The soybean [Glycine max (L.) Merr.] 'Hartwig' by 'Flyer' recombinant inbred line population: I. Comparison between early and conventional soybean planting system. II. Genetic mapping of yield, root, and shoot traits

Soybean [Glycine max (L.) Merr.] is a legume crops grown for their valuable protein and oil contents. Early-planted soybeans (ESPS) were reported to be drought tolerant and high yielding compared to the conventional soybean production system (CSPS). The objective was to compare yield, yield components in ESPS (April) and CSPS (June) in NC Sandhills using the soybean 'Hartwig' by 'Flyer' recombinant inbred line (RIL) population. Significant differences were observed for almost all traits measured in ESPS compared to CSPS. Paired T test confirmed these results. Lateral root numbers increased in CSPS compared to ESPS which, is consistent with other studies showing that the root system's density increases with increased water deficit. There were significant losses of yield in CSPS therefore, CSPS may not be appropriate for soybean at least in NC Sandhills. Quantitative trait loci (QTL) mapping analysis using composite interval mapping reported Forty three QTL. The QTL associated with agronomic traits reported in this study may be useful in soybean breeding programs.