Arsenic Phytotoxicity and Uptake in Six Vegetable Crops

Abstract

Six vegetable crops were greenhouse-grown to maturity in three Maryland soils treated with up to 500 ppm of arsenic (As) added as sodium arsenate. Phytotoxicity of arsenic residues was highest on Lakeland loamy sand and lowest on Hagerstown silty clay loam. Correlations between available arsenic and plant dry weight indicated that crop sensitivity proceeded as follows: green beans (Phaseolus vulgaris L. ‘stringless greenpod’) > lima beans (Phaseolus linensis L. ‘Fordhook 242’) spinach (Spinacia oleracea L. ‘Longstanding Bloomsdale Savoy’) > radish (Raphanus sativus L. ‘Champion’) > tomato (Lycopersicon esculentum Mill. ‘F-7’) > cabbage (Brassica oleracea L. var. capitata L. ‘Jersey Wakefield’). Residues in the total dry plant at the available arsenic level at which growth was reduced 50% (GR50) were highest with radish (43.8 ppm) and spinach (10.0 ppm). Residues in the dry-edible portion increased to 76.0 ppm arsenic for unpeeled, washed radish at the GR50 point. The soil at the GR50 level for radish contained about 19 ppm of available arsenic from a 50 ppm arsenate treatment to Lakeland loamy sand and a 100 ppm treatment to Hagerstown silty clay loam and to Christiana clay loam.