Identification of Soybean Germplasm Lines and Cultivars with Low Incidence of Soybean Mosaic Virus Transmission through Seed 1

Soybean [ Glycine max (L.) Merr.] cultivars and germplasm lines from the USDA soybean germplasm collections were tested to determine the incidence of soybean mosaic virus (SMV) transmission through seeds. Eighthundred ninety‐seven accessions were used, 400 from the tropical maturity groups (VIII, IX, and X) and 497 from temperate maturity groups II and III. Field‐grown soybeans at Isabela, Puerto Rico (18° N Lat) or Urbana, 111 (41° N Lat) were manually inoculated at the primary leaf stage with the “Illinois severe” isolate of SMV (SMV‐I1‐S). Seeds harvested from SMV‐I1‐S infected plants were planted in sand benches in a greenhouse and the incidence of virus infected seedlings was determined by observation of symptoms and by indexing. In 1976, all 897 lines were tested with 200 seeds per line. In 1977, 98 tropical lines and 35 temperate lines which had low incidence of transmission in 1976 were tested with 1,000 seeds per line. Nontransmitting lines from 1977 tests and their maturity group classification were FC 31678 (III), PI 60279 (II), PI 68680 (II), PI 70019 (III), PI 70036 (II), PI 88303 (II), PI 91115 (II), PI 92684 (II), PI 92718‐2 (III), PI 203406 (VIII), PI 240664 (X), PI 325779 (IX), PI 360835 (II), ‘Arisoy’ (VIII), ‘Cloud’ (III), ‘Manchu 2204’ (III), ‘Merit’ (0), ‘Mukden’ (II), and ‘Virginia’ (IV). Most temperate lines selected for absence of seed coat mottling in 1976 had a high degree of mottling when tested in 1977.