Biomonitoring of fluoride pollution with gladiolus in the vicinity of a brick kiln field in Lahore, Pakistan

Although there are thousands of small-scale, poorly regulated brick kilns in rural areas of South Asia their impact on local agricultural crops is largely unknown. The impact of fluoride on crops in a brick kiln area in the Northern Punjab Region of Pakistan was investigated. Fluoride accumulation, leaf necrosis, and reduced corm diameter and weight were found in the brick kiln area in two cultivars of Gladiolus that have been widely used as biomonitors in Europe. The rate of increase in leaf injury of the sensitive Gladiolus cultivar was greatest at all sites when the temperature was lower and there was a high relative humidity of 60–75%. The necrotic leaf tip lengths of the indicator plants correlated very well with their fluoride concentrations. The fluoride accumulation was directly proportional to the Fluoride Injury Index, although a higher injury index was observed with the fluoride-sensitive cultivar Lavendell Puff compared to the fluoride-tolerant cultivar Flower Song. These results suggest that injury to sensitive crops from fluoride may occur in other brick kiln areas in South Asia, and that Gladiolus plants could be used as a cost-effective biomonitor for further investigation in this region.