Soybean Aphid Resistance In Soybean Germplasm Accessions Of Maturity Group I.

Soybean aphid (Aphis glycines Matsumara) is a newer pest of soybean [Glycine max (L.) Merr.] in North America and it has been established as a major pest of soybean in the northern United States. Identification of newer sources of soybean aphid resistance in early maturing soybeans will provide adapted genetic resources for developing soybean aphid resistant cultivars in the northern region. A total of 341 soybean germplasm accessions including 330 accessions from maturity group (MG) I, 8 resistant checks, and 3 susceptible checks were evaluated against soybean aphid under artificial inoculation in greenhouse by caged (no-choice) and non-caged test to identify new sources of soybean aphid resistance. Selected germplasm accessions from greenhouse tests along with resistant and susceptible checks were also tested in field relying on natural conditions with artificial supplement of soybean aphids.  There were three accessions (PI 189946, PI 153214, and PI 437075) exhibiting lower level of aphid colonization similar to resistant checks in the greenhouse tests.  Six accessions (PI 378663, PI 603587A, PI 567250A, PI 603326, PI 603339A, and PI 603546A) had moderate level of aphid colonization. However, PI 567250A and PI 603339A were less colonized in the field similar to resistant checks while PI 153214 and PI 437075 were moderately colonized. Further genetic characterization is necessary to identify the resistant allele(s) in the resistant germplasm accessions.