Seed responses to light.

Abstract

In the first part of this chapter, the seed's light climate is described and the various light responses are dealt with in physiological terms, with particular attention to the effect that environmental factors other than light can have on light responses of seeds. Postulated mechanisms explaining these light responses are considered next, which can help to bring order to the enormous variety of phenomena observed. In the second part, an attempt is made to interpret the ecological significance of the various light responses in different (micro)habitats. The possible adaptive value of the response to the various aspects of the light climate is considered for seeds in the soil and for those on the soil surface, where they may or may not be shaded by leaves. A number of case studies from different climatic regions are treated in the third part. Available data on light responses for selected species are reviewed, and their importance in the life cycle of the plant is also discussed.