Greenhouse Technology and Management, 2nd Edition Nicolas Castilla, PhD Research Coordinator, Department of Horticulture IFAPA (Institute for Agricultural Research and Training), Granada, Spain E-mail: nicolas.castilla @juntadeandalucia.es Based on the second edition of the book Invernaderos de Plastico: Tecnologi'a y Manejo by Nicolas Castilla, PhD Published by Ediciones Mundi-Prensa, Madrid (Spain) and Mexico Translated by Esteban J. Baeza, PhD Agricultural Engineer IFAPA, Spain Reviewed by A.P. Papadopoulos, PhD Senior Research Scientist, Greenhouse Crops Agriculture and Agri-Food Canada, Harrow, Ontario, Canada Adjunct Professor (Laval and Guelph Universities, Canada) E-mail: papadopoulost@agr.gc.ca
Contents Foreword Preface to the First Edition (Spanish) Preface to the Second Edition (Spanish) Acknowledgements xv xvii xix xxi 1 Protected Cultivation 1 1.1 Introduction 1 1.2 Types of Protection 1 1.3 Objectives of Protected Cultivation 3 1.4 History 6 1.5 Importance 7 1.6 Plastic Materials 9 1.7 Summary 10 2 The External Climate 11 2.1 Introduction 11 2.2 The Earth and the Sun 11 2.2.1 Introduction 11 2.2.2 The seasons 11 2.3 Day Length 12 2.4 Solar Radiation 14 2.4.1 Introduction 14 2.4.2 Quality of solar radiation 16 2.4.3 Quantity of solar radiation 19 2.4.4 Measurement of solar radiation 21 2.5 The Earth's Radiation 22 2.6 Net Radiation 23 2.7 Temperature 23 2.7.1 Air temperature 23 2.7.2 Soil temperature 23 2.7.3 The relationship between solar radiation and air temperature 24 2.8 Wind 24 2.9 Composition of the Atmosphere 24 2.9.1 Water vapour content 24 2.9.2 C02 content 27 2.9.3 Atmospheric pollution 27 v
vi Contents 2.10 Rainfall 27 2.11 Altitude and Topography 27 2.12 Summary 28 3 The Greenhouse Climate 30 3.1 Introduction 30 3.2 The Greenhouse Effect 30 3.3 Solar Radiation in Greenhouses 32 3.3.1 Introduction 32 3.3.2 Transmissivity to radiation 32 3.3.3 Orientation and transmissivity 34 3.3.4 Optimization of the transmissivity 35 3.4 Temperature 37 3.4.1 Air temperature 37 3.4.2 Plant temperature 37 3.4.3 Soil temperature 38 3.4.4 Thermal inertia in the greenhouse 38 3.5 The Wind Inside the Greenhouse 39 3.6 The Greenhouse Atmosphere 39 3.6.1 Greenhouse ventilation 39 3.6.2 Air humidity 39 3.6.3 C02 content 40 3.6.4 Pollutant gases 40 3.7 Summary 41 4 The Plastic Greenhouse 43 4.1 Introduction 43 4.2 Evolution of the Greenhouse Concept 43 4.3 Geographical Production Areas 44 4.4 Climatic Suitability for Greenhouse Vegetable Production 46 4.4.1 Introduction 46 4.4.2 Climate requirements of vegetables 47 4.4.3 Obtaining the required climate conditions 47 4.4.4 Climate suitability 48 4.5 The Plastics 50 4.5.1 Introduction 50 4.5.2 Plastic materials commonly used in agriculture 51 4.5.3 Plastic additives 51 4.5.4 Properties of plastic films 52 4.5.5 Plastic films most commonly used in greenhouses 56 4.5.6 Rigid plastic materials 60 4.6 Greenhouse Construction 61 4.6.1 Introduction 61 4.6.2 Greenhouse types 62 4.6.3 Structure materials 63 4.6.4 Covering materials 65 4.6.5 Greenhouse screens 68 4.7 The Selection of the Greenhouse: Options 70 4.8 Greenhouse Site Selection 72 4.9 Criteria for the Design and Construction of Greenhouses 73 4.9.1 Introduction 73 4.9.2 Criteria for the design of plastic-film greenhouses 73
Contents vii 4.9.3 Design criteria in areas with a Mediterranean climate 74 4.9.4 Design criteria in humid tropical climates 75 4.9.5 Greenhouses for other climate conditions 75 4.10 Maximizing the Radiation Inside the Greenhouse 76 4.10.1 Introduction 76 4.10.2 Factors determining the available solar radiation 76 4.10.3 Solar radiation inside the greenhouse 77 4.10.4 Greenhouse orientation 77 4.11 Normalization of Greenhouse Structures 79 4.12 Summary 82 5 Greenhouse Heat Exchanges 84 5.1 Heat Transfer 84 5.1.1 Conduction 84 5.1.2 Convection 84 5.1.3 Radiation 86 5.2 Heat Exchanges by Air Renewal in the Greenhouse 88 5.3 Heat Exchanges in the Greenhouse and Energy Balance 88 5.4 Simplified Greenhouse Energy Balances 89 5.5 Summary 89 6 Crop Physiology: Photosynthesis, Growth, Development and Productivity 91 6.1 Introduction 91 6.2 Physiological Functions and Growth 92 6.3 Photosynthesis 93 6.3.1 Introduction 93 6.3.2 The stomata 94 6.3.3 Internal factors affecting photosynthesis 95 6.3.4 External factors influencing photosynthesis 96 6.4 Photomorphogenesis 100 6.4.1 Introduction 100 6.4.2 Vegetable pigments 100 6.4.3 Periodic rhythms in plants 101 6.4.4 Photoperiodism 101 6.5 Respiration 102 6.6 Distribution of Assimilates and Sink-Source Relations 102 6.6.1 Introduction 102 6.6.2 Distribution of assimilates between organs 102 6.6.3 Management of the assimilate distribution 103 6.7 Growth 104 6.7.1 Introduction 104 6.7.2 Influence of the microclimate on growth 104 6.7.3 Growth analysis 105 6.8 Development 106 6.8.1 Introduction 106 6.8.2 Development stages in greenhouse crops 106 6.9 Bioproductivity 107 6.9.1 Bioproductivity and harvest index (HI) 107 6.9.2 Interception of radiation by the crop 108 6.9.3 Efficiency in the use of solar radiation 109 6.9.4 Strategies to maximize the use of radiation 110
Heating viii Contents 6.10 Production Quality 111 6.10.1 Introduction 111 6.10.2 Effects of climate factors on quality 111 6.10.3 Other factors affecting quality 112 6.11 Summary 113 7 Facilities and Active and Passive Climate Control Equipment: Low Temperature Management - 115 7.1 Introduction 115 7.2 Reduction of Heat Losses 115 7.2.1 Reduction of the exchange surfaces 115 7.2.2 Reduction of heat losses per unit surface 115 7.2.3 Total heat losses 116 7.3 Insulation Devices 117 7.3.1 Inflated double cover 117 7.3.2 Mobile thermal screens 118 7.3.3 External double sidewalls 119 7.3.4 Windbreaks 120 7.3.5 Other insulation devices 120 7.4 Heating 121 7.4.1 Convective heating 121 7.4.2 Radiative-convective heating 123 7.4.3 Soil or substrate heating 127 7.4.4 Heat production 128 7.4.5 Sizing of the heating systems 130 7.4.6 Heating and temperature management 130 7.5 Summary 133 8 Management of High Temperatures: Cooling 134 8.1 Introduction 134 8.2 Function of Ventilation 134 8.3 How Airtight is the Greenhouse? 136 8.4 Natural Ventilation 136 8.4.1 The thermal effect 136 8.4.2 The wind effect 137 8.4.3 Characteristics of the openings 140 8.4.4 The crop and air movements 142 8.4.5 Measuring the ventilation of greenhouses 142 8.4.6 Anti-insect screens 143 8.4.7 Screenhouses 144 8.5 Mechanical or Forced Ventilation 144 8.6 Cooling by Water Evaporation 145 8.6.1 Pad and fan 145 8.6.2 Fogging and misting 146 8.6.3 Cooling by evapotranspiration 148 8.7 Shading 148 8.8 Other Cooling Methods 150 8.9 Ventilation and Climate Management 150 8.9.1 Temperature management 150 8.9.2 Humidity management 151
Light Contents 8.10 Dehumidification 151 8.10.1 Associated heating 151 8.10.2 Dehumidification systems 151 8.11 Summary 152 9 Air Movement in the Greenhouse: Carbon Dioxide Enrichment - Management 154 9.1 Air Movement Inside the Greenhouse 154 9.1.1 Introduction 154 9.1.2 Air movement: objectives 154 9.1.3 Plant responses 154 9.1.4 Air movement regulation 155 9.2 Carbon Enrichment (COJ 156 9.2.1 Introduction 156 9.2.2 Recommended C02 concentrations 156 9.2.3 C02 enrichment techniques 157 9.2.4 Distribution of C02 158 9.2.5 COz balance 159 9.2.6 C02 control 159 9.3 Light 160 9.3.1 Introduction 160 9.3.2 Light increase 161 9.3.3 Artificial light to increase the illumination 161 9.3.4 Partial light reduction 163 9.3.5 Control of the duration of day/night 164 9.4 Summary 166 10 The Root Medium: Soil and Substrates 168 10.1 Introduction 168 10.2 Desirable Characteristics of Horticultural Soils 168 10.2.1 Physical and hydraulic characteristics 168 10.2.2 Chemical characteristics 168 10.2.3 Considerations on the management of greenhouse soils 169 10.3 Soilless Cultivation 170 10.3.1 Introduction: systems 170 10.3.2 Advantages and disadvantages of substrate-grown crops 170 10.3.3 Substrate cultivation systems 171 10.3.4 Characteristics of the substrates 171 10.3.5 Types of substrate 174 10.4 Changes in the Management of the Root Medium 177 10.5 Summary 178 11 Irrigation and Fertilization 179 11.1 The Plants and Water 179 11.2 Transpiration 179 11.3 Evapotranspiration 180 11.4 The Water in the Soil 180 11.4.1 Introduction 180 11.4.2 Characterization of the soil water stress 180 11.4.3 Measurement of the soil water content 182 11.4.4 Quality of the irrigation water 184
X Contents 11.5 The Water in the Plant 184 11.5.1 Introduction 184 11.5.2 Characterization of the water in the plant 184 11.5.3 Water stress 185 11.5.4 Effects of water stress in the plant 185 11.5.5 Saline stress 185 11.6 Greenhouse Irrigation 185 11.6.1 Introduction 185 11.6.2 Components of the drip irrigation system 185 11.6.3 Management of drip irrigation 187 11.6.4 Water and salts movements with drip irrigation 187 11.6.5 Greenhouse irrigation scheduling (soil-grown crops) 188 11.6.6 Irrigation scheduling in soilless crops 194 11.6.7 Water use efficiency 195 11.6.8 Quality of the irrigation water 196 11.7 Fertilization 196 11.7.1 Introduction 196 11.7.2 The nutrients cycle (soil cultivation) 196 11.7.3 Nutrients extractions 197 11.7.4 Tolerance to salinity 197 11.7.5 Fertigation 198 11.7.6 A practical example: a soil-grown tomato crop 198 11.7.7 Fertigation of soilless crops 199 11.8 Summary 201-12 Regulation and Control Systems: Computer Climate Management Mechanization 204 12.1 Regulation and Control Systems 204 12.1.1 Introduction 204 12.1.2 Input-output systems 204 12.1.3 Regulation methods 205 12.1.4 Application to climate management 205 12.1.5 Types of controllers 206 12.1.6 Selection of the type of automatic control 208 12.1.7 Models 208 12.2 Computer Climate Management 209 12.2.1 Controls performed by greenhouse management systems 209 12.2.2 Digital control systems 210 12.2.3 The climate control computer 210 12.2.4 Functions of climate control computers 210 12.2.5 Towards integrated control 213 12.3 Mechanization 213 12.3.1 Introduction 213 12.3.2 Mechanization of operations 214 12.3.3 Occupancy of the greenhouse 215 12.4 Summary 217 13 Plant Protection 220 13.1 Introduction 220 13.2 Chemical Control 220 13.2.1 Main aspects 220 13.2.2 Treatment equipment 221
Contents 13.3 Biological Control 221 13.4 Integrated Pest Management 222 13.5 Climate Control and IPM 224 13.6 Most Common Greenhouse Diseases 224 13.7 Most Common Greenhouse Pests 226 13.8 Prophylaxis 226 13.9 Other Aspects 226 13.10 Summary 226 14 Economic and Environmental Analysis 228 14.1 Economic Analysis 228 14.1.1 Introduction 228 14.1.2 Greenhouse structures and equipment 229 14.1.3 The Spanish greenhouse horticultural farm 230 14.1.4 Production costs 231 14.1.5 Other aspects of interest 234 14.2 Environmental Analysis 235 14.2.1 Introduction 235 14.2.2 Most important residues 236 14.2.3 Environmental impact assessment 237 14.3 Summary 239 15 Postharvest 240 15.1 Introduction 240 15.2 Postharvest Respiratory Metabolism 240 15.3 Ripening 241 15.4 Ethylene 242 15.5 Postharvest Handling 243 15.6 Quality 245 15.7 Food Safety: Traceability 247 15.8 Postharvest Pathologies 248 15.9 Summary 249 16 Marketing 250 16.1 Introduction 250 16.2 Postharvest Alterations: Storage 251 16.3 Standardization and Classification 252 16.4 Marketing Channels 253 16.5 Transport 255 16.6 Distribution 256 16.7 Quality 258 16.8 Quality Management 259 16.9 Future Prospects 260 16.10 Summary 260 17 Greenhouse Production Strategies 262 17.1 Introduction 262 17.2 Crop Productivity and Production Costs 263 17.3 Destination of the Produce 263 17.4 Greenhouse Production Options 263 17.5 Production Strategies and Tactics in Mediterranean Climates 263 17.5.1 General aspects 263
xii Contents 17.5.2 Biological aspects 264 17.5.3 Strategies and tactical management 264 17.5.4 Future perspectives 265 17.6 Summary 265 Appendix 1 267 A.l Chapter 2 267 A.l.l Calculation of the zenith angle 267 A.l.2 Calculation of global radiation as a function of insolation 267 A.1.3 Day length 267 A. 1.4 Wien's law 268 A.1.5 Wavelength and frequency 268 A. 1.6 Hellman's equation 268 A. 1.7 Saturation vapour pressure 268 A.2 Chapter 3 268 A.2.1 Thermal integral 268 A.3 Chapter 4 269 A.3.1 Diffuse solar radiation inside a greenhouse 269 A.4 Chapter 5 269 A.4.1 Conduction 269 A.4.2 Convection without phase change 269 A.4.3 Evaporation and condensation 270 A.4.4 Radiation 270 A.4.5 Air renewal 270 A.4.6 Energy balance 271 A.4.7 Specific heat of a body 271 A.4.8 Latent heat of vaporization 271 A.4.9 Global heat transfer coefficient 271 A. 5 Chapter 6 272 A.5.1 Interception of the radiation by the extinction canopy: coefficient 272 A.5.2 Radiation absorbed by the crop 272 A.5.3 Growth parameters 272 A.5.4 Fruit harvest and biomass indexes 273 A.5.5 Use of radiation in a typical greenhouse ecosystem 273 A.6 Chapter 8 273 A.6.1 Wind effect in natural ventilation 273 A.6.2 Thermal effect in natural ventilation 274 A.6.3 Wind loads 274 A.6.4 Air flow reduction when a screen is placed on a greenhouse vent 274 A. 7 Chapter 9 274 A.7.1 CO, units 274 A. 8 Chapter 11 274 A.8.1 Crop water stress index 274 A.8.2 Irrigation water quality 275 A.8.3 Estimation of the evapotranspiration ( T0) in a greenhouse 275 A.9 Chapter 12 276 A.9.1 Transmissivity models 276 Appendix 2 Symbols and Abbreviated Forms 277
Contents xiii Appendix 3 Units and Equivalences 283 Length 283 Area 283 Volume 283 Mass 284 Thickness of Plastic Films 284 Temperature 284 Pressure 285 Energy and Power 285 Radiation 285 Water Lamina 285 Prefixes 285 List oftables 287 List offigures 291 List of Photos 299 List of Plates 303 References 307 Index 327 The colour plates can be found following p. 178.