Effects of air pollution on tomato plants (lycopersiconesculentum)grown along Waiyaki highway in Nairobi county, kenya

Abstract

Vehicle exhaust fumes emission, as one ofleading major source amongsmoke producing air pollutants, wasexamined in thisstudy. Nairobi,a mega-citywith increasingly high levels of air pollutionwas studied with special emphasison one of its roads,Waiyaki Highway. Objectives were to find if there is air pollution,air pollution effects growth and stress of plants. This roadwasinvestigated to gain scientific understanding of the effects of vehicle fumes on plants. Hotspots (ICEA building, ABC Place, and Kangemi Market), had unique characteristics, whichincluded moribund trees or plants, dark tree trunks and leaves due to air pollution. Lycopersicon esculentumMill., (1768), tomato plants that is highly susceptible to air pollution was exposed to the air at selected sites along the highway. Four experiments were set, (three as test experiments and one, control) using a raised platform containing twelve plants in polythene bags and irrigated frequently. For the study analysis, data was collection on pollution level, seed germination rate, height growth, leaf length, flower count, biomass, stress and stomata account for three months.Thedatawas analysed using Analysis of Variance (ANOVA),Kruskal Wallis and Poisson distribution in Genestat software. Means were separated by use of Least Significant Difference (LSD) α = 0.05.The Waiyaki Highway had consistence air pollution, for whole period of this study (averagingPM1042.6µgm/m3for test sites). The control experiment at NARL had similar environmental conditions but no significant air pollution(PM10 0.6µgm/m3).The control experiment was protected from air pollution related to vehicle fumes by long distance away from the road plus canopies of trees thriving in between to shield experimental plants. Seed germination rate results, showed that,there were no significant differences at(P <0.05). Growth pattern was determined using height, which proved significantlydifferent atP < 0.05. Leaf length of tomatoplants was not significantly different whereP <0.05. Results of flower count showed significantly difference(P < 0.05).Stresswas significantly different where P<0.05. Plants biomass wasnot significantlydifferent between experiments (P<0.05). Open stomata in upper epidermis was significantly different. Air pollution affects plants as evidenced by significance noticed on height growth, number of flowers, plant stress and distribution and status of stomata. Leaves elongation is independentof air pollution. Plants in air pollution had different height to control, more flowers and were stressed more due air pollution. Plants in air pollutedenvironment hadhigh stomata density underneath leaf than controlandno open stomata on the upper epidermis. Stomata number, positionand, if open or closed on leaves of plants is a quick way of determining air pollution. Three months was not enough for air pollution to affect biomass production. It is important for precise threshold levels of air pollution effects to plants be determined. Comprehensive studyon effects of air pollution on seed germination, height growth, leaf growth, biomass and plants physiological behaviour in heavily air polluted environment be instituted on long term basis.