Sweet Potato Cultivation Research Articles

The origins of Amazonian landscapes: Plant cultivation, domestication and the spread of food production in tropical South America

During the last two decades, new archaeological projects which systematically integrate a variety of plant recovery techniques, along with palaeoecology, palaeoclimate, soil science and floristic inventories, have started to transform our understanding of plant exploitation, cultivation and domestication in tropical South America. Archaeobotanical studies are providing a far greater appreciation of the role of plants in the diets of early colonists. Since ∼13ka, these diets relied mainly on palm, tree fruits, and underground tubers, along with terrestrial and riverine faunal resources. Recent evidence indicates two areas of precocious plant cultivation and domestication: the sub-Andean montane forest of NW South America and the shrub savannahs and seasonal forests of SW Amazonia. In the latter area, thousands of anthropic keystone structures represented by forest islands show a significant human footprint in Amazonia from the start of the Holocene. While radiocarbon date databases show a decline in population during the middle Holocene, important developments happened during this epoch, including the domestication of cacao, the adoption of maize and the spread of manioc across the basin. The late Holocene witnessed the domestication of rice and the development of agricultural landscapes characterised by raised fields and Amazonian Dark Earths (ADEs). Our multi-proxy analysis of 23 late Holocene ADEs and two lakes from southern Amazonia provides the first direct evidence of field polyculture agriculture including the cultivation of maize, manioc, sweet potato, squash, arrowroot and leren within closed-canopy forest, as well as enrichment with palms, limited clearing for crop cultivation, and low-severity fire management. Collectively, the evidence shows that during the late Holocene Amazonian farmers engaged in intensive agriculture marked by the cultivation of both annual and perennial crops relying on organic amendments requiring soil preparation and maintenance. Our study has broader implications for sustainable Amazonian futures.

Evaluation of yield and nitrogen utilisation with urease and nitrification inhibitors in sweet potato crop (Ipomoea batatas L.)

Abstract Sweet potato (Ipomoea batatas L.) is a new tuber crop grown in Greece. It constitutes an innovative dietary component for both humans and animals, due to its nutritional properties. The cultivation of sweet potato focuses on the growth of both tubers and plants. Nitrogen is considered an essential element for almost all crops. This study set out to compare the effect of nitrogen inhibitors on yield components of sweet potato. In the literature, it is stated that in sweet potato cultivation nitrogen mainly affects the plants’ growth such as the tuber's yield and some quality characteristics such as dry matter and protein content. To furthermore explore this particular area, field experiments took place in West Greece, during the years 2018 and 2019. Several urea combination treatments were used in the experimental process. The treatments were urea (46-0-0), urea with urease inhibitor (UI), urea with nitrification inhibitor (NI), urea with double inhibitors (UI + NI) and control (without fertilizer) in a randomised complete block design. Leaf area index (LAI) was significantly affected by the fertilizer marking the highest value of 5.35 under urea + UI + NI treatment. Marketable yield was profoundly affected by the fertilizer in the experimental years and ranged from 18,180 to 23,230 Kg · ha−1 whereas non-marketable yield was not affected by the fertilizer. A considerable impact of fertilizers was noticed on yield where the highest value was 30,923 Kg · ha−1 under urea + NI + UI treatment. The percentage of nitrogen on tubers and upper parts was significantly affected by the fertilizers. Nitrogen markers, such as nitrogen use efficiency (NUE), nitrogen harvest index and nitrogen agronomic efficiency (NAE), were used to evaluate nitrogen release. A significant positive correlation was noticed between marketable yield and NUE (0.774). Also, the significant increase in yield showed a positive correlation with NAE (0.727). For yield components of sweet potato, the highest values were observed in urea with double inhibitors treatment in both experimental years.

Pengaruh Pengaturan Komposisi Media Tanam Organik Terhadap Pertumbuhan Dan Hasil Tanaman Ubi Jalar ( Ipomoea batatas L.) Dengan Sistem Tabilampot

Sweet potatoes are an alternative source of carbohydrates that have high nutritional content. Development of sweet potato cultivation methods needs to be done to overcome the decrease of productive agricultural land due to land conversion. This study aimed to test the effect of differences in the composition of the growing media on the growth, yield, and quality of sweet potato. This study was a pot experiment using a Randomized Block Design (RBD) with 7 treatments and 5 replications. The types of treatments tested were P0: 100% soil + inorganic fertilizer; P1: 50% soil + 50% cow manure; P2: soil 50% + vermicompost 50%; P3: soil 50% + biochar rice husk 25%, cow manure 25%, P4: soil 50% + biochar rice husk 25% + vermicompost 25%, P5: soil 50% + cocopeat 25% + cow manure 25%, P6: soil 50% + cocopeat 25% + vermicompost 25%. The research results showed that the composition of the growing medium significantly affected plant growth and yield. The results of the statistical analysis showed that the treatments of P4 and P6 gave the highest growth, while the high yield of fresh weight of tubers per pot were found in the treatments P1, P2, P3, and P4 by 165.59 g, 143.38 g, 171.56 g, and 144.80 g, respectively. The highest number of tubers was found in treatment P6 by 7.66 tubers. The highest yield of dry matter was also found in treatments P1, P2, P3, and P4 by 59.91 g, 51.73 g, 59.02 g, and 48.59 g, respectively. Based on the research results, it can be recommended that the cultivation of sweet potato plants in pots can be carried out using porous growing media in a container that is sufficient and available balanced nutrients for the development of plant tubers.Keywords: Vermicompost, composition of growing media, Sweet Potatoes, Yield, Quality

Efforts to increase production sweet potato as raw materials Kaya Beta Karoten flour by using compost baglog mushroom waste

Research-based community partnership program activities involve two partners, namely the Murti Lestari Farmer Group and Agrina Creation UKM in Helvetia Village, XI Gang Sawit Hamlet, Labuhan Deli District Deli Serdang Regency. This dedication activity is the application of the results of research that had been carried out two years earlier which was USU's Talent Grants in 2017 and 2018. The problem faced was the lack of understanding of oyster mushroom baglog waste management techniques that have the potential to pollute the environment, on the other hand the farmer group Murti Lestari also experienced difficulties in increasing the quantity and quality of sweet potato production which is also widely cultivated in this village. The low interest of farmers is also encouraged because of the low price of sweet potato products and a relatively limited shelf life. The method implemented for training and discussion, accompanied by the practice of making compost from mushroom baglog waste, the practice of preparing planting material in the form of local sweet potato clones with high beta carotene content, compost application in sweet potato cultivation, maintenance to harvesting and post-harvest process using processing equipment into sweet potato flour rich in beta carotene and various other processed food products. Activities that have been carried out are training on composting of baglog mushroom waste using compost counting machines and bioactivators introduced in this activity so that the composting process goes faster, training on technical culture of orange sweet potato cultivation by applying mushroom baglog compost, training on mushroom making mushrooms and composting Oyster mushroom cultivation using shelves made of mild steel and fogging using a sprayer. Production and quality of yields of sweet potatoes that were given compost baglog oyster mushroom waste increased compared without the provision of compost. The next crop is processed into sweet potato flour with high beta carotene content and various food products using an introduced machine, which is a sweet potato slicing machine, flour machine, macaroni making machine and equipment for making sweet potato flour based food processing products.

Development of novel detection system for sweet potato leaf curl virus using recombinant scFv

Sweet potato leaf curl virus (SPLCV) causes yield losses in sweet potato cultivation. Diagnostic techniques such as serological detection have been developed because these plant viruses are difficult to treat. Serological assays have been used extensively with recombinant antibodies such as whole immunoglobulin or single-chain variable fragments (scFv). An scFv consists of variable heavy (VH) and variable light (VL) chains joined with a short, flexible peptide linker. An scFv can serve as a diagnostic application using various combinations of variable chains. Two SPLCV-specific scFv clones, F7 and G7, were screened by bio-panning process with a yeast cell which expressed coat protein (CP) of SPLCV. The scFv genes were subcloned and expressed in Escherichia coli. The binding affinity and characteristics of the expressed proteins were confirmed by enzyme-linked immunosorbent assay using SPLCV-infected plant leaves. Virus-specific scFv selection by a combination of yeast-surface display and scFv-phage display can be applied to detection of any virus.

Studi Potensi Ubi-Ubian Spesifik Lokal dan Upaya Pengembangannya Dalam Mendukung Kemandirian Pangan di Provinsi Bengkulu

<p>To support food resilience it is felt necessary to do an inventory of any lokal specific plant is cultivated mainly in the form of crop growers of potatoes in order to develop its potential, because if not preserved such commodities are feared will become extinct and the community remains dependent on food rice. The objective of this research was to know the existence and distribution of potential cassava to support community food resilience in Bengkulu Province, know lokal specific cassava cultivation techniques and how much potential land can be developed to support food resilience in Bengkulu Province. This research was conducted at Regency of Rejang Lebong and Regency of Kepahiang, Province of Bengkulu from January-April 2019. The method of this research were observation approach, (interviews using questionnaires, dept interview and Focus Group Discussion (FGD). The selection of sample location research done by purposive sampling with consideration of the potential growth of the plant tubers. The result showed that in Bengkulu turned out for lokal specific crop potential was sweet potatoes. From 10 countries in Bengkulu, sweet potatoes spread across 7 districts namely Seluma, Mukomuko, Kaur, Central Bengkulu, Kepahiang, Lebong and Rejang Lebong. The potential of land that can be developed for the sweet potato cultivation based on the assumption of the existence of land in location of research there were as many as 6,407.0 ha or 0.33% of the land area of Bengkulu province.</p>

New sweet potato cultivation method for quality tuber production in home gardens

New sweet potato cultivation method for quality tuber production in home gardens

Understanding the Implications of Alternative Bioenergy Crops to Support Smallholder Farmers in Brazil

Smallholders constitute more than three quarters of the world’s farmers, and despite their numbers, they commonly lack opportunities to advance their development status. Bioenergy production and consumption can help sustain smallholders’ energy needs and generate employment and income, but it also raises concerns over social justice and equity, especially where crops used for bioenergy could also be used for food. This perspective paper is grounded in a literature review related to three different crops in Brazil: sugarcane, landrace maize and sweet potato. It seeks to determine if these crops offer the potential to support smallholder farmers’ development in a more equitable way, focusing on opportunities for their use in bioenergy. We review the literature to identify policies shaping the smallholder development context in relation to these crops, assessing whose knowledge informs policy and institutional decision making, and highlighting the policy attention afforded to the different crops from different sectors. We further evaluate the literature on each crop in relation to water use and calorific value (i.e., food and energy). Our review indicates that while sugarcane has received the most policy and institutional attention, its development is largely anchored in research and development investments that support large-scale commercial farms and agri-businesses. Smallholders have not benefited or had the opportunity to engage in relevant policy decision making for sugarcane cultivation. At the same time, smallholders hold valuable untapped knowledge on the cultivation of sweet potato and landrace maize, both of which have the potential to generate development opportunities for smallholders. Our review suggests that the environmental impact of landrace maize and sweet potato in terms of water use is significantly lower than sugarcane, while they can generate more calories for energy or food consumption and offer diversification opportunities. Despite that these alternative crops offer considerable untapped potential to support rural development, more research is still needed to harness these benefits. Changes are needed to address inequities in policies, institutions and the types of knowledge informing decision making. Such changes need to afford smallholder farmers greater recognition and participation in decision making, so that the distribution of benefits from the three study crops can reach them to support their development better.

Community Empowering through Tubers Crop Cultivation with its Compost Applications And Its Processing Technology

Tuber crops (cassava and sweet potato) are potential sources of food that are widely used by the community. The demand for large quantities of potatoes increases every year. Therefore,we need to increase productivity. The purpose of this action research is to encourage student empathy to contribute and solve the problem in society by applying research results to improve the yield of tubers (cassava and sweet potato) through community service program which is named KKN-PPM. The methods applied by encouraging and motivating farmer groups, community leaders and small-processing industries. The activities are: 1) counseling, 2) training and 3) demonstration of compost application on sweet potato cultivation and cassava in farmer's land 4) manufacturing of various cassava processed products and 5) the application of packaging to products. The results of this KKN-PPM program are: 1) Increased awareness and empathy of students on economic, social and cultural issues so as to increase the income of the people; 2) The occurrence of partnerships between students who have various skills and technology so that can be realized a good cooperation to empower the community in cultivation of tubers and its processing; 3. increasing knowledge and technology among the cultivators and processors of tuber crops and packaging improvements so as to increase the selling price. 4. Positive response which is given by the community in the form of active participation and enthusiasm in following the activity from the beginning to end of the implementation.

English

Creating a nursery for sweet potato cultivation in tropical and subtropical areas including Okinawa is not necessary because planting is possible throughout the year. In general, sweet potato blooms under natural conditions in tropical and subtropical areas. Sweet potatoes are grown from non-flowering slips, which farmers generally select from a field of a previous cropping. Although the selection and collection of non-flowering slips are very time-consuming, the effect on yield when flowering slips are used is unknown. This study sought to investigate the effect of flowering on sweet potato yield. The results revealed no significant difference in yield between flowering and non-flowering slips. This can significantly reduce the preparation time of slips, shorten the working time of the farmers and is useful for sweet potato cultivation in tropical and subtropical areas. Key words: Convolvulaceae, sweet potato cultivation, weevil damage. &nbsp

Diversity Analysis of Sweet Potato Genetic Resources Using Morphological and Qualitative Traits and Molecular Markers.

The European Union (EU) market for sweet potatoes has increased by 100% over the last five years, and sweet potato cultivation in southern European countries is a new opportunity for the EU to exploit and introduce new genotypes. In view of this demand, the origins of the principal Italian sweet potato clones, compared with a core collection of genotypes from Central and Southern America, were investigated for the first time. This was accomplished by combining a genetic analysis, exploiting 14 hypervariable microsatellite markers, with morphological and chemical measurements based on 16 parameters. From the molecular analyses, Italian accessions were determined to be genetically very similar to the South American germplasm, but they were sub-clustered into two groups. This finding was subsequently confirmed by the morphological and chemical measurements. Moreover, the analysis of the genetic structure of the population suggested that one of the two groups of Italian genotypes may have descended from one of the South American accessions, as predicted on the basis of the shared morphological characteristics and molecular fingerprints. Overall, the combination of two different characterization methods, genetic markers and agronomic traits, was effective in differentiating or clustering the sweet potato genotypes, in agreement with their geographical origin or phenotypic descriptors. This information could be exploited by both breeders and farmers to detect and protect commercial varieties, and hence for traceability purposes.

Changing Pattern in Sweet Potato Cultivation in Semi-Arid Environment, Nigeria

Sweet potato, an herbaceous perennial vine is a sweet tasting tuberous root vegetable. Its importance lies on its sweetness and nutritional value. The varieties ranged from wild accessions to farmer varieties. In this study, thechanging pattern in sweet potato cultivation in the semi-arid environment in Nigeria is examined. Questionnaire was administered to 450 respondents from 15 agricultural settlements in 15 local governments in the study area, using clustered sampling technique. Data was analyzed using frequency counts, percentage and pairwise t-test. Results show twenty-seven varieties of sweet potatoes were cultivated in the basin, with 19 varieties planted in 1970’s and 24 varieties cultivated in 2000’s. Farmers no longer plant 3 varieties while 8 varieties were newly introduced. The farmers planting these varieties ranged from 0.2% to 20%. The planting of 7 varieties have reduced while there is an increase in the planting of 9 varieties. White sweet potato was the most popular and widely planted varieties, accounting for 18% and 20% in the 1970’s and 2000’s respectively. Factors that determine choice of the varieties planted include farmers’ choice of sweet potatoes is determined by nutritional value, skin colour, flesh colour, taste, size, personal preference, market value, demand, yield, appearance as well as resistance to pests and diseases. Farmers cultivating sweet potatoes in the basin have increased by 1.4% from 82.3% in 1970’s to 83.7% in 2000’s. Pairwise t-test showed that there is no significant difference in sweet potatoes varieties cultivated between 1970's and 2000's.Keywords: sweet potato, varieties, farmers, changing pattern, Sokoto-Rima River Basin

Recent research on enhanced resistance to parasitic nematodes in sweetpotato

Sweetpotato yields are affected by diverse environmental factors, such as viruses, fungal diseases, and parasitic nematodes. In particular, plant–parasitic nematodes are major pathogenic factors affecting sweetpotato cultivation regionally. Sedentary endoparasitic nematodes, including root-knot nematodes and cyst nematodes, cause serious sweetpotato yield losses in northeast Asia, including South Korea, China, and Japan. In this review, we describe the current status of research on nematode resistance in sweetpotato and molecular methods for resolving these cultivation problems. Conventional breeding and molecular techniques, including genome-editing-based transgenic technology and omics-based analyses, should be combined to develop sweetpotato cultivars with improved resistance to various important nematodes.

Genome-Wide Association Studies (GWAS) for Yield and Weevil Resistance in Sweet potato (Ipomoea batatas (L.) Lam).

We apply the GWAS to sweet potato genome, and identified the SNPs associated with yield and weevil resistance. The sweet potato (Ipomoea batatas (L.) Lam) is a highly heterozygous, outcrossing, polyploid species, which presents challenges for genetic analysis. Therefore, we considered that genome-wide association studies (GWAS) may be applied to the study of the sweet potato genome. The yield of two sweet potato varieties [Purple Sweet Lord (PSL) and 90IDN-47] was assessed at two locations (Kumamoto and Okinawa prefectures) in Japan in 2013 and the yield scores were used for GWAS. The results showed that there were several single nucleotide polymorphisms (SNP) above the significance thresholds in PSL; two peaks were detected in Kumamoto and Okinawa on the Ib03-3 and Ib01-4 linkage groups of PSL, respectively. As for 90IDN-47, one relatively high peak was detected in Kumamoto on the Ib13-8 linkage group. Interestingly, although high peaks above significance thresholds were detected in Kumamoto and Okinawa in PSL, the peaks were located in different linkage groups. This result suggests that the genetic regions controlling yield may change in response to environmental conditions. Additionally, we investigated the degree of weevil damage to the plants, which is the greatest problem in sweet potato cultivation in Okinawa. In this experiment, no SNPs were identified above the significance thresholds. However, one relatively high peak was found in the 90IDN-47 genotype, which showed resistance to weevils. On the other hand, one relatively high peak was also detected in the PSL genotype, which showed susceptibility to weevils. These results suggest that two regions could affect weevil resistance and may contain the gene(s) controlling weevil resistance.

Supplementing Tropical Cattle for Improved Nutrient Utilization and Reduced Enteric Methane Emissions.

Simple SummaryQuality supplementation of roughage-based cattle diets is recommended to improve the animals’ production in tropical regions. We tested the effects of two widely suggested high-quality low-cost feed supplements on feed intake, nutrient utilization and enteric methane emissions of growing female cattle. While free access to urea-molasses blocks did not effectively improve the key variables, sweet potato vine silage, a by-product of sweet potato cultivation, improved diet digestibility as well as the animals’ retention of nitrogen and lowered their methane emissions per unit of digested feed. Supplementing productive cattle with sweet potato vine silage can thus concomitantly contribute to better animal performance and lower environmental impact. Given their high nitrogen (N) concentration and low costs, sweet potato vine silage (SPVS) and urea-molasses blocks (UMB) are recommended supplements for tropical regions; therefore, they were investigated in this study. Six heifers were allocated to three diets: the roughage diet (R) consisted of wheat straw (0.61) and Rhodes grass hay (0.39; on dry matter (DM) basis); R + SPVS combined R (0.81) and SPVS (0.19); and with R + UMB animals had access to UMB. During two experimental periods, feed intake, feces and urine excretion, digesta passage, and rumen microbial protein synthesis were determined during seven days and methane emissions during three days. There was no treatment effect (p > 0.05) on DM and N intake. Apparent DM digestibility of R + SPVS (510 g/kg) was higher (p < 0.05) than of R (474 g/kg). Digesta passage and duodenal microbial N flow were similar for all diets (p > 0.05), while N retention was highest with R + SPVS (p > 0.05). Methane emissions per unit of digested feed (g CH4/kg dDM) were lower (p < 0.05) for R + SPVS (55.2) than for R (64.7). Hence, SPVS supplementation to poor–quality roughage has the potential to increase diet digestibility and N retention while reducing CH4 emissions.

Alteration agronomic traits performance of sweet potato cultivars from drylands to paddy fields

This study aimed to evaluate changes in agronomic performances of some sweet potato cultivars planted in the rain-fed dry land and paddy fields. Completely randomized block design with three replications on a single factor of 12 sweet potato cultivars was done in two locations. The first location is the rain-fed dry land that formerly planted corn; located in Jatikerto, Kromengan District, and second is an irrigated paddy field that previously planted with rice, located in Wringinsongo, Tumpang District, Malang Regency. All cultivars that planted in both locations were applied to packaged standard cultivation technology for sweet potato. The parameters observed were storage root weight and vines weight (kg/plant), storage root yields and vines yield (t/ha), harvest index (%) and root/shoot ratio to describe the efficiency level of dry matter translocation to storage root. The results showed that there was a change of agronomic performance in sweet potato cultivars that planted between on the dry land and paddy fields, especially for storage root weight, storage root yield (t/ha) and root/shoot ratio. Changes in the sweet potato cultivation in the dry land to paddy fields are shown by an increase in storage root yields ranging from 2-4 times or reach 206 - 417%.

Nitrous oxide emission from upland soil amended with different animal manures

The nitrous oxide (N2O) emission of from arable soil following the application of manure is expected to vary by different animal manure types used. This study was conducted to determine the relationship between the type of animal manure used to amend soil and the amount of N2O emitted during the cultivation of sweet potato (Ipomoea batatas). An additional objective was to study the characteristics of nitrogen (N) and carbon (C) in different animal manures. Composted manures from chickens, cows, and pigs were applied to the soil at rates of 0, 10, and 20 Mg ha−1, respectively. The availability and concentration of N and C varied by manure type. The concentration of NH4+ was greater in pig manure (4638 mg kg−1) than in chicken (551 mg kg−1) and cow manure (147 mg kg−1). The mean cumulative N2O emission rate across soil application rates was also the highest with pig manure (11.9 kg ha−1 year−1), followed by chicken and cow manure, with emission rates of 10.8 and 10.1 kg ha−1 year−1, respectively. The majority of N2O measured during the sweet-potato-growing season was produced from aerobic nitrification. Dissolved organic carbon (DOC) concentrations in animal manures did not affect cumulative N2O emission rates, and no significant relationship was observed throughout the growing season between the concentration of DOC in soil and daily N2O emission. Cumulative N2O emission rates depended on the type of animal manure and might be governed by NH4+ concentration, rather than by total N concentration in animal manure type.

DOCUMENTATION OF INDIGENOUS KNOWLEDGE ON PRODUCTION AND POST-HARVEST MANAGEMENT OF SWEET POTATO IN THE BICOL REGION, PHILIPPINES

Sweet potato (locally known as kamote) is a major staple food of people in the Bicol Region who live in the upland areas. They have been growing this crop for so many years, providing some form of food security and income to their households. They have also developed sustainable farming system using indigenous knowledge which they have learned from their ancestors. With increasing attention being given to the sustainable farming system, there is a need to look into the indigenous knowledge and practices of the sweet potato farmers in the Bicol Region, Philippines had adopted through the years in the cultivation, production, and post-harvest management of sweet potato. Hence, his paper aimed to document the various indigenous production and post-harvest practices of the sweet potato farmers; evaluate the cultural, social, economic and environmental aspects/dimensions of these indigenous knowledge; discover the gender division of labor in the sweet potato cultivation, production and post-harvest management; and discover the science behind the indigenous knowledge. The study made used of varied social research methods such as sample survey, key-informants interview, focus group discussions and field observations. This study has proven that indigenous knowledge and practices to the sweet potato farmers cannot be underestimated in terms of enhancing the household and community food production and food security particularly in the upland rural areas of the Bicol Region. The indigenous knowledge of the people is very effective in meeting their food requirements, and effective in areas of land preparation, soil fertility enrichment, planting, pests management and weeding, harvesting and post-harvest management.

Economic Evaluation of Rainwater Harvesting and Conservation (RWHC) Technologies for Sweet Potato Cultivation in Sierra Leone

A field trial was conducted to evaluate the economic performance of rainwater harvesting and conservation (RWHC) technologies for sweet potato cultivation in Sierra Leone during five intensive cropping seasons (2014 second – 2016 second cropping season) at the on-station research site of the Njala Agricultural Research Centre. The experiment was laid out in a randomized complete block design in three replications following a factorial combination of two levels of mulch (no mulch and mulch) and three levels of RWH structures (open ridge, tied ridge and arch ridge). Six RWHC technologies evaluated: open ridge without mulch (OR-M), open ridge with mulch (OR+M), tied ridge without mulch (TR-M) and tied ridge with mulch (TR+M), arch ridge without mulch (AR-M) and arch ridge with mulch (AR+M). Profitability (gross margin, net income and breakeven), investment (NPV, IRR and BCR) and sensitivity analyses (25% root yield loss and 10% fall in the market price of sweet potato roots) were used to evaluate the economic performance of the RWHC techniques. The TR+M (SLL 2,091,280) had the highest net income followed by the AR-M (SLL 693,640) and AR+M (SLL 2,218,160) RWHC technologies. The traditional OR-M was not profitable (SLL -2,487,760) for sweet potato cultivation. Based on the cost of production, the OR-M, OR+M, and TR-M RWHC technologies require a root yield increase of 50.5%, 3.0% and 35.4% to breakeven. The AR+M had the highest and positive net seasonal cash flow returns throughout the five cropping seasons. The breakeven point on the net season seasonal cash flow returns for the TR+M, AR-M and OR+M RWHC technologies was in the 2015 main cropping season. At discount rates of 10%, 15%, 20% and 25% the highest NPV was obtained from the AR+M followed by the TR+M and AR-M RWHC technologies. The highest IRR was obtained from the AR+M (111%) followed by TR+M (84%) and AR-M (61%). The AR+M, TR+M and AR-M RWHC technologies had benefit-cost ratios greater than 1. Under uncertain conditions of 25% root yield loss and 10% fall in the market price of sweet potato roots, the AR+M and TR+M are the most profitable RWHC technologies that could be invested in. These technologies should, therefore, be promoted for adoption through on-farm trials in order to enhance intensive sweet potato cultivation on upland gravelly soils in Sierra Leone.

Current status on global sweetpotato cultivation and its prior tasks of mass production

Sweetpotato [Ipomoea batatas (L.) Lam] represents an attractive starch crop that can be used to facilitate solving global food and environmental problems in the 21st century. It can be used as industrial bioreactors to produce various high value-added materials, including bio-ethanol, functional feed, antioxidants, as well as food resources. The non-profit Center for Science in the Public Interest (CSPI) announced sweetpotato as one of the ten ‘super foods’ for better health, since it contains high levels of low molecular weight antioxidants such as vitamin-C, vitamin-E and carotenoids, as well as dietary fiber and potassium. The United States Department of Agriculture (USDA) also reported that sweetpotato is the best bioenergy crop among starch crops on marginal lands, that does not affect food security. The Food and Agriculture Organization (FAO) estimated that world population in 2050 will be 9.7 billion, and require approximately 1.7 times more food than today. In this respect, sweetpotato will be a solution to solving problems such as food, energy, health, and environment facing the globe in the 21st century. In this paper, the current status of resources, and cultivation of sweetpotato in the world was first described. Development of a new northern route of the sweetpotato and its prior tasks of large scale cultivation of sweetpotato, were also described in terms of global food security, and production of high-value added biomaterials.