VENTILATION AND LIGHT INTENSITY DURING IN VITRO CULTURE AFFECT RELATIVE GROWTH RATE AND PHOTOSYNTHATE PARTITIONING OF CALADIUM PLANTLETS AFTER TRANSPLANTING TO EX VITRO

Abstract

Caladium bicolor 'Candidum' plantlets were cultured on medium containing 2% sucrose and 0.8% agar in vitro under different conditions of ventilation and photosynthetic photon flux density (PPFD) and then transplanted to an ex vitro environment. During in vitro culture, the plantlets were fed with 13 CO 2 . Dry weight of plantlets cultured in the high-ventilated vessel was no greater than that cultured in a low-ventilated vessel, however, after transplanting, the relative growth rate of the plantlets cultured in the high-ventilated vessel was greater than that cultured in a low-ventilated vessel. Culturing in the low-ventilated vessel increased partitioning of 13 C to a stem during in vitro culture and in the long term after transplanting. Culturing under low PPFD did not affect the distribution ratio of 13C in plant parts, but after acclimatization, the 13C atom % excess in the whole plant cultured under low PPFD was lower than that cultured under high PPFD, indicating that the photosynthates obtained under low PPFD conditions were less re-translocated to new tissues and organs. The results indicate that the ventilation condition and light intensity during in vitro culture affect the translocation of photosynthates not only during the culture but also in the long term after transplanting to ex vitro.