Chapter 5 - Germination Ecology of Seeds with Morphophysiological Dormancy

Abstract

This chapter focuses on the fact that some seeds have both morphological and physiological dormancy, and thus, they have morphophysiological dormancy (MPD). It also illustrates the dormancy breaking and germination requirements of seeds with MPD. Particular attention is given to the phenology of embryo growth, germination phenology, and conditions (especially temperature) in the habitat between the time of seed maturation and the time of germination. There are eight types of MPD, which are discussed in detail. However, nondeep simple MPD is observed in seeds found in the temperate regions. But annual and perennial species, which have underdeveloped embryos, germinate during autumn. Seeds come out of PD during summer, and embryo growth, and germination occur during autumn. These seeds have nondeep simple MPD, and period of warm stratification breaks both PD and MD. Moreover, seeds with deep simple MPD require warm followed by cold stratification before they germinate. Thus, these various dormancy-breaking requirements are fulfilled in temperate regions by the summer, autumn, and winter sequence of temperatures, and germination occurs during spring.