GROWTH OF BANANA PLANTLETS CULTURED IN VITRO UNDER RED AND BLUE LIGHT-EMITTING DIODE (LED) IRRADIATION SOURCE

This paper covers the in vitro plantlet development of banana cultured in various culture systems with or without CO2 enrichment (3000 μmol mol^-1) under light-emitting diodes (LEDs) or plant growth fluorescent lamps (PGF), both at 45μmol m^-2 s^-1 for 30 days. Shoot explants with three leaves were cultured on 5 different substrates using Murashige and Skoog (1962) medium with 0.02 mg/l IBA; Rockwool (RW), 2 types of agar, and Gellan gum in two different culture systems (Bottle [BO] and film culture vessel, the “Culture Pack” [CP]). Plantlets cultured on RW in both BO and CP systems gave the highest shoot and root fresh weight. In order to examine the effect of light sources and to clarify the effect of blue to red LED ratios on the growth of banana shoots by using CP·RW system, shoots were cultured under different LEDs: (1) 100% red, (2) 90% red + 10% blue, (3) 80% red + 20% blue, (4) 70% red + 30% blue, and (5) 100% blue, and were also cultured under PGF. The highest total fresh weight of plantlets was obtained under 80% red + 20% blue LED and the value was equivalent to that under PGF. The subsequent growth of plantlets cultured on CP·RW under LEDs and PGF were examined after transferring to soil. After 3 weeks of acclimatization, growth of plantlets was further improved by LED (80% red: 20 blue) light source used for in vitro culture.