A Comparative Analysis on the Physiological Effects of the Physical and Chemical Properties of the Trihalomethanes on Nutrient Levels, Oxidative Stress and Sterol Compositions of Leaf Oils in Solanum Lycopersicum Cultivars

Trihalomethane group of disinfection by-products was used to evaluate the magnitude of physiological changes induced on nutrient levels, oxidative stress and phytosterol content in two tomato cultivars. The tomato cultivars were grown as potted plants in a greenhouse and exposed to the varying concentrations of trihalomethanes and organochlorines via irrigation water for a period of 30 days. The concentration levels of nitrogen, potassium and boron in both cultivars significantly (p<0.05) decreased with increasing chlorination. A significant (p<0.05) increase in total polyphenol content, Ferric Reducing Antioxidant Power (FRAP) and guaiacol peroxidase activity was observed in both cultivars. Increase in chlorination could probably be partly responsible for the induction of a greater antioxidant response, as well as the increased free phytosterol content in the tomatoes leaf oils, while β-sitosterol content decreased. In general, the magnitude of the effect of the increasing number of chlorine atoms in the trihalomethane structure were greater than the effects of increasing concentration on nutrient levels. Although, trihalomethanes induced significant physiological changes in some of the measured parameters, no plant mortality was recorded even at the highest concentrations.