EFFECTS OF MINERAL NUTRIENTS ON IN VITRO GROWTH AND FLOWER FORMATION OF PSYGMORCHIS PUSILLA (ORCHIDACEAE)

Orchidaceae represent one of the largest and most variable families in the plant kingdom, attracting much commercial interest due to their exotic beauty. Psygmorchis pusilla has shown to be an interesting model to study orchid flower formation in vitro. In the present study, the effect of nutrients on floral spike induction was investigated by changing the total mineral salt concentration of standard Vacin and Went medium.
Inorganic N (NH₄⁺ and NO₃^–), P, K and Ca concentrations were investigated separately.
A negative correlation between the total mineral salt concentration and the number of floral spikes was observed.
A low concentration of N stimulated flower formation and this effect was more pronounced than that observed for the lowest total salt level used.
Presence of NH₄⁺ in the medium showed to be essential for plant growth and development, while absence of NO₃^– depressed flowering.
Flower formation was also enhanced by P and K reduction to a half strength level, whereas the highest Ca concentration showed some floral stimulation.
Plants grown under nutrient deficiency were more yellowing than those cultivated on complete medium.
Anthesis was favoured by removal of ethylene using a KMnO₄-trap.

XXV International Horticultural Congress, Part 10: Application of Biotechnology and Molecular Biology and Breeding – In Vitro Culture.

A. P. A. Vaz, G. B. Kerbauy

flower, in vitro, nutrition, orchids, Psygmorchis pusilla

https://doi.org/10.17660/ActaHortic.2000.520.15