Contents of Chlorophylls, β-Carotene and Pesticide Residues in Butter Head Lettuce Produced by Various Cultivation Methods

Abstract

Chlorophylls a and b andβ-carotene levels were measured using HPLC in tissues of butter head lettuce grown in soil, hydroponically and in vitro (callus and regenerated plants). The ratio of chlorophylls a+b toβ-carotene was approximately 25-31. Exceptions were observed in most of the soil-grown plants greater than 70g in weight and hydroponic plants. A high variability in the ratios observed in the hydroponic ones would be concerned with the difference in chlorophyll formations. Residual levels of the pesticides (dichlorvos, fenitrothion, formothion and chlorothalonil), the herbicide (chloronitrofen) and the environmental contaminant (trichloroethylene) were analyzed in soil- and hydroponically-grown materials. No detectable amounts of these chemicals were found inhydroponically-grown plants, while considerable contents of chlorothalonil and fenitrothion were detected in soil-grown plants.