The germination of seeds is a magical event, in which a pinch of dust-like material may give rise to all the power and the beauty of the growing plant. The mechanisms of seed dormancy, of the breaking of seed dormancy and of germination itself continue to remain shrouded in mystery, despite the best efforts of plant scientists. Perhaps we are getting there, but very slowly. This book considers germination and dormancy from the point of view of plant physiology. Plant physiologists attempt to understand the relation ship between plant form and function and to explain, in physical and chemical terms, plant growth and development. The place of germination and dormancy in plant ecophysiology is taken into account with attempts to understand the seed in its ·environment, whether the environment be natural, semi-natural or wholly artificial. In due course plant scientists hope to develop a precise understanding of germination and dormancy in cellular and molecular terms, and therefore there is some biochemistry in this book. Biochemists who wish to learn something about seeds should find this book useful.
Table of Contents1 The Seed.- The role of the seed. Germination.- The germination test.- Dormancy.- 2 Seed Formation.- Morphological aspects of seed formation.- Gymnosperms.- Angiosperms.- Physiological and biochemical aspects of seed formation.- Experimental approaches to embryogenesis.- 3 Seed Structure and Composition.- Some seed types. Dehiscent seeds.- Indehiscent seeds.- Seed size.- Seed reserve substances.- 4 Germination.- The physical requirements for germination.- The morphology of seed germination.- Comparative morphology of seedlings.- The physiology of germination.- Imbibition.- Growth and seedling establishment.- Etiolation.- Development of the photosynthetic machinery.- The biochemistry of germination.- Mobilization of reserves.- Protein synthesis.- 5 The Mechanisms of Seed Dormancy.- Dormancy caused by embryo coverings.- The restriction of gaseous exchange by embryo coverings.- The restriction of water uptake by embryo coverings.- Mechanical restriction of embryo growth.- Water-soluble inhibitors in the embryo coverings.- Dormancy from the failure to mobilize extra-embryonic food reserves.- Embryo dormancy.- Underdeveloped and undifferentiated embryos.- The mechanism of embryo dormancy.- Endogenous inhibitors in embryo dormancy.- The possession of more than one dormancy mechanism.- 6 The Breaking of Seed Dormancy.- Dormancy breaking by single factors.- Chilling.- The mechanism of dormancy breaking during chilling of hazel seeds.- Dry storage and/or exposure of dry seeds to elevated temperatures.- Light.- Leaching.- Scarification.- Treatment with chemicals.- Dormancy breaking by fluctuating temperature.- Dormancy breaking by two or more factors.- Molecular mechanisms of the breaking of seed dormancy.- 7 Seeds in the Natural Environment.- The seed bank of the soil.- The effect of light in dormancy- breaking in seeds in the seed bank.- The effects of seasonal conditions on the germination of seeds in the seed bank.- Laboratory investigation of germination characteristics of the species in the British flora.- Seed production and dispersal.- 8 Seed Viability and Vigour.- Viability.- Vigour.- Factors affecting the maintenance of viability.- and vigour during storage.- Moisture content.- Temperature.- Oxygen concentration.- The mechanism of ageing.- Seed longevity.- 9 Seed Technology.- Seed quality and seed testing.- Seed and crop production.- Seed germination and establishment.- Seed production.- Harvest, post-harvest treatments and storage.- Genotype preservation in seed banks.- Seed technology and plant breeding.- Vernalization.- Seed technology in the developing world.- 10 An Experimental Approach to Seed Biology.- The procedure for an investigation of the seed biology of the natural flora of a temperate zone.- Seed collection.- Seed treatments.- Germination tests.- Further ways for the investigation and breaking of seed dormancy.- Problems with infected seed samples.- The seed bank in the soil Seed biology as an open-ended research problem.- References.