Sweet Potato Cultivars Research Articles

Effect of harvesting time on root yield and nutritional composition of orange-fleshed sweet potato [Ipomoea batatas (L.) Lam] varieties in East Hararghe

In eastern Ethiopia, sweet potato is a vital food and nutrition security crop; moreover, orange-fleshed sweet potato (OFSP) varieties are rich in beta-carotene content and have the potential to alleviate chronic Vitamin A malnutrition in the region. However, the unavailability of adaptable varieties and lack of information on production and post-harvest handling practices have limited its production and utilization in eastern Ethiopia. The research was conducted to identify the proper harvesting stage of OFSP varieties for optimum yield and nutritional compositions at Rare and Babile research stations of Haramaya University during the main rainy season of 2022. Three varieties (Alamura, Kabode, and Bakule) and four harvesting periods (120, 150, 180, and 210 days after planting (DAP) in factorial combinations were evaluated in randomized complete block design with three replications. Data were collected for growth, yield, and physicochemical composition-related parameters. Combined analysis of variance revealed the interaction effect of harvesting time and varieties had a significant (p < 0.05) effect on yield, yield-related parameters, and physicochemical components. Alamura variety produced comparable above-ground biomass (28.99 t ha−1) and the highest marketable root yield of 36.40 t ha−1 at 150 DAP, with dry matter content of 33.01 and 30.58 % at 150 and 120 DAP, respectively. Harvesting Alamura at 150 DAP also had the highest ꞵ-carotene, zinc, and iron contents of 11809 μg/100 g, 3.79, and 14.47 mg/100 g, respectively. It was concluded that growing the Alamura variety and harvesting at 150 DAP was better for obtaining higher root yield with good nutritional compositions in the study area.

Genetic variations underlying root-knot nematode resistance in sweetpotato

Root-knot nematode (Meloidogyne incognita) causes severe crop damage and large economic losses worldwide. Several cultivars of sweetpotato [Ipomoea batatas (L.) Lam)] have been developed with root-knot nematode-resistant traits; however, many of these cultivars do not have favorable agronomic characteristics. To understand the genetic traits underlying M. incognita resistance in sweetpotato, whole genome resequencing was conducted on three RKN-susceptible (Dahomi, Shinhwangmi, and Yulmi) and three RKN-resistant (Danjami, Pungwonmi, and Juhwangmi) sweetpotato cultivars. Three SNPs (single nucleotide polymorphisms) in promotor sequences were shared in RKN-resistant cultivars and were correlated with disease resistance. One of these SNPs was located in G6617|TU10904, which encoded a homolog of RIBOSOMAL PROTEIN EL15Z, and was associated with reduced expression in RKN-resistant cultivars only. Alongside SNP analysis, mRNA-seq data were analyzed for the same cultivars with and without nematode infection, and 18 nematode-sensitive genes were identified that responded in a cultivar-specific manner. Of these genes, expression of G8735|TU14367 was lower in sensitive cultivars than in RKN-resistant cultivars. Overall, this study identified two genes that potentially have key roles in the regulation of nematode resistance and will be useful targets for nematode resistance breeding programs.

Source-sink synergy is the key unlocking sweet potato starch yield potential

Sweet potato starch is in high demand globally for food and industry. However, starch content is negatively correlated with fresh yield. It is urgent to uncover the genetic basis and molecular mechanisms underlying the starch yield of sweet potato. Here we systematically explore source-sink synergy-mediated sweet potato starch yield formation: the production, loading, and transport of photosynthates in leaves, as well as their unloading and allocation in storage roots, lead to starch content divergence between sweet potato varieties. Moreover, we find that six haplotypes of IbPMA1 encoding a plasma membrane H+-ATPase are significantly linked with starch accumulation. Overexpression of IbPMA1 in sweet potato results in significantly increased starch and sucrose contents, while its knockdown exhibits an opposing effect. Furthermore, a basic helix-loop-helix (bHLH) transcription factor IbbHLH49 directly targets IbPMA1 and activates its transcription. Overexpression of IbbHLH49 notably improves source-sink synergy-mediated fresh yield and starch accumulation in sweet potato. Both IbbHLH49 and IbPMA1 substantially influence sugar transport and starch biosynthesis in source and sink tissues. These findings expand our understanding of starch yield formation and provide strategies and candidate genes for high starch breeding in root and tuber crops.

Physiological and Transcriptome Responses of Sweet Potato [Ipomoea batatas (L.) Lam] to Weak-Light Stress.

In the relay intercropping system of maize/sweet potato, the growth of the sweet potatoes is seriously limited by weak light stress in the early stage due to shade from maize plants. However, it is not clear how the weak light affects sweet potatoes and causes tuberous root loss. By setting two light intensity levels (weak light = 30% transmittance of normal light), this study evaluated the responses of two sweet potato cultivars with different tolerances to weak light in a field-based experiment and examined the divergence of gene expression related to light and photosynthesis in a pot-based experiment. The results showed that under weak light, the anatomic structure of functional leaves changed, and the leaf thickness decreased by 39.98% and 17.32% for Yuhongxinshu-4 and Wanshu-7, respectively. The ratio of S/R increased, and root length, root superficial area, and root volume all decreased. The photosynthetic enzyme rubisco was weakened, and the net photosynthetic rate (Pn) declined as well. The level of gene expression in Wanshu-7 was higher than that of Yuhongxinshu-4. The KEGG analysis showed that differentially expressed genes from the two cultivars under weak-light stress used the same enrichment pathway, mainly via glutathione metabolism and flavonoid biosynthesis. After full light levels were restored, the differentially expressed genes were all enriched in pathways such as photosynthesis, photosynthetic pigment synthesis, and carbon metabolism. These findings indicated that weak light changed the plant morphology, photosynthetic physiology and gene expression levels of sweet potatoes, which eventually caused losses in the tuberous root yield. The more light-sensitive cultivar (Wanshu-7) had stronger reactions to weak light. This study provides a theoretical basis and strategy for breeding low-light-tolerant varieties and improving relay intercropping production in sweet potatoes.

Growth and Tuber Yield Improvement of Sweet Potato Cultivars (Ipomoea Batatas L.) as Influenced by Vine Patterns of Planting in Taraba State

Growth and Tuber Yield Improvement of Sweet Potato Cultivars (Ipomoea Batatas L.) as Influenced by Vine Patterns of Planting in Taraba State

Genome-Wide Identification and Analysis of SUS and AGPase Family Members in Sweet Potato: Response to Excessive Nitrogen Stress during Storage Root Formation.

(1) The development of sweet potato storage roots is impacted by nitrogen (N) levels, with excessive nitrogen often impeding development. Starch synthesis enzymes such as sucrose synthase (SUS) and ADP-glucose pyrophosphorylase (AGPase) are pivotal in this context. Although the effects of excessive nitrogen on the formation of sweet potato storage roots are well documented, the specific responses of IbSUSs and IbAGPases have not been extensively reported on. (2) Pot experiments were conducted using the sweet potato cultivar "Pushu 32" at moderate (MN, 120 kg N ha-1) and excessive nitrogen levels (EN, 240 kg N ha-1). (3) Nine IbSUS and nine IbAGPase genes were categorized into three and two distinct subgroups based on phylogenetic analysis. Excessive nitrogen significantly (p < 0.05) suppressed the expression of IbAGPL1, IbAGPL2, IbAGPL4, IbAGPL5, IbAGPL6, IbAGPS1, and IbAGPS2 in fibrous roots and IbSUS2, IbSUS6, IbSUS7, IbSUS8, IbSUS9, IbAGPL2, and IbAGPL4 in storage roots, and then significantly (p < 0.05) decreased the SUS and AGPase activities and starch content of fibrous root and storage root, ultimately reducing the storage root formation of sweet potato. Excessive nitrogen extremely significantly (p < 0.01) enhanced the expression of IbAGPL3, which was strongly negatively correlated with the number and weight of storage roots per plant. (4) IbAGPL3 may be a key gene in the response to excessive nitrogen stress and modifying starch synthesis in sweet potato.

Effect of Different Irrigation Levels on the Productivity of Two Sweet Potato Varieties (Ipomoea batata)

Effect of Different Irrigation Levels on the Productivity of Two Sweet Potato Varieties (Ipomoea batata)

Transcriptome Analysis Reveals Genes and Pathways Associated with Drought Tolerance of Early Stages in Sweet Potato (Ipomoea batatas (L.) Lam.).

The yield of sweet potato [Ipomoea batatas (L.) Lam] can be easily threatened by drought stress. Typically, early stages like the seedling stage and tuber-root expansion stage are more vulnerable to drought stress. In this study, a highly drought-tolerant sweet potato cultivar "WanSu 63" was subjected to drought stress at both the seedling stage (15 days after transplanting, 15 DAT) and the tuber-root expansion stage (45 DAT). Twenty-four cDNA libraries were constructed from leaf segments and root tissues at 15 and 45 DAT for Next-Generation Sequencing. A total of 663, 063, and 218 clean reads were obtained and then aligned to the reference genome with a total mapped ratio greater than 82.73%. A sum of 7119, 8811, 5463, and 930 differentially expressed genes were identified from leaves in 15 days (L15), roots in 15 days (R15), leaves in 45 days (L45), and roots in 45 days (R45), respectively, in drought stress versus control. It was found that genes encoding heat shock proteins, sporamin, LEA protein dehydrin, ABA signaling pathway protein gene NCED1, as well as a group of receptor-like protein kinases genes were enriched in differentially expressed genes. ABA content was significantly higher in drought-treated tissues than in the control. The sweet potato biomass declined sharply to nearly one-quarter after drought stress. In conclusion, this study is the first to identify the differentially expressed drought-responsive genes and signaling pathways in the leaves and roots of sweet potato at the seedling and root expansion stages. The results provide potential resources for drought resistance breeding of sweet potato.

Evaluation of Some Sweetpotato (Ipomoea batatas [L.] Lam) Varieties in Mozambique

In Mozambique, sweetpotato plays a significant role in rural areas, where the farmers use it to feed their families and as an income. In this study, we aimed to investigate the performance of different sweetpotato varieties in Niassa, Mozambique. The trial was set up in Malulu, Sanga district, located 60 km away from Lichinga, capital of Niassa, Mozambique. In Sanga, the rainy and hot season occurs from December to March, and the dry and cold season is from May to October. In this trial, the treatments correspond to sweetpotato varieties. We used the randomized block design with 12 sweetpotato varieties and 3 replications. The evaluated traits were as follows: weevil damage, roots commercial yield, roots non-commercial yield, total yield, and vine yield. Regarding statistical analysis, the results per trait were submitted to the Bartlett test of homogeneity of variances and Shapiro-Wilk normality test, and then the analysis of variance and means comparison using the Scott-Knott test when necessary was performed. All the statistical analysis was conducted at 5% on the R programming language. For commercial and total yield, the varieties Local, Sumaia, Olga, and Alisha presented the best results. Esther and Irene were the varieties most attacked by weevils.

Leaf area prediction of sweet potato cultivars: An approach to a non-destructive and accurate method

Many researchers consider the leaf area the most critical parameter for plant growth and physiology studies. Using allometric equations is considered an effective and non-destructive method for estimating the leaf area of plants. The objectives of this study were to construct allometric equations to predict the leaf area of sweet potato cultivars as a function of leaf dimensions and to verify the effectiveness of the allometric equations constructed for each cultivar individually and for the grouped data. Two hundred fifty leaves of the sweet potato cultivars Beauregard, BRS Amélia, BRS Cuia, and Coquinho were collected, and then the length and width of each leaf were measured. Subsequently, the product between leaf length and width and the actual leaf area was calculated. Linear, linear without intercept, power, and exponential regression models were used to construct allometric equations to predict leaf area. The best equations were chosen according to the highest coefficients of determination and correlation, Willmott agreement index, and lowest Akaike information criterion and root mean square error. The equations obtained with the linear models without intercept and power using the length and width of the leaves were the most indicated for predicting the leaf area of sweet potato cultivars.

Response of sweet potato cultivars to Bacillus velezensis T149-19 and Bacillus safensis T052-76 used as biofertilizers

The global market of sweet potato (Ipomoea batatas (L.) Lam.) is continuously growing and, consequently, demands greater productivity from the agricultural sector. The use of biofertilizers facilitates plant growth by making essential nutrients available to crops or providing resistance against different abiotic and biotic factors. The strains Bacillus safensis T052-76 and Bacillus velezensis T149-19 have previously been inoculated in the sweet potato cultivar Ourinho, showing positive effects on plant shoot growth and inhibiting the phytopathogen Plenodomus destruens. To elucidate the effects of these strains on sweet potato growth, four different cultivars of sweet potato were selected: Capivara, IAPAR 69, Rosinha de Verdan and Roxa. The plants were grown in pots in a greenhouse and inoculated with the combined strains according to a randomized block design. A control (without the inoculation of both strains) was also used. A slight positive effect of the inoculation of the two Bacillus strains was observed on the aerial parts of some of the cultivars. An increase in the fresh weight of the sweet potatoes of the inoculated plants was obtained, varying from 2.7 to 11.4 %. The number of sweet potatoes obtained from the inoculated cultivars IAPAR 69 and Roxa increased 15.2 % and 16.7 %, respectively. The rhizosphere soil of each cultivar was further sampled for DNA extraction, and the 16S rRNA gene metabarcoding technique was used to determine how the introduction of these Bacillus strains influenced the rhizosphere bacterial community. The bacterial communities of the four different cultivars were dominated by Actinobacteria, Proteobacteria and Firmicutes. Nonmetric multidimensional scaling (NMDS) revealed that the rhizosphere bacterial communities of plants inoculated with Bacillus strains were more similar to each other than to the bacterial communities of uninoculated plants. This study highlights the contribution of these Bacillus strains to the promotion of sweet potato growth.

ANALYSIS OF SWEET POTATO PRODUCTION IN EBONYI STATE, NIGERIA

This paper analyzed sweet potato production in Ebonyi State, Nigeria. Multi-stage and proportionate sampling methods were used to collect two hundred and one sweet potato farmers for the study. Data were collected using structured questionnaire and analyzed using descriptive such as frequency and percentages and inferential statistics such as Ordinary Least Square regression model. Results showed that 74.13% of the sweet potato farmers were female with mean age of 38years, mean educational level of 12years with 96.52% of them were married having a mean household size of 8persons. Farm size, quantity of improved sweet potato varieties planted, labour and weeding were significant at 1% and 5% respectively and were positively related to vine yield while farm size, quantity of improved sweet potato varieties planted, fertilizer application and insecticide were significant at 1% and 5% respectively and were positively related to root yield. The production of sweet potato in Ebonyi state was affected by some production factors which causes low yield in the vine and root of sweet potato. Therefore, Organization of field days and farmers’ training on sweet potato production as well as procurement and distribution of improved varieties to farmers are effective strategies for stimulating adoption of the technologies.

Effect of Post-harvest Handling Conditions on Polyphenol Content and Ferric Reducing Antioxidant Properties of Selected Ugandan Sweet Potato Varieties

Effect of Post-harvest Handling Conditions on Polyphenol Content and Ferric Reducing Antioxidant Properties of Selected Ugandan Sweet Potato Varieties

Physicochemical Characterization of In Situ Annealed Starch and Its Application in a Fermented Dairy Beverage

In this study, the aim was to modify the starches of three different sweet potato varieties—Rosada Uruguaiana (RU), Rosada Canadense (RC), and Ligeirinha (L)—through in situ annealing to increase the content of slowly digestible starch (SDS), which has health benefits. The modified carbohydrate was then added to a dairy beverage fermented by Lactobacillus casei 1e (L. casei). After annealing, the starches had different physicochemical properties, and the L variety, which had the highest SDS content, was chosen for the formulation of the fermented dairy beverage. Two concentrations of modified starch (7% and 10.5%) were used in the formulations, and a sensory analysis indicated no differences in acceptance and purchase intention. The beverage containing 10.5% modified starch exhibited good physicochemical and microbiological stability. This study demonstrates the possibility of creating a functional fermented dairy beverage with high SDS content, which could potentially benefit consumers’ health.

Identification of Combined Resistance to Meloidogyne enterolobii and M. incognita in Sweet Potato Genotypes

Root-knot nematodes, genus Meloidogyne, are the most damaging nematodes of sweet potato, causing yield reduction and aesthetic damage of the marketable product. Several sweet potato cultivars currently grown in the Unites States have intermediate-to-high resistance to Meloidogyne incognita; however, many of these cultivars are susceptible to M. enterolobii. Therefore, the response of 69 sweet potato genotypes to M. enterolobii and M. incognita was evaluated under greenhouse conditions to identify potential sources of resistance. The cultivars ‘Beauregard’ and ‘Jewel’ were used as controls. Results showed that sweet potato genotypes were either highly resistant or highly susceptible to M. enterolobii, whereas they showed a wide-spectrum response to M. incognita, ranging from highly susceptible to highly resistant. Twenty-six genotypes were resistant to M. enterolobii and 11 genotypes were resistant to M. incognita. Combined resistance to M. enterolobii and M. incognita was observed in three sweet potato genotypes. Selected genotypes from this study will be used to incorporate the observed resistance into a commercially viable sweet potato cultivar.

Enhancing Reniform Nematode Management in Sweetpotato by Complementing Host-Plant Resistance with Nonfumigant Nematicides.

The reniform nematode (Rotylenchulus reniformis Linford and Oliveira) adversely impacts the quality and quantity of sweetpotato storage roots. Management of R. reniformis in sweetpotato remains a challenge because host plant resistance is not available, fumigants are detrimental to the environment and health, and crop rotation is not effective. We screened a core set of 24 sweetpotato plant introductions (PIs) against R. reniformis. Four PIs were resistant, and 10 were moderately resistant to R. reniformis, suggesting these PIs can serve as sources of resistance for sweetpotato resistance breeding programs. PI 595869, PI 153907, and PI 599386 suppressed 83 to 89% egg production relative to the susceptible control 'Beauregard', and these PIs were employed in subsequent experiments to determine if their efficacy against R. reniformis can be further increased by applying nonfumigant nematicides oxamyl, fluopyram, and fluensulfone. A 34 to 93% suppression of nematode reproduction was achieved by the application of nonfumigant nematicides, with oxamyl providing the best suppression followed by fluopyram and fluensulfone. Although sweetpotato cultivars resistant to R. reniformis are currently not available and there is a need for the development of safer yet highly effective nonfumigant nematicides, results from the current study suggest that complementing host plant resistance with nonfumigant nematicides can serve as an important tool for effective and sustainable nematode management.

Optimization of frying time and temperature for the development of quality chips from varieties of sweet potato (Ipomoea batatas L.Lam)

Consumers seek low-fat fried products with appealing color, texture, and taste to avoid health issues like obesity and cardiovascular disease associated with high-oil-content foods. Frying conditions, including time and temperature, greatly affect the moisture, texture, oil content, and color of fried foods. The objective of this study was to optimize frying time and temperature to obtain quality fried chips from three varieties of orangefleshed sweet potato roots. The study examined how frying temperature (ranging from 140 to 180°C) and time (2 to 6 mins) affect the quality of fried chips, assessing attributes like moisture content, oil content, color, and texture. Significant impacts of frying time and temperature on chip quality were found across all varieties using central composite design tests and mathematical models (p&lt;0.05). Optimal frying conditions were determined through response surface methodology analysis, which was 154.8℃ for 3.82 mins, 160.1℃ for 3.66 mins, and 162.65℃ for 3.04 mins for Kabode, Dilla, and Kulfo varieties, respectively, guiding sweet potato fried chip producers to achieve satisfactory results economically and efficiently.

Acceptability and prospects of integrating sweet potato into dietary habits: Insights from Eritrea

AbstractPopularity of yellow‐fleshed sweet potato is rising due to its versatility, nutritional richness, and environmental advantages, particularly in countries across sub‐Saharan Africa and the Sahel region. Many countries in the region have made efforts to incorporate vitamin A varieties of sweet potato into their farming systems and diets. However, research on the acceptability of sweet potato dishes in these regions is limited. This study aims to fill this gap by providing empirical evidence on acceptability of sweet potato dishes and the comparative preferences of consumers for different value‐added sweet potato‐based meals using sensory analyses of 13 dishes and 55 panelists in Eritrea. We find a significant acceptance level, with a mean score of 4.21 out of 5. Certain products, such as low‐added sugar biscuits (mean score of 4.70 out of 5), low‐added sugar jams (4.56 out of 5), bread (4.59 out of 5), chips (4.56 out of 5), and stew (4.38 out of 5), have emerged as favorites, offering opportunities for agribusiness and household adoption. These findings suggest promising potential for integrating sweet potatoes into diets across these regions. However, the current lack of demand is might be due to inadequate investment in promotions, until a critical mass of adopters is reached.

FOLIAR APPLICATION OF SILICON NANOPARTICLES (SiNPs) EFFECTS ON TUBER YIELDS AND CARBOHYDRATE METABOLISM IN FOUR SWEET POTATOE (Ipomoea batatas L) VARIETIES

Silicon nanoparticles (SiNPs) have been widely utilised in agriculture, however, there are limited reports on sweet potatoes (Ipomoea batatas L). In this study, SiNPs were applied as a foliar spray at a concentration of 0.01% (w/v) three times at five-week intervals after planting. Four sweet potato varieties namely ‘Karak Bakar’, ‘Tanjung Sepat’, ‘V6D215’, and ‘Pejabat’ were tested. Results showed that the foliar application of SiNPs induced changes in the tuber biomass, number, epidermal layer thickness, starch, reducing sugar and invertase levels in four sweet potato varieties. The highest tuber biomass was seen in the ‘Pejabat’ (392.9 ± 88.1 g/plant) and ‘Karak Bakar’ (456.6 ± 102.8 g/plant) varieties. SiNPs treatment also reduced the tuber numbers in all varieties except ‘Karak Bakar’ and did not significantly affect (p &gt; 0.05) the starch and reduced sugar content in the tubers of the ‘V6D215’ variety. For all tested varieties, SiNPs treatment did not significantly alter (p &gt; 0.05) the amylase levels and invertase in the tubers of ‘Tanjung Sepat’ and ‘Karak Bakar’. The findings of the study suggested that the effect of foliar application on sweet potatoes is variety-dependent and further study should be carried out to determine the most suitable SiNPs concentration for each variety.

Effect of processing and storage on the quality of the purees made from different sweet potato cultivars

Effect of processing and storage on the quality of the purees made from different sweet potato cultivars