Fig. 3

Variation in soybean shoot architecture at individual plant level described in terms of shape parameters. (a) Width of the plant along the length of the plant was measured at 0, 12.5 25 37.5, 50, 65.5, 75, 87.5 and 100% height of the plant. A beta distribution function was used to fit the width data to approximate the shape of the plant. Outcome of a beta distribution fit for four visually distinct accessions (upper panel) shown in the lower panel. From the fit, the overall shape could be described in terms of three parameters, peak height (Sh_H), area under the curve (Sh_A), and width scaling factor (Sh_W) (b) Variation for plant shape parameters from 2018 and 2019 is shown in box plots (c) CO₂ assimilation rate plotted against the PAR levels in one-meter-long plant row where the plant shape is modeled using the beta-distribution. Different accessions are in different colors with the mean value in black (left panel). The differences in the CO₂ assimilation rate between each accession from mean is shown (right panel). (d) Correlations between the relative assimilation rate and the two shape parameters (Sh_H and Sh_W) across the genotypes at four representative PAR values, 250, 450, 900, and 1800 µmol/m 2 /s shown (left panel). Change in relative assimilation can be observed as the slope of the relative assimilation rate at particular PAR level. Correlations between the slope of the relative assimilation and Sh_H or Sh_W at the four PAR levels are shown for each accession (right panel)