seed germination in the spring. Seeds germinated best in light, at relatively high temperatures (20°–30°C), in long days. Seeds were able to germinate when flooded; in most cases, flooding supported germination. In field habitats, the optimum conditions for the germination of B. umbellatus seeds may be found on an open emerged bottom saturated with water or under a shallow water layer. The process of germination does not represent a high-risk stage in the sexual reproduction of this cytotype of B. umbellatus. The time of germination (late spring or summer months) contributes to seedling mortality due to the competition of adult plants or other early-germinating species.