Evaluating Sweetpotato Varieties and Accessions in Hawai‘i

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Anna Halpin-McCormick University of Hawai‘i at Mānoa, Department of Tropical Plant and Soil Sciences (TPSS), 3190 Maile Way, Honolulu, HI 96822, USA

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Stacy Lucas University of Hawai‘i at Mānoa, Department of Tropical Plant and Soil Sciences (TPSS), 3190 Maile Way, Honolulu, HI 96822, USA

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James Keach University of Hawai‘i at Mānoa, Department of Tropical Plant and Soil Sciences (TPSS), 3190 Maile Way, Honolulu, HI 96822, USA

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Michael B. Kantar University of Hawai‘i at Mānoa, Department of Tropical Plant and Soil Sciences (TPSS), 3190 Maile Way, Honolulu, HI 96822, USA

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Sharon Motomura-Wages University of Hawai‘i at Mānoa, TPSS, Komohana Research and Extension Center, 875 Komohana St., Hilo, HI 96720, USA

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Susan C. Miyasaka University of Hawai‘i at Mānoa, TPSS, Komohana Research and Extension Center, 875 Komohana St., Hilo, HI 96720, USA

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Abstract

Thirty sweetpotato (Ipomoea batatas var. batatas) genotypes were evaluated for yield, resistances to weevil or nematode pests, and consumer acceptance across three field trials planted at Pepe‘ekeo, Hawai‘i Island between 2017 to 2020. At harvest, storage roots were graded according to market standards, followed by scoring for damage by sweetpotato weevil (Cylas formicarius elegantulus), rough sweetpotato weevil (Blosyrus asellus), or nematodes; namely root-knot nematode (Meloidogyne spp.) or reniform nematode (Rotylenchus reniformis) in each market class. There were significant differences in marketable yields among accessions when data were analyzed statistically across all three field trials, as well as individually. ‘Regal’ (PI 566650) and ‘Sumor’ (PI 566657) were among the top three highest-yielding genotypes for Trials 1 and 2 (when no insecticides were applied to control weevils), and among the top six highest-yielding genotypes for the joint analysis across three trials. Significant differences among genotypes for combined sweetpotato weevil damage (incidence of sweetpotato weevil alone or incidence of both weevils together) were found in the joint analysis across three trials. ‘Regal’ was among the lowest seven genotypes for combined sweetpotato weevil damage, supporting earlier reports of its moderate resistance to this pest. In addition, two genotypes produced by the World Vegetable Center (Shanhua, Taiwan) (WT-320 and WT-108), were among the lowest genotypes for combined sweetpotato weevil damage, in agreement with earlier reports of their substantial resistance to this pest. Providing access to diverse germplasm will help farmers react to increasing pest pressure, while still allowing for high marketable yields. In addition, breeding and selection for pest resistance could be an important addition to integrated pest management of sweetpotato in Hawai‘i.

Sweetpotato [Ipomoea batatas (L.) Lam var. batatas] is grown in more than 100 countries for its starchy, storage root (Huaccho and Hijmans 2000). It has a long history in Hawai‘i, in which it has been an important nutritious staple for hundreds of years (Kagawa-Viviani et al. 2018). In fact, its production has increased in the 21st century largely due to the increased availability of export markets (Follett 2006). In Hawai‘i, sweetpotato is among the top 20 agricultural commodities produced with a value of $2.86 million in 2021 (HDOA 2023). The main commercial variety grown in the state is Okinawan with purple flesh that contains anthocyanins (Miyasaka et al. 2019). Sweetpotatoes with anthocyanins have been reported to have antioxidant, anti-inflammatory, anticancer, antidiabetic, and immunostimulant activities (Elgabry et al. 2023; Teow et al. 2007; Wang et al. 2016).

Three major pests threaten the sustainability of sweetpotato production in Hawai‘i: 1) sweetpotato weevil [Cylas formicarius elegatulus (Summers) (Coleoptera: Curculionidae)]; 2) rough sweetpotato weevil [Blosyrus asellus (Olivier) (Coleoptera: Curculionidae)]; and 3) nematodes including root-knot nematode (Meloidogyne spp.) and reniform nematode [Rotylenchus reniformis (Linford and Oliveira)] (Pulakkatu-thodi et al. 2018; Valenzuela et al. 1994).

Sweetpotato weevils are major, worldwide pests of sweetpotato, reducing both yield and quality. In response to feeding by these insects, terpenoids are produced in storage roots, resulting in an unpleasant, bitter taste (Uritani et al. 1975). Sweetpotato weevils are difficult to control, because their immature larvae grow inside storage roots, protected from chemical pesticides (Nottingham and Kays 2002). In Hawai‘i, typical crop losses due to sweetpotato weevil ranged between 15% and 30%, and up to 97% if populations are not controlled (Valenzuela et al. 1994). The rough sweetpotato weevil was first found in Hawai‘i in 2008 (Heu et al. 2011). Its immature stages feed on surfaces of storage roots, producing shallow grooves, damaging their appearance, reducing marketability, and allowing introduction of secondary pathogens (Pulakkatu-thodi et al. 2018). This pest has not been reported in the continental United States, but it is found in Africa (Stathers et al. 2003a). Varietal differences in resistance to this new pest have been reported, with ‘Okinawan’ exhibiting susceptibility (Miyasaka et al. 2018).

Sweetpotato weevil damage can be controlled by the following integrated pest management (IPM) strategies: 1) sanitation, such as removal of vines after harvesting to eliminate populations of weevils remaining in plants; 2) crop rotation or fallow periods; 3) removal of alternate host plants in the morning glory family; and 4) mulching to conserve soil moisture and prevent soil cracking that allows weevils easy access to storage roots (Nottingham and Kays 2002; Tedesco et al. 2023; Valenzuela et al. 1994). An additional component of IPM is the use of insect-resistant sweetpotato varieties (Jackson and Bohac 2006; Tedesco et al. 2023).

Sweetpotato weevil-resistant varieties have been identified in multiple locations (Jackson and Bohac 2006; Jackson and Harrison 2013; Jackson et al. 2012; Stathers et al. 2003b). Resistance to sweetpotato weevil could result from 1) antibiosis due to inhibition of feeding and oviposition; 2) non-preference (antixenosis); 3) escape; or 4) a combination of these types (Barlow and Rolston 1981; Jackson and Bohac 2006; Nottingham and Kays 2002; Stathers et al. 2003b). Since sweetpotato weevils cannot mine readily through the soil, storage roots located deeper underground could escape infestation (Hahn and Leuschner 1982). However, soil cracking due to drought or enlargement of storage roots could result in exposure of roots to weevils.

Sweetpotato varieties Regal, Ruddy, and Sumor have been identified as resistant to several insect pests, including sweetpotato weevil, and are often used as resistant controls in field trials (Bohac et al. 2002; Jackson and Harrison 2013; Jackson et al. 2012; Thompson et al. 1999). Between 1997 and 2010, Jackson et al. (2012) evaluated 55 sweetpotato varieties and accessions [Plant Introduction (PI) from the US Department of Agriculture, Agricultural Research Service (USDA ARS), Plant Genetic Resources Conservation Unit, Griffin, GA] in 17 field trials at Charleston, SC, 12 field trials at Blackville, SC, and two field trials at Homestead, FL. Between 1993 and 1995, Thompson et al. (1999) evaluated 100 sweetpotato accessions in Beaumont, MS. Both researchers found significant differences among genotypes in percentage of sweetpotato weevil infestations, and concluded that accessions could be a valuable source of resistance in a breeding program.

Disagreement exists in the literature as to whether it is possible to improve resistance of sweetpotato to Cylas spp. through breeding and selection. There are difficulties in breeding of sweetpotato, because 1) it is a hexaploid plant species; 2) it has sterility problems, perhaps due to its high polyploidy; 3) its flowers are self-incompatible; and 4) there is no one dominant gene involved in resistance to sweetpotato weevil (Lebot 2010; Nottingham and Kays 2002). According to Lebot (2010) and Stathers et al. (2003a), widely accepted, sweetpotato weevil-resistant genotypes have not been achieved to date. For example, Jackson et al. (2010) developed the sweetpotato weevil-resistant ‘Charleston Scarlet’ from an open-pollinated polycross breeding block with ‘Regal’ as the maternal parent; however, it is not as high-yielding as sweetpotato weevil-susceptible genotypes, and it is not widely grown. Lebot (2010) indicated that breeding goals are now focusing on deeper formation of storage roots and early maturing genotypes that are less exposed to weevil infestation (i.e., escape mechanisms). Interestingly, it is likely that ‘Okinawan’ has some resistance to sweetpotato weevil, due to its characteristic, deep location of storage roots. In contrast, several researchers (Jackson and Bohac 2006; Jackson and Harrison 2013; Nottingham and Kays 2002) stated that with long-term support, conventional breeding techniques using germplasm with additive sources of resistance, high weevil pressure, and precise evaluation methods could improve resistance to sweetpotato weevil.

Nematodes are another major pest of sweetpotato that reduces both yield and quality, including both root-knot nematode and reniform nematode (Clark et al. 2013; Valenzuela et al. 1994). Symptoms of nematode infestation include cracking and growth deformities of storage roots. IPM of nematodes includes planting nematode-resistant sweetpotato varieties. In field studies in California, ‘Jewel’ has been identified as resistant to nematode species (Roberts and Scheuerman 1984). In greenhouse studies examining root-knot nematode, ‘Sumor’, ‘Tinian’, and ‘Regal’ were found to be highly resistant, highly resistant, and resistant, respectively (Thies 2005).

Although germplasm that shows good resistance or tolerance to various pests is available, Hawai‘i has a different set of consumer preferences than other markets. Consumers prefer purple-fleshed varieties, because of the common commercial variety Okinawan. Therefore, it is important to trial these different sweetpotato genotypes in Hawai’i not only to explore agronomic characteristics but to ensure that they will meet its unique market demands. To this end, our objectives were to evaluate yield, resistance to various pests (sweetpotato weevil, rough sweetpotato weevil, and nematodes), and consumer acceptance of 30 varieties or accessions. These genotypes had been selected based on previous reports of insect resistance, nematode resistance, and/or purple flesh color.

Materials and methods

Site description

All trials were conducted at Pepe‘ekeo Hawai‘i (lat. 19°50′05″ N, long. 155°06′55″ W, 232 m elevation) between 2017 and 2020. The soil series is the Hilo series (medial over hydrous, ferrihydritic, isohyperthermic Acrudoxic Hydrudands) (Walkinshaw et al. 2022).

Selection of varieties or accessions

‘Okinawan’ was selected as the control, because it is the major commercial variety of sweetpotato in Hawai‘i. Twenty-nine varieties/accessions of sweetpotato were obtained from the USDA ARS Plant Genetic Resources Conservation Unit in Griffin, GA (Table 1). For simplicity, varieties/accessions will be referred to as genotypes. ‘Regal’ (PI 566650), ‘Sumor’ (PI 566657), ‘Charleston Scarlet’ (PI 653843), and ‘Ruddy’ (PI 657999) were selected, because they showed consistent resistance to sweetpotato weevil in field trials in South Carolina and Mississippi (Bohac et al. 2002; Jackson et al. 2010, 2012; Thompson et al. 1999). Other genotypes that were identified as having some resistance to sweetpotato weevil were ‘NZ196’ (PI 318846), ‘Camote Morado’ (PI 399163), ‘Chancleta de Chilca’ (PI 538286), ‘Tapato’ (PI 538354), ‘Markham’ (PI 564149), ‘Excel’ (PI 566625), ‘Jewel’ (PI 566638), ‘Camote Blanco’ (PI 585079 and PI 585080), ‘Cuba 2’ (PI 599368), ‘Minamiyutaka’ (PI 599386), ‘Jonathan’ (PI 599387), ‘Liaoshu 40’ (PI 599388), ‘WT-320’ (PI 612681), ‘WT-57’ (PI 633985), ‘WT-108’ (PI 633987), ‘Liberty’ (PI 653844), and ‘W-390’ (PI 666141) (Jackson and Bohac, 2006; Jackson et al. 2012; Story et al. 1999; Thompson et al. 1999). In addition, ‘Tinian’, ‘Jewel’, ‘Regal’, and ‘Sumor’ were identified as resistant to root-knot nematode (Thies 2005). Finally, ‘393’ (PI 585092), ‘TINTO’ (PI 585100), and ‘IITA-TIS-9232’ (PI 595885) were selected because they had purple flesh, a desired trait for its healthful benefit of anthocyanin (Teow et al. 2007; Tedesco et al. 2023) and its similarity to the flesh color of the commercial variety Okinawan.

Table 1.

Origin of sweetpotatoes grown in three trials at Pepe’ekeo, Hawai’i.

Table 1.
Table 1.

Management practices

Field preparation

Glyphosate (Honcho Plus, Monsanto Co., St. Louis, MO) was applied in a 1% solution to control weeds. Then, the field was disc plowed. Phosphorus (P) fertilizer (0N–20P–0K) was banded at 200 lb/acre of P. Hills were made using a rotovator with centers spaced 5 ft apart. Pre-emergent Chateau® Herbicide SW (Valent USA, Walnut Creek, CA) was applied at 2.5 dry oz/acre between 2 and 5 d before planting.

To control movement of both weevils, cuttings of 12-inch lengths were taken from current field plantings or from potted plants, dipped into carbaryl (Sevin XLR Plus, Rhone-Poulenc Ag Co., Research Triangle Park, NC) at 2.5 oz/gal of water, dried overnight, and planted at a spacing of 1 ft within rows and 5 ft between rows. A plot of each variety that consisted of 30 cuttings in a row were separated from other plots by 5-ft spacing.

Each trial was planted in a randomized complete block design. Trial 1 consisted of four blocks; Trials 2 and 3 consisted of three blocks. Trial 1 was planted on 20 Dec 2017; Trial 2 was planted on 8 Oct 2018; and Trial 3 was planted on 2 Apr 2020. The tropical climate of Hawai‘i allows for year-round planting of sweetpotato.

After planting, fertilizer (23N–0P–20K) was broadcast within rows at 0.5, 1.5, and 2.5 months after planting to result in a total of 100 lb/acre of nitrogen (N). Spinosad (Success™ Insecticide, Dow AgroSciences, Calgary, Canada) was applied at 1.4 oz/acre a.i. at 2 and 3 months after planting to control sweetpotato vine borer [Omphisa anastomosalis (Lepidoptera: Pyralidae)]. Periodically, vines were manually thrown back onto the hill to prevent pegging of plants between rows or plots.

In Trials 1 and 2, insecticides were not applied to evaluate the resistance/tolerance of sweetpotato genotypes against the sweetpotato weevil and rough sweetpotato weevil. In Trial 3, weevil pressures were so great that the decision was made to apply insecticides to help to control both weevils (Pulakkatu-thodi et al. 2018). Briefly, before planting Trial 3, clothianidin (Belay® 16 WSG, Valent USA, Walnut Creek, CA) was applied at 2.8 fl oz a.i./acre to control rough sweetpotato weevil. Imidacloprid (Provado® 1.6 flowable insecticide, Bayer Crop Science, Research Triangle Park, NC) was applied at 0.6 fl oz/acre a.i. at 2 and 3 months after planting to control sweetpotato weevil. Carbaryl (Sevin® XLR Plus, Bayer CropScience, Research Triangle Park, NC) was applied at 28 fl oz a.i./acre at 2.5, 3.5, and 4.5 months after planting to control both weevils.

Harvest

Vines were removed manually before mechanical harvest by a sweetpotato harvester (BL-1050; Niplo, Ichinomiya-shi, Japan). Trial 1 was harvested on 15 Jul 2018, 22 Jul 2018, and 30 Jul 2018, ∼7 months after planting. Blocks C, B, and A in Trial 2 were harvested on 21 May 2019, 5 Jun 2019, and 18 Jun 2019, ∼7, 7.5, and 8 months after planting. Blocks A, B, and C in Trial 3 were harvested on 15 Sep 2020, 22 Sep 2020, and 29 Sep 2020, between ∼5.5 to 6 months after planting.

Storage roots were separated into four categories: AA, A, B, and off-grade according to standards of the Hawai‘i Department of Agriculture (1986). Then, storage roots were separated into subcategories: 1) uninjured (i.e., no damage); 2) damage due to sweetpotato weevil; 3) damage due to rough sweetpotato weevil; 4) damage due to nematodes; and 5) other damage (e.g., disease or mechanical damage). If a storage root had damage due to both weevils, it was categorized as “combined sweetpotato weevil” that included damage due to sweetpotato weevil alone and that in combination with both weevils. The reasoning behind this combination category was that damage due to sweetpotato weevil was more serious and resulted in inedible roots. The number of storage roots and their fresh weights were recorded for each sub-category. Low incidence or damage due to weevils or nematodes was considered to indicate resistance to these pests.

Marketable fresh weight yields were calculated by adding together the grading categories AA, A, and B. Incidence of various pests was calculated by dividing fresh weights of damaged storage roots in a grading sub-category by total fresh marketable weight in that grading category.

Consumer acceptance

Consumer acceptance tests were conducted to determine whether genotypes would be satisfactory to communities in Hawai‘i. Storage roots were air-dried for ∼2 weeks before conducting taste tests, and were selected from one harvest date. Storage roots of each genotype were steamed until soft, cut into cubes, and blind taste tests conducted. For Trial 1, the test was conducted on 16 Aug 2018 with 14 consumers. For Trial 2, the test was conducted on 11 Jul 2019 with 18 consumers. For Trial 3, the test was conducted on 1 Oct 2020 with 13 consumers.

Texture was rated from 1 to 5 where 1 = very dry, 2 = slightly dry, 3 = mealy, 4 = moist, and 5 = very moist. Appearance was rated from 1 to 5 where 1 = unappetizing, 2 = slightly unappetizing, 3 = acceptable, 4 = appetizing, and 5 = very appetizing. Sweetness was rated from 1 to 5 with 1 = not sweet at all, 2 = slightly sweet, 3 = medium sweet, 4 = sweet, and 5 = very sweet. Overall acceptance was rated from 1 to 5, with 1 = not good, 2 = could use improvement, 3 = okay, 4 = good, and 5 = excellent.

Analysis

Statistical analyses were conducted to assess the impact of genotype on marketable fresh weight, damage due to weevils, and damage due to nematodes. An analysis of variance was performed and post hoc Tukey’s honestly significant difference test was conducted to identify specific pairwise differences, with letters indicating significant differences. To explore differences in genotypes compared with common checks, we also used a mixed model approach where environment and block were considered random effects and genotype as fixed effects, using the lme4 (Bates et al. 2014), lmerTest (Kuznetsova et al. 2017), and multcomp (Hothorn et al. 2008) r-packages. To compare the multiyear trials, best-linear unbiased predictions were calculated using the r-package metan (Olivoto and Lúcio 2020). This analysis was performed for each individual trial and across three trials to better understand whether ranks of genotypes differed among these analyses. In consumer acceptance tests, means of ratings were calculated for texture, sweetness, appearance, and overall. No further statistical analyses were done and genotypes were ranked simply according to the overall rating.

Results

Joint analysis across trials

For the important trait of marketable fresh weight yield (kg/ha), there were limited significant differences across genotypes tested. The highest-yielding genotype was ‘Margarita’ (PI 564161), followed by ‘Tapato’ (PI 538354), ‘Excel’ (PI 566625), ‘Sumor’ (PI 566657), ‘Markham’ (PI 564149), and ‘Regal’ (PI 566650) (Fig. 1A). The commercial control ‘Okinawan’ (labeled PI 1010) performed well and ranked seventh overall in yield. The six top-yielding genotypes did not differ significantly from ‘Okinawan’ (Fig. 1A). We also explored the potential for variation in planting date across the trials with the four accessions used in every trial. A planting date and planting date × accession interaction was identified. This was largely driven by a single cultivar (PI 599387) in Trial 18, indicating that depending on the genotype used, planting date is important even in an environment that is fairly homogeneous throughout the calendar year.

Fig. 1.
Fig. 1.

(A) Model-adjusted means across all three trials (Trials 1, 2, and 3) for fresh weight marketable yield (kg/ha) showing the differences among genotypes (n = 30). The ‘Okinawan’ commercial control is named PI 1010 and is colored in red. Filled circles indicate adjusted means and error bars indicate the 95% confidence intervals. (B) Model-adjusted means across all trials showing the differences among genotypes (n = 29) for combined sweetpotato weevil damage (i.e., presence of sweetpotato weevil alone or together with rough sweetpotato weevil). The ‘Okinawan’ commercial control is numbered as ‘PI 1010’. (C) Model-adjusted means across all trials showing the differences among genotypes (n = 23) for nematode damage. For each trait there is considerable variation and accessions that differ from the commercial control. Letters indicate significant difference between samples using a Tukey honestly significant difference mean separation.

Citation: HortTechnology 34, 4; 10.21273/HORTTECH05421-24

For the trait of resistance to combined sweetpotato weevil damage, there were limited significant differences across genotypes tested. ‘WT-320’ (PI 612681) had a significantly lower incidence of combined sweetpotato weevil damage than ‘W-390’ (PI 666141) (Fig. 1B). There were nine genotypes with less damage due to combined sweetpotato weevil damage than ‘Okinawan’. Among the nine genotypes were ‘WT-108’ (PI 633987), ‘ Liberty’ (PI 653844), ‘WT-320’ (PI 612681), ‘Unduandopa’ (PI 564155), ‘Chancleta de Chilca’ (PI 538286), ‘IITA-TIS-9232’ (PI 595885), ‘Regal’ (PI 566650), ‘Camote Blanco - 80’ (PI 585080), and ‘ Camote Morado’ (PI 399163). However, differences among these nine genotypes and the commercial check were not significant.

There were no significant differences in damage due to rough sweetpotato weevil (mean = 0.236, SEM = 0.015). For incidence of nematodes, limited significant differences were found across genotypes tested. The accession ‘Liaoshu 40’ (PI 599388) exhibited the worst damage due to nematodes and it was significantly greater than ‘Okinawan’ and ‘Sumor’ (PI 566657) (Fig. 1C).

Trial 1 (year 2017 to 2018)

In addition to the above joint analysis, each trial also was explored individually to understand the different dynamics of growing seasons, as well as possible differences due to insecticide application. In Trial 1 there were significant differences in marketable fresh weight yields among 11 genotypes, with ‘Sumor’ (PI 566657) having the highest mean yield (Fig. 2), although it did not differ significantly from ‘Regal’ (PI 566650) that ranked second, or the commercial control ‘Okinawan’ (labeled PI 1010) that ranked third. ‘Liaoshu 40’ (PI 599388) had the lowest marketable yield and it differed significantly from these top three ranking genotypes.

Fig. 2.
Fig. 2.

(A) Marketable fresh weight yields (kg/ha) of 11 sweetpotato genotypes in Trial 1. ‘Okinawan’ is labeled as ‘PI 1010’. Bold line indicates mean and outer box lines indicates the interquartile range (i.e., range between 25th to 75th percentile). Letters indicate significant difference between samples using a Tukey honestly significant difference mean separation. There is considerable variation and accessions that differ from the commercial control.

Citation: HortTechnology 34, 4; 10.21273/HORTTECH05421-24

There were no differences for damage caused by combined sweetpotato weevil (mean = 0.238, SEM = 0.0226) or rough sweetpotato weevil (mean = 0.313, SEM = 0.0308). In addition, nematode damage remained low across genotypes for the trial, and there were no significant differences in damage among genotypes (mean = 0.079, SEM = 0.014).

In consumer acceptance tests conducted across 11 genotypes, ‘Regal’ (PI 566650) ranked highest followed by the commercial variety ‘Okinawan’ that ranked second (Table 2). Genotype ‘Sumor’ (PI 566657) ranked sixth and ‘Liaoshu 40’ (PI 599388) ranked last (Table 2).

Table 2.

Overall ranking of genotypes following consumer taste tests for Trial 1. Each taster scored the storage root for four traits: Texture (1 = very dry; 2 = slightly dry; 3 = mealy; 4 = moist; 5 = very moist), Appearance (1 = unappetizing; 2 = slightly unappealing; 3 = acceptable; 4 = appetizing; 5 = very appetizing), Sweetness (1 = not sweet at all; 2 = slightly sweet; 3 = medium sweet; 4 = sweet; 5 = very sweet), and Overall (1 = not good; 2 = could use improvement; 3 = okay; 4 = good; 5 = excellent). The mean of all four traits was then used to develop the ranking of accessions.

Table 2.

Trial 2 (year 2018 to 2019)

The 15 genotypes showed significant differences in marketable fresh weight yields (Fig. 3). ‘Regal’ (PI 566650) had the greatest yield, followed by ‘Cuba 2’ (PI 599368), ‘Sumor’ (PI 566657), and ‘Camote Blanco - 79’ (PI 585079); however, none of these genotypes differed significantly from the commercial control ‘Okinawan’ (PI 1010) (Fig. 3). Genotype ‘NZ196’ (PI 318846) had the lowest marketable yield, followed by ‘Jonathan’ (PI 599387) and ‘Chancleta de Chilca’ (PI 538286); these three genotypes were significantly lower than the top-yielding four genotypes and the commercial control.

Fig. 3.
Fig. 3.

Marketable fresh weight yields (kg/ha) of 15 sweetpotato genotypes in Trial 2. ‘Okinawan’ is labeled as ‘PI 1010’. Bold line indicates mean and outer box lines indicates the interquartile range (i.e., range between 25th to 75th percentile). Letters indicate significant difference between samples using a Tukey honestly significant difference mean separation. There is considerable variation and accessions that differ from the commercial control.

Citation: HortTechnology 34, 4; 10.21273/HORTTECH05421-24

There were no differences for damage caused by combined sweetpotato weevil (mean = 0.729, SEM = 0.025) or rough sweetpotato weevil (mean = 0.259, SEM = 0.0248). Incidence of damage from nematodes was low and not significantly different among genotypes (mean = 0.003, SEM = 0.001). Consumer acceptance tests of 18 genotypes found that ‘Jonathan’ ranked the highest, followed by ‘Regal’ and ‘Okinawan’ (Table 3). ‘Sumor’ ranked fourth. ‘WT-108’ of the WT series ranked the lowest, followed by ‘WT-57’, and ‘WT-320’ ranked 10th out of 18 genotypes.

Table 3.

Overall ranking of genotypes following consumer taste tests for Trial 2. Each taster scored the storage root for four traits: Texture (1 = very dry; 2 = slightly dry; 3 = mealy; 4 = moist; 5 = very moist), Appearance (1 = unappetizing; 2 = slightly unappealing; 3 = acceptable; 4 = appetizing; 5 = very appetizing), Sweetness (1 = not sweet at all; 2 = slightly sweet; 3 = medium sweet; 4 = sweet; 5 = very sweet), and Overall (1 = not good; 2 = could use improvement; 3 = okay; 4 = good; 5 = excellent). The mean of all four traits was then used to develop the ranking of accessions.

Table 3.

Trial 3 (year 2020)

Twenty-three genotypes differed significantly in marketable fresh weight yield. ‘Margarita’ (PI 564161) had the greatest yield, followed by ‘Markham’ (PI 564149), ‘Minamiyutaka’ (PI 599386), and ‘Tapato’ (PI 538354) (Fig. 4). ‘Margarita’ had significantly higher marketable yield than commercial check ‘Okinawan’. There were no significant differences for damage caused by combined sweetpotato weevil (mean = 0.336, SEM = 0.0453) or rough sweetpotato weevil (mean = 0.169, SEM = 0.207). Also, there were no statistically significant differences among genotypes for nematode damage (mean = 0.034, SEM = 0.007). Consumer acceptance tests of 14 genotypes showed that ‘Regal’ (PI 566650) (Fig. 5A) ranked first, followed by commercial control ‘Okinawan’ (Table 4). ‘Sumor’ (Fig. 5B) ranked third. ‘WT-108’ of the WT series ranked the lowest.

Fig. 4.
Fig. 4.

Marketable fresh weight yields (kg/ha) of 23 sweetpotato genotypes in Trial 3. ‘Okinawan’ is labeled as ‘PI 1010’. Bold line indicates mean and outer box lines indicate the interquartile range (i.e., range between 25th to 75th percentile). Letters indicate significant difference between samples using a Tukey honestly significant difference mean separation. There is considerable variation and accessions that differ from the commercial control.

Citation: HortTechnology 34, 4; 10.21273/HORTTECH05421-24

Fig. 5.
Fig. 5.

Images of Sweetpotato accessions that showed good agronomic and taste characteristics across trials. (A) PI 566650 ‘Regal’. (B) PI 566657 ‘Sumor’. These accessions, although not the traditional purple that is favored in Hawaii, show excellent characteristics and are worth further evaluation.

Citation: HortTechnology 34, 4; 10.21273/HORTTECH05421-24

Table 4.

Overall ranking of genotypes following consumer taste tests for Trial 3. Each taster scored the storage root for four traits: Texture (1 = very dry; 2 = slightly dry; 3 = mealy; 4 = moist; 5 = very moist), Appearance (1 = unappetizing; 2 = slightly unappealing; 3 = acceptable; 4 = appetizing; 5 = very appetizing), Sweetness (1 = not sweet at all; 2 = slightly sweet; 3 = medium sweet; 4 = sweet; 5 = very sweet), and Overall (1 = not good; 2 = could use improvement; 3 = okay; 4 = good; 5 = excellent). The mean of all four traits was then used to develop the ranking of accessions.

Table 4.

Discussion

In Trials 1 and 2, ‘Regal’ (PI 566650) and ‘Sumor’ (PI 566657) were among the top one to three genotypes with high marketable fresh weight yields. These two trials were conducted without insecticides applied to control sweetpotato weevil or rough sweetpotato weevil. In the joint analysis across three trials, ‘Regal’ and ‘Sumor’ were among the top six genotypes with high marketable fresh weight yields; however, their yields did not differ significantly from the commercial control ‘Okinawan’. In the joint analysis, ‘Margarita’ (564161) had the highest marketable yield; however, it had the fifth highest incidence of combined sweetpotato weevil. Jackson et al. (2012) found similar results with ‘Margarita’ having the second heaviest average weight in 12-plant plots grown in Charleston, SC, and the highest percentage of roots injured by sweetpotato weevil.

Damage due to combined sweetpotato weevil or to rough sweetpotato weevil did not differ significantly in analyses of individual trials. However, the joint analysis showed limited significant differences among genotypes in damage due to combined sweetpotato weevil. There were nine genotypes with lower incidence of combined sweetpotato weevil compared with the commercial control ‘Okinawan’; however, none of these genotypes differed significantly from ‘Okinawan’. Previous work has shown interactions between weevil × planting date × genotype (Hue and Low 2015), and although this is an important additional consideration, our study design did not allow us to explore this.

Interestingly, ‘Regal’ (PI 566650) was among the six genotypes with higher marketable yield than ‘Okinawan’ and among the nine genotypes with lower combined sweetpotato weevil damage than ‘Okinawan’. ‘Regal’ is well known as having moderate resistance to sweetpotato weevil, and is often used as an insect-resistant control (Jackson and Bohac 2006; Jackson and Harrison 2013; Jackson et al. 2012; Thompson et al. 1999). ‘WT-108’ (PI 633987) and ‘WT-320’ (PI 612681) were among the three genotypes with the lowest combined sweetpotato weevil damage. Jackson et al. (2012) reported that the WT series, produced by the World Vegetable Center (Shanhua, Taiwan), was from a cross between I. batatas and 4X Ipomoea trifida, with many lines having substantial resistance to sweetpotato weevil. Our results support these earlier reports of resistance to sweetpotato weevil of ‘Regal’ and several lines of the WT series under environmental conditions in Hawai‘i. It is critical to examine effects of environment on insect resistances, because Jansson et al. (1987) found that ‘Regal’ was not resistant to sweetpotato weevil in southern Florida. These WT series could potentially contribute positively to the biodiversity of sweetpotatoes grown in Hawai‘i by adding sweetpotato weevil resistance genes to the gene pool of sweetpotatoes grown in Hawai‘i.

Consumer acceptance was high for ‘Regal’, but lower for ‘Sumor’. ‘Regal’ and ‘Sumor’ are among acceptable accessions that have the potential to be grown in Hawai‘i, with high yields, satisfactory consumer acceptance, and moderate resistance to insect and nematode pests. ‘WT-320’ would be another acceptable choice of variety to grow in Hawai'i because it has resistance to sweetpotato weevil damage and above-average yields, with the only downside being moderate consumer acceptance.

‘Okinawan’ is the major commercial sweetpotato genotype grown in Hawai‘i with its characteristic white skin and purple flesh. It may be possible to improve its resistance to both sweetpotato weevil and rough sweetpotato weevil through breeding with weevil-resistant genotypes, provided that they are genetically compatible. Based on field studies in South Carolina and Mississippi, Jackson et al. (2012) and Thompson et al. (1999) found additional sources of resistance to sweetpotato weevil among accessions from USDA ARS Plant Genetic Resources Conservation Unit, Griffin, GA. Our study has confirmed resistance of several of these genotypes to sweetpotato weevil under environmental conditions in Hawai‘i.

References cited

  • Bates D, Mächler M, Bolker B, Walker S. 2014. Fitting linear mixed-effects models using lme4. arXiv preprint arXiv:1406.5823.

  • Barlow T, Rolston LH. 1981. Types of host plant resistance to sweetpotato weevil found in sweetpotato roots. J Kansas Entomol Soc. 54: 649–657. JSTOR, http://www.jstor.org/stable/25084201. [accessed 31 Dec 2023].

  • Bohac JR, Jackson DM, Mueller JD, Dukes PD Sr . 2002. ‘Ruddy’: A multiple-pest-resistant sweetpotato. HortScience. 37:993994. https://doi.org/10.21273/HORTSCI.37.6.993.

    • Search Google Scholar
    • Export Citation
  • Clark CA, Ferrin DM, Smith TP, Holmes GJ. 2013. Compendium of sweetpotato diseases, pests, and disorders, 2nd ed. The American Phytopathological Society, St. Paul, MI, USA. https://doi.org/10.1094/9780890544952.

  • Elgabry RM, Sedeek MS, Meselhy KM, Fawzy GA. 2023. A review on the potential health benefits of sweet potato: Insights into its preclinical and clinical studies. Int J Food Sci Technol. 58:28662872. https://doi.org/10.1111/ijfs.16447.

    • Search Google Scholar
    • Export Citation
  • Follett PA. 2006. Irradiation as a methyl bromide alternative for postharvest control of Omphisa anastomosalis (Lepidoptera: Pyralidae) and Euscepes postfasciatus and Cylas formicarius elegantulus (Coleoptera: Curculionidae) in sweetpotatoes. J Econ Entomol. 99:3237. https://doi.org/10.1093/jee/99.1.32.

    • Search Google Scholar
    • Export Citation
  • Hahn SK, Leuschner K. 1982. Breeding Sweetpotato for weevil resistance, p 331336. In: Villareal RL, Griggs TD (eds). Sweetpotato. Proc. 1st Int Symp. Shanhua, Tainan, 23–27 Mar, Taiwan. AVRDC (World Vegetable Center) publication, Shanhua, Tainan.

  • Hawai‘i Department of Agriculture (HDOA). 1986. Standards for Hawaii-grown sweet potatoes. Hawai‘i Dept Agric, Honolulu, HI, USA. https://hdoa.hawaii.gov/qad/files/2012/12/AR-41-57.pdf. [accessed 30 Dec 2023].

  • Hawai‘i Department of Agriculture (HDOA). 2023. Top 20 agricultural commodities produced in the state of Hawaii, 2021. https://hdoa.hawaii.gov/wp-content/uploads/2023/01/Top-20-Commodities-2021_SOH_01.12.23R.pdf. [accessed 26 Oct 2023].

  • Heu A, Tsuda D, Fukuda S, Young C, Lee M. 2011. New pest advisory. http://hdoa.hawaii.gov/pi/files/2013/01/NPA-Sweet-Potato-Weevil.pdf. [accessed 30 Dec 2023].

  • Hothorn T, Bretz F, Westfall P. 2008. Simultaneous inference in general parametric models. Biometrical J. 50:346363.

  • Huaccho L, Hijmans RJ. 2000. A geo-referenced database of global sweetpotato distribution. Prod Syst and Nat Resour Manage Dept Working Pap No. 4, Intl Potato Center, Lima, Peru. https://pdf.usaid.gov/pdf_docs/pnacl703.pdf. [accessed 30 Dec 2023].

  • Hue SM, Low MY. 2015. An insight into sweet potato weevils management: A review. Psyche. 2015:849560. https://doi.org/10.1155/2015/849560.

  • Jackson DM, Bohac JR. 2006. Improved dry-fleshed sweetpotato genotypes resistant to insect pests. J Econ Entomol. 99:18771883. https://doi.org/10.1093/jee/99.5.1877.

    • Search Google Scholar
    • Export Citation
  • Jackson DM, Bohac JR, Thies JA, Harrison HF. 2010. ‘Charleston Scarlet’ sweetpotato. HortScience. 45:306309. https://doi.org/10.21273/HORTSCI.45.2.306.

    • Search Google Scholar
    • Export Citation
  • Jackson DM, Harrison HF Jr . 2013. Insect resistance in traditional and heirloom sweetpotato varieties. J Econ Entomol. 106:14561462. https://doi.org/10.1603/EC12396.

    • Search Google Scholar
    • Export Citation
  • Jackson DM, Harrison HF Jr , Ryan-Bohac JR. 2012. Insect resistance in sweetpotato plant introduction accessions. J Econ Entomol. 105:651658. https://doi.org/10.1603/EC11307.

    • Search Google Scholar
    • Export Citation
  • Jansson RK, Bryan HH, Sorensen KA. 1987. Within-vine distribution and damage of sweetpotato weevil, Cylas formicarius elegantulus (Coleoptera: Curculionidae) on four cultivars of sweet potato in southern Florida. Fla Entomol. 70:523526. https://doi.org/10.2307/3494797.

    • Search Google Scholar
    • Export Citation
  • Kagawa-Viviani A, Levin P, Johnston E, Ooka J, Baker J, Kantar M, Lincoln NK. 2018. I Ke Ēwe ‘Āina o Ke Kupuna: Hawaiian ancestral crops in perspective. Sustainability. 10:4607. https://doi.org/10.3390/su10124607.

    • Search Google Scholar
    • Export Citation
  • Kuznetsova A, Brockhoff PB, Christensen RHB. 2017. lmerTest Package: Tests in linear mixed effects models. J Stat Softw. 82:126. https://doi.org/10.18637/jss.v082.i13.

    • Search Google Scholar
    • Export Citation
  • Lebot V. 2010. Sweet potato, p 97–125. In: Bradshaw JE (ed). Root and Tuber Crops, Handbook of Plant Breeding 7. Springer, New York, NY, USA. https://doi.org/10.1007/978-0-387-92765-7_3.

  • Miyasaka SC, Wall M, LaBonte D, Arakaki A. 2019. Sweetpotato cultivar trials on Hawai‘i Island. HortTechnology. 29:967975. https://doi.org/10.21273/HORTTECH04387-19.

    • Search Google Scholar
    • Export Citation
  • Miyasaka SC, Motomura-Wages S, Clark CA, LaBonte DR, Villordon AQ. 2018 Field Performance of tissue-cultured, virus-tested ‘Okinawan’ sweetpotato and comparison with some promising cultivars in Hawai’i. HortTechnology. 28(5):676–683. https://doi.org/10.21273/HORTTECH04009-18.

  • Nottingham SF, Kays SJ. 2002. Sweetpotato weevil control. Acta Hortic. 583:155161. https://doi.org/10.17660/ActaHortic.2002.583.17.

  • Olivoto T, Lúcio ADC. 2020. metan: An R package for multi‐environment trial analysis. Methods in Ecology and Evolution. 11(6):783789. https://doi.org/10.1111/2041-210X.13384.

    • Search Google Scholar
    • Export Citation
  • Pulakkatu-thodi I, Motomura S, Miyasaka S. 2018. Evaluation of insecticides for the management of rough sweetpotato weevil, Blosyrus asellus (Coleoptera: Curculionidae) in Hawai’i Island. Crop Prot. 114:223227. https://doi.org/10.1016/j.cropro.2018.08.035.

    • Search Google Scholar
    • Export Citation
  • Roberts PA, Scheuerman RW. 1984. Field evaluation of sweet potato clones for reaction to root-knot and stubby root nematodes in California. HortScience. 19:270273. https://doi.org/10.21273/HORTSCI.19.2.270.

    • Search Google Scholar
    • Export Citation
  • Stathers TE, Rees D, Kabi S, Mbilnyi L, Smit N, Kiozya H, Jeremiah S, Nyango A, Jeffries D. 2003a. Sweetpotato infestation by Cylas spp. in East Africa: I. Cultivar differences in field infestation and the role of plant factors. Int J Pest Manage. 49:131140. https://doi.org/10.1080/0967087021000043085.

    • Search Google Scholar
    • Export Citation
  • Stathers TE, Rees D, Nyango A, Kiozya H, Mbilinyi L, Jeremiah S, Kabi S, Smit N. 2003b. Sweetpotato infestation by Cylas spp. in East Africa: II. Investigating the role of root characteristics. Int J Pest Manage. 49:141–146. https://doi.org/10.1080/0967087021000043094.

  • Story RN, Hammond AM, LaBonte DL, Thompson P, Bohac JR. 1999. Sweetpotato: Ipomoea batatas L. Arthropod Manage Tests. 24:436437. https://doi.org/10.1093/amt/24.1.m25.

    • Search Google Scholar
    • Export Citation
  • Tedesco D, de Almeida Moreira BR, Pereira da Silva R, Barbosa MR Jr , Maeda M, da Silva RP. 2023. Sustainable management of sweet potatoes: A review on practices, strategies, and opportunities in nutrition sensitive agriculture, energy security and quality of life. Agric Syst. 210:103693. https://doi.org/10.1016/j.agsy.2023.103693.

    • Search Google Scholar
    • Export Citation
  • Teow CC, Truon V-D, McFeeters RF, Thompson RL, Pecota KV, Yencho GC. 2007. Antioxidant activities, phenolic and beta-carotene contents of sweet potato genotypes with varying flesh colours. Food Chem. 103:829838. https://doi.org/10.1016/j.foodchem.2006.09.033.

    • Search Google Scholar
    • Export Citation
  • Thies JA. 2005. Characterization of resistance to root-knot nematodes in sweetpotato. HortScience. 40:868869. https://doi.org/10.21273/hortsci.40.3.868e.

    • Search Google Scholar
    • Export Citation
  • Thompson PG, Schneider JC, Graves B, Sloan RC Jr . 1999. Insect resistance in sweetpotato plant introductions. HortScience. 34:711714. https://doi.org/10.21273/HORTSCI.34.4.711.

    • Search Google Scholar
    • Export Citation
  • Uritani I, Saito T, Honda H, Kim WK. 1975. Induction of furano-terpenoids in sweet potato roots by the larval components of the sweet potato weevils. Agr Biol Chem. 39:18571862. https://doi.org/10.1080/00021369.1975.10861857.

    • Search Google Scholar
    • Export Citation
  • Valenzuela H, Fukuda S, Araki A. 1994. Sweetpotato production guides for Hawai‘i. 22 Jun 2019. https://www.ctahr.hawaii.edu/oc/freepubs/pdf/RES-146.pdf. [accessed 30 Dec 2023].

  • Walkinshaw M, O’Geen AT, Beaudette DE. Soil properties. California Soil Resource Lab, 1 Oct 2022. https://casoilresource.lawr.ucdavis.edu/soil-properties/. [accessed 10 Apr 2023].

  • Wang S, Nie S, Zhu F. 2016. Chemical constituents and health effects of sweet potato. Food Res Int. 89:90116. https://doi.org/10.1016/j.foodres.2016.08.032.

    • Search Google Scholar
    • Export Citation
  • Fig. 1.

    (A) Model-adjusted means across all three trials (Trials 1, 2, and 3) for fresh weight marketable yield (kg/ha) showing the differences among genotypes (n = 30). The ‘Okinawan’ commercial control is named PI 1010 and is colored in red. Filled circles indicate adjusted means and error bars indicate the 95% confidence intervals. (B) Model-adjusted means across all trials showing the differences among genotypes (n = 29) for combined sweetpotato weevil damage (i.e., presence of sweetpotato weevil alone or together with rough sweetpotato weevil). The ‘Okinawan’ commercial control is numbered as ‘PI 1010’. (C) Model-adjusted means across all trials showing the differences among genotypes (n = 23) for nematode damage. For each trait there is considerable variation and accessions that differ from the commercial control. Letters indicate significant difference between samples using a Tukey honestly significant difference mean separation.

  • Fig. 2.

    (A) Marketable fresh weight yields (kg/ha) of 11 sweetpotato genotypes in Trial 1. ‘Okinawan’ is labeled as ‘PI 1010’. Bold line indicates mean and outer box lines indicates the interquartile range (i.e., range between 25th to 75th percentile). Letters indicate significant difference between samples using a Tukey honestly significant difference mean separation. There is considerable variation and accessions that differ from the commercial control.

  • Fig. 3.

    Marketable fresh weight yields (kg/ha) of 15 sweetpotato genotypes in Trial 2. ‘Okinawan’ is labeled as ‘PI 1010’. Bold line indicates mean and outer box lines indicates the interquartile range (i.e., range between 25th to 75th percentile). Letters indicate significant difference between samples using a Tukey honestly significant difference mean separation. There is considerable variation and accessions that differ from the commercial control.

  • Fig. 4.

    Marketable fresh weight yields (kg/ha) of 23 sweetpotato genotypes in Trial 3. ‘Okinawan’ is labeled as ‘PI 1010’. Bold line indicates mean and outer box lines indicate the interquartile range (i.e., range between 25th to 75th percentile). Letters indicate significant difference between samples using a Tukey honestly significant difference mean separation. There is considerable variation and accessions that differ from the commercial control.

  • Fig. 5.

    Images of Sweetpotato accessions that showed good agronomic and taste characteristics across trials. (A) PI 566650 ‘Regal’. (B) PI 566657 ‘Sumor’. These accessions, although not the traditional purple that is favored in Hawaii, show excellent characteristics and are worth further evaluation.

  • Bates D, Mächler M, Bolker B, Walker S. 2014. Fitting linear mixed-effects models using lme4. arXiv preprint arXiv:1406.5823.

  • Barlow T, Rolston LH. 1981. Types of host plant resistance to sweetpotato weevil found in sweetpotato roots. J Kansas Entomol Soc. 54: 649–657. JSTOR, http://www.jstor.org/stable/25084201. [accessed 31 Dec 2023].

  • Bohac JR, Jackson DM, Mueller JD, Dukes PD Sr . 2002. ‘Ruddy’: A multiple-pest-resistant sweetpotato. HortScience. 37:993994. https://doi.org/10.21273/HORTSCI.37.6.993.

    • Search Google Scholar
    • Export Citation
  • Clark CA, Ferrin DM, Smith TP, Holmes GJ. 2013. Compendium of sweetpotato diseases, pests, and disorders, 2nd ed. The American Phytopathological Society, St. Paul, MI, USA. https://doi.org/10.1094/9780890544952.

  • Elgabry RM, Sedeek MS, Meselhy KM, Fawzy GA. 2023. A review on the potential health benefits of sweet potato: Insights into its preclinical and clinical studies. Int J Food Sci Technol. 58:28662872. https://doi.org/10.1111/ijfs.16447.

    • Search Google Scholar
    • Export Citation
  • Follett PA. 2006. Irradiation as a methyl bromide alternative for postharvest control of Omphisa anastomosalis (Lepidoptera: Pyralidae) and Euscepes postfasciatus and Cylas formicarius elegantulus (Coleoptera: Curculionidae) in sweetpotatoes. J Econ Entomol. 99:3237. https://doi.org/10.1093/jee/99.1.32.

    • Search Google Scholar
    • Export Citation
  • Hahn SK, Leuschner K. 1982. Breeding Sweetpotato for weevil resistance, p 331336. In: Villareal RL, Griggs TD (eds). Sweetpotato. Proc. 1st Int Symp. Shanhua, Tainan, 23–27 Mar, Taiwan. AVRDC (World Vegetable Center) publication, Shanhua, Tainan.

  • Hawai‘i Department of Agriculture (HDOA). 1986. Standards for Hawaii-grown sweet potatoes. Hawai‘i Dept Agric, Honolulu, HI, USA. https://hdoa.hawaii.gov/qad/files/2012/12/AR-41-57.pdf. [accessed 30 Dec 2023].

  • Hawai‘i Department of Agriculture (HDOA). 2023. Top 20 agricultural commodities produced in the state of Hawaii, 2021. https://hdoa.hawaii.gov/wp-content/uploads/2023/01/Top-20-Commodities-2021_SOH_01.12.23R.pdf. [accessed 26 Oct 2023].

  • Heu A, Tsuda D, Fukuda S, Young C, Lee M. 2011. New pest advisory. http://hdoa.hawaii.gov/pi/files/2013/01/NPA-Sweet-Potato-Weevil.pdf. [accessed 30 Dec 2023].

  • Hothorn T, Bretz F, Westfall P. 2008. Simultaneous inference in general parametric models. Biometrical J. 50:346363.

  • Huaccho L, Hijmans RJ. 2000. A geo-referenced database of global sweetpotato distribution. Prod Syst and Nat Resour Manage Dept Working Pap No. 4, Intl Potato Center, Lima, Peru. https://pdf.usaid.gov/pdf_docs/pnacl703.pdf. [accessed 30 Dec 2023].

  • Hue SM, Low MY. 2015. An insight into sweet potato weevils management: A review. Psyche. 2015:849560. https://doi.org/10.1155/2015/849560.

  • Jackson DM, Bohac JR. 2006. Improved dry-fleshed sweetpotato genotypes resistant to insect pests. J Econ Entomol. 99:18771883. https://doi.org/10.1093/jee/99.5.1877.

    • Search Google Scholar
    • Export Citation
  • Jackson DM, Bohac JR, Thies JA, Harrison HF. 2010. ‘Charleston Scarlet’ sweetpotato. HortScience. 45:306309. https://doi.org/10.21273/HORTSCI.45.2.306.

    • Search Google Scholar
    • Export Citation
  • Jackson DM, Harrison HF Jr . 2013. Insect resistance in traditional and heirloom sweetpotato varieties. J Econ Entomol. 106:14561462. https://doi.org/10.1603/EC12396.

    • Search Google Scholar
    • Export Citation
  • Jackson DM, Harrison HF Jr , Ryan-Bohac JR. 2012. Insect resistance in sweetpotato plant introduction accessions. J Econ Entomol. 105:651658. https://doi.org/10.1603/EC11307.

    • Search Google Scholar
    • Export Citation
  • Jansson RK, Bryan HH, Sorensen KA. 1987. Within-vine distribution and damage of sweetpotato weevil, Cylas formicarius elegantulus (Coleoptera: Curculionidae) on four cultivars of sweet potato in southern Florida. Fla Entomol. 70:523526. https://doi.org/10.2307/3494797.

    • Search Google Scholar
    • Export Citation
  • Kagawa-Viviani A, Levin P, Johnston E, Ooka J, Baker J, Kantar M, Lincoln NK. 2018. I Ke Ēwe ‘Āina o Ke Kupuna: Hawaiian ancestral crops in perspective. Sustainability. 10:4607. https://doi.org/10.3390/su10124607.

    • Search Google Scholar
    • Export Citation
  • Kuznetsova A, Brockhoff PB, Christensen RHB. 2017. lmerTest Package: Tests in linear mixed effects models. J Stat Softw. 82:126. https://doi.org/10.18637/jss.v082.i13.

    • Search Google Scholar
    • Export Citation
  • Lebot V. 2010. Sweet potato, p 97–125. In: Bradshaw JE (ed). Root and Tuber Crops, Handbook of Plant Breeding 7. Springer, New York, NY, USA. https://doi.org/10.1007/978-0-387-92765-7_3.

  • Miyasaka SC, Wall M, LaBonte D, Arakaki A. 2019. Sweetpotato cultivar trials on Hawai‘i Island. HortTechnology. 29:967975. https://doi.org/10.21273/HORTTECH04387-19.

    • Search Google Scholar
    • Export Citation
  • Miyasaka SC, Motomura-Wages S, Clark CA, LaBonte DR, Villordon AQ. 2018 Field Performance of tissue-cultured, virus-tested ‘Okinawan’ sweetpotato and comparison with some promising cultivars in Hawai’i. HortTechnology. 28(5):676–683. https://doi.org/10.21273/HORTTECH04009-18.

  • Nottingham SF, Kays SJ. 2002. Sweetpotato weevil control. Acta Hortic. 583:155161. https://doi.org/10.17660/ActaHortic.2002.583.17.

  • Olivoto T, Lúcio ADC. 2020. metan: An R package for multi‐environment trial analysis. Methods in Ecology and Evolution. 11(6):783789. https://doi.org/10.1111/2041-210X.13384.

    • Search Google Scholar
    • Export Citation
  • Pulakkatu-thodi I, Motomura S, Miyasaka S. 2018. Evaluation of insecticides for the management of rough sweetpotato weevil, Blosyrus asellus (Coleoptera: Curculionidae) in Hawai’i Island. Crop Prot. 114:223227. https://doi.org/10.1016/j.cropro.2018.08.035.

    • Search Google Scholar
    • Export Citation
  • Roberts PA, Scheuerman RW. 1984. Field evaluation of sweet potato clones for reaction to root-knot and stubby root nematodes in California. HortScience. 19:270273. https://doi.org/10.21273/HORTSCI.19.2.270.

    • Search Google Scholar
    • Export Citation
  • Stathers TE, Rees D, Kabi S, Mbilnyi L, Smit N, Kiozya H, Jeremiah S, Nyango A, Jeffries D. 2003a. Sweetpotato infestation by Cylas spp. in East Africa: I. Cultivar differences in field infestation and the role of plant factors. Int J Pest Manage. 49:131140. https://doi.org/10.1080/0967087021000043085.

    • Search Google Scholar
    • Export Citation
  • Stathers TE, Rees D, Nyango A, Kiozya H, Mbilinyi L, Jeremiah S, Kabi S, Smit N. 2003b. Sweetpotato infestation by Cylas spp. in East Africa: II. Investigating the role of root characteristics. Int J Pest Manage. 49:141–146. https://doi.org/10.1080/0967087021000043094.

  • Story RN, Hammond AM, LaBonte DL, Thompson P, Bohac JR. 1999. Sweetpotato: Ipomoea batatas L. Arthropod Manage Tests. 24:436437. https://doi.org/10.1093/amt/24.1.m25.

    • Search Google Scholar
    • Export Citation
  • Tedesco D, de Almeida Moreira BR, Pereira da Silva R, Barbosa MR Jr , Maeda M, da Silva RP. 2023. Sustainable management of sweet potatoes: A review on practices, strategies, and opportunities in nutrition sensitive agriculture, energy security and quality of life. Agric Syst. 210:103693. https://doi.org/10.1016/j.agsy.2023.103693.

    • Search Google Scholar
    • Export Citation
  • Teow CC, Truon V-D, McFeeters RF, Thompson RL, Pecota KV, Yencho GC. 2007. Antioxidant activities, phenolic and beta-carotene contents of sweet potato genotypes with varying flesh colours. Food Chem. 103:829838. https://doi.org/10.1016/j.foodchem.2006.09.033.

    • Search Google Scholar
    • Export Citation
  • Thies JA. 2005. Characterization of resistance to root-knot nematodes in sweetpotato. HortScience. 40:868869. https://doi.org/10.21273/hortsci.40.3.868e.

    • Search Google Scholar
    • Export Citation
  • Thompson PG, Schneider JC, Graves B, Sloan RC Jr . 1999. Insect resistance in sweetpotato plant introductions. HortScience. 34:711714. https://doi.org/10.21273/HORTSCI.34.4.711.

    • Search Google Scholar
    • Export Citation
  • Uritani I, Saito T, Honda H, Kim WK. 1975. Induction of furano-terpenoids in sweet potato roots by the larval components of the sweet potato weevils. Agr Biol Chem. 39:18571862. https://doi.org/10.1080/00021369.1975.10861857.

    • Search Google Scholar
    • Export Citation
  • Valenzuela H, Fukuda S, Araki A. 1994. Sweetpotato production guides for Hawai‘i. 22 Jun 2019. https://www.ctahr.hawaii.edu/oc/freepubs/pdf/RES-146.pdf. [accessed 30 Dec 2023].

  • Walkinshaw M, O’Geen AT, Beaudette DE. Soil properties. California Soil Resource Lab, 1 Oct 2022. https://casoilresource.lawr.ucdavis.edu/soil-properties/. [accessed 10 Apr 2023].

  • Wang S, Nie S, Zhu F. 2016. Chemical constituents and health effects of sweet potato. Food Res Int. 89:90116. https://doi.org/10.1016/j.foodres.2016.08.032.

    • Search Google Scholar
    • Export Citation
Anna Halpin-McCormick University of Hawai‘i at Mānoa, Department of Tropical Plant and Soil Sciences (TPSS), 3190 Maile Way, Honolulu, HI 96822, USA

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Michael B. Kantar University of Hawai‘i at Mānoa, Department of Tropical Plant and Soil Sciences (TPSS), 3190 Maile Way, Honolulu, HI 96822, USA

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Sharon Motomura-Wages University of Hawai‘i at Mānoa, TPSS, Komohana Research and Extension Center, 875 Komohana St., Hilo, HI 96720, USA

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Susan C. Miyasaka University of Hawai‘i at Mānoa, TPSS, Komohana Research and Extension Center, 875 Komohana St., Hilo, HI 96720, USA

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Contributor Notes

Funding for this research was provided by the County of Hawai‘i Department of Research and Development, and by the US Department of Agriculture National Institute of Food and Agriculture Hatch projects HAW#08029-H and HAW#08043-H, and managed by the University of Hawai‘i at Mānoa College of Tropical Agriculture and Human Resources. This research was supported by the intramural research program of the US Department of Agriculture, National Institute of Food and Agriculture, Specialty Crop Research Initiative, accession no. 1029242. We would like to acknowledge the hard work and dedication of agricultural technicians Mary Kaheiki, Layne Matsushita, and Dayle Tsuha at the Waiākea Research Station, who capably prepared the field, planted, maintained, harvested, and collected data for these trials, even during the start of the Covid-19 pandemic in 2020. Also, we would like to thank farm manager Angel Magno, other agricultural technicians Eric Magno and Elton Mow, and research support Nicholle Konanui for assisting with these trials. In addition, we would like to acknowledge landowner Richard Ha, for allowing us to lease his land for these field trials. Mention of a trademark, proprietary product, or vendor does not constitute a guarantee or warranty by the University of Hawai‘i at Mānoa, and does not imply its approval to the exclusion of other products or vendors that might also be suitable. The findings and conclusions in this publication have not been formally disseminated by the US Department of Agriculture and should not be construed to represent any agency determination or policy.

M.B.K. is the corresponding author. E-mail: mbkantar@hawaii.edu.

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  • Fig. 1.

    (A) Model-adjusted means across all three trials (Trials 1, 2, and 3) for fresh weight marketable yield (kg/ha) showing the differences among genotypes (n = 30). The ‘Okinawan’ commercial control is named PI 1010 and is colored in red. Filled circles indicate adjusted means and error bars indicate the 95% confidence intervals. (B) Model-adjusted means across all trials showing the differences among genotypes (n = 29) for combined sweetpotato weevil damage (i.e., presence of sweetpotato weevil alone or together with rough sweetpotato weevil). The ‘Okinawan’ commercial control is numbered as ‘PI 1010’. (C) Model-adjusted means across all trials showing the differences among genotypes (n = 23) for nematode damage. For each trait there is considerable variation and accessions that differ from the commercial control. Letters indicate significant difference between samples using a Tukey honestly significant difference mean separation.

  • Fig. 2.

    (A) Marketable fresh weight yields (kg/ha) of 11 sweetpotato genotypes in Trial 1. ‘Okinawan’ is labeled as ‘PI 1010’. Bold line indicates mean and outer box lines indicates the interquartile range (i.e., range between 25th to 75th percentile). Letters indicate significant difference between samples using a Tukey honestly significant difference mean separation. There is considerable variation and accessions that differ from the commercial control.

  • Fig. 3.

    Marketable fresh weight yields (kg/ha) of 15 sweetpotato genotypes in Trial 2. ‘Okinawan’ is labeled as ‘PI 1010’. Bold line indicates mean and outer box lines indicates the interquartile range (i.e., range between 25th to 75th percentile). Letters indicate significant difference between samples using a Tukey honestly significant difference mean separation. There is considerable variation and accessions that differ from the commercial control.

  • Fig. 4.

    Marketable fresh weight yields (kg/ha) of 23 sweetpotato genotypes in Trial 3. ‘Okinawan’ is labeled as ‘PI 1010’. Bold line indicates mean and outer box lines indicate the interquartile range (i.e., range between 25th to 75th percentile). Letters indicate significant difference between samples using a Tukey honestly significant difference mean separation. There is considerable variation and accessions that differ from the commercial control.

  • Fig. 5.

    Images of Sweetpotato accessions that showed good agronomic and taste characteristics across trials. (A) PI 566650 ‘Regal’. (B) PI 566657 ‘Sumor’. These accessions, although not the traditional purple that is favored in Hawaii, show excellent characteristics and are worth further evaluation.

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