Registration of Soybean Germplasm Lines R01‐416F and R01‐581F for Improved Yield and Nitrogen Fixation under Drought Stress

166 Journal of Plant Registrations, Vol. 1, No. 2, September 2007 Soybean [Glycine max (L.) Merr.] germplasm lines R01416F (Reg. No. GP-356, PI 647960) and R01-581F (Reg. No. GP-357, PI 647961) were developed by the Arkansas Agricultural Experiment Station and released as maturity group V lines with high yield potential and sustained nitrogen fi xation under moderate water-defi cit conditions. R01-416F and R01-581F originated as F9 plant selections from a cross between ‘Jackson’ and ‘KS4895’. Jackson (PI 548657) was released in 1953 and classifi ed as maturity group VII (Johnson, 1958). Jackson has been reported to possess drought-tolerant nitrogen fi xation, in which decline of nitrogen fi xation rate occurs at lower soil water contents than other cultivars (Sall and Sinclair, 1991). KS4895 (PI 595081) is a widely adapted and high-yielding maturity group IV cultivar derived from the cross of ‘Sherman’ × ‘Bay’ (Schapaugh and Dille, 1998). However, KS4895 does not possess nitrogen fi xation drought tolerance (Purcell et al., 2000). The cross of Jackson × KS4895 was made in 1993, and the plant population derived from Jackson × KS4895 was advanced to the F3 generation by single-seed descent (Fehr, 1991). The F3 plants were grown in the fi eld, and 100 F3:4 maturity group V lines were selected for preliminary evaluation of potential nitrogen fi xation under drought. These 100 selected F3:4 lines were screened for the amount of nitrogen accumulated in the shoots under drought stress in a greenhouse experiment (Sinclair et al., 2007). Subsequently, the F3:5 and F3:6 lines were evaluated in the fi eld for agronomic performance in 1998 and 1999, respectively. Sixty F3:7 lines were Registration of Soybean Germplasm Lines R01-416F and R01-581F for Improved Yield and Nitrogen Fixation under Drought Stress