Sweetpotato Yield Research Articles

Desempenho de genótipos e cultivares de batata-doce no subtropical sul do Brasil

ABSTRACT The average yield and quality of sweetpotato in Brazil are below the crop potential due to several traits that can be improved by plant breeding. This study aimed to evaluate the performance of sweet potato advanced clones with potential to be released as new cultivars, recommend cultivars with better attributes for grower's needs at the subtropical region of Brazil or to be used as parents in breeding programs. The genotypes MD1604002, MD1611010, MD1609023, MD1609024, MD1609026, and MD1610036 and cultivars Brazlândia Roxa, Beauregard, BRS Cuia, BRS Amélia, and BRS Rubissol, were evaluated during two seasons 2020/2021 and 2021/2022, in Canoinhas-SC. The experiments were conducted in complete randomized blocks design with four replications where plots were composed of three rows with 15 plants each, spaced 0.75 m apart with 0.35 m between plants. Storage roots were harvested 180 days after planting and evaluated for yield, appearance, insect damage, and shape characteristics. ‘BRS Rubissol’, the genotype MD1610036, with higher root yield, storage roots shape, appearance, and less susceptible to insect damage, and MD1609024, with a good root yield, similar or superior to cultivars Brazlândia Roxa, Beauregard, and BRS Amélia, stood out, and have potential to be cultivated in this region. ‘Brazlândia Roxa’ and genotype MD1611010 are potential sources of resistance genes to insect damage, which is one of the biggest challenges in sweetpotato production in Brazil.

Improving the quality of barren rocky soil by culturing sweetpotato, with special reference to plant-microbes-soil interactions

Biological process is an effective strategy to improve soil quality in agroecosystems. Sweetpotato has long been cultivated in barren rocky soil (BRS) to improve soil fertility and obtain considerably high yield. However, how sweetpotato cultivation affects soil quality is still unclear. We cultured sweetpotato in virgin BRS, and investigated its transcriptome, rhizospheric microbial community and soil properties. A high sweetpotato yield (22.69 t.ha−1) was obtained through upregulating the expression of genes associated with stress resistance, nitrogen/phosphorus/potassium (N/P/K) uptake, and root exudates transport. Meanwhile, the rhizospheric microbial diversity in BRS increased, and the rhizospheric microbial community structure became more similar to that of fertile soil, which might benefit from the increased root exudates. Notably, the relative abundances of N-fixing and P/K-solubilizing microbes increased, and the copy number of nifH increased 6.67 times. Moreover, the activities of acid, neutral, and alkaline phosphatases increased strongly from 0.63, 0.02, and 1.15–1.58, 0.31, and 2.11 mg phenol·g−1·d−1, respectively, and total carbon, dissolved organic carbon, available N/P content also increased, while bulk density and pH of BRS decreased, indicating the enhanced soil fertility. Our study found sweetpotato cultivation improved BRS quality through shaping microbial communities, which has important guiding significance for sustainable agriculture.

Orange Fleshed Sweet Potato Response to Filter Cake and Macadamia Husk Compost in Two Agroecologies of KwaZulu-Natal Province, South Africa

Field experiments were carried out during the summer/autumn (first trial) and winter/spring (second trial) seasons of 2019 and 2021 in the Dlangubo, Ngwelezane, and Mtubatuba areas of KwaZulu-Natal Province of South Africa to study the drought amelioration effects and impact of two locally available organic wastes (filter cake—a residue derived from sugar cane filtration (FC) and macadamia husk compost (MHC)) on the productivity and physiological responses of four orange-fleshed sweet potato cultivars (Beauregard cv., Impilo, W-119 and 199062.1). The effects of FC and MHC were compared with that of inorganic fertilizer (IF) [2:3:2 (30)], FC + IF, MHC + IF, and the control. The soil amendments were applied in the first trials only. Climatic data such as humidity, temperature, and rainfall were taken via remote sensing. The results of the first trial indicated that filter cake and IF significantly performed better than MHC. The strength of filter cake may be attributable to its rich array of mineral nutrients such as calcium, magnesium, potassium, sodium, zinc, copper, manganese, iron, and phosphorus. The limited performance of MHC may be attributable to its ability to hold water. Furthermore, a positive correction occurred between the yield of the test orange-fleshed sweet potato (OFSP) cultivars, rainfall, and vegetation indices (normalized difference vegetation index, enhanced vegetation index, and normalized difference water index) investigated in the study. In season two, IF treatment did not have any significant effect on the growth and productivity of any of the tested sweet potato cultivars, but, FC, FC + IF, and MHC treatments largely maintained their performances. In conclusion, the use of FC is highly recommended in the production of the test OFSP cultivars. Furthermore, the study indicates that both FC and MHC may not only supply the needed plant nutrients but has the capacity to reduce the impact of drought on the growth of the test cultivars. These findings are of great value to farmers, especially the resource-poor ones.

Construction of a high-density SSR genetic linkage map and identification of QTL for storage-root yield and dry-matter content in sweetpotato

Sweetpotato (Ipomoea batatas (L.) Lam.) is a widely grown food crop especially in developing countries. Increasing storage-root yield and dry-matter content has been the main breeding objective of the crop, and DNA marker-assisted breeding is needed for this purpose. In this study, using a mapping population of 500 F1 individuals from a cross between Xushu 18 (female) and Xu 781 (male), we constructed a high-density genetic linkage map of sweetpotato using 601 simple-sequence repeat (SSR) primer pairs. The Xushu 18 map contained 90 linkage groups with 5547 SSR markers and spanned 18,263.5 cM, and the Xu 781 map contained 90 linkage groups with 4599 SSR markers and spanned 18,043.7 cM, representing the highest genome coverage yet reported for sweetpotato. We identified 33 QTL for storage-root yield and 16 QTL for dry-matter content, explaining respectively 6.5%–47.5% and 3.2%–18.9% of variation. These results provide a foundation for fine-mapping and cloning of QTL and for marker-assisted breeding in sweetpotato.

Effect of Leaf Harvest Intensity and Frequency on Sweet Potato Weevil (Cylas puncticollis) Infestation, Yield and Quality Traits of Sweet potatoes (Ipomoea batatas L.)

Objective: The present study assessed Cylas puncticollis (C. puncticollis) infestation, foliage, and root yields of sweet potatoes as influenced by the leaf harvest intensity and frequency in the inland valley swamp (IVS) and upland soils of Njala. Methods: The trial involved 2 varieties namely Kabia and Gbanie; 4 levels of foliage harvests: 0, 30, 60 and 90 days after planting; and 4 levels of leaf harvest intensities: 0, 25, 50 and 100%. The treatments were established in a randomized complete block design and replicated 3 times. The parameters that were investigated included the severity of C. puncticollis infestation on vines and storage roots, fresh foliage yield, storage root yields and other related traits (fresh storage root length, width and numbers). Results: Our findings showed that there were significant differences in foliage and root yields, as well as related traits among different leaf harvest frequency intensities. The 25 and 50% harvest plots produced optimum fresh foliage and storage root yields and other related traits of the crop. C. puncticollis infestation in sweet potatoes cultivated during the dry season in the IVS ecology was more severe than that in those grown in the upland during the wet season. The ecology and time of cultivation of sweet potatoes influence infestation by C. puncticollis on vines and roots more than the combined effects of putative varieties, leaf harvest intensity and frequency. Conclusion: Improved agronomic management practices support optimization of fresh leaf and root yields of sweet potatoes. These can be exploited and chosen to achieve optimum productivity and quality of the crop for both the fresh foliage and storage root consumers.

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.

Assessment of Growth and Yield of Sweet Potato Genotypes

The experiment was conducted taking Fifteen genotypes of sweet potato were evaluated in RBD with three replications during kharif season of 2019 & 2020 at in the K.V.K Dhenkanal District ,Odisha. Among the characters studied, different high PCV and GCV were observed for characters like vine length, vine internodal length, number of branches per plant, number of leaves per plant, total leaf area, number of roots per plant, root yield per plant, β-carotene content, starch content, total sugars, reducing sugars, non reducing sugars and total root yield per hectare content indicating high variability available in the germplasm for these characters for further improvement. High heritability coupled with high genetic advance as per cent of mean was observed for characters vine length, vine internodal length, number of branches per plant, length of leaf lobe, number of leaves per plant, total leaf area, root girth, root yield per plant, β-carotene content, starch content, total sugars, reducing sugars, non reducing sugars and total root yield per hectare indicated that these characters were least influenced by the environmental effects, and these characters were governed by additive genes and selection will be rewarding for improvement of such traits. The total root yield per hectare (t/ha) had significant positive correlation with traits like number of branches per plant, number of roots per plant, root girth, root yield per plant and β-carotene content suggesting the importance of these traits in selection for yield and can be identified as yield attributing characters for the genetic improvement of yield in sweet potato. The total root yield per hectare (t/ha) was result of direct effect of number of branches per plant, number of roots per plant, root length, root yield per plant, starch content and reducing sugars. The high direct effect of these traits appeared to be the main factor for their strong association with total root yield per hectare. Analysis for divergence using D2 statistic revealed highly significant differences for different traits, grouping the 15 genotypes into 6 clusters. Cluster II had the maximum number of genotypes (8) followed by cluster I (7). Maximum inter cluster distance was observed between clusters III and VI while the intra cluster distance was maximum in cluster II and VI. Highest percent contribution to divergence came from β-carotene content, starch content, total sugar, total leaf area, root dry matter content, number of leaves per plant, root yield per plant, petiole length, root girth, vine length and reducing sugar suggested that selection of one or two elite genotypes from divergent (II & VI) and (III & VI) clusters based on the above characters and crossing would result in more heterosis and novel hybrid.

Effects of wood biochar and potassium fertilizer on soil properties, growth and yield of sweet potato (Ipomeabatata)

Studies on integrating biochar with potassium (K) fertilizer is not common. Hence, experiments were conducted in 2020 and 2021 to evaluate the sole and combined applications of biochar and K fertilizer on soil properties and performance of sweet potato. It was hypothesized that the effects of combined applications of biochar and K fertilizer on the growth, and yield of sweet potato will be more than their individual applications. The study each year consisted of a 3 × 3 factorial experiment with three levels (0, 10, and 20 t ha−1) of wood biochar and three levels (0, 70, and 120 kg ha−1) of K fertilizer (potassium chloride). The 9 treatment combinations have three replications and follow a randomized complete block design. Results revealed that biochar alone or in combination with K fertilizer improved soil physical and chemical properties, growth, and yield of sweet potato relative to the control and K fertilizer alone. The interaction of biochar and K (biochar × K fertilizer) fertilizer was significant for growth and yield parameters. The addition of K fertilizer to biochar improved the performance of sweet potato compared with sole applications of K fertilizer or biochar. 20 t ha−1 biochar +70 kg ha−1 K fertilizer and 20 t ha−1 biochar +120 kg ha−1 K fertilizer increased growth and yield relative to 10 t ha−1 biochar +70 kg ha−1 K fertilizer and 10 t ha−1 biochar +120 ha−1 kg K fertilizer. Since 20 t ha−1 biochar +120 kg ha−1 K fertilizer and 20 t ha−1 biochar +70 kg ha−1 K fertilizer were statistically similar, for this experiment, 20 t ha−1 biochar +70 kg ha−1 K fertilizer would be recommended for sweet potato production. Therefore, the addition of 70 kg K fertilizer with biochar has reduced the cost of increasing the rate to 120 kg ha−1 which would have been economical in view of the high price and lack of K fertilizer in Nigeria and other sub-Saharan African countries.

Effect of phosphorus application on economic yield, quality and phosphorus utilisation efficiency of purple-fleshed sweetpotato

This study aims to explore the effect of phosphorus (P) application on the economic yield, quality, P accumulation, and P utilisation efficiency of purple-fleshed sweetpotato and to provide a basis for the P efficient utilisation and high crop yield. Field experiments were conducted in 2018–2019, and five P application rates (0, 10.9, 21.8, 32.7, and 43.6 kg P/ha, expressed as P0, P1, P2, P3, and P4, respectively) were set. The results showed that P application significantly increased the yield and commodity potato yield of purple-fleshed sweetpotato, and that of P3 treatment was the highest, followed by P2 treatment. P application also increased the starch content in the storage root and increased the reducing sugar and soluble sugar (except for P2 treatment). P fertiliser supply significantly increased P accumulation and dry matter production of purple-fleshed sweetpotato during the growth period of 90 to 120 days. When the P application rate was over 21.8 kg/ha, the fertiliser investment rate, apparent P utilisation efficiency and P agronomic efficiency decreased with the increase of the application rate. Considering all the indexes, the supply of 21.8 kg/ha P fertiliser can meet the demand for high economic yield and P efficient utilisation in purple-fleshed type sweetpotato under the condition of this experiment.

CARACTERIZAÇÃO AGRONÔMICA DE GENÓTIPOS DE BATATA-DOCE OBTIDOS POR MEIO DE POLICRUZAMENTOS

ABSTRACT The average national sweet potato yield of Brazil falls below the productive potential of the crop because of the cultivation of local and unimproved varieties. To improve this, more productive cultivars must be adopted along with adequate culture treatments. This study was conducted between January and May 2019 in Selvíria, Mato Grosso do Sul, Brazil, to characterize sweet potato genotypes obtained through crossbreeding. The experimental design consisted of randomized blocks containing 264 genotypes, the control (‘Beauregard’), and two replicates. Plant harvesting began 127 d after planting. After harvesting, the roots were washed and dried in a covered area ready for evaluation. The total, commercial, and non-commercial yield; total, commercial, and non-commercial root number; root dry matter content; and dry matter productivity were evaluated. The genotypes CERAT16-20, CERAT31-1, and CERAT21-2 are promising in terms of root production for household consumption because of their high productivity of commercial roots. In contrast, genotypes CERAT16-20, CERAT31-1, CERAT25-17, CERAT25-12, CERAT21-2, CERAT29-26, CERAT34- 4, CERAT31-11, and CERAT24-8 are promising for industry because of the high production of dry mass per hectare. The main components, total number of commercial roots, production of non-commercial roots, mass of commercial roots, total production of dry mass of roots, mass of roots, and total production of roots have a low contribution to the discrimination of the genotypes; therefore, their analysis can be discarded in future studies, under the same soil and climate conditions, thus reducing workload, expense, and time.

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.

The role of biochar, poultry manure, and biochar-poultry manure in improving leaf nutrient concentrations, root storage minerals, growth, and yield of sweet potato (Ipomoea batatas L.)

The role of biochar, poultry manure, and biochar-poultry manure in improving leaf nutrient concentrations, root storage minerals, growth, and yield of sweet potato (Ipomoea batatas L.)

Sweet Potato (Ipomoea batatas L.) Response to Incremental Application Rates of Potassium Fertilizer in Mississippi

Potassium (K) fertilization is a crucial component of sweet potato (Ipomoea batatas L.) production. The basis for K fertilizer recommendations in sweet potato production varies greatly and relies on studies conducted in the late 1950s–1970s. Changes in agronomic practices and increasing costs emphasize the need to revisit fertilizer recommendations. A field experiment was conducted to investigate the impact of seven different K fertilizer (K2O) application rates on sweet potato storage root yield, tissue K concentration, and economic implications in Mississippi. Incremental applications of K fertilizer did not influence sweet potato yield at any grade. Leaf tissue K concentration exhibited a quadratic trend in response to K fertilizer rate, with maximum leaf and root K content achieved at 269 and 404 kg·ha−1 K2O, respectively. Both the predicted K application rate for maximum yield and maximum profitability were the same, at 174 kg·ha−1 K2O. Accordingly, comparable sweet potato yields were achieved while applying substantially less fertilizer than the recommended rate. Further research is warranted to examine the impacts of only potassium fertilizer applications on soil characteristics and temporal trends in sweet potato potassium uptake, as well as refine fertilization recommendations for sweet potato production.

Effect of Crop Geometry on Growth, Yield and Quality of Sweet Potato (Ipomoea batatas L.) Genotypes

Field experiments were conducted in 2018 and 2019 at the National Potato Research Programme (NPRP), Lalitpur (1360 masl), Nepal, to determine the effect of crop geometry on the growth, yield, and quality of sweet potato genotypes. The experiment was laid out on sandy loam soil in a factorial randomized complete block design (RCBD) with three replications and comprised of a total of twelve treatment combinations of four crop geometry (60cm×25 cm, 60cm×30 cm, 70cm×25 cm, and 70cm×30 cm) and three genotypes (CIP 440015, CIP 440267 and Local White). Among the different crop geometries and genotypes evaluated, 70cm×30 cm plant spacing and Local White genotype were found statistically superior to enhance marketable tuberous root weight per plant (0.572 and 0.541 kg), tuberous root diameter (62.59 and 61.0 mm), shoot fresh weight (509 and 524 g), and tuberous root yield per plant (616 and 620 g). The genotype, Local White yielded higher among the genotypes. The reducing sugar content was influenced significantly by crop geometry and genotypes. The pooled mean showed the highest (15.48 and 17.26 %) reducing sugar in closer geometry 60 cm × 25 cm and Local White genotype respectively and the lowest (11.54 %) in the genotype CIP 440015. CIP genotypes, on the other hand, were high in ß carotene content, whereas the Local genotype had a negligible amount (0.35 mg/100g). On hectare level, our result showed that highest plant density of 66,666 plants ha-1 (60 cm × 25 cm) could give the highest yield per unit area due to greater crop biomass. Our findings suggest that crop geometry can have a considerable impact on sweet potato production. As a result, the geometry of sweet potatoes can be wide or narrow depending on our needs and the area available in our study area or a similar situation.

Combining ability and heritability analysis of sweetpotato weevil resistance, root yield, and dry matter content in sweetpotato

Efficient breeding and selection of superior genotypes requires a comprehensive understanding of the genetics of traits. This study was aimed at establishing the general combining ability (GCA), specific combining ability (SCA), and heritability of sweetpotato weevil (Cylas spp.) resistance, storage root yield, and dry matter content in a sweetpotato multi-parental breeding population. A population of 1,896 F1 clones obtained from an 8 × 8 North Carolina II design cross was evaluated with its parents in the field at two sweetpotato weevil hotspots in Uganda, using an augmented row-column design. Clone roots were further evaluated in three rounds of a no-choice feeding laboratory bioassay. Significant GCA effects for parents and SCA effects for families were observed for most traits and all variance components were highly significant (p ≤ 0.001). Narrow-sense heritability estimates for weevil severity, storage root yield, and dry matter content were 0.35, 0.36, and 0.45, respectively. Parental genotypes with superior GCA for weevil resistance included “Mugande,” NASPOT 5, “Dimbuka-bukulula,” and “Wagabolige.” On the other hand, families that displayed the highest levels of resistance to weevils included “Wagabolige” × NASPOT 10 O, NASPOT 5 × “Dimbuka-bukulula,” “Mugande” × “Dimbuka-bukulula,” and NASPOT 11 × NASPOT 7. The moderate levels of narrow-sense heritability observed for the traits, coupled with the significant GCA and SCA effects, suggest that there is potential for their improvement through conventional breeding via hybridization and progeny selection and advancement. Although selection for weevil resistance may, to some extent, be challenging for breeders, efforts could be boosted through applying genomics-assisted breeding. Superior parents and families identified through this study could be deployed in further research involving the genetic improvement of these traits.

Perbedaan Hasil dan Kualitas Ubi Jalar (Ipomoea Batatas L.) Akibat Perendaman Stek Menggunakan Ekstrak Bawang Merah

One of the obstacles to the cultivation of sweet potatoes planted in the dry season is the lack of seedlings. One solution is to use cuttings that are cut smaller than the size of the cuttings should be. To increase the growth and yield of sweet potatoes, shallot extract is used as an exogenous hormone as a pre-planting treatment. The purpose of this study was to determine the effect of onion extract and soaking duration on the yield and quality of sweet potato. This experiment was carried out from March to June 2021 in the experimental field of the Faculty of Agriculture, University of Garut, Tarogong Kaler District, Garut Regency with an altitude of 761 meters above sea level. This experiment used a non-factorial randomized block design with nine treatments repeated three times. The concentration of shallot extract and the duration of soaking affect the weight of tuber per plant, the weight of tuber per plot, the weight of economical tuber per plot, the weight of non-economical tuber per plot and the brix test of fresh tuber. The best results were found in the treatment of shallot extract concentration of 90% and soaking duration of 90 minutes.

Effect of Different Nitrogen Concentration on Plant Growth, Yield and Quality of Sweet Potato (Ipomea Batatas [L.] Lam) Cultivated in Soilless Culture System

The soilless culture system effectively promotes plant growth by facilitating water and nutrient uptake by plant roots. To increase sweet potato production (Ipomoea batatas), we developed containerized planting in which tuberous roots were grown in solid substrates in the polybags supplied with a nutrient solution through an irrigation system. This study was conducted to investigate the effect of different nitrogen concentrations on sweet potato plant growth performance, yield, and tuber quality cultivated using a soilless culture system. The experimental setup included five treatments (T1-T5) with different levels of N (0-50-150-200-250 mg L-1), which were mixed in the nutrient solution, while P and K levels were held constant at 150 and 200 mg L-1 respectively. After three months of cultivation, there were significant differences between treatments in terms of plant growth performance, yield and tuber quality. Plants cultivated in the 250 mg L-1 of N showed the highest growth rate including plant height, shoot and leaves fresh weight, number of tillers, SPAD values, number of leaves, and diameter of tillers compared to other treatments. Data also revealed that the highest tuber yield was obtained from plants treated with 200 mg L-1 of N. Tuber harvested from the treatment of 200 mg L-1 of N showed the best quality in terms of Brix value, moisture content and tuber shape and length. Therefore, planting sweet potatoes using a soilless culture system is recommended with the application of 200 mg L-1 of N to obtain the optimum plant performance in terms of growth, yields, and tuber quality.

Black plastic mulch affects soil temperature and yield of sweet potato under short season temperate climates

ABSTRACT Temperature is critical for the plant growth and yield of sweet potato (Ipomoea batatas L.) in northern cool season climates. Few studies have quantified the effect of temperature using different crop systems to improve the growth of sweet potato (Ipomoea batatas L.). Our study examined the impact of black mulch on raised beds for sweet potato (Ipomoea batatas L.) production in open field conditions in Manitoba. Black mulched plots were compared with non-mulched plots over 3 years for effects on soil temperature and commercial yields. Three year mean soil temperatures (19.9°C) were significantly higher under mulched plots compared to non-mulched soil (19°C). Higher total, marketable and US#1 yields were harvested from mulched plots than non-mulched plots; however, no differences were recorded for US#2, jumbo and cull yields over 3 years. Marketable yield increases of 47, 39 and 30%, were recorded for mulched plots over non-mulched plots in years 2018, 2019 and 2020, respectively, with a 3-year average yield increase of 39%. Use of black mulch contributed to increased sweet potato commercial yields in short season-temperate climates.

Sewage Sludge Fertilization—A Case Study of Sweet Potato Yield and Heavy Metal Accumulation

Sewage sludge (SS) is derived from wastewater treatment plants and can be used as a biofertilizer when properly stabilized. This work aimed to evaluate SS application for agricultural production improvement. SS was tested on Porto Santo Island (Portugal). The experiment was randomly designed with three 25 m2 plots for each treatment (2 SS concentrations + control without SS) and performed in two consecutive cycles. For the first cycle, dehydrated sludge was mixed with soil, obtaining final concentrations of 0.8 kg/m2 (C1) and 1.6 kg/m2 (C2). Half of the concentration was used for the second cycle. Fifty-eight sweet potato plants were used in each plot. SS application boosted the agronomic parameters of biomass, productivity, and shoot biomass. Furthermore, improvements in soil properties were observed, mainly for pH, CEC, and NO3-N, with no significant increase in heavy metals. For the edible parts, heavy metal concentrations decreased, and Pb was the only one that still exceeded the maximum limits. The results demonstrated that SS application to low-fertility soil is effective in improving the agronomic parameters of sweet potato and enhancing soil features. Further studies considering other variables, i.e., SS origin, soil properties, and the crop, must be carried out to propose custom applications.

Effect of Phosphorus Application on Yield of Sweet Potatoes in Embu West Sub-County, Kenya

Sweet potato is a crop that plays a great role in food security in Kenya since it is a drought resistant crop, takes a short time to mature and is highly flexible. The main economic activity in Embu West Sub County is agriculture, which is the economic pillar of Embu County with most farmers there being small scale farmers and depending on this sector for their livelihood. Phosphorus as a plant nutrient is a key component of several chemical compounds necessary for metabolic activities, flowering, and root development; hence, it is essential for proper plants growth including sweet potatoes. This study purposed to evaluate how P application affects yield of three sweet potato varieties in Embu West Sub County. The sweet potato varieties used were SPK004 (V1), Kenspot 3 (V2) and Kenspot 4 (V3). The P fertilizer levels used were 0 kg/ha (P1), 25 kg/ha (P2), 50 kg/ha (P3), and 75 kg/ha (P4). Data on two specific yield parameters was collected at harvest; the collected data was summarized using excel. Analysis of variance of the data was done using SPSS version 23, at α=0.05. For treatment means that were significantly different, LSD as Post hoc test was used to separate them. The study showed significant yield potential difference in the yield parameters among the three sweet potato varieties with Kenspot 4 being the highest producer of both total and marketable tubers yield. The study showed that the amount of P applied significantly affected yield of sweet potatoes with a P level of 50 kg/ha producing significantly higher yields.