In vitro cultivation is the main propagation method for the family Orchidaceae, whereas nitrogen is the most important nutrient in the culture media. This work was carried out to study the influence of different nitrogen concentrations on the in vitro growth of the orchid Phalaenopsis amabilis. Nitrogen concentrations varied by altering the ionic balance of the Murashige & Skoog (MS) culture medium. Plants, 360 days old, were cultivated in liquid MS, modified with 7.5, 15, 30, 45, and 60 mM N. After 180 days, we assessed plant and root length, number of leaves and roots, and fresh and dry weight of leaves, roots and plants. Treatments were assigned to completely randomized plots, with four replications. Plots consisted of five three-plant flasks. The lowest nitrogen level (7.5 mM) in the medium induced root development in length, number, and fresh and dry weight. The concentration 30 mM N stimulated both emission and dry weight accumulation of leaves. The original nitrogen concentration in the MS medium (60 mM) was excessive for the in vitro growth of P. amabilis.
Phalaenopsis amabilis; MS; mineral nutrition; nitrogen
