Composition, functional components, and physical characteristics of grain from staygreen and senescent sorghum lines grown under variable water availability

Abstract

Background and objectives The inclusion of sorghum into human food and feed is limited by its low digestibility compared to corn, due to the presence of high total kafirin levels in sorghum grain. Water stress after pollination reduced grain filling, affecting the grain composition, grain functional components, and grain physical characteristics. Sorghum lines possessing the staygreen trait continue to fill their grain under postflowering water deficit. Understanding the environmental effect on the grain nutritional composition and grain physical characteristics of staygreen and senescent sorghum lines will be critical for breeders when selecting traits. This research evaluated a diverse group of staygreen and senescent sorghum lines subjected to full, preflowering water deficit, and postflowering water deficit irrigations. Findings Staygreen lines had significantly higher levels of total protein and total kafirin, but lower total starch than senescent types. Higher kafirin level was linked to kernel hardness, and this level increased under water deficit. There were no differences between staygreen and senescent sorghum lines in protein digestibility, fermentation efficiency, kafirin per percent protein, kernel hardness, kernel weight, and kernel diameter irrespective of irrigation treatment. Conclusions The nutritional quality and digestibility of sorghum grains were affected by the environment and varies across lines and cultivars. Higher total kafirin level in grains reduces digestibility and impedes energy utilization by interfering with starch digestion. Staygreen lines had significantly higher levels of total protein and total kafirin, but lower total starch than senescent types. Significance and novelty With considerable variability in grain digestibility and feeding value among sorghum cultivars, the effect of environments on grain nutritional composition and other quality traits should be considered to match the user's purpose.

Moisture effects on robustness of sorghum grain protein near‐infrared spectroscopy calibration

“…In addition, it is often desirable to determine how different environmental conditions including high temperature and water‐deficit stress impact protein levels. Such environmental stresses can alter grain protein content significantly; hence, it is highly relevant to identify lines and develop varieties that can produce grains without losing nutritional quality when subjected to stress factors prevalent in specific growing areas (Emendack et al, ; Kaufman et al, ). Therefore, sorghum researchers often need to know grain protein levels to improve the quality and quantity of proteins in new improved varieties and breeding materials.…”

Comparative assessment of grain quality in tannin versus non‐tannin sorghums in the sorghum association panel

“…Lower protein digestibility in sorghum is mainly attributed to the structure and the disulfide bond crosslinking of the protein bodies, especially on the outer edges (Duodu et al, 2003). Located in the endosperm, the protein bodies are the primary location of the seed storage protein called kafirins, which account for 70%–80% total proteins in sorghum (Duodu et al, 2003; Emendack et al, 2018; Liu et al, 2019; Wong et al, 2010). Interaction of sorghum proteins with chemical compounds such as polyphenols, phytic acids, lipids, and cell wall polysaccharides would also render sorghum protein resistant to enzymatic digestion (Duodu et al, 2003; Duressa et al, 2018).…”