Heterosis and Responses to Selection in Orange-Fleshed Sweetpotato (Ipomoea batatas L.) Improved Using Reciprocal Recurrent Selection

Abstract

Sweetpotato is a highly heterozygous hybrid, and populations of orange-fleshed sweetpotato (OFSP) have a considerable importance for food security and health. The objectives were to estimate heterosis increments and response to selection in three OFSP hybrid populations (H1) developed in Peru for different product profiles after one reciprocal recurrent selection cycle, namely, H1 for wide adaptation and earliness (O-WAE), H1 for no sweetness after cooking (O-NSSP), and H1 for high iron (O-HIFE). The H1 populations were evaluated at two contrasting locations together with parents, foundation (parents in H0), and two widely adapted checks. Additionally, O-WAE was tested under two environmental conditions of 90-day and a normal 120-day harvest. In each H1, the yield and selected quality traits were recorded. The data were analyzed using linear mixed models. The storage root yield traits exhibited population average heterosis increments of up to 43.5%. The quality traits examined have exhibited no heterosis increments that are worth exploiting. The storage root yield genetic gain relative to the foundation was remarkable: 118.8% for H1-O-WAE for early harvest time, 81.5% for H1-O-WAE for normal harvest time, 132.4% for H1-O-NSSP, and 97.1% for H1-O-HIFE. Population hybrid breeding is a tool to achieve large genetic gains in sweetpotato yield via more efficient population improvement and allows a rapid dissemination of globally true seed that is generated from reproducible elite crosses, thus, avoiding costly and time-consuming virus cleaning of elite clones typically transferred as vegetative plantlets. The population hybrid breeding approach is probably applicable to other clonally propagated crops, where potential for true seed production exists.

Selection of parents in a population hybrid breeding scheme for sweetpotato in Uganda

“…were subsequently observed (Diaz et al, 2021;Grüneberg et al, 2022). The strikingly low mid-parent mid-offspring association in the EA breeding platform observed in this study might underline the importance of determining the breeding value of parents on the basis of offspring performance and the selection of parents using their combining ability.…”

“…The HEBS concept in sweetpotato has been previously described (David et al, 2018;Diaz et al, 2021;Grüneberg et al, 2015): heterosis increments can be determined by comparing (a) the parental mean with the mean across the segregating offspring clones (Diaz et al, 2021;Grüneberg et al, 2022), and/or (b) comparing the mean estimates of intraand inter-gene pool crosses. The latter approach was used in the fundamental maize study by Moll et al (1965), where homozygous inbreed lines were still too weak to be used in hybrid breeding.…”

Crossing possibility for breeding promising orange-fleshed sweetpotato genotypes in Benin

“…For instance, population derived from Tio-joe and ACAB220, and population derived from Vobodouaho and ACAB220. Positive heterosis effects were reported for resistance to sweetpotato virus diseases, storage root yield, beta-carotene and dry matter content (Ngailo et al 2019), and explored using poly-cross and diallel mating design (Musembi et al 2015;Naidoo et al 2016;Baafi et al 2017;Mbusa et al 2018), bi-parental crossing (Afuape et al 2019) and reciprocal recurrent selection (Grüneberg et al 2022). So far, VOBO genotypes can be used for further backcrossing to stabilise beta-carotene content in the background of Vobodouaho.…”

“…Afuape et al (2019) reported the possibility to combined elevated content of antagonist quality traits such as dry matter and betacarotene using biparental crossing. Grüneberg et al (2022) reported large genetic gains for tuber yield https://doi.org/10.17221/104/2022-CJGPB and other quality traits (iron and zinc micronutrients) in OFSP hybrids developed from reciprocal recurrent selection. The current research aimed at developing OFSP genotypes that meet the food culture of local communities in Benin and other West African countries.…”

Variability of high dry matter orange‐fleshed sweetpotato [Ipomoea batatas (L.) Lam.] in later breeding stages and allocation of breeding resources in the humid tropics of Peru

“…Population improvement aims at the selection of a "best" set of parents to generate new genetic variation around an improved population mean over recurrent cycles of parental selections, whereas variety extraction aims at the selection of the best or very few best clones with complete or nearly complete exploitation of the genetic variation in breeding populations. For an overview of a comprehensive breeding scheme for sweetpotato, comprising population improvement and variety development, see Grüneberg et al (2022). This study provides a valid data set for estimating VarComp and correlations among traits needed to compare selection scenarios in later breeding stages after the selection in first yield trials targeting population improvement and considers multistage selection for "OFSP dry and starchy" within the humid tropics of the Amazon basin.…”