Yam Tubers Research Articles

Effect of warehouse storage on the alteration, cooking and organoleptic characteristics of Kponan yam (Dioscorea cayenensis-rotundata) of Côte d'Ivoire

Yam holds the top position in food crop production, and Kponan yam is highly prized by Ivorians. However, storage deterioration poses economic challenges for wholesalers and producers. This study assesses Kponan yam quality in warehouse storage, considering its geographical origin. To achieve this, yams from the Bondoukou, Bouna, and Kouassi-Kouassikro regions were kept at a warehouse in Abidjan, allowing an assessment of alterations, cooking properties, and organoleptic characteristics over a 3-month storage period. Kponan yam tubers were placed on boards at the warehouse's temperature (27.98 °C) and relative humidity (85.61 %). Temperature and humidity levels were recorded three times per week and four times daily at 08:00, 12:00, 16:00, and 20:00. Physical, cooking, and sensory characteristics were checked at harvest and during each month. The results showed that the main damage observed during storage at the warehouse was rotting and dehydration of the tubers. Rot rates were 47.53 % for yams grown in Bondoukou, 51.96 % for those grown in Bouna and 60.65 % for those grown in Kouassi-Kouassikro. Dehydrated tubers rates were 17.88 %, 25.04 % and 29.20 % for yams from Bondoukou, Bouna and Kouassi-Kouassikro, respectively. The browning indices of Kponan yams decrease (P < 0.05) during storage, with a much more marked effect for yams grown in Bouna (23.43-18.56) and Bondoukou (24.73-18.11), in contrast to those grown in Kouassi-Kouassikro (26.09–22.96). Hardness also dropped for Kponan yams grown in Bouna, Bondoukou and Kouassi-Kouassikro (38.94–25.19 N, 39.39–26.52 N and 35.59–26.66 N respectively). Sensory analysis showed that yams from Bouna stored for three months were rated highest in taste (score = 4). The storage quality of Kponan yams was influenced by the cultivation region. Organic production of Kponan yams benefits the environment and human health, while increasing shelf life.

Impact of Tuber Section, Steeping Solution, and Concentration on Physicochemical Properties of Yam (Dioscorea rotundata) Flour

This study examined various factors such as Tuber Cutting (TC), Tuber Processing Method and Duration (TPM and TPD), Soaking Solution Type and Concentration (SST and SSC), as well as Parameter Analytical Temperature (PAT) on flour samples prepared from different parts of yam tubers.

Effect of Plant-derived Biofertilizers (Azolla filiculoides and Tithonia diversifolia) on Growth and Yield Parameters of Lokpa Yam (Dioscorea cayenensis-rotundata) Grown on Distric Plinthic Ferralsol in the Forest Zone of Côte d'Ivoire

Aims: The study aims to assess the fertilizing potential of Azolla filiculoides and Tithonia diversifolia leaves on Lokpa (D-rotundata) yam cultivation in the forest zone of Côte d'Ivoire. Place and Duration of Study: The study took place over 9 months (April-December) in 2022 at M'Bayakoffikro in the Daloa department of central-western Côte d'Ivoire. Methodology: After clearing a soil fallow classified Distric plinthic ferralsol, microplots in randomized Fisher blocks of 2 replicates each with five treatments (Azolla filiculoides-AZ; Tithonia diversifolia with fresh biomass-TDF; Tithonia diversifolia with decomposed biomass-TDD; Azolla filiculoides + Tithonia diversifolia with fresh biomass-AZ+TDF and Azolla filiculoides + Tithonia diversifolia with decomposed biomass-AZ+TDD) and a control without fertilizer were delimited in which,10 mounds were levelled for sowing yam tuber pieces. Before sowing the tubers, the mounds were opened by hand and 0.5kg of each formulated fertilizer was ploughed in and then resealed. After 14 days of fertilization, the mounds were reopened and a single seedling was buried 20cm deep in each mound from top to bottom, followed by 300ml of water and then resealed. After germination, growth and production parameters were evaluated and the data obtained were subjected to an analysis of variance with Statistica 7.1 software at the 5% threshold. Results: The different biofertilizer formulations had a significant effect on all growth and yield parameters of lokpa yam (D-rotundata). However, the highest values for both growth and yield parameters compared with other fertilizers at all measurement times and at maturity were obtained with Azolla filiculoides combining decomposed Tithonia diversifolia leaves on the one hand and fresh Tithonia diversifolia leaves on the other. Conclusion: Improving soil productivity in forest areas by finding reliable and effective alternatives to mineral fertilizers is a necessity, and the combination of Azolla filiculoides and Tithonia diversifolia could be a good alternative for sustainable, environmentally-friendly agriculture.

Determination of proximate analysis of individual and combined samples of &lt;i&gt;Dioscorea alata&lt;/i&gt;, &lt;i&gt;Musa parasidiaca&lt;/i&gt; and &lt;i&gt;Xanthosoma sagittifolium&lt;/i&gt; peels

This study investigates the proximate composition of yam (Dioscorea alata), cocoyam (Musa parasidiaca) and plantain (Xanthosoma sagittifolium) plant wastes, with a focus on evaluating the impact of the individual and combined plant wastes. Tubers of yam (Dioscorea alata), cocoyam (Musa parasidiaca) and plantain (Xanthosoma sagittifolium) used in this study were obtained from Obibi in Etche Local Government Area of Rivers State, Nigeria. Yams are tubers, plantains are fruits, whereas cocoyam is derived from corms, underground stems, and swollen hypocotyls. All these crops can be propagated by vegetative parts and these include tubers (yams), sucker (Plantain) and side shoots, stolons, or corm heads (cocoyam). Peels from the yam tubers were obtained by using a kitchen knife to carefully remove the peels. The peels were then immediately oven dried at 45oC for 24 hours. The dried peels were then ground through a 40-mesh screen using a Wiley. Analyses conducted isproximate determination using AOAC method. The results highlight the high ash content of Yam and Cocoyam Peel, which contributes to mineral enrichment; the enhanced moisture content of Plantain Peel, which has implications for water retention; and the low fat and oil content of Cocoyam Peel, which suggests that it is appropriate for use as a low-fat organic material. Yam Peel has a high crude fiber level, which indicates that it has the capacity to improve the structure of the soil. On the other hand, Yam and Cocoyam Peel stand out because it has largest protein content, which is essential for the development of plants. Plantain and cocoyam peel have the largest carbohydrate content, making it an excellent source of energy for the bacteria and plants that live in the soil below it. These findings have practical implications for sustainable agriculture by optimizing crop yields in diverse agro ecosystems.

Impact of planting and harvest dates on yam infestation by white grubs

AbstractThe white grub, Diaprepes abbreviatus L. (Coleoptera: Curculionidae), is a significant pest of yam tubers and the second cause of tuber rot in Haiti. Larval feeding inflicts severe damage to tubers, leading to notable losses due to decreased tuber quality, reduced marketability and increased susceptibility to secondary parasites and pathogens. This study examined the influence of planting and harvesting dates on the vulnerability of yam tubers to white grub infestation and the resulting tuber quality across 24 farmers' fields. At harvest, we assessed the level of tuber infestation, white grub density and the tuber quality index. The results indicated that 85% of grub populations were found in fields planted on the traditional date. In addition, 69.5% of tuber damage occurred in early‐planted fields with fewer tubers damaged (30%) when harvested early. In contrast, in fields planted 30 days after the traditional date, the harvest date did not affect tuber infestation and damage by the pest. Overall, both planting and harvest dates impacted the quality grade of yam tubers. Delayed planting by 30 days and early harvesting (34th–38th week after planting) improved the marketability of yams. These findings highlight the importance of optimising planting and harvest schedules to better manage white grub infestation and enhance the marketability of yam tubers.

THE PROCESSING TECHNIQUE AFFECTS THE PHYSICOCHEMICAL AND TEXTURAL CHARACTERISTICS OF PURPLE YAM BASED GLUTEN-FREE DOUGH

Purple yam tuber in the form of flour has been applied for functional food products. Processing purple yam tubers into flour eliminates many beneficial compounds of the tubers. Another alternative for processing purple yam tubers is to process them directly into a paste to be mixed into the dough. This study was carried out to determine the effect of the processing technique of yam tuber on the texture profile of gluten-free dough made up of yam tuber and modified cassava flour (mocaf). Four (4) types of processing techniques were applied to produce purple yam+mocaf dough. First (ST), steaming yam tuber, mashing + mocaf + water. Second (SST), steaming slice of yam tuber, mashing + mocaf + water. Third (SCT0.5), soaking slices of yam tuber in citric acid 0.5%, mashing + mocaf + yam tuber mucus. The last (SCT1) is soaking slices of yam tuber in citric acid 1%, mashing + mocaf + yam tuber mucus. The result showed that the amount of water, the ratio between purple yam paste and mocaf, the lead time, and the processing technique play important roles in shaping the texture of the dough. The third technique (SCT0.5) produced higher hardness, adhesiveness, springiness, and cohesiveness dough than the other techniques. However, none of the texture profiles strongly correlate with the dietary fiber content. These results can be used better to understand the free gluten food application of yam tuber.

Evaluating the dry matter content of raw yams using hyperspectral imaging spectroscopy and machine learning

Yams (Dioscorea spp.) are important food and commercial crops in West African countries. They contribute significantly to global food production and provide dietary energy. The quality of yam food products depends on specific internal and external parameters, such as the DMC and other biochemical traits. However, measuring these traits can be challenging, particularly when analyzing many genotypes. This study aimed to evaluate the feasibility of using near-infrared (NIR) hyperspectral imaging (932–1721 nm) along with machine learning to rapidly measure the dry matter content (DMC) of fresh, intact yam tubers. Hyperspectral images were acquired across the yam tuber’s cross-sections, and the resulting spectra from the images were averaged and preprocessed. Partial least square regression (PLSR) combined with successive progressions algorithms (SPA), Competitive Adaptive Reweighted Sampling (CARS), Artificial Neural network (ANN) and Boruta algorithms (BA) were used to select the important wavelengths for developing a prediction model for DMC (g/100 g). The PLSR-SPA-CARS model showed the most accurate prediction performances with a coefficient of determinations in calibration (R2cal) and prediction (R2pred) of 0.974 and 0.958, respectively, and low root mean square error (RMSEP) of 0.898 g/100 g. The distribution of DMC was visually represented by projecting the developed model to generate color chemical maps. This study resolves that NIR hyperspectral imaging can rapidly assess the DMC of fresh, intact yam tubers.

Abscisic acid treatment positively regulates suberin polyaliphatics biosynthesis at wound sites in postharvest yam tubers

Suberin polyaliphatics (SPA) accumulation on the closing layer plays a significant role in wound healing of fruit and vegetables. However, no literature is available on abscisic acid (ABA) effect on yam tuber healing in relation to SPA biosynthesis. In this study, ABA treatment decreased weight loss and disease incidence of yam tubers, maintained the integrity of cell membrane, and promoted the accumulation and polymerization of SPA monomers such as fatty acids (FAs), ω-hydroxyacid (ω-OHA) and α, ω-dicarboxylic acid (α, ω-diA). Gene expression of β-ketoacyl CoA synthases (DoKCS2, DoKCS6), cytochrome P450 fatty acid ω-hydroxylases (DoCYP86A1, DoCYP94B3), Glycerol-3-phosphate acyltransferases (DoDPAT5, DoGPAT7) and feruloyl-CoA transferase (DoFHT), which were associated with the biosynthesis of SPA monomers, were enhanced by ABA treatment. ABA improved gene expression of ATP-binding cassette transporters (DoABCG2, DoABCG6) and GDSL-type esterase/lipases (DoGELP38, DoGELP51, DoGELP96), which might facilitate the transport and polymerization of SPA monomers. Contrarily, applied fluridone (FLD, an inhibitor of ABA biosynthesis) exhibited an opposite effect to ABA treatment. The results indicate that ABA accelerates yam tuber healing via positively regulating SPA biosynthesis.

First report of basal stem rot caused by three Fusarium species on Chinese yam in China.

The cultivated variety of Chinese yam (Dioscorea polystachya Turcz. cv. Tiegun) is an economically important plant, capable of producing tubers that are used as food and traditional Chinese medicine. The basal stem rot was found on approximately 65% of yam (tuber expansion stage) in a total of 10 ha field in Wuzhi, Wen, and Hua counties, Henan, China (Sep 2021). Dark brown fusiform lesions initially occurred at the stems basal, irregularly extending to join together and leading to loop-stem necrotic indentation. Three diseased samples from Wuzhi county were collected, cut into 5 × 5 mm pieces, surface sterilized in 75% ethanol (30 s) and 1% NaClO (1 min), washed in sterile water 3 times, and placed on PDA in the dark for 3 days at 28℃. A total of 44 isolates forming three groups of Fusarium colonies were obtained using monosporic isolation, of which 19, 8, and 17 isolates were identified as F. oxysporum, F. solani, and F. proliferatum based on colony morphology, respectively. Typical isolates SYJJ6, 9, and 10 for each group were further studied. The SYJJ6 colonies showed gray white abundant fluffy aerial mycelium with rough edges, formation of ellipsoid, unicellular microconidia without septa, 5.6 to 13.4 × 2.4 to 4.7 μm (n = 50), and sickle-shaped, slightly curved macroconidia with 2 to 4 septa, 14.0 to 23.9 × 3.4 to 5.1 μm (n = 50). Isolate SYJJ9 produced flocculent white colonies, grew in a circular pattern with a sharp edge, forming oval or oblong microconidia with zero or one septum, 11.2 to 18.8 × 3.4 to 6.2 μm (n = 50), and slightly curved macroconidia with 2 to 3 septa, 27.6 to 44.0 × 3.9 to 7.4 μm (n = 50). SYJJ10 produced whitish or pinkish white colonies with fluffy aerial mycelium and a red pigmentation, produced renal or oval microconidia with no septa, 5.1 to 11.8 × 1.8 to 4.2 μm (n = 50), and falcate, slightly curved macroconidia with 3 to 4 septa, 16.1 to 30.2 × 3.1 to 5.9 μm (n = 50). Additionally, TUB, EF-1α, and RPB2 genes were amplified with primers BT2a/BT2b, EF1/EF2, and 5f2/-7cr, respectively (Glass and Donaldson 1995; O'Donnell et al. 1998, 2010). BLASTn analysis on SYJJ6 (OR047663, OR047666, OR047669), SYJJ9 (OR047665, OR047667, OR047670), and SYJJ10 (OR047664, OR047668, OR047671) gene sequences were over 99% identical to those of F. oxysporum (100%, MK432917; 100%, MN417196; 99.61%, MN457531), F. solani (100%, MF662662; 100%, MN223440; 99.80%, CP104055), and F. proliferatum (100%, ON557521; 100%, ON458137; 99.90%, LT841266), respectively. Pathogenicity tests of three isolates were separately performed on 60-day-old yam seedlings. The basal stems were wounded using needle, and the wounds were wrapped with cotton balls soaked with conidial suspension (1 mL, 3×106 conidia/mL) or water (control). Each isolate treated three plants and repeated three times. All plants were grown at 28℃ under a 16/8-h light/dark cycle. Typical symptoms emerged on basal stems at 16, 13, and 17 days after inoculation with the conidia of isolates SYJJ6, 9, and 10, while the control basal stems appeared healthy. The re-isolated fungi were identical to the original three isolates. Fusarium species (F. oxysporum, F. commune, F. humuli, etc.)were previously reported to cause wilt or stem rot on different D. polystachya cultivars (Fang et al. 2020; Li et al. 2023; Zhao et al. 2013), or basal stem rot on Panax ginseng (Ma et al. 2020). This is the first report of Chinese yam basal stem rot caused by Fusarium species, which threatens the production of Chinese yam 'Tiegun' and should be further studied.

Genome-wide association analysis and transgenic characterization for amylose content regulating gene in tuber of Dioscorea zingiberensis

BackgroundAmylose, a prebiotic found in yams is known to be beneficial for the gut microflora and is particularly advantageous for diabetic patients’ diet. However, the genetic machinery underlying amylose production remains elusive. A comprehensive characterization of the genetic basis of amylose content in yam tubers is a prerequisite for accelerating the genetic engineering of yams with respect to amylose content variation.ResultsTo uncover the genetic variants underlying variation in amylose content, we evaluated amylose content in freshly harvested tubers from 150 accessions of Dioscorea zingibensis. With 30,000 high-quality single nucleotide polymorphisms (SNP), we performed a genome-wide association analysis (GWAS). The population structure analysis classified the D. zingiberensis accessions into three groups. A total of 115 significant loci were detected on four chromosomes. Of these, 112 significant SNPs (log10(p) = 5, q-value < 0.004) were clustered in a narrow window on the chromosome 6 (chr6). The peak SNP at the position 75,609,202 on chr6 could explain 63.15% of amylose variation in the population and fell into the first exon of the ADP-glucose pyrophosphorylase (AGPase) small subunit gene, causing a non-synonymous modification of the resulting protein sequence. Allele segregation analysis showed that accessions with the rare G allele had a higher amylose content than those harboring the common A allele. However, AGPase, a key enzyme precursor of amylose biosynthesis, was not expressed differentially between accessions with A and G alleles. Overexpression of the two variants of AGPase in Arabidopsis thaliana resulted in a significantly higher amylose content in lines transformed with the AGPase-G allele.ConclusionsOverall, this study showed that a major genetic variant in AGPase probably enhances the enzyme activity leading to high amylose content in D. zingiberensis tuber. The results provide valuable insights for the development of amylose-enriched genotypes.

Chemical Compositions, Phytochemical Screenings and Antifungal Activities of Cashew Nut Shell Liquid Extracts on Phytopathogenic Fungi of Yam (Dioscorea rotundata)

This study was carried out to evaluate the antifungal activity of Cashew (Anacardium occidentale L.) nutshell liquid on fungal pathogens of dry rot diseases of yam (Dioscorea cayennensis subsp. rotundata). The Soxhlet extraction method was used and constituents were identified and quantified using Gas chromatography. Isolation and identification of fungi complexes associated with dry rot disease of yam were made using Potato dextrose agar (PDA) as a medium. The antifungal activity of CNSL was evaluated using the food poisoning technique on PDA at 25, 50, 75 and 100% concentrations of CNSL dissolved in dimethyl sulphoxide. Azulene (57.65%) was the major chemical component of CNSL with phenolic compounds; anacardol, cresols and anacardic acid, among other compounds. CNSL phytochemical screening showed the presence of flavonoids, alkaloids, saponins, tannins, phenols, terpenoids, volatile oil and steroids. Infected yam tubers were isolated, four fungal strains (Fusarium solani, Lasiodiplodia theobromae, Aspergillus fumigatus, and A. niger) were identified, and pathogenicity test confirmed the association of the fungi species with the dry rot disease of white yam. CNSL was active against the identified fungi and could potentially compete with conventional standard as a suitable fungicide against dry rot disease of white yam.

Effect of Varied NaCl Soaking Treatment on Chemical Composition of Lesser Yam Flour and Its Use in the Production of Gluten-Free Noodles

In order to reduce dependence on wheat flour, it was necessary to use alternative options, such as lesser yam flour. The production of lesser yam flour consisted of soaking yam tubers in NaCl solutions of different concentrations (20% and 25%). This soaking process was necessary for enhancing the physical characteristics of the flour, resulting in reduced mucus and a whiter appearance. The diverse NaCl concentrations during soaking significantly affected chemical composition of lesser yam flour, impacting parameters, including moisture, ash, fat, total protein, reducing sugar, total sugar, glucomannan content, and calories. However, no discernible effect was observed on the crude fiber and carbohydrate content. In comparison to the 25% NaCl, the 20% NaCl had lesser yam flour with lower moisture, ash, protein, total sugar, and reducing sugar content, but higher fat, glucomannan, and calories. The 25% NaCl soaked lesser yam flour was selected for the production of gluten-free dry noodles. Dry noodles were prepared with various proportions of lesser yam flour and mocaf flour, including 0:100 (TG0), 50:50 (TG1), 50:40 (TG2), 70:30 (TG3), 80:20 (TG4), and 90:10 (TG5). An increase in the proportions of lesser yam flour resulted in increased hardness and chewiness, along with decreased springiness and cohesiveness. Therefore, lesser yam could be processed into flour by soaking in NaCl solutions to produce better flour, with the optimal flour composition being 80% lesser yam flour and 20% mocaf flour for gluten-free noodles production. This suggested the potential for further development of lesser yam flour as a raw material for the production of gluten-free noodles.

Biological potentials of Landolphia owariensis leaf methanolic extract against pathogenic fungi isolates from different Dioscorea species

Abstract Regarding economic significance, the Dioscoreaceae family, which includes the well-known Dioscorea (yam) species, is the fourth most important tuber crop globally. A basic meal found all across the world, yams encourage and ensure the food security of households. Although they are challenging to preserve and store however a post-harvest deterioration control must be developed. Over the years, Nigerian farmers have employed medicinal herbs to manage post-harvest pest invasion; nevertheless, the scientific basis for this fungal management has not yet been well documented. As a result, Landolphia owarensis leaf extract was used as a biological control, and fungi were isolated from Dioscorea cayenensis, Dioscorea alata, and Discorea rotundata. Samples of yam tubers – both rotten and healthy – were procured in the markets and brought to the lab for fungus isolation and identification. Leaves of Landolphia oweriensis were collected, air-dried, milled, and macerated in pure methanol for 72 h, extracted and concentrated with a rotary evaporator. The agar-well diffusion method was used for the biological control assay against the fungal isolates. The biological control results were presented as mean ± SD (standard deviation) while analysis of variance (Anova) was used to deduce least significant difference (LSD). A total number of 605 fungi isolates were observed in which D. cayenensis had the highest, 50.58 %, D. alata and Discorea rotundata 24.71 % respectively. Aspergillus niger and Aspergillus fumigatus were found in the three species while Aspergillus flavus, Rhizopus stolonifer, Collentotricum spp. and Penicillium spp. in either of the species. L. owarensis methanolic leaves extracts possesses biological potentials against Colletotrium spp., A. fumigatus, A. niger and A. flavus only. The problem of postharvest fungal invasion of Dioscorea species can be solved with the inhibition observed with L. owarensis methanolic leaves extracts as a biological control measure thereby sustaining food security in the world.

Investigating the impact of ultrasound on the structural, physicochemical, and emulsifying characteristics of Dioscorin: Insights from experimental data and molecular dynamics simulation

This study investigated the impact of ultrasound treatment on dioscorin, the primary storage protein found in yam tubers. Three key factors, namely ultrasound power, duration, and frequency, were focused on. The research revealed that ultrasound-induced cavitation effects disrupted non-covalent bonds, resulting in a reduction in α-helix and β-sheet contents, decreased thermal stability, and a decrease in the apparent hydrodynamic diameter (Dh) of dioscorin. Additionally, previously hidden amino acid groups within the molecule became exposed on its surface, resulting in increased surface hydrophobicity (Ho) and zeta-potential. Under specific ultrasound conditions (200 W, 25 kHz, 30 min), Dh decreased while Ho increased, facilitating the adsorption of dioscorin molecules onto the oil-water interface. Molecular dynamics (MD) simulations showed that at lower frequencies and pressures, the structural flexibility of dioscorin's main chain atoms increased, leading to more significant fluctuations between amino acid residues. This transformation improved dioscorin's emulsifying properties and its oil-water interface affinity.

Resistance of Dried Chips of Three Yam Cultivars to Damage by Prostephanus truncatus (Horn) (Coleoptera: Bostrichidae)

Yam (Dioscorea spp) is one of the most common tuber crops consumed by man due to its nutritional benefits. Yam tubers are often processed into products like Dry Yam Chips (DYC) to minimize postharvest losses. The crop could be processed into other products to reduce perishability and scarcity at certain periods. The insect is mainly controlled with conventional insecticides. However, use of conventional insecticide in preserving DYC is contentious due to concerns about undesirable effects on consumers. This has necessitated the search for safer and more effective control strategies such as resistance traits that is innate. The study was therefore conducted to evaluate the resistance of three yam species (Dioscorea cayenensis, D. rotundata, and D. alata) used in making DYC to infestation and damage by Larger Grain Borer (LGB). Two hundred (200) g of parboiled DYC were weighed into 250 ml Kilner jars and separately infested with twenty adult LGB of 0-5 days old. The treatments were replicated four times and arranged on the experimental table using Completely Randomized Design (CRD). At 90 days post-infestation, the insects were sieved out to separate insects from DYC. Data were collected on weight loss of DYC, damage to DYC, adult mortality of LGB, dust of DYC, and number of emerged LGB. The percentage damage of LGB to DYC of D. alata and D. rotundata was 100.00% and 96.43%, respectively, which were not significantly (p&gt; 0.05) different from each other. The percentage weight loss (70.61) of DYC of D. alata was significantly (p&lt; 0.05) higher than the weight loss in D. cayenensis (28.63) and D. rotundata (46.27). The percent weight loss in the DYC of D. cayenensis was significantly (p&lt; 0.05) lower than the weight loss in DYC of D. alata (70.61) and D. rotundata (46.27). The number of adult LGB (539.80) in the DYC of D. alata was significantly (p &lt; 0.05) higher than the number of the insect in D. cayenensis (117.8) and D. rotundata (216.80). The number of adult mortality of LGB in the DYC of D. alata (38.50) and D. cayenensis (21.12) is comparable, but significantly lower than number of adult mortality of the insect in D. rotundata (41.50) DYC. The number of the insect larvae in DYC of D. cayenensis (4.25) was significantly (p&lt; 0.05) lower than the number of the larvae of LGB in DYC of D. alata (30.00) and D. rotundata (21.00). DYC of D. cayenensis and D. rotundata were moderately resistant to damage by LGB and could be use in preparation of DYC to mitigate damage of LGB to DYC in storage before use.

Evaluation of Nutritional Quality and Organoleptic Properties of Soy-poundo Yam Flour

This study was designed specifically to evaluate the nutrient composition and sensory properties of soy-poundo yam flours produced from white yam and soybean flours. The white yam tubers and soybean seeds were processed into flours and blended in the ratios of 100:0, 90:10, 80:20, 70:30, 60:40 and 50:50, respectively and used to produce soy-poundo yam flours with 100 % instant yam flour used as control. The samples of soy-poundo yam flour produced were evaluated for nutrient composition and sensory properties using standard methods. The moisture, crude protein, fat, ash and crude fibre contents of the samples increased significantly (p&lt;0.05) with increase in substitution of soybean flour from 7.56 - 8.36%, 4.41 – 21.14%, 4.18- 5.09%, 2.51- 4.16% and 2.76 - 4.06%, respectively, while their carbohydrate and energy contents decreased from 78.74-57.21% and 370.16- 359.15KJ/100g, respectively. The mineral composition of the samples revealed that the potassium, magnesium, manganese, iron, zinc and copper contents of the products ranged from 78.34 – 164.11mg/100g, 2.46 -17.14mg/100g, 20.48 -125.53mg/100g,1.56 -2.23mg/100g, 1.78 -263mg/100g and 2.88 – 3.64mg/100g, respectively. The vitamin content of the samples showed that the vitamin A, pyridoxine, ascorbic acid, thiamine, vitamin E and niacin contents ranged from 12.00-12.70mg/100g, 2.28-2.59mg/100g, 16.1-17.07mg/100g, 56.07- 74.46mg/100g, 3.34-4.10mg/100g and 2.29 -3.22mg/100g, respectively with the control sample having the least values for all the vitamins evaluated. The sensory properties of the soy-poundo yam flour doughs obtained upon reconstitution of the samples with boiling water also revealed that the colour, taste, texture and aroma of the control sample (Poundo yam prepared from 100% instant yam flour) were the most acceptable to the assessors compared to the samples prepared from the substituted samples. Although the poundo yam dough made from the control sample was the most acceptable, the other test samples prepared from soy-yam composite blends were equally acceptable based on their relatively high scores in all the sensory attributes evaluated by the judges. The study, therefore, showed that the enrichment of yam flour with soybean at different graded levels would not only improve the nutrient contents of soy-poundo yam flour but would also add varieties to poundo yam meal due to improvement in its colour and texture.

Evaluation of the Effect of Pre-Harvest Treatment on the Yield and Storability of Yam Tubers

Evaluation of the Effect of Pre-Harvest Treatment on the Yield and Storability of Yam Tubers

Evaluation of the Effect of Pre-Harvest Treatment on the Yield and Storability of Yam Tubers

Evaluation of the Effect of Pre-Harvest Treatment on the Yield and Storability of Yam Tubers

Whole-genome sequencing and comparative genomics reveal candidate genes associated with quality traits in Dioscorea alata

BackgroundQuality traits are essential determinants of consumer preferences. Dioscorea alata (Greater Yam), is a starchy tuber crop in tropical regions. However, a comprehensive understanding of the genetic basis underlying yam tuber quality remains elusive. To address this knowledge gap, we employed population genomics and candidate gene association approaches to unravel the genetic factors influencing the quality attributes of boiled yam.Methods and ResultsComparative genomics analysis of 45 plant species revealed numerous novel genes absent in the existing D. alata gene annotation. This approach, adding 48% more genes, significantly enhanced the functional annotation of three crucial metabolic pathways associated with boiled yam quality traits: pentose and glucuronate interconversions, starch and sucrose metabolism, and flavonoid biosynthesis. In addition, the whole-genome sequencing of 127 genotypes identified 27 genes under selection and 22 genes linked to texture, starch content, and color through a candidate gene association analysis. Notably, five genes involved in starch content and cell wall composition, including 1,3-beta Glucan synthase, β-amylase, and Pectin methyl esterase, were common to both approaches and their expression levels were assessed by transcriptomic data.ConclusionsThe analysis of the whole-genome of 127 genotypes of D. alata and the study of three specific pathways allowed the identification of important genes for tuber quality. Our findings provide insights into the genetic basis of yam quality traits and will help the enhancement of yam tuber quality through breeding programs.

Effect of tillage, fertilizers and storage structures on quality shelf life of white yam (Dioscorea rotundata Poir) in south west Nigeria

This study examined the effect of tillage, fertilizers and storage structures on quality shelf life of white yam in South West Nigeria. The study was a factorial experiment consisting of Tillage, Fertilizers and Storage Structure. The tillage system involved Heap Tillage (HT) and Ridge Tillage (RT), while Fertilizers involved Poultry Manure (PM), N15P15K15 (NPK) and Control (CLT) and two types of Storage Structures namely; Traditional Barn (TB) and Open Sided Storage Structure (OSSS) were combined to form the treatments. The experiment was a 2x3x2 factorial combination arranged in a Randomised Complete Block Design (RCBD). The treatments were replicated three times for each location respectively. A total of 72 ridges and 144 heaps were used to make a population of 288 plants per location. The tubers were weighed to ensure uniformity before planting. The plot size was 18mx18m square with a pathway of 1.0m between blocks making a total of 324 square metres. At harvest, the tubers were weighed immediately. They were then kept separately in the two storage structures namely: Traditional Barn (TB) and the Open Side Storage Structure (OSSS) for a period of 3 months. After the 3rd months of storage, the tubers were examined and data collected. The weight of each tuber from each storage structure was taken periodically to evaluate the weight loss and assess the keeping quality periodically. The findings of this study demonstrated the significant influence of tillage, fertilizers, and storage structures on the quality, shelf life, nutrient use efficiency, and nutrient composition of white yam. Excessive fertilizer application was found to increase rotting and deterioration levels. Hence, farmers and stakeholders should carefully consider fertilizer application rates to minimize post-harvest losses and enhance food security. Further investigations are needed to explore the underlying mechanisms responsible for the observed effects and to optimize fertilizer management practices for yam storage. Organic fertilization enhances the nutrient use efficiency and nutritional quality of yam, while appropriate storage structures, play a crucial role in preserving the quality and extending the shelf life of the harvested tubers. Based on the result of the study, open sided storage should be considered by producers of yams for storing their harvested tubers due to the facts that, it performed well in minimizing nutrient lost, weight loss and decay to considerable level and prevented pests/rodents attack on yam tubers.