Effects of Fertilizers, Salinity, and Medium on Growth of Phalaenopsis Orchid
Seedling Phalaenopsis (P. Taisuco Eagle × P. Taisuco Rose) plants with an 8- to 10-cm leaf span were grown in 10-cm pots filled with a medium consisting of 70% fine fir bark and 30% peatmoss (by volume). Plants were given (in N–P2O5–K2O) 10–30–20, 15–10–30, 15–20–25, 20–5–19, 20–10–20, or 20–20–20 fertilizers at the 100 or 200 mg N/liter rate. Pots were leached with water following every two fertigations. After 7 months, leaf span, leaf size, total leaf area, and fresh weight were not affected by fertilizer type. The differences in leaf numbers were small. The higher rate of fertilizer resulted in plants with wider leaf span (32.8 vs. 28.5 cm), more (5.5 vs. 4.8), larger (103 vs. 89 cm2) leaves, and greater total leaf area (355 vs. 275 cm2) than did the lower rate. In another experiment, similar plants with a leaf span of 15 to 18 cm were grown in 10-cm pots with 100% fine fir bark or a mixture of 80% fine fir bark and 20% peatmoss. They were fertigated with water having an EC - 0.05, 0.40, 0.75, 1.10, or 1.40 dS·m–1 containing 1 g·liter–1 20–20–20 fertilizer three times and then drenched with their respective water containing 0.6 g·liter–1 Ca NO3)2·4H2O. After 11 months, water salinity did not affect the date of spiking. Plants receiving water with EC = 1.10 dS·m–1 had more leaves and spikes than other treatments. Plants in the bark/peatmoss mix began spiking earlier, had more leaves (6.7 vs. 5.7), and more inflorescences (1.9 vs. 1.5) than those in 100% bark. There was no salinity x medium interaction in all the parameters recorded.