Abstract:
Decades of soybean (Glycine max (L.) Merr.) breeding have delivered substantial yield gains, yet how root systems have changed over this period has remained unclear. We evaluated 24 maturity group IV soybean cultivars released between 1930 and 2005 in field experiments at two locations over 2 years, and quantified topsoil root and nodulation traits alongside seed yield. Root crown complexity (RC) increased with cultivar year of release (YoR), accompanied by increases in convex area, total root length (TRL), root network area, solidity, first-order lateral root number, second-order lateral root density, and number of root tips. Across environments, RC increased by 31.3% while TRL increased by 28.3%. In contrast, lateral root crown angle (LRCA) decreased 5.2% with YoR, indicating a shift toward shallower root systems. Nodule size and nodule density also increased 20% and 46% over time, respectively. Correlation and principal component analyses revealed strong integration among traits associated with root branching, crown expansion, and root length density. Stepwise regression identified RC, LRCA, TRL, solidity, and average root diameter as the root traits most strongly associated with yield across environments (cross-validation R2 = 0.67). Together, these results indicate that soybean breeding has been accompanied by coordinated changes in root system architecture (RSA), favoring larger, more highly branched root systems concentrated in the upper soil profile. While breeders focused on yield and aboveground traits, substantial shifts in RSA occurred alongside historical yield improvements. These findings highlight opportunities to leverage root architectural traits in efforts to improve productivity, resource acquisition, and adaptation to diverse production environments.
Links:
Citation:
J. R. Costa Netto, H. I. T. Almtarfi, A. Seethepalli, L. M. York, A. Zare, and F. B. Fritschi, "Decades of progress: Breeding modified soybean root systems," Crop Sci., vol. 66, no. 1, p. e70355, 2026, doi: 10.1002/csc2.70355.@article{costanetto2026decades,
author={Costa Netto, J. R. and Almtarfi, H. I. T. and Seethepalli, A. and York, L. M. and Zare, A. and Fritschi, F. B.},
title={Decades of progress: Breeding modified soybean root systems},
journal={Crop Science},
volume={66},
number={1},
pages={e70355},
year={2026},
doi={10.1002/csc2.70355}
}