Combining Ability and Genetic Components of Yield Characteristics, Dry Matter Content, and Total Carotenoids in Provitamin A Cassava F1 Cross-Progeny

Abstract

Cassava is an important root crop in sub-Saharan Africa, largely cultivated for its starchy edible roots. Biofortified cassava varieties with enhanced provitamin A carotenoid content (PVAC) developed through conventional breeding provide a solution for vitamin A deficiency among vulnerable communities. The aim of this study was to use diallel analysis of six provitamin A cassava genotypes to determine the combining ability, genetic components, heritability, and heterosis of the most important yield characteristics and total carotenoids. Genetic variability for measured characteristics were evident. Fresh root yield was mainly determined by non-additive genetic effects, while dry matter content and total carotenoids were determined by additive effects. Total carotenoids were negatively correlated with fresh root yield, indicating that selection for higher provitamin A content could reduce yield. Mid and higher parent heterosis was seen in some of the crosses for fresh root yield, dry matter content, and total carotenoids. Narrow sense heritability was moderate for fresh root yield and dry matter content, and was high for total carotenoids. This study indicated that yield and dry matter content can be improved in provitamin A cassava but that increased provitamin A content may carry a yield penalty.

Phenotypic diversity and selection in biofortified cassava germplasm for yield and quality root traits

“…The estimation of FRY values is also of great importance for the ranking, selection, and adoption of cassava varieties. In the present study, the general mean of 16.49 t ha − 1 of fresh roots was similar to that of an earlier report (Parkes et al 2020), which analyzed elite parental yellow genotypes cassava from IITA to nd a mean of 16.32 t ha − 1 .…”

“…High estimates of broad-sense heritability were found for TCC ( = 0.72). Similar values for TCC were reported in other studies, such as = 0.73 (Esuma et al 2012) and = 0.60 (Parkes et al 2020). The absence of the genotype × environment interaction effect and high heritability for carotenoid content suggests the possibility of a good response to selection via recombination of favorable alleles.…”

“…The absence of the genotype × environment interaction effect and high heritability for carotenoid content suggests the possibility of a good response to selection via recombination of favorable alleles. In addition, high heritability values allow for more accurate parental selection (Parkes et al 2020;Ceballos et al 2017). However, the DMC gave of medium magnitude (DMC.Grav 0.45 and DMC.OD 0.54), similar to the values reported by (Parkes et al 2020) and (Rabbi et al 2017), who also found moderate values (ranging from 0.40 to 0.51) for this trait.…”

“…In addition, high heritability values allow for more accurate parental selection (Parkes et al 2020;Ceballos et al 2017). However, the DMC gave of medium magnitude (DMC.Grav 0.45 and DMC.OD 0.54), similar to the values reported by (Parkes et al 2020) and (Rabbi et al 2017), who also found moderate values (ranging from 0.40 to 0.51) for this trait.…”

“…The possibility of combining bioforti ed varieties with desirable culinary traits and high agronomic performance has demanded huge attention from breeders (Belalcazar et al 2016;Fuhrmann et al 2019;Parkes et al 2020). However, the cassava bioforti cation program should focus on the development of fresh consumption varieties (sweet cassava), considering that the retention of carotenoids in cooked root samples is between 95-100% (Taleon et al 2019).…”