Combining Ability and Heterosis of Selected Grain and Forage Dual Purpose Sorghum Genotypes

Abstract

Sorghum is an important food and feed source in mixed crop-livestock production systems where its dual usage is a preferred option, especially among the resource poor small-scale farmers. Attempts to improve fodder quality traits in maize have been at the expense of grain traits and vice versa, but other studies demonstrated that it was possible to select for high stem biomass without compromising the improvement of grain yields in sorghum. As a follow up to this effort, this study was undertaken to estimate the combining ability of grain and forage sorghum genotypes and determine heterosis for several traits as a criteria for improving dual purpose sorghum cultivars. Four grain and four forage sorghum cultivars were crossed to generate 23 crosses following the half diallel mating design scheme at Makerere University Agricultural Research institute Kabanyolo (MUARIK) in 2013. The crosses were evaluated at three locations in Uganda during two rainy seasons of 2014. Data were taken and analysed on leaf area, leaf-stem ratio, plant height, seed weight, grain yield, and biomass. Results indicated that the gene action for the traits under observation was controlled by both additive and non additive genetic effects. Majority of the parental lines had significant GCA estimates for all traits except line 20 for grain yield, lines 22 and 34 for plant height, line 35 for leaf-stem ratio, and line 22 for days to flowering. Significant (P ≤ 0.05) SCA estimates were prominent in most of the individual parental combinations for all traits except leaf area and leaf-stem ratio indicating the role of dominance gene action. Bakers ratio and heritability coefficients were  52% for biomass, flowering duration and plant height indicating that genetic gains can be achieved by conventional breeding for the three traits. Heterosis in grain yield and biomass over both the mid and better parents was shown by more than half of the crosses studied. This study suggested that both inter and intra allelic interactions were involved in the expression of the traits.

Field Insights into the Genetic Symphony: Decoding Gene Dynamics for Enhanced Sorghum Yield (Sorghum bicolor [L.] Moench)

“…The preponderance of nonadditive types of gene action for grain yield and other traits was previously reported by Thakare et al [10]. The preponderance of the additive type of gene action for determining 1000 seed weight was previously reported by Chikuta et al [11].…”

Combining ability and performance of three-way maize hybrids for grain yield and resistance to maize lethal necrosis under contrasting environments

“…Both hybrids and their parents were considered fixed while environment was random variable (Mohammed, 2009). Variance components (GCA and SCA) were estimated to identify genetic variability among genotypes and to determine their genetic effects using combining ability model (Chikuta et al, 2017):…”

“…To develop MLN resistant and farmers' preferred hybrids, understanding of performances of the parent lines in hybrid combination is important. However, development of superior hybrids depends on information on combining ability of the parents involved (Chikuta et al, 2017). General combining ability (GCA) of the parent lines helps dissect the gene action for heritability of traits of interest as well as utilisation of the parents in a breeding programme.…”

“…For a hybrid to be useful to farmers in the wider environment, it has to be tested for its yield stability across locations (de Mattos et al, 2013). Studies of combining ability have been extensively used in assessing gene action associated with disease resistance and traits of economic importance in various crops including maize (Aliu et al, 2008;Nyadanu et al, 2012;Azad et al, 2014;Beyene et al, 2017;Chikuta et al, 2017). A set of Superior BC3F2 lines (with 93.5% homozygosity) and doubled haploid (DH) lines of maize were developed for resistance to MLN using foreground marker selection at CIMMYT, Kenya.…”

Breeding Sorghum for Grain, Forage and Bioenergy in Brazil

“…In addition, the evaluation of the best combinations aids the sorghum breeders in deciding which ones will be synthesized on a commercial scale. Among several methodologies, the use of diallel crosses to determine general (GCA) and specific (SCA) combining ability is the most applied (Parmar et al, 2019;Chikuta et al, 2017;Menezes et al, 2014).…”