Wolfgang J. Gruneberg

Genotype × environment (G × E) interaction is a key factor influencing the selection of stable and high‐yielding sweet potato ( Ipomoea batatas L.) cultivars across diverse agroecological zones. The complexity of G × E interaction often leads to biased yield estimates in multienvironment trials, hindering phenotypic selection and impede breeding progress. This study aimed to evaluate the yield stability and adaptability of seven elite CIP‐developed sweet potato genotypes across three diverse locations in Bangladesh—university research field, farmers’ field, and the Brahmaputra riverbank char land—over two successive growing seasons in 2023 and 2024. To ensure experimental precision, a randomized complete block design (RCBD) with three replications was adopted. To assess phenotypic stability, the additive main effects and multiplicative interaction (AMMI), genotype + genotype × environment interaction (GGE) biplot models, and the multitrait stability index (MTSI) were employed. The combined analysis of variance revealed significant genotype × environment (G × E) interactions for most of the studied agronomic and nutritional traits. Pearson’s correlation analysis showed strong positive associations among key nutritional and yield‐contributing traits. The AMMI and GGE biplot models explained over 85.4% of the total variability, highlighting their effectiveness in analyzing G × E interactions. Genotypes G353 and G310 were consistently high‐performing and stable, while G15, G138, and G5 showed environment‐specific adaptation to E6 and E3, respectively. The riverbank char lands (E3 and E6) generally exhibited high mean yields and strong discriminatory power for genotype evaluation. Based on the MTSI method, G353 was identified as the most stable and productive genotype. The study revealed substantial genotype × environment interaction effects on the yield performance of sweet potato genotypes across diverse environments of Bangladesh and provided useful guidance for future breeding programs.

Root and tuber crop breeding is at the front and center of CIP’s science program, which seeks to develop and disseminate sustainable agri-food technologies, information and practices to serve objectives including poverty alleviation, income generation, food security and the sustainable use of natural resources. CIP was established in 1971 in Peru, which is part of potato’s center of origin and diversity, with an initial mandate on potato and expanding to include sweetpotato in 1986. Potato and sweetpotato are among the top 10 most consumed food staples globally and provide some of the most affordable sources of energy and vital nutrients. Sweetpotato plays a key role in securing food for many households in Africa and South Asia, while potato is important worldwide. Both crops grow in a range of conditions with relatively few inputs and simple agronomic techniques. Potato is adapted to the cooler environments, while sweetpotato grows well in hot climates, and hence, the two crops complement each other. Germplasm enhancement (pre-breeding), the development of new varieties and building capacity for breeding and variety testing in changing climates with emphasis on adaptation, resistance, nutritional quality and resource-use efficiency are CIP’s central activities with significant benefits to the poor. Investments in potato and sweetpotato breeding and allied disciplines at CIP have resulted in the release of many varieties some of which have had documented impact in the release countries. Partnership with diverse types of organizations has been key to the centers way of working toward improving livelihoods through crop production in the global South.

Orange‐fleshed sweetpotato (OFSP) [ Ipomoea batatas (L.) Lam] often lacks high dry matter (DM) in elite breeding material. The objectives were to examine the potential to combine yield with high root DM and high root β‐carotene (BC) content by variance‐covariance analysis and optimization of breeding scenarios for “OFSP dry and starchy,” which was exemplarily shown for the humid tropics of Peru. The trial series across seasons suggested a good chance to combine yield and quality (high DM and high BC). The unique data were used to estimate variance components and correlations among four yield traits and four quality traits. For the optimization of selections in our breeding program, we used the selection response by Cochran's approach and developed a small R script. Responses to selection were predicted for storage root yield and a modified Elston index aggregating eight traits. The differences between two‐ and three‐stage selection scenarios were small. For storage root yield, the recommended optimized two‐stage selection increased the response relative to the standard (one‐stage selection 100%) to 141.6% for 2268 plots and to 189.1% for 540 plots; the corresponding optimized three‐stage selection increased the response to 144.3% for 2268 plots and to 190.5% for 540 plots. A two‐stage selection is recommended with two to three locations at the first stage and 6–12 locations at the second stage, according to low‐ or high‐test capacity, respectively. Optimization of breeding schemes is much more important for smaller breeding programs than those with larger test capacity, and this allows testing even larger numbers of genotypes in a small breeding program.

Sweetpotato ( Ipomoea batatas [L.] Lam. [2 n = 6 x = 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.

Sweet potato virus disease (SPVD) is a global constraint to sweetpotato (Ipomoea batatas) production, especially under intensive cultivation in the humid tropics such as East Africa. The objectives of this study were to develop a precision SPVD phenotyping protocol, to find new SPVD-resistant genotypes, and to standardize the first stages of screening for SPVD resistance. The first part of the protocol was based on enzyme-linked immunosorbent assay results for sweet potato chlorotic stunt virus (SPCSV) and sweet potato virus C (SPVC) with adjustments to a negative control (uninfected clone Tanzania) and was performed on a prebreeding population (VZ08) comprising 455 clones and 27 check clones graft inoculated under screenhouse conditions. The second part included field studies with 52 selected clones for SPCSV resistance from VZ08 and 8 checks. In screenhouse conditions, the resistant and susceptible check clones performed as expected; 63 clones from VZ08 exhibited lower relative absorbance values for SPCSV and SPVC than inoculated check Tanzania. Field experiments confirmed SPVD resistance of several clones selected by relative absorbance values (nine resistant clones in two locations; that is, 17.3% of the screenhouse selection), supporting the reliability of our method for SPVD-resistance selection. Two clones were promising, exhibiting high storage root yields of 28.7 to 34.9 t ha⁻¹ and SPVD resistance, based on the proposed selection procedure. This modified serological analysis for SPVD-resistance phenotyping might lead to more efficient development of resistant varieties by reducing costs and time at early stages, and provide solid data for marker-assisted selection with a quantitative tool for classifying resistance. [Formula: see text] Copyright © 2023 The Author(s). This is an open access article distributed under the CC BY 4.0 International license .

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.

Sweetpotato is a crucial crop to guarantee food security in sub‐Saharan Africa, and drought events are considered one of the most critical factors affecting sweetpotato productivity in this region. In this study, airborne imagery based on reflectance (NDVI, CI_red‐edge) and canopy temperature minus air temperature (dT) indices was used to characterize sweetpotato genotypes under drought treatments in Mozambique. Two field experiments established in rainy/hot (Trial A) and dry/cool (Trial B) seasons were assessed. In Trial A, 24 genotypes were subjected to early‐ (ESD), mid‐ (MSD) and late‐season (LSD) drought stress treatments and compared against a control. In Trial B, 120 genotypes were subjected to LSD only. The percentage of reduction in vine weight (PR_VW) under drought was related primarily to temporal variation of NDVI and CI, regardless of drought treatment and seasons. dT in relation to control (dT_Amp) was associated with PR_VW in ESD‐Trial A and LSD‐Trial B, whereas under LSD‐Trial A, dT_Amp was related to total fresh storage root weight (TRW). During the rainy/hot season, higher TRW reduction was promoted under ESD; however, under LSD, it was possible to identify productive genotypes able to withstand drought stress, highlighting their relevance for drought‐tolerance selection purposes.

Orange fleshed sweet potatoes (OFSP) are desirable for high productivity and profitability and their distribution to improve the nutrition of river bank inhabitants of Gaibandha and Rangpur districts of Bangladesh. In this context, a field trial was conducted in two riverbank-based farmers’ fields such as Saghata, Gaibandha, and Pirganj, Rangpur, particularly in the Active Tista Floodplain Agro-ecological Zone of Bangladesh. Four OFSP varieties were evaluated, i.e., G1: BARI SP-8; G2: BARI SP-12; G3: BARI SP-14; G4: BARI SP-15, along with one local cultivar as a control (Red skin with white flesh). Significant variations among the sweet potato genotypes were noted for a number of tuberous roots plant⁻¹, length of root diameter of roots, tuberous root weight plant⁻¹, root yield (fresh), root yield (dry), beta-carotene yield, as well as energy output. Over the locations, BARI SP-12 produced about 73% higher root yield (32.00 t ha⁻¹) and it was like the BARI SP-8 (31.07 t ha⁻¹), which produced about 68% higher yield in comparison with local cultivar (18.51 t ha⁻¹). Across the location, BARI SP-8 performed better in root yield (31.89 t ha⁻¹) in Gaibandha, 69% superior to local cultivar, whereas BARI SP-12 performed better in Rangpur (33.66 t ha⁻¹), which was 86% greater than the local sweet potato cultivar. Considering the root dry yield production, BARI SP-8 produced the highest in the Gaibandha location after that Rangpur location. Further, BARI SP-14 had wider adaptability and stability over the year and location depended on the AMMI model. The beta carotene yield (Vitamin-A precursor) ranged 336–2957 kg ha⁻¹ among the OFSP varieties, whereas the highest (2957 kg ha⁻¹) carotene was recorded in BARI SP-14, similar to BARI SP-15 (2952 kg ha⁻¹) but was much lower in BARI SP-8 and BARI SP-12. Moreover, BARI SP-8 and BARI SP-12 were also economically profitable in terms of gross margin (3233 and 3364 US$ ha⁻¹, respectively), net return (3039 and 3170 US$ ha⁻¹, respectively) and BCR (3.21 and 3.31, respectively, vs. 1.91) due to higher returns with a similar production cost of the local cultivar. The results suggested that BARI SP-8 is economically profitable in the riverbank areas of Gaibandha, and BARI SP-12 is suitable for the riverbank areas of Rangpur.

Orange‐fleshed sweetpotato [Ipomoea batatas (L.) Lam.] (OFSP) breeding populations have gained importance for food security and health reasons. This study's main objectives were to determine genetic diversity in parental material of two OFSP populations developed in Peru (Jewel [PJ] and Zapallo [PZ]) relative to mega‐clones (MCs) using agronomic traits and simple sequence repeat (SSR) markers and to determine whether PJ and PZ are mutually heterotic by developing a PJ × PZ hybrid population (H₀). Field trials were performed with clones for PJ (n = 49), PZ (n = 31), MC (n = 21), and H₀ (n = 6,898) in Peru. Traits recorded were storage root yield (RYTHA), number of commercial roots per plant, foliage yield, biomass, harvest index, and dry matter (RDM), β‐carotene (RBC), protein, starch, sucrose, iron, zinc, and calcium content of storage roots. Sixty‐six pairs of SSR primers were used to determine molecular diversity. Statistics used were linear mixed models, principal component analysis, and standard procedures for molecular data. New genetic variation was found in PJ and PZ (e.g., RDM ≥29% with RBC ≥25 mg 100 g⁻¹ dry weight basis). For most traits, genetic variance in PJ and PZ was as large as in MC. The SSR marker data clearly separated PJ and PZ into two gene‐pools, together covering nearly the entire MC molecular diversity. Average RYTHA in H₀ was high (40.7 t ha⁻¹) with average heterosis increment of 21.8% and range −30.6 to 139.4%. The PJ and PZ lend themselves to study of the efficiency of reciprocal recurrent selection in sweetpotato population hybrid breeding.

The goal of yam bean improvement in Africa is to develop superior high yielding and high dry matter cultivars that are preferred for adoption. In this study, the estimates of variance components, heritability and response to selection were studied in F₃ yam bean families selected from interspecies crosses targeting improvement of storage root dry matter and associated traits. Breeding populations were generated using North Carolina II (NC II) mating design involving high dry matter P. tuberosus chuin cultivar, low dry matter P. ahipa and the high yielding P. erosus yam beans. The progenies were advanced through selfing from F₁ to F₂ population and then exposed to selection at 10% selection intensity to obtain 83 high dry matter lines. The selected lines were evaluated in an F₃ trial using a randomized complete block design (RCBD) with three replications at the National Crops Resources Research Institute (NaCRRI) Namulonge, in Central Uganda. The results revealed significant (P < 0.001) genetic variation for storage root dry matter (RDM), storage root fresh yield (RFY), storage root dry yield (RDY), vine yield (VNY), fresh biomass yield (FBY), harvest index (HI), starch (STA) and protein (PRO) content. High genotypic coefficient of variation (GCV) and phenotypic coefficient of variation (PCV) were obtained for VNY, RDY, FBY, RFY, RDM and STA. Narrow sense heritability was higher than 0.5 and response to selection was 15.5 to 33.1 for RDM, RFY, RDY, VNY, FBY and STA, indicating rapid genetic progress is achievable and early generation selection would be effective to improve these traits. Significant (P < 0.01) positive genetic correlations were observed between RDM, RDY, RFY, VNY, FBY and STA ranging from 0.422 to 0.963 implying that simultaneous improvement of these traits is possible in the current yam bean populations.