Pericarp thickness (determined by Z gene) varies greatly among sorghum varieties ranging· from very thin (8 ~ m) to very thick (160 ~m ) . Pericarp thickness also varies within an individuual kernel. The areas below the style and near the hilum are the thickest with the sides of the kernel being thinnest . Scanning electron microscopy was used to document differences in pericarp thickness and to explain milling differences . Varieties with a thick pericarp had starch granules in the mesocarp cell layers. Sorghums with a thin pericarp did not have starch granules in the mesocarp except near the hilum and stylar area. U.S. sorghum varieties studied had a testa thickness of 16-40 ~m (side of the kernel) but recently four Malian sorghums from a recent collection had very thin testae of 8-16 ~ m. The Sudanese sorghum Shawaya had a testa ranging in thickness from 28-40~m.
Earp, C. F. and Rooney, L. W.
"Scanning Electron Microscopy of the Pericarp and Testa of Several Sorghum Varieties,"
Food Structure: Vol. 1
, Article 3.
Available at: http://digitalcommons.usu.edu/foodmicrostructure/vol1/iss2/3