Dioscorea Rotundata Poir Research Articles

Identification of Characters Correlated with Tuber Yield in Guinea White Yam (Dioscorea rotundata Poir)

Identification of Characters Correlated with Tuber Yield in Guinea White Yam (Dioscorea rotundata Poir)

Potency of Plant-based Fungicides against a Rot Pathogen of White Yam (Dioscorea rotundata Poir)

Potency of Plant-based Fungicides against a Rot Pathogen of White Yam (Dioscorea rotundata Poir)

The Response of White Yam (Dioscorea rotundata Poir) Tuber Portions to Positive Selection for Quality Seed Yam Production

The production of yams is constrained by high cost and unavailability of clean planting materials, pests and diseases. Vegetative propagation has also caused a build of up diseases, reported to cause up to 80% yield reduction due to scarcity of quality declared seeds. Planting of disease-free material has been found to be effective in reducing disease problems in plants. This study was conducted to produce clean seed yam by reducing yam diseases through positive selection method. In this method, apparently healthy yam plants were identified, tagged (positive selection), assessed for yam mosaic virus incidence and severity using the scale 0 or 1 and 1-5 respectively. The harvested clean tubers from tagged plants were planted the following season so as to determine the rate of response of each genotype and tuber portion to positive selection. At the end of two cycles of positive selection, analysis of variance for percentage number of positive yam plants, YMV incidence, YMV severity and tuber yield shows significant difference (p ≤ 0.05) between positive selection and no selection for both field and screen house plants. It was observed that positively selected plants performed significantly (p ≤ 0.05) better than no selection plants. For field experiment, Number of positively selected plants was highest in positive TDr89/02665 with mean value of 75.00% while no selection Ogoja had the least number of positive plants (17.8%). A yield increase of 1.80 t/ha was recorded due to the application of positive selection method in two cycles. For screen house experiment, result followed a similar trend; however with a reduction in YMV incidence and severity. It is worthy to note that tail portions of yam were lest infected with YMV, hence more healthy plants were selected from the tail portion.

Evaluation of the Progenies from a Cross between Obiaoturugo and Adaka for Evidence of Segregation for Morphological Attributes and Resistance to Major Field Diseases of White Yam (Dioscorea Rotundata Poir)

Evaluation of the Progenies from a Cross between Obiaoturugo and Adaka for Evidence of Segregation for Morphological Attributes and Resistance to Major Field Diseases of White Yam (Dioscorea Rotundata Poir)

Amino Acid Profiles, Total Nitrogen Contents, and Computed-Protein Efficiency Ratios of Manihot esculenta Root and Dioscorea rotundata Tuber Peels

Tuberous roots of cassava and yam are major sources of dietary carbohydrate to human, alternative sources of energy in livestock feeds, and sources of starch in small-scale industries. Investigations on amino acid profiles, total nitrogen contents, and computed-protein efficiency ratios (C-PER) of tuberous root peels of Manihot esculenta Crantz and Dioscorea rotundata Poir. were carried out. Amino acid analysis was carried out using ion-exchange chromatography methods. Total nitrogen content was measured using the micro-Kjeldahl methods. The C-PER was calculated using regression equation. The concentrations of amino acids detected in the cassava peels ranged from 0.54 to 6.54 g/100 g protein, whereas those of yam peels were between 0.37 and 6.25 g/100 g protein. The total amino acid concentration of the cassava peels was not significantly (p>0.05) higher than that of the yam peels. Essential amino acid scores showed that Phe + Tyr and Met + Cys were the most abundant and limiting amino acids, respectively, in cassava and yam peels. The percentage nitrogen content and C-PER of the cassava peels were significantly (p<0.05) higher than those of the yam peels. The cassava and yam peels were not sources of good quality proteins. Therefore, the use of cassava or yam peels as livestock feeds should be supplemented with other sources rich in good quality proteins.

Antimicrobial Effects of Four Plant Extracts against Post Harvest Spoilage Fungi of Yam (Dioscorea rotundata Poir)

Antimicrobial Effects of Four Plant Extracts against Post Harvest Spoilage Fungi of Yam (Dioscorea rotundata Poir)

Field Survey of Symptoms and Isolation of Fungi Associated with Post-harvest Rots of White Yam (Dioscorea Rotundata Poir.)

Investigations were carried out on field survey of symptoms and isolation of fungi associated with the Post-harvest rots of white yam (Dioscorea rotundata Poir.) at Orlu, Imo State. The results of disease incidence and severity showed that dry rot had the highest percentage incidence of 67.5%, followed by wet rot (47.5%) and soft rot 45.0%. Anthracnose recorded 37.5% and powdery mildew recorded 42.5%. The severity result also followed the same trend, with dry rot having the highest percentage of 26.8%, soft rot 23.7%, wet rot 23.2%, anthracnose 16.3% and powdery mildew recorded 15.1%. The fungi were isolated and identified as Trichoderma viride (Pers.), Pythium aphanidermatum (Edson), Aspergillus fumigatus (Fresenius), Penicillium expansum (Link.), Geotrichum candidum (Link.), Fusarium oxysporum (Link.), Botryodiplodia theobromae (Sac.) and Aspergillus niger (van Thieghem). Fungal organisms occurred consistently with soft rot, dry rot, wet rot and anthracnose of D. rotundata with A. fumigatus (Fresenius) occurring more frequently, 45.00%, followed by T. viride (Pers.) 20.00%, P. aphanidermatum (Edson) recorded 15.00%, P. expansum (Link.) and G. candidum (Link.) have 10.00% each.

Effects of planting methods and tuber weights on growth and yield of yam cultivars (Dioscorea rotundata Poir.) in Gabon

A study was conducted to investigate the influence of planting methods and tuber weight on growth and yield of local yam cultivars obtained by the minisett technique from white yam (D. rotundata) in Gabon. Trials were carried out in 2014 and 2015 at the experimental ground of the Higher National Institute of Agronomy and Biotechnology, under natural conditions of lightness, temperature and relative humidity. Twenty- four weeks old mini tubers obtained from local cultivar MVA of D. rotundata were harvested, weighed and categorized (40-80g; 100-150g; 200-300g), and three planting methods (horizontal, oblique and vertical),arranged in ridges constituted the main factors. The experiment was laid out in Randomized Completely Block Design with eighteen treatments and two replications. Data pertaining to sprouting were recorded for 30, 60, 90 and 180 DAP, for tuber length (cm), tuber weight (Kg) and number of tubers per plant 270 DAP. Significant differences among tuber weight in all variables tested were observed. The larger tubers had better sprouting ability than the rest of the tuber weight. The methods of planting had no effects on yield and its components but they affect the depth and spread of tubers. Vertical planting produced deeper but more compactly arranged tubers while horizontal planting produced tubers which were shallowerbut more widespread. Slanting was intermediate for both depth and spread. The number and weight of tubers obtained from mini tubers planted out according to slanting method were significantly different (P< 0.05) from other planting methods. The production of seedlings from mini tuber is an improvement of traditional production of seed yam. Mini tubers must have at least 100-300 g and they should be planted slanting or vertically.

Ácido abscísico y sacarosa afectan la formación in vitro de túberos en plantas de ñame (Dioscorea rotundata Poir.)

El túbero de ñame (Dioscorea rotundata Poir.) es una de las principales fuentes alimenticias de los pobladores de la Costa Atlántica Colombiana y la cuenca del Caribe, y su demanda ha aumentado en el mercado internacional en los últimos años; sin embargo, las técnicas convencionales de cultivo afectan la cantidad y calidad de la producción. Con el fin de ofrecer mecanismos de producción de material de siembra de ñame de buena calidad, se evaluó el efecto de tres concentraciones de sacarosa y cuatro niveles de ácido abscísico en la producción in vitro de microtúberos a partir de explantes nodales. Los tratamientos se distribuyeron con un diseño completamente al azar con ocho repeticiones por tratamiento. El análisis de varianza y la prueba de media de Duncan indicaron que tanto las variables del crecimiento de las plantas como el número de microtúberos mostraron diferencias significativas (Pr&lt;0,05) como resultado de los niveles de ABA/sacarosa, una dosis de 60 g L-1 de sacarosa combinada con 3,0 mg L-1 de ABA indujo el mayor número de microtúberos, mientras que las plantas cultivadas en presencia de 90 g L-1 de sacarosa formaron mayor número de tallos, hojas y raíces.

Preliminary investigations on the control of yam (Dioscorea rotundata Poir) tuber rot through nanoscience

Abstractand

EFFECT OF FUSARIUM NYGAMAI INFECTION ON THE CHEMICAL COMPOSITION OF FLOUR FROM TWO YAM VARIETIES

Yams (Dioscorea spp) are among the oldest food crops. It is estimated that after six months of storage up to 56% of the crop is lost to rot. In Nigeria, fresh yam tubers are used for production of Elubo (yam flour) for preparation of amala, as it is called among the Yoruba in Western Nigeria, and akwunaji in the east of the River Niger. Many researchershave emphasized the importance of microbial rotting in causing storage losses. This study evaluated the effect of yam rot on the nutritional values of Fusarium infected yam tubers.Tubers from two yam (Dioscorea rotundata Poir.)varieties-Nwopoko and TDr95/19177-were infected with Fusarium nygamai pure culture and stored for 12 weeks, after which the tubers were used to produce yam flour and were analyzed for their nutrient composition comprising: dry matter/ moisture content, ash, total sugar, starch, amylose, vitamin C, protein and tannins. Wholesome yams of the same varieties were also used to produce yam flour and equally evaluated for the same nutrients. Infection with Fusariumnygamai led to a significant reduction (p&lt;0.05) in the nutrient composition of the infected yam flour compared with those ofwholesome samples. Vitamin C content reduced from 41.10 to 27.26 (mg/100g) in variety Nwopoko and 36.30 to 30.53 (mg/100g); in variety TDr95/19177. Corresponding values for protein content was from 5.05 to 4.60% and 4.93 to 4.62%; Ash Content from 1.32 to 1.30% and 1.36 to 1.24%; Total Sugar Content from 5.34 to 5.20% and 5.21 to 5.02%; Starch 78.71 to 77.61 and 89.28 to 81.53%; Amylose from 29.95 to 28.87% and 30.01 to 27.95%. However, an increase in the tannin content – (1.84 and 1.94 mg/g) as against (0.31 and 0.26 mg/g) in Nwopoko and TDr 95/19177 varieties respectively was observed. The increase in the tannin content implies an increase in the antinutrient composition. The tendency to produce Elubo used for preparation of amala with rotten yam (possibly Fusarium infected) should be discouraged.

Improved propagation methods to raise the productivity of yam (Dioscorea rotundata Poir.)

White Guinea yam (Dioscorea rotundata Poir.) is an important staple to millions of people in West Africa. Obtaining good quality planting material for yam cultivation is a major challenge. Multiplication ratios are low, and seed tubers are prone to contamination with pests and pathogens in the traditional systems of production. Some approaches to producing quality seed of yam are as follows: farmers select small whole tubers from a ware crop harvest; stimulate the production of seed tubers by ‘milking’ ware tubers while the leaves of the plant are still green (double harvest system); cut ware tubers into setts about the same sizes as regular seed tubers; or use the ‘Anambra’ system where smaller setts are cut and used to produce seed tubers. New methods that have been developed to address some of the challenges of quantity and quality of seed tubers are not yet widely applied, so farmers continue to use traditional methods and save seed from a previous harvest to plant the ware crop. This document presents an overview of traditional and modern methods of seed yam production and gives a perspective for the future. Among the modern methods of seed yam production, only the minisett technique, which uses 25–100 g tuber pieces, is currently used at farmer level, although on a limited scale. While tissue and organ culture techniques are the most rapid methods of multiplying disease free propagules, their limitations include high costs, need for skilled personnel and specialized equipment. The aeroponics and temporary immersion bioreactor methods of producing seed yam are relatively new, and still need more research. To build and sustain a viable seed yam production system, a multiplication scheme is required that combines two or more methods including tissue culture for cleaning the seed stock.

English

Yam is one of the most staple foods in West African countries and provides an important part of the energetic for people. This study examines chemical composition of Dioscorea cayenensis and Dioscorea rotundata Poir species dried yam chips obtained using two methods of production in Togo. Three local varieties of yams (Koukou, Keki and Laboco) were processed in chips and were sun dried (at 28-30°C) or oven-dried (at 50°C). Nutritive components (carbohydrates, protein fats, mineral salt, vitamin C and anti-nutritional factors) of yam chips were assessed and compared with those of fresh yam. Sugar is a major component of yam chips followed by proteins, vitamin, fats, mineral salt and anti-nutritionals factors. For the same variety of yam, the nutritional quality depends on the method of production followed and the drying methods. Key words: Yam chips, Dioscorea cayenensis, Dioscorea rotundata, nutritional potential.

Dry matter, Free Sugar and Starch Changes in Tuber Regions of White Yam (Dioscorea rotundata Poir.), and the Effect of Storage Environment

This study was conducted to determine the changes in dry matter (DM), free sugar (FS) and starch contents in the three yam (D. rotundata) tuber regions under two storage environmental conditions (natural light- yam barn, or and darkness). Three varieties of D. rotundata (alaako, Dodoro and Odo) were studied. The dry matter content of the Head region was the highest (28.6%), followed by the Middle (26.9%) and Tail (22.3%) regions. Change in dry matter content of the tuber is mainly due to rapid changes in the dry matter content of the Tail region over time. Storage environment significantly (P&lt; 0.05) affected dry matter content of the three tuber regions at 8 and 16 weeks in storage (WIS). Head regions per variety were lower in dry matter when stored under Light than in the Dark at 8 WIS, while the reverse was the case for the Tail. This may relate to the release of endodormancy. By 16 WIS, when tubers stored under Light had well developed sprouts and those stored in the Dark only showed the first sign of sprouting, all Head regions had higher dry matter content under Light than in Dark storage. This may be due to the presence of sprouts. Storage environment did not significantly affect starch content at the various tuber regions. Head regions had higher percentage free sugar content under Light than Dark storage, and these effects were manifested between 8 and 16 WIS.

The potentials of pre-storage curing and nanobiotectnology in the control of postharvest losses of yam (Dioscorea rotundata Poir.) tuber

The potentials of pre-storage curing and nanobiotectnology in the control of postharvest losses of yam (Dioscorea rotundata Poir.) tuber

Effect of Biochar and Inorganic Fertilizer in Yam (Dioscorea rotundata Poir) Production in a Forest Agroecological Zone

Yam production is characterized by low fertilizer input and annual shifting in search for fertile lands. This practice usually leads to reduction in the yield potential of the crop and destruction of the environment. Biochar additions through its ability to improve soil fertility and increase crop yields could be used to solve these problems. This study therefore investigated the effect of biochar and inorganic fertilizer application on yam production in a forest agro ecological zone in Ghana. A 4×3 factorial experiment in a randomised complete block design with three replications was used. The treatments consisted of four application rates of wood shaving biochar (0 t ha-1 , 5 t ha-1 , 10 t ha-1 and 15 t ha-1) and three inorganic fertilizer rates ( 0-0-0 N-P2O5-K2O kg ha-1, 30-30-30 N-P2O5-K2O kg ha-1 and 60-60-60 N-P2O5-K2O kg ha-1). No significant differences in soil parameters in response to the treatment were observed, with the exception of total N, where a decline was observed for all the treatments compared to the controls after harvest. Vegetative growth parameters of yam were not significantly influenced by biochar and inorganic fertilizer application. The number of seed yams per hectare was the only yield parameter that was significantly (p = 0.05) decreased by biochar application. Dry matter, production was also significantly (p = 0.05) increased by fertilizer application at 24 weeks after planting and at harvest. It is suggested that aged and higher rates of biochar would efficiently support yam production.

Yield and Storage Characteristics of White Yam (Dioscorea rotundata Poir) as Influenced by Fertilizer Application and Time of Harvesting in Forest Zone of Ghana

Yield and Storage Characteristics of White Yam (Dioscorea rotundata Poir) as Influenced by Fertilizer Application and Time of Harvesting in Forest Zone of Ghana

Efficacy of Oryza sativa husk and Quercus phillyraeoides extracts for the in vitro and in vivo control of fungal rot disease of white yam (Dioscorea rotundata Poir).

Tuber rot disease is a major constraint to white yam (Dioscorea rotundata) production, accounting for 50-60% of annual yield losses in Nigeria. The main method of control using synthetic fungicides is being discouraged due to human and environmental health hazards. The potential of Oryza sativa husk (OSH) and Quercus phillyraeoides (QP) extracts for the in vitro and in vivo control of six virulent rot-causing fungal pathogens, Lasiodiplodia theobromae, Aspergillus niger, Rhizoctonia solani, Penicillium oxalicum, Sclerotium rolfsii, and Fusarium oxysporum was evaluated, using five different extract concentrations of 0.5%, 1.0%, 1.5%, 2.5%, and 3.5% w/v. These fungi were isolated from rotted tubers of D. rotundata, across three agroecological zones in Nigeria―the Humid rainforest, Derived savanna, and southern Guinea savanna. All treatments were subjected to three methods of inoculation 48 hours before the application of both extracts and stored at 28 ± 2°C for 6 months. Radial mycelial growth of the test pathogens was effectively inhibited at concentrations ≤ 3.5% w/v in vitro for both OSH and QP extracts. Rotting was significantly reduced (P ≤ 0.05) to between 0 to 18.8% and 0% to 20.9% for OSH and QP extracts respectively. The extracts significantly (P ≤ 0.05) inhibited percent rot of the test pathogens at 3.5% concentration w/v in vivo. Rot incidence was, however, lower in replicate tubers that were inoculated, treated with extracts and exposed than treatments that were covered. Phytochemical analysis of OSH and QP extracts revealed the presence of secondary metabolites such as alkaloids, flavonoids, saponins, tannins, ferulic acid, phlobatanins, Terpenoids, phenols, anthraquinone and pyroligneous acid. The efficacy of both extracts in reducing rot in this study recommends their development as prospective biopesticide formulation and use in the management of post-harvest rot of yam tubers.

Effects of plant density and npk application on the growth and yield of white guinea yam (Dioscorea rotundata Poir) in a forest zone of Nigeria

Studies were conducted at Evboneka, Edo State, Nigeria in a forest zone to examine the effect of increasing plant population and NPK application on the growth and tuber yield of Dioscorea rotundata (Poir) cv “Obiaoturugo”. This study involved three trials. The first was conducted in 2010 involving five plant densities (10000, 13333, 17778, 20000 and 266667 plants per hectare (pph)) laid in a randomized complete block design (RCBD) and replicated four times. The second trial was conducted in 2010 involving five NPK application rate (0, 100, 200, 300 and 400 kg NPK 15:15:15 ha-1) using RCBD and replicated three times. In the third trial, the best three plant densities (10000, 13333 and 17778 pph) from the first trial were re-evaluated with the best two NPK application rates (200 and 300 kg NPK ha-1) and control (0 kg ha-1) from the second trial using a 3 x 3 factorial arrangement fitted into RCBD with three replicates. Results from the plant density trial revealed that increasing plant density significantly resulted in increased fresh tuber yield and decreased in number of tuber per stand, tuber size, % unmarketable tuber and multiplication ratio (MR). Based on MR, the best tuber yield was produced from 10000 pph, followed by 13333 and 17778, which were statistically comparable. Results from the fertilizer trial showed that the application of 300 kg ha-1 had the highest tuber yield (19.16 t ha-1 ) statistically similar to 200 kg ha-1 (19.12 t ha-1). There was no significant interaction effect on agronomic traits assessed as both factors acted independently on yam plants. Increasing plant density and NPK application rate resulted in increased degree of foliation and leaf area index (LAI). These parameters imparted higher photosynthetic capacity and translocation leading to higher total dry matter production and tuber yield. A plant density of 10000 pph and 300 kg ha-1 could be most profitable and also bring about a considerable increase in growth and tuber yield of yam.

A comparative analysis of barn and platform as storage structures for yam tuber in Ibadan, Nigeria

An experimental study was undertaken to evaluate and compare the performances of a local barn and a platform, as storage structures for yam tubers (Dioscorea rotundata poir.). The criteria used for evaluation and comparison were the degree of weight loss during storage, tuber sprouting and rotting of yam tubers during 17 weeks storage duration between March and June 2008. Measurements of temperatures and relative humidity in the storage environment were taken thrice daily during the period. Weight loss in each tuber was measured weekly while sprouts were removed from tubers fortnightly. Results show that, the average temperature and relative humidity on the platform were 30.4°C and 57.3% respectively while for the barn, they were 26.5°C and 55.5%, respectively. The average weight loss in tubers in the barn during the duration was 32.8% while for tubers on the platform, it was 30.3%. Yam tubers on the platform recorded 5.4% sprouting while those in the barn had 4.9% sprouting. Palm leaves cover for yam tubers on the platform protected the tubers from excessive heat and moisture loss. Rotting was observed in 10% of the tubers stored in the barn but was completely absent from those stored on the platform. Key words: Barn, platform, sprouting, weight loss, yam tuber.