Registration of 'S16-5503GT' soybean cultivar with high yield, broad adaptation, and glyphosate tolerance

'S16-5503GT' (Reg. no. CV-555, PI 700002) is a semi-determinate, late-maturity group IV (relative maturity, 4.8), glyphosate-tolerant, high-yielding soybean [Glycine max (L.) Merr.] cultivar developed and released in 2021 by the University of Missouri-Fisher Delta Research, Extension, and Education Center (MU-FDREEC) soybean breeding program. Southern U.S. growers' preference for high-yielding, early-maturing cultivars with glyphosate tolerance and broad disease resistance motivated the development of S16-5503GT soybean. It was evaluated in a total of 92 environments across 12 U.S. mid-southern states from 2017 to 2021 for yield and agronomic traits. Across all testing environments, S16-5503GT yielded 4,258 kg ha(-1), which was equivalent to 108% of the non-Xtend check mean and 102% of the Xtend check mean, ranking in the top 19% overall. In the 2021 Southern State Variety Trials, S16-5503GT yielded 4,455 kg ha(-1) and ranked in the top 43% overall. S16-5503GT is resistant to soybean cyst nematode races 3 (HG type 5.7) and 5 (HG type 2.5.7) and moderately resistant to race 2 (HG type 1.2.5.7). It is also resistant to southern root-knot nematode, reniform nematode, frogeye leaf spot, charcoal rot, and brown stem rot and is tolerant to extreme salinity conditions. The broad disease resistance package combined with high-yielding performance and wide adaptability across multiple mid-southern states make S16-5503GT an excellent cultivar choice for soybean growers in the southern United States, where late-maturity group IV varieties are in demand.