Abstract
The effects of nitrogen (N), phosphates (P2O5), and potash (K2O) application on growth and flowering of Odontioda orchid were investigated for two years to demonstrate the optimal amounts of fertilizer for Odontioda potted in bark. N application caused an increase of dry matter production and leaf area of the current shoot (CS), and an increase in the number of florets; the effects were remarkable at the second year. The optimal amount of N application was 560 mg/pot/year using slow release fertilizer. When Odontioda were grown under the optimal N application, N concentration of the final leaf of CS before flowering was 1.86%. Chlorophyll concentration (SPAD) was positively correlated with N concentration (r = 0.854) in the final leaf, N concentration in the leaf could be estimated easily by measuring chlorophyll concentration (SPAD). The impact of P2O5 and K2O application on growth and flowering was limited, and the application of 240 mg P2O5/pot/year and 280 mg K2O/pot/year using slow release fertilizer was sufficient for the stable production of Odontioda.
