Chapter 1 - Introduction

Abstract

The chapter discusses available information related to seed germination ecology, including its evolutionary aspects. It also determines that plants with specialized life cycle or habitats are unique regarding seed dormancy and germination characteristics. It provides an understanding of the world biogeography of seed dormancy and discusses the formulation of hypotheses concerning the origin and relationships of various types of dormancy in seeds. Information on many topics (such as dormancy-breaking requirements of seeds with each type of dormancy and genetics of seed dormancy and germination) is placed in an ecological context. A critical evaluation of the methodology used in soil seed bank studies of plant communities is presented, which shows that many researchers have sampled mixtures of persistent and transient seed banks rather than persistent seed banks only. Data on environmental conditions, required to break seed dormancy and stimulate germination, have been synthesized for species with specialized life cycles and/or habitats, including parasites, saprophytes, orchids, carnivorous plants, aquatics, halophytes, and psammophytes. For the first time, an attempt has been made to unravel the evolutionary/phylogenetic origins, relationships of the various kinds of seed dormancy, and to explain the conditions under which each may have evolved.