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

Abstract

Sweetpotato (Ipomoea batatas [L.] Lam. [2n = 6x = 90]) is a highly heterozygous, clonally propagated crop for which population hybrid breeding is expected to result in yield jumps and large genetic gain increases. The main objective of this study was to select parents for a heterosis exploiting breeding scheme in Uganda using general combining ability and index selection aggregating yield and biotic stress traits. Two large and very diverse breeding populations established in Uganda (UGA A, 50 parents; UGA B, 80 parents) were recombined for this study into a hybrid population comprising 8097 genotypes from 1097 interpopulation families. Parents and offspring clones were evaluated in unreplicated trials across five environments during 2018/2019, together with two commercial checks (Ejumula and NASPOT 8). Using mixed model analysis, breeding values (BVs) were estimated across traits (i.e., storage root yield, commercial roots per plant, foliage yield, and resistance to sweetpotato virus disease [SPVD] and Alternaria blight). For storage root yield, the BVs ranged from 3.5 to 10 t ha−1 and from 2 to 12 t ha−1 for parents in UGA A and B, respectively. For SPVD resistance, scored one month before harvest, the BVs ranged from 3.3 to 4.3 and from 3.1 to 4.7 for parents in UGA A and B, respectively. Out of 130 parental candidates, 40 parents were selected (20 for each parental group). The plan is to use in the future GCA values combined by a modified Pesek‐Baker index using standardized desired genetic gains to select parents together with other information such as flesh color of parental material.

Potato and sweetpotato breeding at the International Potato Center: approaches, outcomes and the way forward

“…We have documented very high genetic gains of from 85 to 132% for storage root yield in four OFSP H1 (hybrid 1) populations relative to the foundation after a complete reciprocal recurrent selection (RRS) cycle (Grüneberg et al 2022 ). CIP presently practices a heterosis exploitation breeding scheme (HEBS), in which heterozygous parents from two mutually heterotic heterogeneous sweetpotato genepools are combined in population hybrid breeding under RRS (David et al 2018 ; Diaz et al 2021 ; Grüneberg et al 2022 ; Swanckaert et al 2023 ).…”

“…We have documented very high genetic gains of from 85 to 132% for storage root yield in four OFSP H1 (hybrid 1) populations relative to the foundation after a complete reciprocal recurrent selection (RRS) cycle (Grüneberg et al 2022). CIP presently practices a heterosis exploitation breeding scheme (HEBS), in which heterozygous parents from two mutually heterotic heterogeneous sweetpotato genepools are combined in population hybrid breeding under RRS (David et al 2018;Diaz et al 2021;Grüneberg et al 2022;Swanckaert et al 2023). CIP's breeding pipelines toward OFSP and WFSP with SPVD resistance in Uganda and OFSP and WFSP in Mozambique were originally improved by polycross breeding with recurrent selection (RS) using many parents (130 in Uganda and 80 in Mozambique), and long breeding cycles.…”