Seasonal Variations of Selected Ornamental Plants as Biomonitors of Air Pollutants in Ondo State, Nigeria

Abstract

This objective of this paper was to evaluate the seasonal variations of fourteen (14) ornamental plants as biomonitors of air pollution in three urban areas of Ondo State, Nigeria. The study was carried out in three areas that were purposively selected in Ondo State which are Oduduwa Road, Oloko (traffic congested area), FUTA area (Less traffic congested area) and uncongested area in Elizade University as control. The ornamental plants namely Roystonea regai, Convallaria majalis, Polyalthia longifolia, Ficus benjamina, Dieffebachia amoena, Colocasia esculent, Caesalpinia pulcherrima, Codyline fructicosa, Viburnumt tinus variegatum, Variegatum punctatum, Hibiscus rosa-sinensis, Tradescantia pallida, Codiaeum variegatum, Acalypha wilkesiana were selected purposively and their ascorbic acid contents, pH, relative water contents, total chlorophyll contents and air pollution tolerance index were evaluated using standard methods.  The biochemical parameters and APTI values of the ornamentals showed that they have less (APTI<17) tolerance indices during the dry and the wet seasons. Thus, they are more susceptible to air pollutants as biomonitors. At congested areas ornamentals had lesser APTI values at the sampling site than the control site with Tradescantia pallida having the highest (8.86) mean value while Variegatum punctatum had the lowest value of 6.81 during the wet season while Codiaeum variegatum with value 7.08 and the lowest for Variegatum punctatum with value 4.71. Conclusively, this study recommends that in addition with the aesthetic values of the ornamental plants, they can be useful as model bioindicators of air pollution in urban settings.