Environmental and Plant Factors That Influence Trace Element Bioavailability in Food Crops 

Objective 1: Characterize effects of flood and soil management on As (inorganic and total) and Cd accumulation in rice grain. 1A: Does alternate wetting and drying (AWD) irrigation management reliably lower inorganic As (iAs) in rice grain without causing excessive grain Cd in rice genotypes? 1B: Develop extraction and analysis methods to rapidly measure the inorganic As (iAs) in rice grain samples. Objective 2: Characterize competition of other cations with Cd accumulation by rice and vegetables. 2A: Clarify whether increased Zn2+ activity reduces Cd2+ accumulation by spinach, lettuce and rice and whether plant Zn deficiency causes up-regulation of Zn transporters which increases uptake of Zn and Cd compared to Zn-sufficient crops. 2B: Clarify whether increased manganese (Mn2+) is more important than Zn2+ in inhibiting uptake of Cd2+ by rice and vegetables from nutrient solutions with environmentally relevant activity of Cd2+. Objective 3: Characterize effects of soil amendments on Pb, Cd and As accumulation by garden crops to improve advice to urban gardeners regarding risk reduction for contaminated urban soils. 3A: Characterize the effects of soil amendments and mulch on Pb and Cd accumulation by garden crops from contaminated urban garden soils. 3B: Characterize the effects of soil amendments on Pb and Cd accumulation by crops grown in contaminated urban gardens. Objective 4: Continue evaluation of the effects of crop species and crop Zn on bioavailability of crop Cd to animals. Test whether crop Zn concentration and crop species affect the bioavailability of crop Cd to monogastric animals in order to clarify if crop species and crop Zn should be included in technically valid limits for Cd in crops.