Yam Tubers Research Articles

Pesticide residues in seed yams produced using the adaptive Yam Minisett Technique

ABSTRACT This paper provides the results of the first research designed to test for pesticide residue analysis conducted on seed yam (Dioscorea rotundata Poir) tubers produced via the Adaptive Yam Minisett technique (AYMT). AYMT uses a pesticide-based water dip to treat setts (~75 g) cut from a yam tuber, and these setts are planted to produce healthy seed yams. While the dip is known to be effective in terms of sett survival in the field along with quantity and yield of seed yams produced, one potential issue is the carry-over of chlorpyrifos from treated setts into the seed yams. The research reported here describes the results from an experimental plot established in the Federal Capital Territory of Nigeria designed to address this issue. A total of 54 seed yam tubers (18 seed yams from each plot) were analyzed from control (untreated), half-dose and full-dose pesticide dip treatments and results show that there is no carryover of chlorpyrifos from treated setts into the seed yams. There may also be potential to significantly reduce pesticide concentration in the dip, although this requires further research before a new recommendation can be developed.

Physico-chemical Properties of Starches from Two Varieties of Sweet Potato and Yam Tubers Available in Nigeria

The research sought to investigate the functional properties of starches obtained from four Nigerian root and tubers, yam and sweet potato varieties, in order to facilitate their exploitation as substitute raw material for the local food and pharmaceutical manufacturing industry. The varieties, namely: white yam (Dioscorea rotundata), water yam (Dioscorea alorta), orange flesh sweet potato (Ipomoea batatas) and cream flesh sweet potato (Ipomoea batatas), their respective starches were obtained by wet separation techniques and were analyzed for their pasting properties, physic-chemical properties, starch yield on dry and wet basis, functional, starch purity, amylase and amylo-pectin were undertaken in order to determine their suitability for food and other uses. The peak time, pasting temperature, peak viscosity, holding strength, breakdown, set from peak and set back from through ranged from 7.3 – 8.3 mins, 65.4 – 71.3°C, 511.5 – 1001.2 BU, 860.8 – 871.3 BU, 300.1 – 306.9 BU, 240.8 – 248.1 BU and 400.4 – 510.9 BU respectively. There were significant differences (p<0.05) in the pasting properties. The crude protein, crude fat, crude fibre, ash, moisture and carbohydrate ranged from 1.55 – 1.85%, 0.09 – 0.12%, 0.12 – 0.22%, 1.32 – 2.05%, 10.72 – 11.09% and 85.59 – 86.20% respectively. There were significant differences (p<0.05) in the proximate composition of the starches. The starch yield on dry weight basis, starch weight on fresh weight basis, starch yield from tubers and percentage dry matter ranged from 56.84 – 85.88%, 22.75 – 36.07%, 18.02 – 26.00% and 40.02 – 44.01% respectively. There were significant differences (p<0.05) in the all the parameters. The bulk density, water absorption capacity, oil absorption capacity, gelatinization temperature, starch purity, amylase, amylo-pectin and pH ranged from 0.56 – 0.61g/cm3, 86.8 – 99.4%, 103.2 – 125.4%, 59.78 – 60.42°C, 95.28 – 96.55%, 27.25 – 29.37%, 70.63 – 72.63% and 6.82 – 6.91 respectively. There were significant differences (p<0.05) in all the parameters but no significant difference (p>0.05) in the pH. The starches from yam and sweet potato varieties starches can be exploited for diverse uses based on their different characteristics.

Biochemical Composition and Antimicrobial Activities of Seed Extracts of Avocado (Persea americana)

Evaluation of the bioactive compounds present in plant extracts play an important role in developing effective antimicrobial agents that can combat resistant plant and animal fungal pathogens. The objectives of the study were to evaluate the biochemical composition and antifungal activities of Avocado (Persea americana) seed extracts. The fungal pathogens for the study were isolated from yam tuber. They were Botryodiploidia theobromae, Rhizopus stolonifer, Aspergillus flavus, Fusarium oxysporium and Geothricum candidum. Pathogencity tests showed that all the fungal isolates were pathogenic on the yam tuber. The results of the antifungal activity of Avacado pear seed using paper disc diffusion technique against the pathogenic fungi showed that it had varied degree of inhibitions on all the fungal pathogens, Botryodiploidia theobromae (13.20), Rhizopus stolonifera (14.02) A. flavus (12.10), F. oxysporium (9.30), G. candidum (7.00).Identification of antifungal compounds using GCMS revealed the presence of 119 compounds. The compounds with highest in abundance are 2‐n‐Octylfuran,this was followed by 13‐tetradecenal and 9,12‐Octadecadienoic acid and finally 2,15‐Octadecedien‐1‐ol acetate. It is suggested that Avacado pear seed be used on the treatment of plant and animal fungal diseases.Support or Funding InformationSelf

Production, purification and characterization of thermostable alpha amylase from Bacillus subtilis Y25 isolated from decaying yam (Dioscorea rotundata) tuber

Amylases have wide biotechnological potentials for applications in various industries. An α-amylase-producing bacterium was isolated from deteriorating yam tubers. Molecular characterization using the 16S rRNA gene sequencing was used to confirm the identity of the bacterium as Bacillus subtilis Y25. The effect of some cultural and nutritional factors such as pH, temperature, carbon and nitrogen sources on α-amylase production from the bacterium was determined. Maximum α-amylase production was observed using starch and peptone as carbon and nitrogen sources, respectively, with an initial medium pH of 8.0 and incubation at 45 °C for 36 h. The enzyme was purified by ion exchange chromatography on CM Sepharose CL-6B. The kinetic parameters Km and Vmax of the enzyme, as well as the effect of pH, temperature, metal ions and ethylenediaminetetra acetic acid (EDTA) on the activity of the purified enzyme were studied. The specific activity of the partially purified enzyme was determined to be 15.21 Units/mg protein with a purification fold of 3.80. The molecular weight of the purified enzyme was estimated to be 58.0 kDa. The Vmax and Km values obtained with soluble starch for Bacillus subtilis Y25 α-amylase were 314.10 ± 23.30 Units/mg protein and 53.98 ± 12.03 mg/ml, respectively. The enzyme exhibited optimum activity at a temperature of 60 °C and pH 8.0. The metal ion Ca2+ had no effect on the enzyme at 20 mM concentration, whereas Na+ and Mg2+, as well as EDTA inhibited the enzyme at the same concentration. The characteristics of the α-amylase from Bacillus subtilis Y25 revealed it to be a thermostable and an alkaline metalloenzyme with potential for applications in the detergent and saccharification industries.

Introduction Pages

Notulae Scientia Biologicae (http://www.notulaebiologicae.ro), Issue 1, Volume 12, 2020: The papers published in this issue represent interesting novelties in different topics of life science. Among the exciting researches, we invite readers to find news about: vultures, their population status and some ecological aspects in an Indian stronghold; analysis of secondary metabolites and in vitro evaluation of extracts of Carica papaya and Azadirachta indica leaves on selected human pathogens; the risk mitigation indices associated with some risk mitigation protocols performed on contaminated aqua-cultured catfish (Clarias gariepinus); evaluation of three plant species to control black scurf disease of Irish potato (Solanum tuberosum Linn.); production, purification and characterization of thermostable alpha amylase from Bacillus subtilis Y25 isolated from decaying yam (Dioscorea rotundata) tuber; influence of ammonium and moisture on survival and nifH transcription in the diazotrophic Pseudomonas mendocina S10; two additions to the Asteraceae of Egypt; micromorphology studies of three important medicinal plants of Asclepiadaceae family; phenological attributes of Pyracantha crenulata - a high-value multipurpose shrub of the Himalaya; in vitro callus and shoot regeneration in Enterolobium cyclocarpum (Jacq.) Grised. - a fast timber yielding species.

Structure and physicochemical properties of native starch and resistant starch in Chinese yam (Dioscorea opposita Thunb.)

The physicochemical properties of starch in Chinese yam (Dioscorea opposita Thunb.) are highly dependent on the growth stage. However, relevant information available is limited. In this work, native starch and resistant starch (RS) were prepared from Chinese yam tuber at expansion stage and dormant stage, respectively. Their structural and physicochemical properties were determined. They presented A-type polymorphic structure. The starches from dormant stage had smaller granule sizes, lower amylose contents, less branching degrees of amylopectin, and higher proportions of double helix than those from expansion stage. Dormant stage induced starch to form a more compact structure with a higher crystallinity and larger amount of short-range ordering than expansion stage. Moreover, the starch paste from dormant stage had a high thermal stability. These results were helpful for further application of Chinese yam starch in food products.

Determination of thermophysical and desorption properties of elephant foot yam using composition based and fast sorption method

In the present work, thermophysical properties (thermal conductivity, specific heat, density and thermal diffusivity), and sorption properties (water activity and total isosteric heat of desorption) of elephant foot yam (EFY) tuber crop are determined at different temperatures. EFY is a widely consumed tuber crop which is mainly grown in tropical and subtropical regions of Southeast Asian countries. The thermophysical properties are determined using composition and temperature based thermophysical property models for each constituent in conjunction with the constituents present in the food material. Two different methods - gravimetric and fast sorption have been used for determining the sorption properties of EFY. Three sorption models are used to find the best model which describes the experimental sorption behaviour of EFY. It is found that all thermophysical properties increase with temperature except the density of the EFY. The sorption behaviour of EFY is observed as sigmoid shape for all temperatures which comes under II type of sorption isotherm. GAB model is found to be the best model followed by BET and OSWIN model to describe the desorption isotherm of EFY. The total isosteric heat of desorption of EFY drastically increases at lower moisture content as compared to higher moisture content of EFY.

Integrated mRNA and miRNA transcriptome analysis reveals a regulatory network for tuber expansion in Chinese yam (Dioscorea opposita)

BackgroundYam tuber is a storage organ, derived from the modified stem. Tuber expansion is a complex process, and depends on the expressions of genes that can be influenced by environmental and endogenous factors. However, little is known about the regulatory mechanism of tuber expansion. In order to identify the genes and miRNAs involved in tuber expansion, we examined the mRNAs and small RNAs in Dioscorea opposita (Chinese yam) cv. Guihuai 16 tuber during its initiation and expansion stages.ResultsA total of 14,238 differentially expressed genes in yam tuber at its expansion stage were identified by using RNA sequencing technology. Among them, 5723 genes were up-regulated, and 8515 genes were down-regulated. Functional analysis revealed the coordination of tuber plant involved in processes of cell events, metabolism, biosynthesis, and signal transduction pathways at transcriptional level, suggesting that these differentially expressed genes are somehow involved in response to tuber expansion, including CDPK, CaM, CDL, SAUR, DELLA, SuSy, and expansin. In addition, 541 transcription factor genes showed differential expression during the expansion stage at transcriptional level. MADS, bHLH, and GRAS were involved in cell differentiation, division, and expansion, which may relate to tuber expansion. Noteworthy, data analysis revealed that 22 known tuber miRNAs belong to 10 miRNA families, and 50 novel miRNAs were identified. The integrated analysis of miRNA-mRNA showed that 4 known miRNAs and 11 genes formed 14 miRNA-target mRNA pairs were co-expressed in expansion stage. miRNA160, miRNA396, miRNA535 and miRNA5021 may be involved in complex network to regulate cell division and differentiation in yam during its expansion stage.ConclusionThe mRNA and miRNA datasets presented here identified a subset of candidate genes and miRNAs that are putatively associated with tuber expansion in yam, a hypothetical model of genetic regulatory network associated with tuber expansion in yam was put forward, which may provide a foundation for molecular regulatory mechanism researching on tuber expansion in Dioscorea species.

Morpho-anatomical adaptation of lesser yam (Dioscorea esculenta) on different planting pattern and relative light intensity in Java community forest

Lesser yam (Dioscorea esculenta) is traditionally cultivated as a valuable crop species in a various planting pattern of teak-based agroforestry (AF) system in Watubonang village, Sukoharjo District, Central Java. Different planting pattern contributes to various light intensity which is associated with plant morphological and anatomical changes and directly affect to yam tuber production. Research site was selected by mean of purposive sampling method with three yam planting patterns, i.e. yam monoculture (Y), yam in trees along border (TAB) and yam in full teak trees (T-Y), in three replicates of 20 m x 20 m plots. In each plot, four subplots were established to investigate relative light intensity and take leaf samples. Changes in morphological and anatomical characteristics of yam to different planting pattern and relative light intensity (RLI) were studied, including leaf size, leaf color, tendril and internode length, chlorophyll content and stomatal density. The result showed that RLI were significantly different among planting pattern (Y: 78.66%, TAB: 66.94%, T-Y: 34.05%). Planting pattern and interaction between planting pattern and RLI significantly affected yam morphological and anatomical characteristics (of leaf size, tendril & internode length, and stomatal density) at P < 0.05. Leaf size, tendril and internode length increased with decreasing of RLI in TAB, but opposite adaptation was found in T-Y planting pattern. Higher RLI resulted in reductions of chlorophyll a and chlorophyll b content, and therefore increased of chlorophyll a:b ratio. Leaf color of yam grown under high RLI (Y) were light green, while those grown under shaded condition with relatively low light intensity (TAB, T-Y) were dark green that may related to the foliar chlorophyll content. Hence, a trend of decreasing stomatal density was found associated with lower RLI (Y: 35 stomatal/mm2, TAB: 25 stomatal/mm2, T-Y: 19 stomatal/mm2). Approximately 50-60% of RLI is suggested to be an optimum intensity for yam cultivation to support yam tuber production. Agroforestry practice by applying pruning and managing planting density are needed to reach the optimum light.

Design and Performance Evaluation of a Multi-Tuber Peeling Machine

Tuber peeling is an essential unit operation prior to further processing. In this research, a batch loading tuber-peeling machine, with a capacity of 10 kg/min, was designed, fabricated and tested for cocoyam, sweet potato, yam and cassava tubers. The machine was designed to operate at a speed range of 350–750 rpm and time range of 5–12 min based on the principle of surface scratching. The performance of the machine was determined with respect to the peeling efficiency, percent weight of peel and flesh loss. The results showed that the peeling efficiency increased with an increase in the shaft speed for all the tubers. Also, the flesh loss and percent weight of peel decreased with an increase in the shaft speed for cassava and cocoyam tubers but increased for sweet potato and yam tubers (p &lt; 0.05). Effective peeling of the tubers was achieved for sweet potato and yam at all the shaft speeds and time ranges considered.

Nutritional, anti-nutritional and physico-functional properties of wild edible yam (Dioscorea spp.) tubers from Koraput, India

Wild yams (Dioscorea spp.) make a significant contribution to the diets and economic welfare of tribal people of Koraput, India. However, there is a lack of information on the food quality of the tubers. The present study was carried out to evaluate the proximate, nutritional and anti-nutritional compositions as well as the physico-functional properties in 8 wild and one cultivated Dioscorea species. The proximate compositions, i.e., moisture, ash, fat, fiber, and crude protein content of yam tubers ranged from 54 to 83, 2.5 to 5.4, 0.56 to 2.0, 1 to 2.02 and 5.4–10.3% respectively. The mineral composition ranged from 31.4 to 89.4 mg 100 g−1 of sodium, 0.83–1.36 g 100 g−1 of potassium, with significant amounts of vitamin C and E. In addition, some wild species showed better nutritional and physico-functional parameters in comparison to the cultivated ones. Furthermore, the anti-nutritional compounds such as diosgenin, amylase- and trypsin-inhibitors were also significantly higher in some wild Dioscorea species. The biochemical characterization with multivariate data analysis led to a feasible classification of the usage of wild yam species. Taken together, the wild species, such as D. oppositifolia, D. hamiltonii and D. pubera showed better nutritional composition than the other yam species. The study also suggested that these wild yam species are a safe food source for local consumption and domestication, leading to potential improvement of food security.

Morphological and molecular characterization of Pratylenchus species from Yam (Dioscorea spp.) in West Africa.

The root-lesion nematodes (RLN), Pratylenchus spp., are among the major plant-parasitic nematodes affecting yam (Dioscorea spp.) production in West Africa. The distribution and diversity of RLN species associated with yam was investigated through a soil and tuber survey of the main producing areas in Nigeria and Ghana. Pratylenchus spp. were detected in the yam rhizosphere in 59% of 81 soil samples from Ghana and 39% of 114 soil samples from Nigeria. Pratylenchus spp. were detected in 24 of 400 tubers examined, in combination with root-knot nematodes (Meloidogyne spp.) and their associated damage of galls and crazy roots (79%), and with yam nematode (Scutellonema bradys) and their associated damage of dry rot (17%), although no specific additional symptoms were observed for Pratylenchus spp. Species of Pratylenchus were identified by their morphological features and by sequences of the D2-D3 region of the 28 S rDNA gene and the mitochondrial cytochrome oxidase I gene (COI). Pratylenchus brachyurus was the most frequent RLN species in both the rhizosphere and tubers of yam. Pratylenchus hexincisus was recovered from one tuber collected in Nigeria. While further investigations are required to establish the host status of yam for this nematode, this appears to be the first record of P. hexincisus on yam. The present taxonomical status of P. scribneri and P. hexincisus is discussed.

Chromatographic investigation of phytoconstituents in milk yam (Ipomoea digitata L.) tubers

Background: Milk yam commonly called Ksheervidhari is a perennial climber; its tubers are an integral crude drug in different Ayurvedic formulations as well as folkloric medicine. It is used as antidiabetic, restorative, carminative, expectorant, galactagogue, stomachic, and appetizer. Objective: The present study is done with the aim of identifying the maturity stage of milk yam tuber containing maximum concentration of umbelliferone – a coumarin present in the tubers. Materials and Methods: Umbelliferone present in immature tubers (6 months after planting), overmature tubers (36 months after planting), and tubers at optimum maturity (21 months after planting) was assessed using high-performance liquid chromatography (HPLC) and high-performance thin-layer chromatography (HPTLC) analysis. Results: HPLC and HPTLC techniques revealed the presence of umbelliferone and it was quantified to be higher in over mature tubers (0.44 and 0.42 μg/g, respectively), followed by optimally mature (0.31 and 0.22 μg/g, respectively) and immature tubers (0.20 and

Utilization of Lesser Yam (Dioscorea esculenta L.) Flour as Prebiotic in Yogurt to Total Lactic Acid Bacteria (LAB), Sugar Reduction, and Organoleptic Properties

This study aims to determine the effect of the concentration the addition of lesser yam as prebiotic to total Lactic Acid Bacteria (LAB), reducing sugar content, crude fiber, viscosity, and organoleptic properties of yogurt with a combination of three bacteria (Streptococcus thermophilus, Lactobacillus bulgaricus, and Lactobacillus acidophilus). The design of this study used a completely randomized design (CRD) with 4 treatments and 5 replications with variations in the addition of lesser yam tuber, namely T1 with a concentration of 0%, T2 with a concentration of 2%, T3 with a concentration of 4% and T4 with a concentration of 6%. The raw materials used are pasteurized fresh cow's milk, lesser yam tuber flour, and yogurt starter. The results showed that the addition of different lesser yam tuber flour had a significant effect (P &amp;lt;0.05) on total LAB, sugar reduction, crude fiber, viscosity, and organoleptic properties of yogurt. The ideal treatment for the addition of lesser yam tuber flour is the concentration of 2% lesser yam tuber, which produces a total LAB is 9.2 x 109, a sugar reduction is 0.653 mg/mL, crude fiber is 1.3%, 82.25 cPs, and organoleptic properties had sour taste and viscosity is rather thick which the most preferred.&lt;br&gt;

Successful manipulation of the growth cycle of yam (Dioscorea spp.) for year-round production for food security and climate change

Yams are important items of diet throughout the Caribbean Region and, among them, the cultivars of the species, Dioscorea alata L. and D. esculenta (Lour.) Burkill are particularly important in the Eastern and Southern Caribbean, although the latter is so to a lesser extent. With a growing period of approximately nine months and a corresponding dormancy period, these cultivars are produced on an annual basis like clockwork, providing food yams for approximately three months of the year, the period of availability coinciding with the period of dormancy as the latter marks the natural period of storage of the tuber. Consequently, the breakage of dormancy marks the beginning of the end of natural storage as the emerging sprouts signal the onset of the next growing period. This coincides with the start of the rainy season and the yam is adapted to existing climatic conditions that provide the ideal environment for both plant establishment and tuber growth. Cultivars of the two species bear no reproductive seed and therefore, are completely dependent on vegetative means for perpetuation. Any adverse development during storage or early growth that prevents sprouting or tuber initiation and growth, results in the permanent loss of the affected material and potentially threatens loss of the specific cultivar. Hence, climate change events such as shifts in the onset of the rainy season, extension of the dry period and incidences of severe weather associated with excessive flooding that can result in death of roots and developing tubers, pose real risks to the persistence of the cultivars of D. alata and D. esculenta that are produced in the Caribbean Region. In order to counteract these effects, what is needed is the manipulation of the growth cycle to allow for year-round production so that the changes that have been observed with respect to climatic and weather patterns will not result in a loss of planting material and, by extension, loss of germplasm. It is well-established that the growth cycle is under hormonal control and that the key to year-round production is the breaking of the physiological lock on the growth cycle that is responsible for the seasonal production by which these species are characterized. There have been many attempts by researchers in the past to achieve this, but without success until relatively recently. Most attempts have explored the use of natural and synthetic plant growth regulators. Further, past attempts have focussed on the breakage of natural dormancy and induction of early sprouting, but instead, the success reported here, was achieved by delaying sprouting to beyond the period of natural dormancy in a novel approach that eliminates the use of growth regulators and other chemicals. This paper reports how reduced temperature storage has been used successfully to break the physiologically controlled growth cycle in cultivars of D. alata and D. esculenta, producing yams all year long by delaying the breakage of dormancy, ensuring not only an extension of the availability of yam tubers for food but also availability of viable planting material throughout the year. It was found that tubers can be stored successfully for an entire cycle, so that tubers from the previous year can meet tubers of the current year’s harvest providing a buffer against crop loss from any adverse biotic or climatic event. The effects on sprouting patterns are described. The use of reduced temperature storage for this purpose has not been reported and this account serves to fill an important gap in documented yam dormancy research.

Successful manipulation of the growth cycle of yam (Dioscorea spp.) for year-round production for food security and climate change

Yams are important items of diet throughout the Caribbean Region and, among them, the cultivars of the species, Dioscorea alata L. and D. esculenta (Lour.) Burkill are particularly important in the Eastern and Southern Caribbean, although the latter is so to a lesser extent. With a growing period of approximately nine months and a corresponding dormancy period, these cultivars are produced on an annual basis like clockwork, providing food yams for approximately three months of the year, the period of availability coinciding with the period of dormancy as the latter marks the natural period of storage of the tuber. Consequently, the breakage of dormancy marks the beginning of the end of natural storage as the emerging sprouts signal the onset of the next growing period. This coincides with the start of the rainy season and the yam is adapted to existing climatic conditions that provide the ideal environment for both plant establishment and tuber growth. Cultivars of the two species bear no reproductive seed and therefore, are completely dependent on vegetative means for perpetuation. Any adverse development during storage or early growth that prevents sprouting or tuber initiation and growth, results in the permanent loss of the affected material and potentially threatens loss of the specific cultivar. Hence, climate change events such as shifts in the onset of the rainy season, extension of the dry period and incidences of severe weather associated with excessive flooding that can result in death of roots and developing tubers, pose real risks to the persistence of the cultivars of D. alata and D. esculenta that are produced in the Caribbean Region. In order to counteract these effects, what is needed is the manipulation of the growth cycle to allow for year-round production so that the changes that have been observed with respect to climatic and weather patterns will not result in a loss of planting material and, by extension, loss of germplasm. It is well-established that the growth cycle is under hormonal control and that the key to year-round production is the breaking of the physiological lock on the growth cycle that is responsible for the seasonal production by which these species are characterized. There have been many attempts by researchers in the past to achieve this, but without success until relatively recently. Most attempts have explored the use of natural and synthetic plant growth regulators. Further, past attempts have focussed on the breakage of natural dormancy and induction of early sprouting, but instead, the success reported here, was achieved by delaying sprouting to beyond the period of natural dormancy in a novel approach that eliminates the use of growth regulators and other chemicals. This paper reports how reduced temperature storage has been used successfully to break the physiologically controlled growth cycle in cultivars of D. alata and D. esculenta , producing yams all year long by delaying the breakage of dormancy, ensuring not only an extension of the availability of yam tubers for food but also availability of viable planting material throughout the year. It was found that tubers can be stored successfully for an entire cycle, so that tubers from the previous year can meet tubers of the current year’s harvest providing a buffer against crop loss from any adverse biotic or climatic event. The effects on sprouting patterns are described. The use of reduced temperature storage for this purpose has not been reported and this account serves to fill an important gap in documented yam dormancy research.

Phytochemical Screening and Antimicrobial Activity of False Yam &lt;i&gt;(Icacina oliviformis)&lt;/i&gt; Extracts on Microbes

This study compares the phytochemicals and antimicrobial activity of Icacina oliviformis tuber and seed extracts on Staphylococcus aureus, Streptococcus pyogenes, Pseudomonas aerugino­sa, Escherichia coli and Candida albicans. False yam tubers were washed and peeled and the mesocarp removed to obtain the seeds. Methanol was used to obtain tuber and seed extracts of the false yam, after they were pulverized. Phytochemical screening showed the presence of tannins, saponins, alkaloids and glycosides in both extracts but the proportion of tannins and alkaloids were relatively higher in false yam seed extract than tuber extract. Antimicrobial assay showed that both extracts had antimicrobial activity justifying its use in the treatment of diseases in Northern Ghana. False yam seed extract had a relatively higher antimicrobial activity than tuber extract. The least minimum inhibition concentration recorded was 1.56 mg/ ml for false yam seed on Gram-positive bacteria and Candida albicans. False yam seed extract exhibited a higher antimicrobial activity against the microorganisms than the tuber extract, this provides a cheaper source of antimicrobial agent to treat infectious diseases.&#x0D; Keywords: False yam tuber, False yam seed, Icacina oliviformis, Phytochemical screening, Minimum Inhibition Concentration (MIC), Microorganisms&#x0D;

Micronutrient Biofortification with Fe, Zn and Cu for Enhanced Growth, Increased Yield and High Profitability of Purple Yam

The importance of micronutrient biofortification in improving the growth and yield of crops is needed nowadays due to the rapid decline in crop yield caused by soil infertility and the prevalence of malnutrition among young children. Micronutrients (Fe, Zn, and Cu) were added to NPK fertilizers to investigate their effects on the growth and yield of purple yam tubers and assess the profitability of their addition on yam production. The different treatments used in the study were: T1 control; T = 150-50-150 kg/ha (N-P O - K O); T = T + 8 kg/ha Zn; T = T + 8 kg/ha Fe; = 2 2 5 2 3 2 4 2 and T = T + 8 kg/ha Cu. The results showed that the addition of micronutrients such 5 2 as Fe, Zn, and Cu to NPK fertilizers statistically increased the growth and yield of purple yam. The addition of 8 kg/ha Fe and Cu to 150-50-150 kg/ha N-P O -K O 2 5 2 increased the size of tubers and the intensity of purple coloration. These treatments likewise produced high yields equivalent to 29.39 to 29.83 tons/ha. This was about 129 to 133 percent higher than the control group which yielded only 12.80 tons/ha. Moreover, treatment T which is a combination of 150-50-150 kg/ha N-P O -K O + 8 5 2 5 2 kg/ha Fe, has produced the highest net income of PhP1,420,704.00/ha. This was 155% higher than the net income obtained by the control group that only amounted to PhP 557,790.00.

Enhancing productivity of farmer-saved seed yam in Ghana: Positive selection and neem leaf powder factors

Recycling of diseased and pests infested seed yam (Dioscorea spp.) has resulted in drastic yield reductions in yam production. The objective of this study was to determine the effect of positive selection on the quality of farmer-saved seed yam and also evaluate the effect of neem leaf powder in managing plant parasitic nematodes damage to yam. Two farming systems namely; Positive selection (PS) and Farmer practice (FP) and two soil amendment regimes; neem leaf powder at 20 g stand-1 (NA20) and no neem amendment (NA0) were tested on one variety of yam (Dente). A 2 x 2 x 1 factorial study, mounted on a randomised complete block design in a split plot arrangement was conducted in four replications. Positive selection occupied main plots; while Farmer practice occupied sub-plots. The study was conducted in eight communities located in two municipalities of Ghana, during 2015-2017. Parameters evaluated included Yam Mosaic Virus incidence and severity, incidence and severity of nematode cracks and galling on yam tubers, plant establishment and yield of yam. It was observed that Yam Mosaic Virus (YMV) disease incidence decreased from 38% in 2016 to 31% in 2017 in PS plots as a result of using virus-free planting materials. However, in FP plots, it increased from 67% in 2016 to 72% in 2017. Neem leaf powder amendment resulted in significantly (P&lt; 0.05) low tuber galling (7%) compared with 40% in unamended plots. Similarly, PS plots yielded 7.7 t ha-1 compared to 5.9 t ha-1 in FP fields. In conclusion, Positive selection out-yielded FP by 30.5%; while PS-neem leaf powder interaction resulted in 38.5% over and above FP without neem amendment.Key words: Dioscorea spp., parasitic nematodes, yam mosaic

Determination of Effects of Location of Loading on Mechanical Properties of Different Cultivars of Yam (Dioscorea Spp) Tubers

Determination of Effects of Location of Loading on Mechanical Properties of Different Cultivars of Yam (Dioscorea Spp) Tubers