Effect of lead (Pb) in soils on the growth and lead accumulation of water spinach (Ipomoea aquatica)

Abstract

This research aimed to assess the effect of lead (Pb) concentration in soils on the growth and development of water spinach (Ipomoea aquatica) and Pb accumulation in the plant. Water spinach was cultivated in soil pots for 40 days, including one control treatment with uncontaminated soil and six treatments with Pb-contaminated soils (85.6 - 1053.3 mg/kg). After 40 days, fresh root and shoot weights were measured. Also, the content of chlorophyll a and chlorophyll b in leaves, and Pb concentration in shoots were determined. The results showed that when water spinach was cultivated in soils with Pb levels of up to 328.4 mg Pb/kg, the fresh root and shoot weights, the contents of chlorophyll a and chlorophyll b in leaves were statistically similar to those observed in the control treatment. However, in soils with Pb concentrations of ³ 520.4 mg Pb/kg, the fresh root and shoot weights and the contents of chlorophyll a and chlorophyll b significantly decreased compared to the control treatment. For Pb uptake by the plant, the bioaccumulation of Pb in water spinach shoots increased with increasing Pb concentrations in the soils. The Pb concentration in the edible parts of water spinach harvested from soils contaminated with 148.3 - 1053.3 mg Pb/kg exceeded 2 - 65-fold the maximum permissible level for Pb in fresh vegetables as regulated by the Ministry of Health. Therefore, the Pb levels in soils cultivating water spinach must be controlled to ensure food safety and protect human health.