Fig. 6

Estimated a volume and b area index per seed of carbonized millet seeds. a In total, 30 broomcorn millet (Panicum miliaceum) and 98 foxtail millet (Setaria italica) seeds were used for estimations. Length, width and thickness were measured by using a digital ruler. The Y-axis is for seed volume and the unit is mm⁻³. b The area index per seed of the two millet seed types was estimated from the scanned images of 50 seeds each. The Y-axis is for seed area index and the unit is mm⁻². Data are box-and-whisker plots (median and interquartile range, Schmuller 2013) were used for illustration