PHYSIOLOGY OF WOODY PLANTS Third Edition DR. STEPHEN G. PALLARDY School of Natural Resources University of Missouri Columbia, Missouri ELSfc,V1 t,r\ AMSTERDAM BOSTON HEIDELBERG LONDON NEW Y O RK * OXEORD PARIS SAN DIEGO SAN FRANGISCO SINGAPORE SYDNEY TOKYO AiTiidemic I'ivss is,m imprint of n^c\ ior
Preface xiii C H A PT E R Introduction 1 Heredity and Environmental Regulation of Growth 1 Physiological Regulation of Growth 2 Some Important Physiological Processes and Conditions 3 Complexity of Physiological Processes ', Problems of Foresters, Horticulturists, and Arborists 3 Physiology in Relation to Present and Future Problems 4 Summary 6 General References 6 The Woody Plant Body 9 Introduction 9 Crown Form 10 Variations in Crown Form 10 Stern Form 11 Vegetative Organs and Tissues 12 Leaves 12 Angiosperms 13 Variations in Size and Structure of Leaves 15 Gymnosperms 17 Sterns 19 Sapwood and Heartwood 19 Xylem Increments and Annual Rings 20 Earlywood and Latewood 21 Phloem Increments 22 Wood Structure of Gymnosperms 23 Axial Elements 24 Horizontal Elements 25 Wood Structure of Angiosperms 25 Axial Elements 26 Horizontal Elements 27 Bark 27 Roots 28 Adventitious Roots 30 Root Tips 30 Root Hairs 31 Suberized and Unsuberized Roots 32 Mycorrhizas 33 Reproductive Structures 35 Angiosperms 35 Gymnosperms 36 Summary 37 General References 38 Vegetative Growth 39 Introduction 39 Cell and Tissue Growth 40 Dormancy 42 Dormancy Concepts 42 Hormonal Influences on Bud Dormancy 44 VII
VU1 Shoot Growth 45 Bud Characteristics 46 Dormant and Adventitious Buds 46 Hormonal Influences on Shoot Growth 47 Leaf Growth 48 Seasonal Leaf Growth Characteristics 49 Leaf Area Index 50 Shoot Growth Types and Patterns 50 Determinate and Indeterminate Shoots 50 Epicormic Shoots 50 Preformed and Neoformed Shoots 51 Recurrently Flushing Shoots 51 Abnormal Late-Season Shoots 52 Apical Dominance 53 Maximum Height 54 Shoot Growth in the Tropics 54 Cambial Growth 55 Cell Division in the Cambium 55 Production of Xylem and Phloem 55 Time of Growth Initiation and Amounts of Xylem and Phloem Produced 56 Differentiation of Cambial Derivatives 56 Increase in Cell Size 58 Hormonal Influences on Cambial Growth 58 Cell Wall Thickening 62 Loss of Protoplasts 62 Formation and Development of Rays 63 Expansion of the Cambium 63 Variations in Growth Increments 63 Seasonal Duration of Cambial Growth 64 Anomalous Cambial Growth 64 Sapwood and Heartwood Formation 64 Wounding and Wound Healing 67 Root Growth 68 Root Elongation 69 Rate of Root growth 70 Seasonal Variations 70 Cambial Growth in Roots 71 Shedding of Plant Parts 72 Leaves 73 Branches 77 Bark 78 Roots 79 Measurement and Analysis of Growth 80 Analysis of Growth 80 Relative Growth Rates 81 Allometric Formula and the Allometric Coefficient 81 Net Assimilation Rate and Other Growth Parameters 82 Limitations of Traditional Growth Analysis for Woody Plants 84 Summary 85 General References 86 C II A P T E R Reproductive Growth 87 Introduction 87 Reciprocal Relations between Vegetative and Reproductive Growth 88 Sexual Reproduction in Angiosperms 88 Flovvering Periodicity 88 Pollination 90 Fruit Set 90 Fertilization 91 Postfertilization Development 91 Polyembryony 92 Apomixis 92 Parthenocarpy 92 Growth of Fruits 92 Fruit Ripening 93 Sexual Reproduction in Gymnosperms 96 Cone Initiation and Development 96 Polyembryony 99 Parthenocarpy 99 Duration and Timing of Cone Development 99 Increase in Size and Dry Weight of Cones andseeds 100 Maturation of Seeds 102 Abscission of Reproductive Structures 103 Abscission and Crop Yield 103 Summary 105 General References 106 Photosynthesis 107 Introduction 107 Chloroplast Development and Structure 108 Pigments 109 Proteins 110 Membrane Systems 110 The Photosynthetic Mechanism 110 Light Reactions HO Photochemistry 111 Electron Transport 112 NADP + Reduction 112 Photophosphorylation 112 Photoinhibition 113 Dark Reactions 116 Carbon Dioxide Uptake by Photosynthetic Tissues 119 Carbon and Oxygen Isotope Discrimination During Photosynthesis 121
IX Variations in Rates of Photosynthesis 122 Species and Genetic Variations 123 Photosynthesis and Productivity 124 Diurnal Variations 126 Seasonal Variations 128 Environmental Factors 132 Light Intensity 132 Air Temperature 140 Soil Temperature 142 Carbon Dioxide 144 Water Supply 147 Soil Drying and Photosynthesis 147 Humidity 151 Flooding 152 Mineral Nutrition 152 Salinity 155 Pollution 156 Applied Chemicals 158 Plant Factors 158 Stomatal Characteristics and Capacity of Photosynthetic Partial Processes 159 Source-Sink Relations 160 Age of Leaves and of the Plant 162 Summary 164 General References 166 Enzymes, Energetics and Respiration 169 Introduction 169 Enzymes and Energetics 169 Enzymes 169 Energetics 172 Respiration 173 Biological Oxidations 174 ATP 174 Other High-Energy Compounds 175 Glycolysis and the Krebs Cycle 175 Electron Transfer and Oxidative Phosphorylation 176 Metabolie Decomposition of Respiration 176 Other Oxidases 177 The Pentose Shunt 178 Anaerobic Respiration 178 Respiratory Quotient 179 Photorespiration 179 Respiration of Plants and Plant Parts 180 Amount of Food Used in Respiration 180 Respiration of Entire Trees 180 Respiration of Various Plant Parts 181 Seasonal Variations 185 Scaling of Respiration to the Ecosystem Level 185 Respiration of Harvested Fruits 187 Factors Affecting Respiration 188 Age and Physiological Condition of Tissues 188 Available Substrate 188 Light 188 Hydration 188 Temperature 189 Composition of the Atmosphere 190 Soil Aeration 191 Mechanical Stimuli and Injuries 191 Chemicals 192 Air Pollutants 193 Assimilation 194 Summary 195 General References 197 Carbohydrates 199 Introduction 199 Kinds of Carbohydrates 199 Monosaccharides 199 Oligosaccharides 200 Polysaccharides 201 Carbohydrate Transformations 204 Phosphorylation 204 Sucrose 205 Starch 205 Uses of Carbohydrates 205 Respiration 206 Growth 206 Defense 207 Leaching 207 Exudation 208 Accumulation of Carbohydrates 208 Carbohydrate Distribution 208 Storage Sites 208 Autumn Coloration 211 Summary 214 General References 215 8 Lipids, Terpenoids, and Related Substances 217 Introduction 217 Lipids 218 Simple Lipids 218
Fatty Acids 218 Lipid Distribution 219 Waxes, Cutin, and Suberin 220 Cuticle 220 Waxes 220 Cutin and Suberin 222 Infernal Lipids 223 Phospholipids 223 Glycolipids 224 Membrane Lipids 224 Isoprenoids or Terpenoids 224 Essential Oils 224 Resins 225 Oleoresins 226 Monoterpenes 227 Carotenoids 229 Rubber 229 Related Compounds 231 Summary 231 General References 232 Nitrogen Metabolism 233 Introduction 233 Distribution and Seasonal Fluctuations of Nitrogen 234 Concentration in Various Tissues 234 Seasonal Changes in Nitrogen Concentration 235 Changes in Distribution with Age 238 Important Nitrogen Compounds 240 Amino Acids 240 Amino Acid Synthesis 240 Nitrate Reduction 240 Ammonia Assimilation 242 Transamination 242 Peptides 242 Amides 242 Proteins 243 Nucleic Acids and Related Compounds 244 Alkaloids 244 Nitrogen Requirements 244 Sources of Nitrogen 246 Nitrogen Fixation 247 Release from Litter 249 The Nitrogen cycle 250 Summary 253 General References 253 CM A P T [ : K 10 Mineral Nutrition 255 Introduction 255 Functions of Mineral Nutrients and Effects of Deficiencies 256 Nitrogen 256 Phosphorits 256 Potassium 256 Sulfur 257 Calcium 257 Magnesium 258 Iron 258 Manganese 259 Zinc 259 Copper 259 Boron 259 Molybdenum 260 Chlorine 260 Nickel 260 Other Mineral Nutrients 260 Accumulation and Distribution of Mineral Nutrients 261 Mineral Cycling 262 The Soil Mineral pool 262 Atmospheric Deposition 262 Leaching from Plants 264 Throughfall and Stemflow 266 Weathering of Rocks and Minerals 268 Decomposition of Organic Matter 268 Temperature 269 Exudation from Roots 270 Losses of Mineral Nutrients From Ecosystems 270 Ecosystem Disturbance 270 Temperate Forests 270 Tropical Forests 274 Leaching from Soil 276 Absorption of Mineral Nutrients 277 Terminology 277 Ion Movement in Soil 279 The Absorbing Zone 279 Factors Affecting Absorption 280 Absorption by Leaves and Twigs 283 Summary 284 General References 285 11 Absorption of Water and Ascent of Sap 287
XI Introduction 287 Importance of Water 287 Cell Water Relations 288 Cell Structure 288 Water Status Quantification and Terminology Water Movement 290 Measurement of Water Potential and Its Components 291 The Soil-Plant-Atmosphere Continuum 292 Absorption of Water 294 Soil Water 294 Concentration and Composition of Soil Solution 298 Soil Aeration 298 Soil Temperature 299 Absorption through Leaves and Sterns 300 Absorption through Roots 301 Root Resistance 304 Extent and Efficiency of Root Systems 305 Mycorrhizas and Water Relations 307 Water Absorption Processes 308 Osmotically Driven Absorption 308 Passive Absorption 308 Root and Stern Pressures 309 Root Pressure 309 Guttation 309 Maple Sap Flow 309 Other Examples of Stern Pressure 312 Ascent of Sap 312 The Water Conducting System 313 Efficiency of Water Conduction 315 Air Embolism and Xylem Blockage 317 Disease 321 Summary 321 General References 322 12 Transpiration, Plant Water Balance and Adaptation to Drought 325 Introduction 325 The Process of Transpiration 326 Transpiration as a Physical Process 326 Vapor Concentration Gradient from Leaf to Air Resistances in the Water Vapor Pathway 328 Factors Affecting Transpiration 330 Leaf Area 330 Root-Shoot Ratio 331 Leaf Size and Shape 331 Leaf Orientation 331 Leaf Surfaces 332 Stomata 333 Stomatal Control of Transpiration 338 Interaction of Factors Affecting Transpiration 338 Transpiration Rates 340 288 Water Loss From Plant Stands 342 Factors Controlling Evapotranspiration 342 Effects of Changes in Plant Cover 343 Thinning 343 Relative Losses by Evaporation and Transpiration 344 Changes in Species Composition 345 Methods for Reducing Transpiration 345 Transpiration Ratio and Water Use Efficiency 346 The Water Balance 349 The Dynamics of Plant Water Status 349 The Absorption Lag 350 Internal Competition for Water 351 Long-Term Variations in Water Content 352 Seasonal Variations in Water Content 352 Effects of Water Stress 354 Adaptation to Drought 355 Drought Avoidance 356 Drought Tolerance 356 Drought Hardening 364 Summary 365 General References 366 13 Plant Hormones and Other Endogenous Growth Regulators 367 Introduction 367 Major Classes of Plant Hormones 367 Auxins 368 Gibberellins 368 Cytokinins 369 Abscisic Acid (ABA) 371 Ethylene 371 Other Regulatory Compounds 373 Brassinosteroids 373 Jasmonates 374 Salicylic Acid 374 Phenolic Compounds 374 327 Polyamines 375 Other Compounds 375 Mechanisms of Hormone Action 376 Summary 377 General Reference 377 Bibliography 379 Index 441