ENVIRONMENTAL-CONTROL FOR THE LARGE-SCALE PRODUCTION OF PLANTS THROUGH IN-VITRO TECHNIQUES

Leafy or chlorophyllous explants of a number of plant species currentl y micropropagated have been found to have high photosynthetic ability. Their growth and development have been promoted on sugar-free medium rather than on sugar-containing medium, provided that the environmenta l factors, such as CO2 concentration, light intensity and relative hum idity, are controlled for promoting photosynthesis and transpiration o f explants/shoots/plantlets in. vitro. Thus, environmental control is essential for promoting photosynthetic growth and development of in vi tro plantlets. Several types of sugar-free (photoautotrophic) culture systems for large-scale micropropagation of plants have been developed . Advantages of sugar-free over conventional (heterotrophic or photomi xotrophic) micropropagation systems are as follows: growth and develop ment of plantlets in vitro are faster and more uniform, plantlets in v itro have less physiological and morphological disorders, biological c ontamination in vitro is less, plantlets have a higher percentage of s urvival during acclimatization ex vitro, and larger culture vessels co uld be used because of less biological contamination. Hence, productio n costs could be reduced and plant quality could be improved significa ntly with photoautotrophic micropropagation. Methods for the measureme nt and control of in vitro environments and the beneficial effects of environmental control on photosynthetic growth, development, and morph ogenesis in large-scale production of micropropagated plantlets are pr esented.