In Vitro Culture of Higher Plants

16. 2. Techniques 141 16. 3. Factors affecting the success of embryo culture 143 16. 4. Practical applications . . 146 17. Germination of orchid seeds . . . . . . . 149 17. 1. Introduction . . . . . . . . . . . . . 149 17. 2. Factors affecting germination and growth 154 18. Vegetative propagation of orchids 159 18. 1. Introduction . . . . . . . . . 159 18. 2. Meristem culture . . . . . . . 161 18. 2. 1. Production of virus-free plants 161 18. 2. 2. Propagation through meristem culture 162 18. 3. Other methods of propagation 165 18. 4. Variation arising during culture 166 18. 5. Practical applications . . . . 167 19. Production of disease-free plants 169 19. 1. Introduction . . . . . . . . 169 19. 2. Production of virus-free plants 171 19. 2. 1. Heat treatment . 171 19. 2. 2. Meristem culture . 172 19. 2. 2. 1. History . . . . 172 19. 2. 2. 2. Accomplishment 174 19. 2. 3. Heat treatment and meristem culture 177 19. 2. 4. Adventitious shoot formation, eventually followed by - ristem culture . . . . . . . . . . . . . . . . . . 177 19. 2. 5. Virus-free plants produced from callus and protoplasts. 178 19. 2. 6. Grafting of meristems on virus-free (seedling) rootstocks (micrografting) . . . . . . . . . . . . . . . . . . 179 19. 2. 7. Virus identification . . . . . . . . . . . . . . . . 179 19. 3. Production of bacteria- and fungal-free plants by meristem culture . . . . . . 180 20. Vegetative propagation 183 20. 1. General introduction 183 20. 2. Single-node culture . 190 20. 3. The axillary bud method 194 20. 4. Regeneration of explants 200 20. 4. 1. Introduction . . . . . 200 20. 4. 2. Adventitious root formation 203 20. 4. 3. Adventitious shoot formation 209 III 20. 5.