Registration of non-nodulating and nodulating isolines and heterogenous inbred families developed from an elite soybean cultivar ‘KS4120NSGT’

The non-nodulation trait from Harosoy-NN and Williams-NN was introgressed into an elite soybean [(Glycine max (L.) Merr.] cultivar, ‘KS4120NSGT’ (Reg. no. GP-545, PI 708128), through backcrossing to combine non-nodulation with high yield, and desirable agronomic traits. The effort aimed to address the gap in yield between older non-nodulation lines and modern nodulating cultivars. Four non-nodulating near-isogenic lines—KS4120-1_rj1 (Reg. no. GP-533, PI 708116), KS4120-2_rj1 (Reg. no. GP-534, PI 708117), KS4120-3_rj1 (Reg. no. GP-539, PI 708118), and KS4120-4_rj1 (Reg. no. GP-540, PI 708119)—were developed from the Harosoy-NN source, while four nodulating lines—KS4120-5_Rj5/rj6 (Reg. no. GP-542, PI 708121), KS4120-6_Rj5/rj6 (Reg. no. GP-536, PI 708123), KS4120-7-1_Rj5/rj6 (GP-538, PI 708125), and KS4120-7-2_Rj5/rj6 (Reg. no. GP-544, PI 708127)—and four non-nodulating lines—KS4120-5_rj5/6 (Reg. no. GP-541, PI 708120), KS4120-6_rj5/6 (Reg. no. GP-535, PI 708122), KS4120-7-1_rj5/6 (Reg. no. GP-537, PI 708124), and KS4120-7-2_rj5/6 (Reg. no. GP-543, PI 708126)—were developed from heterogeneous BC₄F₂-derived inbred families (HIFs) from Williams-NN source. Molecular marker analysis confirmed the presences of rj1, or rj5 and rj6 in the non-nodulating lines. All lines retained key agronomic traits of the recurrent parent, including purple flowers, tawny pubescence, brown pods at maturity, indeterminate growth habit, yellow seed coats and black hilum. Selection for non-nodulation/nodulation from the elite × non-nodulation donors was made using both phenotypic and marker-assisted selection methods. Field evaluations across Arkansas, Georgia, and Kansas in 2021 and 2022 demonstrated the superior yield potential, agronomic performance, and adaptability of the recurrent parent and derived lines compared to the NN check genotypes, Harosoy-NN and William-NN. When fertilized with N, seed yield, maturity, lodging, plant height, seed weight, and protein and oil concentrations were usually not significantly different between the recurrent parent and the NN lines within environments. The lines are potentially important resources in soybean studies to elucidate biological N fixation and N management in relation to soybean yield and seed composition.