The Improvement of Grain Sorghum Productivity, Black Pericarp Color, and Protein Digestibility

Abstract

Sorghum [Sorghum bicolor (L.) Moench] is an important cereal crop for the semiarid regions of the world. The improvement of sorghum grain production and sorghum grain quality are essential for the future of the crop. This study explores the genetic gain of hybrid sorghum breeding programs and investigates the nature of two important grain quality traits. A multi-environment trial was conducted that included hybrids ranging from the 1950s to today. Genetic yield gains in grain sorghum are increasing at approximately .008 t ha^-1 annually and many other physiological traits have demonstrated changes as well. Also, a Fv5 recombinant inbred line (RIL) population segregating for black and red pericarp color was evaluated in two Texas environments in the summer of 2017. Heritability and repeatability estimates were calculated and secondary plant metabolite biosynthesis genes were explored using RNAseq. The black pericarp trait appeared to be moderately heritable. Many of the same genes involved in 3-deoxyanthocyanidins (3-DOA) production in leaf tissue during fungal invasion appeared upregulated in black pericarp sorghum versus red pericarp sorghum. Finally, sorghum grain protein digestibility was investigated in a biparental mapping population and evaluated in two environments for two years. A near-infared spectrometry (NIR) calibration curve for in-vitro protein digestibility was developed to assist the phenotyping of this important quality trait. The protein digestibility trait was highly heritable and a significant genotype x environment effect was observed. Understanding key components of genetic gains in yield and other traits, as well as factors involved with important quality traits will benefit sorghum production in the future.