Effects of Seed Size on the Germination, Growth and Competitive Ability of Rumex Crispus and Rumex Obtusifolius

Abstract

Seed size has no effect on percentage germination of R. obtusifolius or on the heavier seeds of R. crispus but germination of small seeds of R. crispus is reduced. Germination rate of seeds of R. obtusifolius increases as seed size decreases. Seed size has no effect on the subsequent growth of R. crispus. In R. obtusifolius initial growth is slower from smaller seeds, though no difference is detectable at the end of the growing season. Intraspecific competition results in reduced growth of plants from 1.4 to 1.2 mm seeds compared with those from > 1.4 mm seeds, but there are no competitive interactions. The results are interpreted in terms of the response of the Rumex spp. to grazing by the chrysomelid beetle, Gastrophysa viridula.