GERMINATION, EMERGENCE AND SEEDLING GROWTH OF HYPERICUM-PERFORATUM L

Germination of new seeds (1-6 mo. old) of H. perforatum L. was restricted by high temperatures (16 h/8 h, 20/30.degree. C), darkness and a chemical inhibitor in exudate from the capsule, whereas germination of old seeds (9 yr) was only restricted by the inhibitor. The effect of the chemical inhibitor and high temperatures was overcome, respectively, by washing seeds in water and by reducing temperatures to constant 15.degree. C. Ca in solution from CaCO3 and from 3 different soils did not prevent the germination of new or old seeds or of seeds collected from 5 different locations. There were differences in the germination characteristics and dormancy mechanisms of seeds collected from different localities. Restriction of the emergence of seedlings by a covering of > 2mm of soil appeared to be due to a lack of seedling vigor rather than to a lack of light. Seedling growth was much slower than in other pasture species. Thus, the requirements for germination of H. perforatum of low temperature and moisture to wash away the chemical inhibitor favor its establishment, but the slow growth of its seedling restricts its emergence and renders it extremely susceptible to competition from other plants.