Artificial light source using light-emitting diodes (LEDs) in the efficient micropropagation of Spathiphyllum plantlets

Spathiphyllum plantlets were cultured in "Culture Pack", a rockwool system, with CO2 enrichment (3000 mu mol mol(-1)) under different blue to red LED ratios and different LED irradiation levels. Growth was compared to that under plant growth fluorescent lamps (PGF) at 45 mu mol m(-2) s(-1) PPF for 60 days. The highest total shoot and root fresh weight of plantlets was obtained under 80% red + 20% blue LED as compared to others. Total shoot and root fresh weight of in vitro plantlets grown under 60 mu mol m(-2) s(-1) was higher than that under 45, 75 mu mol m(-2) s(-1) and PGF. Attempts were also made to examine whether the light source during in vitro culture affected the subsequent growth of plantlets 90 days after transferring to soil. The fresh shoot and root weight of in vitro plantlets grown under 80 % red + 20% blue LED was highest compared to others. Fresh shoot and root weights of in vitro plantlets grown under 60 mu mol m(-2) s(-1) and 75 mu mol m(-2) s(-1) were higher than those under 45 mu mol m(-2) s(-1) and PGF. These results suggested that a culture system using LED and film is advantageous for the micropropagation of Spathiphyllum plantlets.