PHYSICAL AND CHEMICAL PROPERTIES OF GAOYAO PEAT FORMULATED SUBSTRATES AND THEIR EFFECTS ON ZAMIOCULCAS ZAMIIFOLIA GROWTH

This study analyzed the physical and chemical properties and stability of Gaoyao peat (GP) and GP-formulated substrates and evaluated their effects on Zamioculcas zamiifolia (ZZ) growth. Compared to a commercial substrate used in this study, GP had higher bulk density, significantly lower total pore space and air capacity, lower pH, organic content, N and P content. ZZ plant grown in the commercial substrate had over 90% of lateral buds to develop pinnate compared to only 56.9% when plants were grown in the GP-based substrates. Net photosynthetic rates of ZZ grown in GP were lower than those grown in the control substrate. Correspondingly, plants grown in GP substrates had shorter pinnate length and smaller petiole diameter and produced significantly lower leaf dry weight, root dry weight, total plant dry weight, compared to those produced in the commercial substrate. However, no signif¬icant differences were found in total rhizome dry weight among the tested substrates. The reduced ZZ plant growth was related to lower concentrations of P, K, and Mg but higher concentration of Mn in leaves. After 270 days of growth, the physical and chemical properties of GP based substrates changed significantly by a drop in pH values, great increase of EC values, and dramatic accumulation of P and K.