Targeted Breeding for Sweetpotato-Based Enterprises: Variability, Genotype-by-Environment Interaction, Heritability and Correlation Studies of Important Sweetpotato Root Processing Quality Traits

Abstract

Sweetpotato breeding in Nigeria and many other countries has largely focused on increasing productivity on farmers’ fields and for fresh root consumption. In order to target the breeding program to processing end-use, the variability, location performance, Genotype-by-Environment Interaction (GEI), heritability estimates and relationships among important root processing traits among elite sweetpotato lines were studied in two locations. The genotypes exhibited significant (p<0.05) genotypic variability at each location for dry matter, starch content, flour content and fresh root peel-loss. The combined location analyses also showed that the expression of the traits was under the influence of genotype, environment and GEI. At Makurdi, starch content ranged 14.02-20.53%, while the range of dry matter, flour content and peel-loss were 20.48-37.73, 18.95-31.00 and 11.69-28.40%, respectively. At Umudike, starch was 17.58-23.00%, dry matter was 24.16-34.17%, flour content was 21.34-32.32% and peel-loss was 18.17-24.01%. Correlation study showed that dry matter was moderately correlated to starch (r = 0.53 at Makurdi and r = 0.52 at Umudike) and flour content (r = 0.79 at Makurdi and r = 0.76 at Umudike). Genotypes and traits biplot revealed that NRSP/05/1B, Ex-Igbariam and CIP 440163 largely influenced dry matter, while elevated flour content and peel-loss were related to Ex-Igbariam, CIP 440163 and TIS 87/0087. For heritability study, all the traits showed moderate to high heritability (broadsense) in each location and across locations. This work shows how to identify genotypes with desirable processing traits for release as new varieties. It also enhances the selection of new parent lines for developing new population for processing end-use.