Bioassay of Diphenamid and Linuron in Soil

Abstract

1. The effect of varying levels of diphenamid and linuron in Maury silt loam soil on the seed germination, height, and fresh and dry weights of 4-week-old plants of oats, barley, ryegrass, cucumber, sunflower, soybean, and pea was studied under greenhouse conditions. The chemicals were employed at eight concentrations from 0.1 to 12.8 p.p.m. increasing logarithmically. 2. Linuron did not affect germination. Diphenamid did not affect the germination of broadleaf species but reduced the germination of Gramineae species only within a narrow range at higher concentrations. Reduction in germination percentage of these crops, therefore, would not be suitable for evaluating residues of these chemicals in the soil. 3. Reduction in shoot height and weight indicated that broadleaf species were less susceptible to diphenamid than grasses. Of the three Gramineae, oats gave the most satisfactory response curves and, therefore, is considered a suitable indicator plant for estimating the concentration of diphenamid in s...