Combining Ability, Maternal Effects, and Heritability of Drought Tolerance, Yield and Yield Components in Sweetpotato

Abstract

Knowledge on gene action and trait expression are important for effective breeding. The objective of this study was to determine the general combining ability (GCA), specific combining ability (SCA), maternal effects and heritability of drought tolerance, yield and yield components of candidate sweetpotato clones. Twelve genotypes selected for their high yield, dry matter content or drought tolerance were crossed using a full diallel mating design. Families were field evaluated at Masoro, Karama, and Rubona Research Stations of Rwanda Agriculture Board. Success rate of crosses varied from 1.8 to 62.5% with a mean of 18.8%. Family by site interaction had significant effect (P < 0.01) on storage root and vine yields, total biomass and dry matter content of storage roots. The family effects were significant (P < 0.01) for all parameters measured. Broad sense heritability estimates were 0.95, 0.84, 0.68, 0.47, 0.74, 0.75, 0.50, and 0.58 for canopy temperature (CT), canopy wilting (CW), root yield, skin color, flesh color, dry matter content, vine yield and total biomass, respectively. The GCA effects of parents and SCA effects of crosses were significant (P < 0.01) for CT, CW, storage root, vine and biomass yields, and dry matter content of storage root. The ratio of GCA/SCA effects for CT, CW, yield of storage roots and dry matter content of storage roots were higher than 50%, suggesting the preponderance of additive over non-additive gene action in the expression of these traits. Maternal effects were significant (P < 0.05) among families for CT, CW, flesh color and dry matter content, vine yield and total biomass. Across sites, the best five selected families with significant SCA effects for storage root yield were, Nsasagatebo × Otada 24, Otada 24 × Ukerewe, 4-160 × Nsasagatebo, K513261 × 2005-034 and Ukerewe × K513261 with 11.0, 9.7, 9.3, 9.2, 8.6 t/ha, respectively. The selected families are valuable genetic resources for sweetpotato breeding for drought tolerance, yield and yield components in Rwanda or similar environments.

Heterosis and combining ability for storage root, flesh color, virus disease resistance and vine weight in Sweet potato [Ipomoea batatas (L.) Lam.]

“…Significant differences (p≤ 0.001) were also noticed between families from the Kruskal-Wallis test for all the other traits across the two seasons. These results are consistent with the findings of Rukundo et al (2017). That study concluded that there was a significant difference between means of sweetpotato families on storage root, flesh color, vine weight and biomass though the authors used ANOVA.…”

“…The former is defined as a cultivar"s ability to transmit desirable genes or characters to their progenies in a very efficient way (Fasahat et al, 2016). Combining ability analysis helps breeders in identifying the potential parents and also informs on the genetic action governing the expression of a given trait (Rukundo et al, 2017). When crossing a genotype to several others we can calculate its mean performance in all crosses: this is referred to as the general combining ability (GCA) (Fasahat et al, 2016).…”

“…When crossing a genotype to several others we can calculate its mean performance in all crosses: this is referred to as the general combining ability (GCA) (Fasahat et al, 2016). GCA is directly related to the breeding value of a parent and is associated with additive genetic effects, while specific combining ability (SCA) is the relative performance of a cross and is mostly associated with non-additive gene actions, such as dominance, over dominance, epistasis (Rukundo et al, 2017). Therefore, both GCA and SCA effects are important in a breeding program (Rukundo et al, 2017).…”

The Inheritance of Yield Components and Beta Carotene Content in Sweet Potato

“…Kivuva et al (2015), Balcha (2015), and Rukundo et al (2017) reported that the positive and significant GCA effects in agronomic traits indicate the presence of additive gene action and parents with these genetic characters could be considered as good combiners in a hybridization program. In this study, clone Tio-Joe had positive and significant GCA effects for number of storage roots, harvest index and beta carotene content, while clone Ininda had positive GCA effect for fresh root yield and dry matter content only (Table 6).…”

Induced expression of Xerophyta viscosa XvSap1 gene greatly impacts tolerance to drought stress in transgenic sweetpotato

“…The orange-fleshed sweetpotato cultivars contain portentous β-carotene quantities which is a viable solution to combat vitamin A deficiency in sub-Saharan Africa (Laurie et al 2018). The crop’s effective clonal propagation, its cultivation simplicity and high biomass generation make sweetpotato conceivably appropriate for molecular farming of valuable and novel products (Rukundo et al 2017). Like other crops, sweetpotato is adversely affected by drought stress, which seriously hampers the crop productivity and negatively influence the expansion of sweetpotato cultivation (Jin et al 2017).…”