Germplasm, Site Description, and Experimental Design

A total of 368 accessions from the cowpea UCR Minicore (Muñoz-Amatriaín et al., 2021) were planted in Ft. Collins, CO (40.6553°N, −104.9966°W) on June 17, 2019. This collection includes landraces and breeding materials from 50 countries. Seeds from each accession were planted in 6.4 m rows with 0.9 m alley and 50 seeds per plot. The experiment was set up as row/column design with one replication and augmented representation of two control lines (CB5 and CB46). Plots were irrigated at the rate of 25.4 mm every week until the end of the study. The experiment was repeated in 2020 when the plots were planted on June 5, 2020. List of accessions evaluated has been provided in Supplementary Table 1.

A total of 292 cowpea accessions from the cowpea mini-core collection that had mature pods in October 2017 were selected from a University of California-Riverside field location and planted in the field at the Plant Science Research and Experimental Unit (PSREU), Citra, FL (29.4119°N; 82.1098°W) on September 7, 2018 (Dareus et al., 2021). The soil was a Chipley sand (thermic, coated Aquic Quartzipsamments) with a pH of 6.9 and characterized by high P₂O₅ content, and low K₂O, S, and Mg content. Seeds from each accession were planted in single row of 10 plants per plot, and the experiment was set up as a row/column design with two replications and augmented representation of 10 control lines. Each experimental unit (3 m × 0.6 m) consisted of 10 plants manually seeded and spaced at 0.3 m within row and 0.6 m between row spacing (Dareus et al., 2021). List of accessions evaluated has been provided in Supplementary Table 2.