Sweet Potato Cultivars Research Articles

Plastidial Phosphoglucomutase (pPGM) Overexpression Increases the Starch Content of Transgenic Sweet Potato Storage Roots.

Sweet potato (Ipomoea batatas), an important root crop, has storage roots rich in starch that are edible and serve as a raw material in bioenergy production. Increasing the storage-root starch contents is a key sweet potato breeding goal. Phosphoglucomutase (PGM) is the catalytic enzyme for the interconversion of glucose-6-phosphate and glucose-1-phosphate, precursors in the plant starch synthetic pathway. Plant PGMs have plastidial and cytosolic isoforms, based on their subcellular localization. Here, IbpPGM, containing 22 exons and 21 introns, was cloned from the sweet potato line Xu 781. This gene was highly expressed in the storage roots and leaves, and its expression was induced by exogenous sucrose treatments. The mature IbpPGM protein was successfully expressed in Escherichia coli when a 73-aa chloroplastic transit peptide detected in the N-terminus was excised. The subcellular localization confirmed that IbpPGM was localized to the chloroplasts. The low-starch sweet potato cultivar Lizixiang IbpPGM-overexpression lines showed significantly increased starch, glucose, and fructose levels but a decreased sucrose level. Additionally, the expression levels of the starch synthetic pathway genes in the storage roots were up-regulated to different extents. Thus, IbpPGM significantly increased the starch content of the sweet potato storage roots, which makes it a candidate gene for the genetic engineering of the sweet potato.

Effects of Foliar Application of Uniconazole on the Storage Quality of Tuberous Roots in Sweetpotato

Uniconazole (UCZ), as a plant growth regulator, has been extensively applied in sweetpotato (Ipomoea batatas (L.) Lam) to increase tuberous root yield and quality. It is usually used in the production of sweetpotato by foliar spray. The post-harvest storage stage is crucial for forming the quality of the sweetpotato’s tuberous root. Few studies have focused on the foliar spraying UCZ-affected storage quality of sweetpotato during pro-harvest storage. To examine the effects of foliar application of UCZ on the storage quality of tuberous root, this study mainly analyzed the influence of storage quality, with (K2 and K4) and without (K1 and K3) 100 mg·L−1 foliar spraying of UCZ, at a storage period of normal fertilizing treatments (K1 and K2) and rich fertilizing treatments (K3 and K4), on the storage quality of three representative sweetpotato varieties (Z13, Z33 and J26). Compared to the no-use UCZ treatments, the decay rate of K2 was the lowest for any storage time. The decay rate of all the varieties was 0.0% before 45 DAS. Only the decay rate of Z33 increased to 4.4% at 60 DAS (p < 0.05). The dry matter rate of K2 and K4 was still higher than that of K1 during 15–60 DAS in Z13 and J26 (p < 0.05). UCZ foliar spraying was higher than without treatment at 30–60 DAS. In Z33, the springiness of UCZ spraying was higher than no spraying treatments at 45–60 DAS. These results indicate that foliar spraying of UCZ had no effect on the storage quality of tuberous root decreasing sharply, and it sometimes kept the quality stable.

Salicylic Acid Protects Sweet Potato Seedlings from Drought Stress by Mediating Abscisic Acid-Related Gene Expression and Enhancing the Antioxidant Defense System.

China has the largest sweet potato planting area worldwide, as well as the highest yield per unit area and total yield. Drought is the most frequently encountered environmental stress during the sweet potato growing season. In this study, we investigated salicylic acid (SA)-mediated defense mechanisms under drought conditions in two sweet potato varieties, Zheshu 77 and Zheshu 13. Drought stress decreased growth traits, photosynthetic pigments and relative water contents, as well as the photosynthetic capability parameters net photosynthetic rate, stomatal conductance and transpiration rate, whereas it increased reactive oxygen species production, as well as malondialdehyde and abscisic acid contents. The application of SA to drought-stressed plants reduced oxidative damage by triggering the modulation of antioxidant enzyme activities and the maintenance of optimized osmotic environments in vivo in the two sweet potato varieties. After SA solution applications, NCED-like3 expression was downregulated and the abscisic acid contents of drought-stressed plants decreased, promoting photosynthesis and plant growth. Thus, foliar spraying an appropriate dose of SA, 2.00-4.00 mg·L-1, on drought-stressed sweet potato varieties may induce resistance in field conditions, thereby increasing growth and crop yield in the face of increasingly frequent drought conditions.

Assessment of genetic diversity and characterization of distinctness, uniformity, and stability of newly bred sweet potato clones

Abstract. Mau YS, Ndiwa ASS, Arsa IGBA, Asa GV, Nana A, Londingkene JA, Hosang EY, Kotta NRE. 2022. Assessment of genetic diversity and characterization of distinctness, uniformity, and stability of newly bred sweet potato clones. Biodiversitas 23: 5923-5934. Genetic diversity assessment is vitally important for germplasm management and the assembly of new varieties. This study aimed to 1) assess the genetic diversity and 2) characterize the distinctness, uniformity, and stability of newly bred clones and check varieties of sweet potatoes based on morphological characters. The present study was conducted in the experimental farm of Universitas Nusa Cendana for two cycles (years) in 2021 and 2022, involving 13 newly bred (hybrid) clones and 6 control varieties. The observations were made on morphological characters of leaf, vine, and storage root, including 31 characteristics. The observed characters were given scores based on the sweet potato descriptors of IPGBR and PPVTPP. The scored morphological data were subjected to cluster analysis followed by a Principal Component Analysis to reveal the genetic diversity level. Euclidean index was used to characterize the distinctness, while the variation of the scored morphological data was used to reveal the uniformity and stability of tested genotypes. The results revealed a high genetic diversity of the studied genotypes. The cluster analysis placed the studied genotypes into four clusters; cluster I consisted of only one genotype, cluster II comprised two sub-clusters and 13 genotype members, cluster II comprised two members, and cluster IV comprised two sub-clusters and three members. The first eight principal components were responsible for about 79% of the observed variability. Euclidean distance index revealed that each of the studied genotypes is distinct from others. No off-type plant was observed; thus, each of the tested genotypes was considered uniform. Phenotypic expressions of the studied genotypes were similar over the two growing cycles; thus, each is said to be stable. The newly bred genotypes G16 and G29 genotypes that meet the distinctness, uniformity, and stability criteria based on their highest number of distinctive characters are eligible for registration as new sweet potato varieties, more specifically for their unique purplish white and purple tuber flesh characters.

Morpho-sensory Evaluation of Orange Fleshed Sweet Potato (Ipomoea batatas L.) Varieties in the Low Lands of North Shewa Zone

Background: Though sweet potato (Ipomoea batatas L.) is one of the internationally as well as nationally important root crops. Its production is challenged with various bottlenecks. Lack of planting materials, shortage of farmer preferred varieties, poor extension system among many other constraints. This study was conducted to assess the performance and test of different orange fleshed sweet potato varieties in participatory approach in the lowlands of North shewa. Methods: Evaluation of eight varieties was carried out in main cropping season using a randomized complete block design with three replications. Number of roots per plant, root weight per plant, root length, root diameter, marketable and total root yield were measured and analyzed using the GLM procedure of SAS version 9.2. Moreover, farmers’ perception assessment and sensory analysis which had an important constituency in the selection process were done using pairwise matrix and hedonic scale, respectively. Result: Except root length, all the traits showed significant difference between varieties. Variety Kulfo gave the highest root yield (38.8 t ha-1) and root diameter (98.8 mm); whereas the lowest root yield (22.1 t ha-1) and root diameter (64.5 mm) were recorded from varieties Teo jet and Delvia, respectively. Farmers were also selecting varieties Lords, Cicilia and Birtukane. Panelists selected Bela, Birtukane and Kulfo as the best varieties. Hence, varieties Kulfo, Lords and Birtukane were recommended for further popularization to boost the production and productivity of the crop for production the lowlands of north shewa and other similar agro-ecologies.

Quantifying unintended effects of an agroecological research project on farmers' practices and social network in Papua New Guinea

Abstract Agroecological researchers and advocates often make assumptions about the social impact and dissemination of their work: researchers may assume that their work has impact through postresearch dissemination, while advocates may assume that new agroecological practices can be effectively spread through existing social networks. Here, we test these assumptions by quantifying the effects of an agroecological research project on farming practices and the social network in a village community in Papua New Guinea. The project aimed to test the effect of applying banana peel compost, chicken manure and NPK fertiliser on sweet potato yields. Local farmers were involved in the research as project garden owners or research assistants. Using stochastic actor‐oriented modelling, we tracked changes in farming practices and the social network. Over the course of the research project, more people started to use food waste on their farms, while animal manure and NPK fertiliser were not frequently adopted. Farmers also took up practices that were not directly researched, such as mulching and planting the specific variety of sweet potato that was used in the project. This suggests that local farmers created meaning from the project, despite the researchers not intending to give advice until the end of the project. The research project also affected the community's social network. Research assistants became more often sought‐after for advice, while knowledge about the project did not flow far from those directly involved. These results indicate that who gets involved in a project may have social consequences, and show the importance of understanding existing social networks before they are relied upon for spreading farming practices. Overall, this work challenges often‐held assumptions about the social impact and dissemination of agroecological research, provides insights into the types of agricultural innovations more likely to be accepted among farmers, and explores how new practices may most effectively be promoted within a community. Read the free Plain Language Summary for this article on the Journal blog.

Metabolic Profiling and Antioxidant Analysis for the Juvenile Red Fading Leaves of Sweetpotato.

Leaves of sweetpotato (Ipomoea batatas L.) are promising healthy leafy vegetable. Juvenile red fading (JRF) leaves of sweetpotato, with anthocyanins in young leaves, are good candidates for developing functional vegetables. Here, metabolic profiling and possible antioxidants were analyzed for five leaf stages of the sweetpotato cultivar "Chuanshan Zi". The contents of anthocyanins, total phenolics, and flavonoids all declined during leaf maturation, corresponding to declining antioxidant activities. By widely targeted metabolomics, we characterized 449 metabolites belonging to 23 classes. A total of 193 secondary metabolites were identified, including 82 simple phenols, 85 flavonoids, 18 alkaloids, and eight terpenes. Analysis of the metabolic data indicates that the antioxidant capacity of sweetpotato leaves is the combined result of anthocyanins and many other colorless compounds. Increased levels of "chlorogenic acid methyl ester", a compromised form of chlorogenic acid, significantly correlated with the declined antioxidant abilities. Besides anthocyanins, some significant metabolites contributing to the high antioxidant property of the sweetpotato leaves were highlighted, including chlorogenic acids, isorhamnetin glycosides, trans-4-hydroxycinnamic acid methyl ester, 4-methoxycinnamic acid, esculetin, caffeate, and trigonelline. This study provides metabolic data for the utilization of sweetpotato leaves as food sources, and sheds light on the metabolomic change for JRF leaves of other plants.

Diversity among Morphological Traits of Segregating Sweetpotato [Ipomoea batatas (L.) Lam] Genotypes in Umudike, Nigeria

Genotypes of the sweet potato (Ipomoea batatas (L.) Lam) normally exhibit high variability in their morphological characters. A field experiment was carried out in 2017 at the National Root Crops Research Institute, Umudike, Abia State, Nigeria to assess the morphological diversity among the population of 68 first filial generation (F1) sweet potato genotypes (Ligri PC) derived from seeds produced through poly cross systems from the International Potato Center, Kumasi, Ghana, including two local check varieties (UMUSPO3 and TIS87/0087). A randomized complete block design with three replicates was used to set up this experiment. The morphology descriptor was used to evaluate the genotypes of sweet potatoes on sixteen characters that covered both folial and fresh storage root morphology. The data were then subjected to an analysis of variance to identify any differences between the measured morphological parameters and agronomic variables. Using cluster analysis, it was established that all of the genotypes could be categorized into four distinct groups based on their physical characteristics. Consequent, a vast gene pool would provide for effective recombination to create a viable sweetpotato variety with high agricultural value.

Exploring plant growth promoting rhizobacteria potential for green agriculture system to optimize sweet potato productivity and soil sustainability in northern Jiangsu, China

The beneficial effects of plant growth-promoting rhizobacteria (PGPR) on crop growth and yield have been widely recognized. However, the application of PGPR in traditional planting systems is often restricted due to the concerns about the incompatibility between PGPR and chemical agricultural inputs. The aim of this study is to test whether the application of PGPR has a beneficial effect on the productivity and sustainability of the green planting system, where the use of low-toxic chemical pesticides and proper amount of chemical fertilizer is allowed. In the current study, field trials of four agriculture systems: green agriculture system, green agriculture system supplemented with beneficial microorganism consortium, organic agriculture system supplemented with the consortium and the control system, were carried out with white, yellow and purple flesh sweet potato varieties. The application of PGPR increased the plant growth and suppressed the stem nematode disease in green system. As a consequence, PGPR increased the yield by 26.44% and raised the farmers’ projected returns in green system on an average of the two-year assessment. Moreover, PGPR promoted the product nutritive quality by 7.51% in soluble sugar and 14.30% in vitamin C content, and also increased the anthocyanin content of the purple sweet potato by 10.73%. Exogenous PGPR significantly retarded the depletion of soil fertility during the crop cultivation, promoted the soil bacterial diversity and altered the bacteria community structure. PGPR treatment increased the relative abundances of Pseudomonas and Lysobacter in the rhizosphere soil, while reduced the amounts of Erwinia and Ralstonia. The changes of soil nutrient and microbes were correlated with the application of exogenous beneficial bacteria regardless of in organic or green agriculture system. Here, we showed the ability of PGPR to efficiently improve the productivity in green agriculture system under the tested condition, and provided evidence for the feasibility of using exogenous PGPR to achieve agricultural sustainability by constructing a positive feedback in crop-soil-microbe interactions.

Performance of High Yielding Sweet Potato Varieties under Different Seasons

In sweet potato, though a number of high yielding varieties are available for cultivation, there is lack of information on suitability of various varieties to different seasons. The results of the study will be useful to recommend varieties ideal for different seasons. Field experiments were conducted during Kharif, Rabi and Summer seasons from 2021 to 2022 with an objective to assess the seasonal influence on growth and tuber yield of five sweet potato varieties [High yielding varieties were Bhu Krishna (V1), Sree Arun (V2), Sree Bhadra (V3), Bhu Sona (V4) and local variety was Kanjanghad Local (V5)]. Randomized Block Design was followed with four replications. Variety Bhu Sona recorded significantly the highest vine length (211.38 cm) compared to other varieties and variety Sree Bhadra (114.71 cm) and variety Kanjanghad Local (112.54 cm) recorded significantly lower vine length. Sree Arun and Bhu Sona were the superior varieties and recorded significantly higher average tuber weight (236.77 g/plant and 219.14 g/plant, respectively), tuber yield per plant (514.65 g/plant and 404.22 g/plant, respectively) and tuber yield per ha (18.92 tha-1 and 15.96 tha-1, respectively). Rabi season was found ideal for all sweet potato varieties with higher average tuber weight (188.96 g/plant) and tuber yield per ha (20.17 tha-1). Per cent contribution of total dry matter to tuber dry matter was more in Rabi season for Sree Arun and Sree Bhadra varieties. Among the varieties, Sree Arun can be recommended for Rabi and Summer seasons and Bhu Sona for Kharif season.

Establishment of a quality evaluation system of sweet potato starch using multivariate statistics.

The quality of starch greatly affects the quality of processed products. There are many indexes for quality evaluation of starch. Currently, amylose content is considered the chief index in the quality evaluation of sweet potato starch, which is entirely based on tradition (experience) method. The existing evaluation standards lack quality evaluation standards for sweet potato starch. To screen reasonable evaluation indexes of sweet potato starch, and establish a scientific and systematic evaluation system of sweet potato starch. Twenty-two components and quality indexes of sweet potato starch were measured. The evaluation indexes of sweet potato starch were screened based on a statistical description, correlation analysis, and principal component analysis (PCA), and a quality evaluation model of sweet potato starch for brewing was established based on analytic hierarchy process. The calculated values of the model were verified by linear fitting with standardized sensory evaluation values. The coefficient of variation of total starch content (%), amylose content (%), amylopectin content (%), L* value, ΔE, water absorption capacity (g/g), and pasting temperature was less than 6%, while the coefficient of variation of other indexes was larger. In addition, there were different degrees of correlation among the indexes. PCA was used to identify interrelated variables, and the first six principal components together account for 82.26% of the total variability. Then, seven core indexes - setback (cp), rate of regression (%), ratio of amylose to amylopectin (%), gel strength (kgf/cm2), a* value, ash content (%), and solubility (%) - were selected from the six principal components according to the load value of the rotation matrix. These seven core indexes replaced the original 22 indexes to simplify the evaluation of sweet potato starch. The quality evaluation model of sweet potato starch was Y = 0.034X2 + 0.321X6 + 0.141X8 + 0.08X17 + 0.023X19 + 0.08X21 + 0.321X22. The comprehensive evaluation system of sweet potato starch can accurately predict the quality of sweet potato starch. The development of such a system is of great significance to the post-harvest processing of high-starch sweet potato and the breeding of high-quality and high-starch sweet potato varieties.

Expression of the Sweet Potato MYB Transcription Factor IbMYB48 Confers Salt and Drought Tolerance in Arabidopsis.

Sweet potato (Ipomoea batatas (L.) Lam) is one of the most crucial food crops widely cultivated worldwide. In plants, MYB transcription factors play crucial roles in plant growth, defense regulation, and stress resistance. However, the regulatory mechanism of MYBs in salt and drought response remain poorly studied in sweet potato. By screening a transcriptome database for differentially expressed genes between the sweet potato variety Jingshu 6 and its mutant JS6-5 with high anthocyanin and increased tolerance to salt and drought stresses, we identified a R2R3-MYB gene IbMYB48, for which expression was induced by PEG6000, NaCl, abscisic acid (ABA), methyl jasmonic acid (MeJA), salicylic acid (SA) and H2O2. Particle-mediated transient transformation of onion epidermal cells showed IbMYB48 is localized in the nucleus. Transactivation activity assay in yeast cells revealed that IbMYB48 has transactivation activity, and its active domain is located in the carboxyl (C)-terminal region. Furthermore, expression of IbMYB48 confers enhanced tolerance to salt and drought stresses in transgenic Arabidopsis. The contents of endogenous ABA, JA, and proline in transgenic lines were higher than control, and the activity of superoxide dismutase (SOD) was significantly increased under salt and drought stress conditions. By contrast, the accumulation of malondialdehyde (MDA) and H2O2 were lower. Moreover, genes encoding enzymes involved in ABA biosynthetic pathway, JA biosynthesis and signaling pathway, and reactive oxygen species (ROS) scavenging system were significantly up-regulated in transgenic Arabidopsis under salt or drought stress. Altogether, these results suggest IbMYB48 may be a candidate gene for improvement of abiotic stress tolerance.

Allelopathic potential and competitive traits of sweetpotato cultivars

Allelopathy and competition are components of plant-plant interactions, delimiting the level of interference. Understanding this interaction has practical applications in agriculture. Crop cultivars possessing high allelopathic ability and competitive traits are themselves tools for sustainable weed management, enabling reduced use of herbicides. Greenhouse and field experiments were conducted to assess the weed suppressive ability of selected sweetpotato (Ipomoea batatas L.) cultivars. The effect of nine cultivars on Palmer amaranth (Amaranthus palmeri S. Watson), junglerice (Echinochloa colona L.), and hemp sesbania (Sesbania hederacea P. Mill.) was first evaluated in the greenhouse. The experiment was set up in a completely randomized design with four replications and conducted twice. Sweetpotatoes were cultured in sand. The target weeds were seeded in pots filled with a 2:1 mix of field soil:potting mix and watered with 100-ml aliquot of sweetpotato root leachates once every 2 d. Weed height and shoot biomass were measured. ‘Heartogold’, ‘Centennial’, and ‘Stokes Purple’ were the most allelopathic cultivars. Junglerice was most inhibited by sweetpotato leachates. Nine cultivars were evaluated in the field. Experiments were conducted at Fayetteville and Kibler, Arkansas, USA, in a split-plot design, with weed infestation (broadleaf spp., grass spp., or weed-free) as whole plot and the cultivars as split-plot. Across locations, ‘Beauregard-14’ had the longest vines, whereas ‘Hatteras’ and ‘Heartogold’ had the tallest canopy. ‘Heartogold’ had the largest leaf area. This cultivar reduced weed biomass 2- to 4-fold in both locations. Yield was reduced on average 55 and 68% with grass and broadleaf weeds across locations, respectively. ‘Beauregard-14’ and ‘Bayou Belle-6’were the high-yielding cultivars in Kibler and Fayetteville. The highest yielding cultivars were not the most weed suppressive but did not incur the highest yield loss from weed competition, indicating the ability to withstand weed interference. Cultivar competitiveness, weed-suppressive ability, and weed tolerance are important factors that should be considered before making a cultivar selection.

An Aquaponic System with Hydroponic Culture of Sweet Potato and Tilapia Culture

An integrated system with a hydroponic culture of sweet potato and tilapia culture was assessed as a new combination in aquaponics to investigate its potential and productivity. The first experiment was conducted inside a glasshouse using plastic tanks as water reservoirs to compare the growth and development of two sweet potato (Ipomoea batatas (L.) Lam.) varieties Beniazuma and purple sweet lord using hydroballs, granular plastics, cut rockwool, and rockwool blocks as supporting materials in hydroponic culture. The supporting material was placed inside plastic pots. Greater growth and development of the storage roots of sweet potatoes in both varieties were obtained in hydroballs. In the second experiment, four sweet potato varieties, Kokei 14, Suioh, Beniazuma, and Elegant summer, with hydroballs as the supporting material, were examined hydroponically with an integrated culture of tilapia fish in the pond. Two ponds were 7.7 m and 5.3 m, in length and width, respectively, and water depth was maintained at 0.38 cm. Styrofoam boxes with holes on the bottom side were used to culture sweet potato on the water surface. Nylon net containers filled with hydroballs were placed in the Styrofoam boxes. The variety Kokei 14 produced the greatest fresh and dry weights of storage roots and percent harvest index in both ponds, with and without fish. The number and diameter of the storage roots of Kokei 14 were higher. Tilapia fish were cultured in one of the two ponds and fed artificial feed. The average length and weight of tilapia fishes increased to 10 cm and 188 g, respectively, 143 days after culturing, and those were 1.8 and 6.9 times, respectively, greater than at the start. The integrated culture of sweet potato hydroponically on the water surface and tilapia in pond water increases the food production in a limited space and profitable.

Culinary Treatments Affect Sensory Attributes and Consumer Preference for Sweet Potato Cultivars

Food quality and taste preference are important factors influencing the production and adoption of sweet potato (Ipomea batatas L.) cultivars in a specific growing region. There is very limited published information available on the sensory attributes and quality profile of sweet potato cultivars grown in Canada, even though there is a substantial increase in both production and consumption over the last few years. This study analyzed five different culinary treatments on sweet potato sensory attributes along with taste preferences. Oven-baked, boiled, fried, steamed and mashed culinary treatments were found significantly different (P < 0.05) for mealiness, sweetness and for taste profiles. Sweet potato cultivars were significant different (P < 0.05) for taste and sweetness attributes. A non-significant difference was recorded for interaction between culinary treatments and the tested cultivars for bitterness, mealiness, sweetness and taste profile. Expert panel preferences significantly differed (P < 0.05) for boiled, fried and steamed culinary treatments for tested cultivars, whereas, no difference was observed for oven-baked and mashed sweet potatoes. Boiled, fried, steamed and mashed culinary treatments for ‘Covington’ were most liked by the panelists, followed by ‘Radiance’. These sensory analysis and preferences of tested sweet potato cultivars can provide a reference for the food processing industry in preparing sweet potatoes for Canadian consumer consumption and the study outcomes can be used to guide sweet potato variety development for specific quality traits.

Consumer acceptability of fried chips made from South African sweet potato cultivars

In South Africa, the processing of sweet potatoes has a high potential for economic gain, therefore, chips were prepared from six sweet potato cultivars with varying flesh colours for consumer preference evaluation. Scoring was based on colour, crispness, taste and overall ranking by four groups of a total of 159 people at distinct locations. Instrumental assessment included colour measurement of chips, and dry mass and total carotenoid content of fresh roots. Analysis of variance, principal component analysis and Pearson correlation analysis were performed. Significant differences were found in taste/flavour, crispness and overall consumer ranking as well as for all instrumental measurements among chips made from the different cultivars. Orange-fleshed cultivars Bophelo, W-119 and Beauregard had values of 108.27, 112.37 and 113.33 µg/g for total carotenoids, respectively. The six cultivars were grouped into three clusters based on overall consumer rating, crispness, carotenoid content, colour a*, taste/flavour, oxidation and dry mass, colour L* and appearance. The results indicate that cultivars Beauregard and Bophelo can be recommended for making fried chips for South African consumers.

TEMPO DE COLHEITA COMO MODULADOR DE FITOQUÍMICOS EM CULTIVARES DE BATATA DOCE PARA A INDÚSTRIA

ABSTRACT As a fresh food, sweet potatoes are highlighted for their taste and appearance. In the industry, they are valued for their starch and sugar content. In both scenarios, much attention has been given to the composition of bioactive compounds. The application of abiotic stresses seems to induce an overproduction of these compounds in some vegetables. The objective was to examine the influence of harvest time on the synthesis and accumulation of bioactive compounds in varieties of minimally processed sweet potatoes with different flesh colors. Sweet potato cultivars (Beterraba, Jerimum, Mãe de Família Roxa, and BRS Cuia) were harvested at 120, 150, and 180 days after planting, then subjected to minimal processing and stored at 5 ºC for 10 days. The most recommended time for harvesting sweet potatoes in semi-arid conditions for minimal processing by the industry is between 150 and 180 days. This is the period when the sweet potatoes exhibit the best quality for fresh consumption, as detected in ‘Mãe de Família Roxa’ and ‘Jerimum’. ‘BRS Cuia’ harvested at 120 days showed the highest phenolic compound levels, the highest polyphenol oxidase and peroxidase enzyme activities, and the most intense browning symptoms. In addition to its starch content, it can be used as a raw material for the extraction of phenolic compounds of interest. ‘Beterraba’ showed low sugar values, rendering them unfavorable for fresh consumption or minimal processing. However, this cultivar also exhibited a high content of carotenoids, making them bio-factories for the food and pharmaceutical industries.

Evaluation of released sweet potato [Ipomoea batatas (L.) Lam] varieties for yield and yield-related attributes in Semen-Bench district of Bench-Sheko-Zone, South-Western Ethiopia

Sweet potato is a significant root crop that can be used for both food and feed. Bench-Sheko zone mid-altitudes, in general, are among the most important sweet potato growing regions in southwest Ethiopia. During the 2017 and 2018 growing seasons, a study was carried out in the Semen-Bench district of the Bench-sheko zone, southwestern Ethiopia, to investigate the adaptability and performance of improved sweet potato varieties and to identify the best performer variety. A randomized complete block design with three replications was used to compare the performance of five improved (viz., Awassa-83, Beletch, Berkume, Kulfo, Tula) and one Local sweet potato variety. The results of both years and over year combined statistical analysis indicated that the varieties significantly varied in terms of all yield and yield-related traits. As a result, the Awassa-83 variety acquired the greatest values of average root diameter in both the 2017 (11.9 cm) and 2018 (10.1 cm) growing seasons, followed by the Berkume variety. In both 2017 and 2018 growing seasons and over year combined analysis, the highest average storage root length (21.5 cm), marketable storage root yield (29.06 ton/ha), total storage root yield (43.22 ton/ha), and storage root dry weight (42%) was recorded from variety Awassa-83. Variety Beletech and Berkume were found to be statistically similar and the next highest in terms of marketable storage root yield, and total storage root yield; moreover, variety Berkume was found to be the next highest in terms of storage root dry weight in two years combined result. On the other hand, the variety Beletech, which was closely followed by Awassa-83, had the highest average number of roots per plant (8.28) and the greatest number of marketable roots per plant (7.04). Therefore, considering overall traits Awassa-83 was found to be superior in overall performance and can be recommended for production in the study area and related agro-ecologies.

Identification, Characterization, and Conservation of Sweet Potato Germplasm (Ipomoea batatas L.) in West Sumatera Production Center

Sweet potato (Ipomoea batatas L.) is an important food crop in West Sumatra and potentially develops in suitable land conditions to produce various snack food industries. As one of the sweet potato production centers in Indonesia, West Sumatra has a very high diversity of germplasm. Unfortunately, the information on this diversity is not yet available. In fact, this information is pivotal to develop and produce new high-yielding sweet potato varieties. This study characterized 109 sweet potato accessions from four sweet potato production centers in West Sumatra. To find out more about the differences in each sweet potato accession, molecular identification and characterization were carried out. The second year of the research was a follow-up study to obtain (1) molecular information about the genetic diversity of sweet potatoes in the West Sumatra production centers by using the RAPD technique, (2) the collections of local varieties of sweet potato with potentially superior varieties and genetic sources of several traits or important characters, and (3) a database of kinship/genetic similarity of sweet potato varieties. The results have shown that 79 of 80 morphological characterization varieties have genetic differences. The dendrogram denotes that the accessions vary with a coefficient between 0.15 - 0.20 and are classified into 7 groups with a range of 2-38 accessions.

The Application of Nitrogen Source in Regulating Lignin Biosynthesis, Storage Root Development and Yield of Sweet Potato

The understanding of the effects of nitrogen sources on lignin synthesis in sweet potato during storage root formation is limited. In this study, we investigated the effects of different nitrogen source on sweet potato storage root formation and development, as well as lignin synthesis in potential storage roots. The sweet potato cultivars Shangshu 19 and Jixu 23 were used in field experiments in 2019 and 2020. Three treatments were tested: (a) no nitrogen fertilizer application (control); (b) 60 kg hm−2 ammonium nitrogen; and (c) 60 kg hm−2 amide nitrogen. The results indicate that during sweet potato storage root formation, ammonium nitrogen significantly enhanced root activity compared to that of the control. The ammonium nitrogen treatment promoted IbEXP1 and inhibited Ibkn1 and Ibkn2 expression during the early stages of storage root formation, then increased gibberellic acid and decreased zeatin riboside content, enhanced phenylalanine ammonia lyase and peroxidase activities, and promoted lignin synthesis in potential storage roots. The opposite effects of ammonium nitrogen treatment on gene expression, hormone contents, and enzyme activity were observed in the late stages of storage root formation. Relative to the control, the ammonium nitrogen treatment significantly increased the number of storage roots during canopy closure. The ammonium nitrogen treatment produced the highest storage root yield and number of storage roots per plant. These results indicated that the ammonium nitrogen can inhibit root lignin synthesis, then promote storage root formation and increase the yield of sweet potato.