Response of Leafy Vegetable Kalmi (Water Spinach; Ipomoea aquatica L.) at Elevated Concentrations of Arsenic in Hydroponic Culture

Shaibur, Molla Rahman; Islam, Tamanna; Kawai, Shigenao

Response of Leafy Vegetable Kalmi (Water Spinach; Ipomoea aquatica L.) at Elevated Concentrations of Arsenic in Hydroponic Culture

2009

Shaibur, Molla Rahman | Islam, Tamanna | Kawai, Shigenao

Effects of elevated arsenic (As) concentrations on hydroponic Kalmi (Ipomoea aquatica L.) were investigated. Plants were treated with 0, 10, 25, and 50 μM As in the greenhouse for 14 days. Arsenic was added from sodium meta-arsenite (NaAsO₂). Visible toxicity symptom could not easily be recognized without visible growth reduction. Little brown spots on the leaf blade were found at 50 μM As treatment. Dry matter yields decreased by 18.8%, 43.2%, and 78.2% in leaves; 23.6%, 56.4%, and 81.8% in stems; and 11.0%, 28.6%, and 63.7% in roots in the 10-, 25-, and 50-μM As treatments, respectively. Arsenic concentrations increased in leaves (except in 50 μM As treatment), stems, and roots with increasing As concentrations in the medium. Roots contained 12.7, 11.3, and 10.5 times higher As concentrations as compared to stems and 15.5, 15.9, and 52.8 times higher as compared to leaves in the 10-, 25-, and 50-μM As treatments, respectively. Arsenic concentration followed the trend of roots > stems > leaves. Kalmi concentrated unaccepted levels of As in leaf and stem tissues for human consumption in the As-treated plants. Based on 10% dry weight (DW) reduction, the critical toxicity level (CTL) of As in the leaves was 7.02 and 23.6 μg g⁻¹ DW in stems.

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