Luminosity and water immersion in the intermediate acclimatization of Dendrobium phalaenopsis

ABSTRACT:

Dendrobium phalaenopsis is an ornamental orchid that presents good germination and development in asymbiotic culture medium. However its ex vitro adaptation still requires studies, since the dehydration of seedlings may delay its growth and development. This study aimed to investigate the effects of the water immersion and two luminosity conditions in the intermediate acclimatization of D. phalaenopsis. Plants were divided into sets of 40, and immersed in distilled water during 0, 12, 24, 36, 48, 60, 72 or 84 hours. After each immersion period the plants were transferred to containers and allocated inside a growth room for intermediate acclimatization during 30 days. A set of 20 plants from each period of immersion and from the control remained under white fluorescent light (18.9 µmol/m²/s) and the other 20 plants remained under white fluorescent light + red fluorescent light (14.85 µmol/m²/s). Plants were acclimatized in a greenhouse (162.0 µmol/m²/s) for 10 months. As immersion time increased, a decrease in fresh weight and length of pseudobulbs relation occurred, as well as in the number of roots of the plants grown under white light + red light. On the other hand, plants grown under white light did not respond to immersion time. Immersion in distilled water, regardless of light conditions, is not recommended for D. phalaenopsis.

Keywords:
Orchidaceae; floriculture; water immersion; light conditions.