Ｉｎ ｖｉｔｒｏ培養における培養器内へのＣＯ２施用が培養植物の生育に及ぼす影響

Abstract

Plantlets of Caladium bicolor (C3 plant), Saccharum officinarum (C4 plant), and Phalaenopsis hybrid (CAM plant) at the preparation stage for acclimatization (the final stage of in vitro culture) were cultured on the medium containing 2% sucrose. The culture vessels were kept under continuous, 16 hr, or 8 hr lighting conditions; half of the vessels were ventilated continuously with 0.8 ± 0.4% CO2 enriched atmosphere; while the remainder was exposed to ambient atmosphere.The growth of plantlets was promoted with an increase in daylength under both ambient and CO2 enriched atmospheres. When the plantlets were supplied with adequate CO2, dry matter production increased under all daylength treatments except Caladium cultured under continuous lighting. This promotive effect of CO2 enrichment was especially noticeable in root growth.In Caladium and Phalaenopsis, the leaf chlorophyll content of plantlets cultured under CO2 enriched atmosphere was less than that of leaves from plantlets grown in ambient atmosphere. Although the chlorophyll was less concentrated in leaves of plantlets growing under the CO2 enriched treatment, the rate of CO2 uptake of these plantlets measured at the midpoint of the light period was higher than that of leaves exposed to ambient atmosphere.Increasing the O2 concentration in culture vessels to 37% also promoted the growth of Caladium and Dendrobium phalaenopsis (CAM plant) under CO2 enriched condition.Because of the development of photoautotrophy, the Caladium plantlets exposed to enriched CO2 atmosphere and cultured on sugar-free medium using ceramic wool plug system responded with vigorous growth when transplanted into pots.