Seed Germination in Desert Plants

1 The Negev Desert of Israel and Other Hot Deserts of the World: Classification According to Quantities, Distribution and Seasons of Rain. Their Influences on the Germination of Desert Plants.- 1.1 Classification of Deserts of Semi-Arid and Arid Zones and the Season of Rain.- 1.2 Abiotic Environmental Factors of the Negev Desert.- 1.2.1 Quantities and Distribution of Rain.- 1.2.2 Range of Temperatures, Relative Humidity and Dew.- 1.2.3 Species, Length of Growing Season, Environmental and Micro-Habitat Effects.- 1.2.4 Habitats and Topographic Sites.- 1.3 Some Biotic Factors Affecting the Vegetation of the Negev Desert.- 1.3.1 Overgrazing and the Activity of Seed Eaters.- 1.3.2 Porcupine Diggings as a Favourable Desert Micro-Habitat.- 1.4 Autecological Adaptations, Life Forms and the Annual Cycle of Desert Angiospermae.- 1.4.1 Arido-Passive Perennials and Annuals.- 1.4.2 Arido-Active Plants.- 1.4.3 Species, Ecogenotypes and Ecotypes.- 1.4.4 Genotypic and Phenotypic Influences on Seed Germination.- 2 Phenotypic Effects on Seeds During Development.- 2.1 Introduction.- 2.2 Position Effects.- 2.2.1 Position Effects in Plants with Aerial and Subterranian Fruits (Amphicarpy).- 2.2.2 Position of the Capsules on the Plant Canopy Affects Germination.- 2.2.3 Position Effects of Seeds in the Inflorescence When It Is a Dispersal Unit.- 2.2.4 Position of Achenes in the Capitulum Whorls and Their Germination.- 2.2.5 Position of Female and Hermaphroditic Flowers and Their Seed Germinability.- 2.2.6 Position of Flowers and Dimorphism.- 2.2.7 Position, Heteromorphism and Germinability.- 2.2.8 Position Effect of Seeds in the Fruit.- 2.2.9 Position and Annual Rhythm in Seed Germinability.- 2.3 Age Effects.- 2.3.1 Senescence of the Mother Plant Affecting Seed Germination.- 2.3.2 Age of the Mother Plants Affecting Seed Germination Was also Found in Non-Desert Plants.- 2.4 Environmental Effects.- 2.4.1 Photothermal and Position Effects.- 2.4.2 Day Length Affecting Seed Germination of Plant Species with Dry Fruit.- 2.4.3 Day Length Affecting Seed Germination of Species with Soft Fruit.- 2.4.4 The Critical Time for the Day Length Effects.- 2.4.5 Natural Conditions of Maturation During Summer and Autumn Affecting Seed Germination.- 2.4.6 Natural Winter, Spring or Summer Conditions of Maturation Affecting Seed Germinability.- 2.4.7 Altitudinal Effects.- 2.4.8 Influences of Light Quality During Maturation on Seed Germination.- 2.4.9 Temperatures During Maturation Affecting Seed Germination.- 2.4.10 Conditions of Maturation and Different Levels of Germination Under Different Temperatures During Imbibition.- 2.4.11 Water Stress During Maturation Affecting Seed Germination.- 2.4.12 Dimorphism and Achene Germination Dependent on Plant Size.- 2.4.13 Heterocarpy and Germinability.- 2.5 Polymorphic Seeds and Germination.- 2.6 Conclusions.- 3 Seed Dispersal and Seed Predation of Plants Species in the Negev Desert.- 3.1 The Annual Cycle of Seed Maturation and Dispersal of Some of the Common Species in the Negev Desert Highlands.- 3.2 Seed Maturation and Dispersal in Summer.- 3.2.1 Seed Dispersal by Wind.- 3.2.2 Porcupine Diggings and Other Depressions as Wind-Traps for Seeds, and the ‘Treasure Effect’.- 3.2.3 Seed Predation and Seed Dispersal by Ants, Birds and Mammals.- 3.2.4 Changes in the ‘Seed Bank’ — During Summer.- 3.2.5 Seed Dynamics in the Soil of Species Dispersed by Wind.- 3.2.6 Changes in the ‘Seed Bank’ of Plants That Disperse Their Seeds by Rain.- 3.3 Seed Maturation in Summer and Dispersal by Rain in Winter.- 3.3.1 Plants Whose Seeds Are Dispersed by Rain (Ombrohydrochory) and/or Runoff Water.- 3.3.2 Mechanisms of Seed Release by Rain.- 3.3.3 Differences in Dispersal Mechanisms of Some Groups of Species.- 3.4 Seed Maturation in Summer and Germination in Situ (Atelechory) in Winter.- 3.5 Seeds That Mature and Are Dispersed in Winter.- 3.6 Heterocarpy and Species Survival.- 3.7 Conclusions.- 4 Storage Conditions Affecting the Germinability of Seeds in the Seed Bank.- 4.1 Introduction.- 4.1.1 Seed Bank Location of Some Desert Plant Species.- 4.1.2 Soil and Seed Turnover.- 4.1.3 Environmental Factors and the Changes at Different Soil Depths.- 4.2 Seed Internal and Environmental Factors During Storage Affecting Germination.- 4.2.1 Seed Coat Effects.- 4.2.2 Short, Wet Storage at High Temperatures.- 4.2.3 The Short-Term Changes of Seeds Influenced by Temperatures During Dry Storage.- 4.2.4 Long-Term Changes During Dry Storage and Viability.- 4.3 Conclusions.- 4.3.1 Short-Storage Seeds.- 4.3.2 Long-Storage Seeds and Regulation of Germination.- 4.3.3 Seeds with Strategies of Dispersal and Germination over Many Years.- 5 Environmental Factors During Seed Imbibition Affecting Germination.- 5.1 Introduction.- 5.1.1 Germination at the Right Time.- 5.1.2 The Genotypic and Phenotypic Regulation for Seed Germination.- 5.1.3 High- or Low-Risk Strategies for Seed Dispersal and Germination.- 5.2 Water.- 5.2.1 The Minimum Amount of Rain That Engenders Germination in Desert Plants?.- 5.2.2 Germination Inhibitors as ‘Rain Gauges’.- 5.3 The Period of Wetting for Germination.- 5.3.1 Fast-Germinating Seeds.- 5.3.2 Slow-Germinating Seeds.- 5.3.3 Air, Mucilaginous Seeds (Myxospermy) and Seed Germination.- 5.4 Temperature.- 5.4.1 Temperature and Germination of Winter or Summer Annuals.- 5.4.2 Temperatures, Day Length and Seasonal Genoecotypes.- 5.4.3 Thermodormancy and Winter-Germinating Species.- 5.4.4 Summer-Germinating Species.- 5.4.5 Different Strategies of Two Negev Plants.- 5.4.6 Species Habitat, Speed and Range of Temperatures for Germination.- 5.4.7 Thermoperiodism Affecting Seed Germination.- 5.5 Light and Germination.- 5.5.1 Maturation in Natural Conditions Affecting Seed Light Sensitivity.- 5.5.2 Maturation under Artificial Light Affecting Seed Light Sensitivity.- 5.5.3 Storage Conditions and Seed Light Sensitivity.- 5.5.4 Types of Response of Seeds to Light.- 5.6 Annual Rhythm Regulating Seed Germination.- 5.7 Mass Germination and Seedling Emergence from Below the Soil Crust.- 5.8 Conclusion.- 6 Germination, the Survival of Seedlings and Competition.- 6.1 Introduction.- 6.1.1 Selective Process of Seed Germination and Seedling Survival.- 6.1.2 Rain Amount, Distribution and Survival.- 6.1.3 Micro-Habitat and Seedling Survival.- 6.1.4 Day Length and Water Stress Affecting Life Span of Annuals.- 6.2 ‘Opportunistic’ or ‘Cautious’ Strategy. Low or High Chance of Seedling Survival.- 6.2.1 Seedling Congestion and Survival.- 6.3 Depressions and Porcupine Diggings as Favourable Micro-Habitats in the Desert.- 6.4 Drought Tolerance and the Survival of Seedlings.- 6.4.1 Seedling ‘Point of No Return’.- 6.4.2 Plant Drought Tolerance.- 6.5 Mass Germination and Age Groups Replace Dead Plants.- 6.6 Conclusion.- 7 Conclusion.- References.- Latin Name Index.