PROMOTION OF THE GROWTH OF CARROT PLANTLETS IN VITRO BY CONTROLLING ENVIRONMENTAL CONDITIONS IN CULTURE VESSELS

Relationship between environmental conditions in culture vessels and the growth and acclimatization of carrot plantlets was studied. By using medium-supports in stead of agar, somatic embryos of carrot normally grew to plantlets. Their dry matter ratio was higher than that on the agar medium. Ventilation in vessels promoted the growth and acclimatization of carrot plantlets, and the optimum humidity of ventilating air was 80%RH. The enrichment of CO₂ concentration of 2000ppm also promoted the growth. Drastic decrease of phosphate ion in MS-medium was observed in the latter period of cultivation, and it suggested a shortage of phosphate ion in culture as growth of carrot plantlets was promoted on phosphate-supplemented medium. Consequently, it is sure that environmental control in vitro promotes the growth and acclimatization of plantlets effectively and makes it feasible to increase the efficiency of propagation of plantlets.