Effects of Physico-chemical Properties of Various Potting Materials on Phalaenopsis Hybrid Cultivation

Phalaenopsis Hybrid is an orchid plant which has been mainly grown in the tropical and sub-tropical regions of Southeast Asia in recent years. Although sphagnum moss is commonly used as potting material, it is expensive and the resources for this material are becoming scarce. Consequently, a viable alternative potting material should be identified.<BR>This study examined four potting materials: rock wool, cryptomeria bark, coconut husk and peat moss. For each material, we evoluted the performance in water retention and nitrate nitrogen retention ability. Based on these determinating, we grew Phalaenopsis Hybrid in the respective materials, with a view to evoluting them as possible substitutes for sphagnum moss.<BR>The results indicated that the water retention ability varied considerably; peat moss displayed the highest water retention ability, and cryptomeria bark the lowest. Also, both the pF value and moisture content of the materials appeared to be important factors for estimating the timing of irrigation. In this experiment, we considered that when the moisture content of the media reached 40% of the water-holding capacity, irrigation was required. Furthermore, since most of the water applied was drained, most of the nitrate nitrogen applied leached for all the materials. Moreover, there was a high correlation (r=0.99) between the amount of nitrate nitrogen leached and EC, suggesting that the timing of fertilizer application could be estimated appropriately by measuring EC.<BR>Based on previous findings, we selected the optimum irrigation and fertilization frequencies for each potting material, and cultivated Phalaenopsis Hybrid to determine which materials could be substituted for sphagnum moss. There was no difference in Phalaenopsis Hybrid growth among all the potting materials, except for peat moss.<BR>The results indicated that, considering the running cost and the availability of the materials in the tropics, coconut husk may be the best alternative potting material.