The germination of watercress (Rorippa nasturtium- aquaticum) seeds. I. The effects of age,storage, temperature,light and hormones on germination

The upper temperature limit for germination of watercress seeds was higher in the light than in the dark. Seeds became progressively less dormant following harvest, the upper temperature limit for germination in both light and dark becoming higher and the rate of germination increasing. Earlier-ripening seeds were more dormant than later-ripening ones. High humidity or a short period at high temperature during storage hastened dormancy loss. Germination at 20 °C in the dark could be induced by treatment with a combination of GA₄, GA₇ and benzyladenine. The promotion of germination by red light was nullified by immediate exposure to far-red light, indicating that the effect of light was mediated through phytochrome. The practical relevance of the results is discussed.