Modified compact fluorescent lamps improve light-induced off-season floral stimulation in dragon fruit farming.

Efficient light-induced floral stimulation plays a key role in energy conservation and maintaining stable productivity during off-season periods of dragon fruit plants. In this study, we first reported on results of a survey on dragon fruit farmers regarding use of lamps in performing artificially induced flowering process in Vietnam. It was found that the use of incandescent lamp was prevalent in dragon fruit cultivation practices, resulting in heavy electricity consumption, and that low-power compact fluorescent light (CFL) bulbs were not extensively utilized, possibly due to low floral induction performance of domestic CFL bulbs. Arguing that emission spectra of currently used lamps were not consistent with adsorption spectra of phytochromes, whose transformation is responsible for flowering process of dragon fruit, we then proposed three improved CFL lamps (power capacity of 20 W) having emission spectra focused on red and far-red regions. New lamp prototypes were tested in 7 field experiments in three different provinces in Vietnam. One improved CFL bulb (treatment 2) performed relatively well in comparison with the incandescent control lamp (60 W) in six out of seven experiments with regard to some growth indicators (e.g., number of floral stems, number of bubs, number of fruits per plant) and fruit yield. Recent success on commercialization of the improved CFL lamp demonstrates the potential of CFL lamps in floral stimulating irradiation of other crops and plants and in alleviating electricity burden in dragon fruit growing areas.