Agricultural waste materials as component of organic potting media for the endangered Nepenthes truncata Macf. (Philippine pitcher plant)

Agricultural waste materials, namely, coconut fiber (CF), coir dust (CD), and charcoaled rice husk (CRH) taken singly or in combination with commonly used organic substrates wood charcoal chips (WCC), chopped tree fern (CTF), sphagnum moss (SM), and osmunda fiber (OF) were characterized for their suitability as components of mixed potting media for Nepenthes truncata (Macf.) plantlets. Several mixed media were evaluated, each with a component for aeration (WCC, CTF, or CRH), moisture retention (CF, CD or SM), and drainage (OF). Conventionally used container media mixes served as controls. Based on survival and leaf condition of plantlets, CD could replace SM, and both were superior to CF in moisture retention, while CRH was superior to wood charcoal chips and tree fern for aeration. Both CD and CRH are locally available and inexpensive compared to the materials they could replace. Small-sized plantlets performed better in Treatment 6 (T6) (2:1:1 mixture of SM, OF, and CRH) and Control 1 (pure SM) while medium-sized plantlets only preferred T6. Physico-chemical properties of T6 suggest that the appropriate medium for N. truncata plantlets is slightly acidic with low electrical conductivity, high porosity, moderate water holding capacity, and moderate water retention efficiency.