Effects of different artificial topsoils on some ornamental plants

Abstract

This project was designed to study the effects of different artificial topsoils produced from mixing incinerator flyash, sewage sludge, biochips and subsoil (from granite origin)on the physiology of some local popular ornamental plants. These artificial topsoils contained various levels of heavy metals such as Cd, Cr, Cu, Fe, Pb and Zn which affected the physiology of plants when they exceeded certain threshold levels. The plants used were BougainviUea spectabilis, Ixora coccinea, Heliconia psithacorum x H. spathocircinata cv. Golden Torch, Heliconia rostrata and Heliconia psithacorum cv. Tay. They are hereby simply referred to as BougainviUea, Ixora, Golden Torch, Rostrata and Tay respectively. The physiological responses of these plants were determined by chlorophyll fluorescence YJYm ratios, photosynthetic light responses; and analyses of their chlorophyll, nitrogen and soluble protein contents. Their morphology and toxicity symptoms were also recorded. After six weeks of growth in the artificial topsoils, the plants were analysed for the heavy metal content in their tissue. Finally, one of the optimal artificial topsoil mixture with 2% flyash was used to conduct leachate test to study the feasibility of using such artificial topsoil in open areas subjected to rainfall.