Submitted to: Crop Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 9/30/2000
Publication Date: N/A
Interpretive Summary: The soybean looper, a foliar-feeding insect, can cause significant defoliation of soybean in the southern United States. Chemicals can be used to control the insect, but planting a resistant soybean would be more benign to the environment. A productive soybean germplasm line with insect resistance was developed by crossing a productive susceptible soybean variety with insect-resistant germplasm. A high yielding soybean line wit high protein content, insect resistance, and resistance to the stem canker disease was extracted from progeny of this cross. Soybean breeders can use this germplasm line in crosses with today's best varieties to develop future varieties with insect resistance that will reduce the need for insecticides.
Technical Abstract: DMK93-9048 was released in 1999 by the USDA Agricultural Research Service in cooperation with the Mississippi Agricultural and Forestry Experiment Station. This line has value as a parent because it possesses high protein and is highly resistant to foliar-feeding by the soybean looper Pseudoplusia includens and southern stem canker disease caused by Diaporthe ephaseolorum v. meridionalis. DMK93-9048 was derived from the cross D86-342 X Braxton. D86-3429 is a breeding line having a high level of resistance to the soybean looper and southern (Meloidogyne incognita) and peanut (M. arenaria) root-knot nematodes. In 1991, 968 F2 plants were evaluated for soybean looper feeding in a field cage infested with egg-laying moths. Thirty-nine plants showing the least defoliation were selected for harvest. Later generations of plants were selected for agronomic qualities and lack of feeding by the soybean looper. The selected lines were also tested for resistance to stem canker following inoculation by inserting an infested toothpick into the stem. Advanced selections were screened in the greenhouse for tolerance to the herbicide, metribuzin, and in the field for seed yield. Yield of DMK93-9048 was better than Braxton and less than Stonewall soybean varieties. DMK93-9048 is of Maturity Group VII, averaging two days later than Stonewall. It has determinate stem termination, white flowers, gray pubescence, and tan pod wall. Seed are yellow with buff hila, averaging 146 mg per seed. Seed protein and oil average 462 and 200 grams per kilogram, compared with 440 and 201 for Braxton. DMK93-9048 is tolerant to metribuzin and has shown resistance to southern root-knot nematode and moderate resistance to peanut root-knot nematode. It is susceptible to the soybean cyst nematode, Heterodera glycines.