Ecological and physiological aspects of tissue-cultured plants

Tissue-cultured plants are different from normal plants because of the environmental conditions in a tissue-culture container. Together with the water retention capacity (WRC) of the headspace in a container, the gas composition is responsible for a divergent physiological behaviour. By controlling the WRC of the headspace the physiology and anatomy of tissue-cultured plants can be improved to resemble normal plants. During culture in vitro under our conditions, the C02-level showed a typical circadian shift depending upon illumination, but was always higher than the normal atmospheric concentration. Carbon accumulating in tissue-cultured plants in vitro originated both from headspace-C02 and sucrose in the culture medium. The evolution of photosynthesis during the acclimatization process allowed the determination of the condition of the plant and indicated the occurrence of stress after planting and after transfer from weaning to normal conditions.