Sorghum bicolor (L.) Moench is amongst the most significant crop throughout the semi- arid region of the world, after maize, wheat, rice, and barley (Meena et al., 2020). It is resistance to a variety of biotic and abiotic stress and commonly grown in water –stressed areas (Abebe et al., 2020; Badigannavar et al., 2018; Boyles et al., 2019; Mace et al.,2020; Yadav et al., 2020; Yang et al., 2020). Among its beneficial qualities are its ability to produce high grain yield, stem sugar, and lignocellulosic factors (Chandra et al.,2012; He et al., 2020).
Sorghum is grown in Ethiopia for food,fodder and feed in both main and off_ season (Tasie and Gebreyes, 2020). After the main season, off-season sorghum is typically plant in verti-soils under soil moister conditions stock up and replanting following the main-season, where both soil and atmospheric drought occur (Samdur et al., 2020). In order to meet the growing demand for food in the face of changing climate conditions, progress in the genetic improvement of important traits, such as grain yield and component traits, is necessary (Senapati et al., 2019a; Senapati et al., 2019b; Torres-Tiji et al., 2020). However as most of the off-season sorghum lines, the genetic enhancement of off-season sorghum is at present caught up by lack of genetic multiplicity along with breeding lines (Are et al., 2019; Nanaiah and Rakshit, 2020).
Grain yield and sugar related traits are complex characters involving numerous component characters, each of which is regulated by several genes, epistasis, and interactions (Banerjee et al., 2020; Disasa et al., 2018a; Fu et al., 2019). A significant method that has received increasing awareness in plant improvement for commerce with polygenic characteristics is quantitative trait loci (QTL) mapping (Ali et al., 2019). DNA markers can be used to dissect polygenic traits that were difficult to influence by conventional plant improvement methods in to individual QTL and these markers used plant developer to establish and go after the many interacting genes that affect complex traits (Ali et al., 2019; Cobb et al., 2019; Kim et al., 2020). In sorghum, many DNA markers such as RFLPs, AFLPs, SSRs and DArTs were developed and helps to construct linkage goups (Rahman et al., 2019; Srivastava et al., 2019). QTL of sorghum study have manipulated many genomic regions linked with essential agronomic and stem sugar traits, such as plant maturity, plant height, grain yield and related traits (Breitzman et al., 2019; Kang et al., 2020), and resistance to drought after flowering (Wang et al., 2020a), resistance to disease and insects (Jadhav et al., 2019), concentration of stem sugar. Building of genetic groups using unique functional genetic markers enables the co-location of genetic markers and QTL to be evaluated and can also improve our consideration of the biochemical pathway and system manipulating stem brix content traits (Disasa et al., 2018b; Kajiya-Kanegae et al., 2020; Kang et al., 2020; Mengistu et al., 2020). However, there are not numerous application in sorghum, particularly in off-season sorghum, for the linkage of genetic markers with QTL scheming the concentration of stem sugar and essential agronomic traits.
This would help us better understand the genetics of these traits by discovering QTL that regulate stem brix content and associated properties, as well as elucidating the links between QTL and candidate genes and laying the groundwork for MAS sugar yield in off-season sorghums. The objective of this experiment were to detect and QTL map for stem oBrix content and stem diameter from sorghum RILs using genotype by sequence data using the creation of a mapping population recombinant inbreed lines (RILs) derived from both grain and sweet sorghum germplasims.