Registration of Near‐Isogenic Soybean Germplasm Lines D68‐0099 and D68‐0102, Differing in Ability to Form Nodules

D68-0099 (nonnodulating) (Reg. no. GP-158, P1 573285) and D68-0102 (nodulating) (Reg. no. GP-159, P1 573286) are near-isogenic soybean [Glycine max (L.) Men.] lines released to provide germplasm for research purposes. They are of Group VI maturity in a basically 'Lee' (1) background. They were developed in a cooperative research program conducted by USDA, ARS and the Mississippi Agricultural and Forestry Experiment Station and approved for release in April 1993. Yellowish plants were found in an F2 population of 'Lincoln' (2)/'Richland' growing in the breeding nursery at the University of Illinois, Urbana. Further studies showed these yellowed plants to be free of nodules. Williams and Lynch (3) reported that the nonnodulating character was inherited as a simple recessive character. T201 (nonnodulating) and T202 (nodulating) are near-isogenic lines of Group n maturity. These lines are maintained in the USDA-ARS soybean collection at Urbana, IL. A program was initiated at Stoneville, MS, in 1956 to develop near-isogenic nodulating/nonnodulating lines adapted to another environment. The cultivar Lee was chosen as the recurrent parent and T201 as the donor parent. Crosses were made in the field, FI plants grown in the greenhouse during the winter months, and F2 populations grown in the field on Sharkey clay soil (very-fine, montmorillonitic, nonacid, thermic Vertic Haplaquept). This soil contains little N as a result of denitrification. Nonnodulating seedlings will show N deficiency by the third trifoliolate. Thus, it was possible to select nonnodulating plants to use as male parents for the next cycle of backcrossing. After the sixth backcross, a Lee type having the gene Rpsl-c conferring resistance to phytophthora rot (caused by Phytophthora sojae J.J. Kaufmann & J.W. Gerdemann) replaced Lee as the female parent. Two more backcrosses were made. A segregating F3 line, eighth backcross, was the parent line from which D68-0099 and D68-0102 were developed. Both D68-0099 and D68-0102 are of late Group VI maturity, have purple flowers, tawny pubescence, and tan pod walls at maturity. Seed are yellow, with black hila. They are resistant to bacterial pustule caused by Xanthomonas campestris pv. glycities (Nakano) Dye and phytophthora rot (genotype Rpslc). When grown on Sharkey clay, D68-0099 produced a seed yield of 423 kg ha", with seed protein and oU content of 284 and 257 g kg", respectively, in comparison with a seed yield of 3046 kg ha" and seed protein and oil content of 388 and 228 g kg" for D68-0102. When grown in sandy loam soil with more residual N, the nonnodulating line is usually slightly taller than the nodulating line, and the plant type is Christmas-tree shaped. Seed of D68-0099 and D68-0102 will be available for research purposes for at least 5 yr from Soybean Production Research, P.O. Box 196, Stoneville, MS 38776.