Within the framework of a project entitled “Development of Advanced Sweet Potato Cultivation Technology for Smallholder Farmers in Paraguay” implemented by KOPIA Paraguay Center (Korea Partnership for Innovation of Agriculture) in collaboration with Paraguayan Institute of Agricultural T echnology (I PTA) d uring the period 2021-2024, r esults o f four m ain e xperiments are described in this research: selection of suitable varieties, optimal planting and harvesting times, the use of ridges, and optimal chemical fertilization doses. In the selection of suitable varieties for Paraguay, 11 sweet potato varieties were evaluated in departments of San Pedro and Misiones. As a result, varieties Andaí, Jety Paraguay, and Chaco I showed the highest productivity in San Pedro, while varieties Jety Uruguayo, Chaco I, and Taiwanés showed higher productivity in Misiones. The other three experiments were carried out in San Pedro only. Optimal planting and harvesting times were determined with three varieties: Andaí, Pyta Guasu, and Jety Paraguay. For Andaí and Jety Paraguay varieties, they should be planted in December and harvested at 122 days post planting (DPP). For Pyta Guasu, it should be planted in October and harvested at 124 DPP. Regarding productivity response with soil preparation methods, the use of ridges showed higher yields in all planting methods, with the curved method planting being the most productive. Finally, optimal chemical fertilization doses were established in order to improve the total yield. The optimal nitrogen fertilizer dose (urea 45% N) was 40 kg/ha. The optimal phosphorus fertilizer dose (triple superphosphate 45% P2O5) was 80 kg/ha and the optimal potassium fertilizer dose (potassium chloride 60% K2O) was 120 kg/ha.

Sweet potato (Ipomoea batatas L.) is an essential crop in the Paraguayan diet. It plays a crucial role in food security. It is a source of income for family agriculture. It has a significant potential to adapt to various climatic and soil conditions in Paraguay, making it a promising crop for improving productivity. However, Paraguay faces a deficit in the development of sweet potato cultivation technology, resulting in a low productivity of 5.3 ton/ha. Efforts have been made to collect and characterize sweet potato genotypes, covering a diversity of native varieties. These efforts have laid the groundwork for future sweet potato research and development. Still, ongoing research and development of strategies are needed to address existing challenges of improving genetic resource traits and developing cultivation technology and to fully exploit growth opportunities in this sector. This review summarizes sweet potato cultivation in Paraguay, focusing on several key technical aspects. It analyzes current market situation and production conditions as well as the availability of genetic materials adapted to different ecoregions. Additionally, it explores prospects for the development of advanced sweet potato crops, including the production of high-quality, virus-free sweet potato plants with improved productivity.

The key to invasive pest management lies in preemptive action. However, most current research using species distribution models is conducted after an invasion has occurred. This study modeled the potential distribution of the globally notorious sweet potato pest, the sweet potato weevil (Cylas formicarius), that has not yet invaded Korea using MaxEnt. Using global occurrence data, bioclimatic variables, and topsoil characteristics, MaxEnt showed high explanatory power as both the training and test areas under the curve exceeded 0.9. Among the environmental variables used in this study, minimum temperature in the coldest month (BIO06), precipitation in the driest month (BIO14), mean diurnal range (BIO02), and bulk density (BDOD) were identified as key variables. The predicted global distribution showed high values in most countries where the species is currently present, with a significant potential invasion risk in most South American countries where C. formicarius is not yet present. In Korea, Jeju Island and the southwestern coasts of Jeollanam-do showed very high probabilities. The impact of climate change under shared socioeconomic pathway (SSP) scenarios indicated an expansion along coasts as climate change progresses. By applying the 10th percentile minimum training presence rule, the potential area of occurrence was estimated at 1,439 km2 under current climate conditions and could expand up to 9,485 km2 under the SSP585 scenario. However, the model predicted that an inland invasion would not be serious. The results of this study suggest a need to focus on the risk of invasion in islands and coastal areas.

This study investigated the antioxidant characteristics of sweet potato according to different plant parts and drying methods. The sweet potato plant parts were divided into root tubers, stems, stalks, leaves, and tips, and the drying methods were freeze-drying and hot air drying. Total polyphenol and flavonoid contents and radical scavenging activity of the sweet potato plant parts were significantly different depending on the plant parts and drying methods. The total polyphenol content of freeze-dried sweet potato leaves and tips were 52.76 and 46.19 mg chlorogenic acid equivalents/g sample, and the total flavonoid contents were 222.47 and 214.12 mg quercetin equivalents/g sample, respectively, and decreased with hot air drying. DPPH radical scavenging activity was higher in freeze-drying than hot air drying and was significantly different depending on the plant parts. The ABTS radical scavenging activity of freeze-dried sweet potato leaves and tips were 43.48 and 44.68 mg Trolox equivalents/g sample, respectively, and decreased with hot air drying. Therefore, additional studies on the functionality of using by-products from sweet potato cultivation are needed.

As the average temperature on Earth increases due to global climate change, crops are further needed to overcome this issue. Since sweet potato has high yield potential, can grow in harsh environments, and contains abundant nutrients, it is a potential substitute food in response to environmental crises. Compared to grains such as rice and barley, sweet potato has a lower glycemic load and contains various natural antioxidants, showing a variety of physiological functions. Thus, sweet potato is in the spotlight as a healthy food. Although domestic sweet potato production continued to decrease from 1990 to 2010, its production was maintained or slightly increased until 2020 due to the changes in consumers’ dietary habits that emphasize health. In this regard, steamed or roasted sweet potatoes were consumed as a snack substitute in the previous eating form. Furthermore, sweet potato starch has been used in various industries, including food. Therefore, this study intends to discuss the value of sweet potatoes as food, the production trend and cultivation method of sweet potatoes in South Korea, and the industrial application of sweet potatoes.

This study was performed to evaluate the quality characteristics and antioxidant activity of Nurungji by varying the purple sweet potato powder addition time (AR: added after rice cooking, BR: added before rice cooking) and powder ratio (0, 2, 4, 6, 8%) on the prepared rice during Nurungji’s manufacturing. In both AR and BR samples, water binding capacity, soluble solid content, reducing sugar, and hardness increased with an increasing proportion of purple sweet potato powder; however, the pH and moisture content decreased. The L value and b value decreased and increased with the influence of anthocyanin in purple sweet potato powder. The total polyphenol, flavonoid, anthocyanin contents, DPPH, and ABTS radical scavenging activity were highest in Nurungji with 8% of purple sweet potato powder. Moreover, AR samples showed higher antioxidant activity than BR samples. Based on the study results above, the preparation of Nurungji with 8% purple sweet potato powder by AR process was more favorable based on the content of antioxidants and antioxidant activity.

This study examined the quality characteristics of Makgeolli to investigate the availability of Korean sweet potato cultivars as alcoholic beverages. The following sweet potato varieties were used: Gogunmi, Daeyumi, Shingunmi, Shinyulmi, Shincheonmi, Jinyulmi, Jinhongmi, Jeungmi and Pungwonmi; their alcohol contents ranged from 12.20% to 14.20%, with the lowest value in Makgeolli made with Jeungmi and the highest value in Makgeolli made with Jinhongmi. The DPPH radical scavenging activity was in the range of 37.51~77.02%, with the lowest value in Makgeolli made with rice (control) and the highest value in Makgeolli made with Gogunmi. As a result of analyzing the aroma component of sweet potato Makgeolli, 27 kinds of aroma components were detected, and six kinds of alcohols, 13 kinds of esters, four kinds of acids, and four kinds of other compounds were found. Regarding the number of aroma compounds, Makgeolli made with Shinyulmi showed the lowest number with 14 kinds, while Makgeolli made with Pungwonmi showed the highest number with 27 kinds.

In this study, the effects of heat-moisture treatment (boiling or steaming for 45 min) prior to hot air drying (70 o C for 8 h) on water activity (Aw), moisture (MC), Brix, color, and texture of dried sweet potato slices were investigated to identify the best pretreatment condition for producing dried sweet potato with the best eating quality. Dried sweet potato slices pretreated by boiling (BL) showed significantly lower Aw, MC, and hardness while Brix was significantly higher than with steaming (ST) treatment. There were no significant differences for the color, springiness, cohesiveness, gumminess, and brittleness indexes. At 8 h drying, the Aw, MC, Brix, and hardness of the BL and ST samples were 0.81 and 0.82, 19.71% and 25.53%, 53.80% and 49.40%, and 20.49 kg/cm 2 and 31.98 kg/ cm 2 , respectively. This information will be useful for manufacturers in the production of dried sweet potato slices. These findings provide evidence of the feasibility of heat-moisture treatments in the production of dried sweet potato.

A new WRKY transcription factor gene was isolated by ESTs screening from a cDNA library of suspension cultured cells of Sweet potato (Ipomoea batatas). The 2,285 bp cDNA fragment, IbWRKY, was sequenced, from which a 505 amino acid residue protein was deduced. A search of the protein BLAST database identified significant similarity to other plant WRKY31 protein sequences. RT-PCR analysis showed expression patterns of IbWRKY31 in various intact tissues and suspension cultured cells of Sweet potato, and in leaves exposed to different stresses. The IbWRKY31 gene was highly expressed in suspension cultured cells. In leaf tissues, IbWRKY31 showed strong expression during salicylic acid and methyl jasmonate treatments. Expression of IbWRKY31 was also induced under various abiotic stress and pathogen infection conditions, such as wounding, H2O2, MV, PEG, NaCl, and bacterial pathogen infection. These results suggest that IbWRKY31 is involved in plant responses to various stress conditions, such as abiotic stresses and pathogen infection through a defense signaling pathway.

Pumpkin sweet potato (Ipomoea batas L.) has been known as a traditional remedy and food source, not only in South Korea but worldwide. It is rich in fiber, potassium, vitamin C, and other minerals and vitamins, making it a nutritional food loved by many. showed that pumpkin sweet potato had antioxidant biological effects. The in vitro study showed that both splenocytes and cytokine production byactivated peritoneal macrophages increased when water extracts were supplemented at 100 and 250 μL/mL. Notably, the production of IL-1β, TNF-α, and IFN-γ by splenocytes was significantly increased at 100 μL/mL. The results suggest that supplementation with pumpkin sweet potato (Ipomoea batas L.) water extract may enhance immune function by stimulating splenocyte proliferation and improving cytokine production, activating macrophages in vitro.

고구마 바이러스 무병묘의 기내급속증식을 위한 적정 생장 조절물질 및 sucrose 농도, 최소생장 기내보존(15°C)에 미치는 광의 영향과 생존율 및 기내생장 특성 등을 조사하였다. 고구마 무병묘의 마디배양은 0.2mg·L-1 BA 첨가배지에서 줄기신장, 줄기직경, 잎수, 뿌리수, 생체중 및 건물중 등이 가장 양호하였다. 배양부위 및 배지물리성에 따른 적정 sucrose 농도는 마디배양은 5% sucrose를 첨가한 고체배지에서, 정단배양은 3% sucrose를 첨가한 액체배지에서 줄기두께, 잎수, 뿌리수, 뿌리길이, 생체중 및 건물중 등의 생육에 가장 효과적이었다. 15°C 저온항온기에서 고구마 무병묘의 최소생장 기내보존은 암상태에서는 3개월 내에 모두 고사하였으나, 적색:청색(7:3) 혼합 LED (150±5μmol·m-2·s-1 PPFD)에서는 5개월까지 100% 생존하였다. 따라서 고구마 무병묘의 최소생장 기내보존에는 광이 필요하며, 샬레에 밀식(10 개체/샬레)할 경우, 좁은 공간에서 대량보존이 가능하였다.

본 연구는 돈분액비에 화학비료를 첨가한 양분조정 맞춤액비 시용효과를 평가하기 위하여 기존의 3요소 단비 처리 및 돈분 맞춤액비 시용에 따른 고구마 생육과 수량 그리고 품질에 미치는 효과 등을 평가하였다. 돈분액비구의 10a당 괴근수량은 관행 화학비료 재배구(2,966 kg/10a)보다 약 5% 감수되었으나, 양분조정 맞춤액비 처리구 (NBSLM)에서는 3,217 kg/10a로 관행시비구(CF)와 돈분액비 시용구(SLM)에 비하여 각각 8, 14% 높았다. 관행시비구에 비하여 8% 높았다. 고구마 유리당 함량은 양분조정 맞춤액비구 (NBSLM)에서 6,11%로 관행재배구의 3,11% 보다 높았다. 특히 sucrose 함량이 양분조정 맞춤액비 시용구가 대조구보다 높았다. 고구마의 색도(Hunter value)를 조사한 결과 적색도의 정도를 나타내는 a값은 양분조정 맞춤액비(NBSLM)가 화학비료구보다 높았다. 결과적으로 양분조정 맞춤액비 시용 (NBSLM)은 고구마 괴근 수량이 돈분액비 시용구(SLM)에 비하여 14% 높은 수량 증수와 고구마 유리당 함량 증가, 고구 마의 적색도(a값) 증가에 의한 품질 향상 증대 뿐만아니라 화학비료를 대체할 수 있을 것으로 판단되었다.

The purpose of this study was to investigate the quality and antioxidant properties of three fermented sweet potato cultivars (Shinyulmi, Hogammi, and Shinjami) using lactic acid bacteria. During the fermentation, the pH was lowered and the titratable acidity increased. The viable cell counts of lactic acid bacteria increased 8.44-9.62 log CFU/g. Organic acid content (especially lactic acid) of sweet potatoes increased by fermentation. Also, γ-Aminobutyric acid increased more than 8.6 times by fermentation in all samples. The total polyphenol and flavonoid contents of sweet potato, showed insignificant changes in all samples by fermentation. ABTS radical scavenging activity of all samples slightly decreased by fermentation, but not significantly. DPPH radical scavenging activity decreased slightly by fermentation except Shinyulmi. However, when compared with the varieties, Shinjami showed the highest activity. The reducing power of Shinjami decreased slightly by fermentation, but activity was the highest among all samples. Based on these results, most of the chemical properties and functionality of fermented sweet potato are retained after fermentation, although some antioxidant activity decreases. We suggest that three fermented sweet potato cultivars (Shinyulmi, Hogammi, and Shinjami) using lactic acid bacteria can be used in various applications because of their effective functional properties.

본 연구에서는 고구마(Ipomoea batatas L.) 수확 후 버려지는 잔재물의 활용가치를 위해 이들로부터 추출한 발효 추출물과 열수 추출물의 생리활성과 세포독성을 분석 하였다. 추출물의 pH는 모두 산성을 나타내었고, 유기물 함량은 발효 추출물과 열수 추출물에서 각각 0.98%와 0.97%로 비슷하게 나타내었다. 다량원소 중 인산, 칼륨, 칼슘, 마그네슘 성분의 함량은 열수 추출물에서 발효 추출물보다 모두 높게 나왔고, 질소 함량만 두 추출물에서 동일하게 나왔다. 미량원소 함량은 아연을 제외하고 발효 추출물보다 열수 추출물에서 높게 나타내었다. 총 폴리페놀 함량은 열수 추출물에서 60.5±2.7 mg/g로서 발효 추출물의 총 폴리페놀 함량의 22.7±4.2 mg/g 보다 37.8 mg/g 높은 함량을 나타내었다(p<0.05). 총 플라보노이드 함량은 열수 추출물에서 50.7±2.7 mg/g로서 발효 추출물의 함량인 14.0±2.1 mg/g 보다 36.7 mg/g 높은 함량을 나타내어 총 폴리페놀 함량과 마찬가지로 열수 추출물이 발효 추출물보다 높은 함량을 나타내었다(p<0.05). DPPH와 ABTS radical 소거능력은 모두 열수 추출물에서 발효 추출물 보다 높은 항산화력을 보였다(p<0.05). MTT assay를 이용한 추출물의 세포독성 실험에서는 두 추출물의 모든 농도에서 세포독성이 미약한 것으로 확인되었다. 따라서 고구마 수확 후 잔재물의 추출물이 향후 각종 바이오 소재로 이용 시에도 큰 문제가 없을 것이라 판단된다.