Yellow Yam Research Articles

Uticaj metoda sušenja na funkcionalne osobine Jam (Dioscorea sp.) brašna

The effect of drying method on functional properties of five different yam flour varieties namely, white yam, purple yam, yellow yam, water yam and three leaves yam were studied using oven, solar and sun drying method. The functional properties were determined using AACC approved method. Results revealed that White yam recorded wettability range of 173.22 - 181.31 secs while the purple yam had wettability range from 151.69 to 201 secs, the three leave Yam, had wettability range from 138.41 to 190.20 secs, the water yam and yellow yam recorded wettability range from 143.62 to 182.11 secs and 153.42 to 174.34 secs respectively. Result also indicated that white yam recorded water absorption capacity (WAC) range from 134.32 to 146.11, while purple yam had WAC range from 134.32 to 145.46; three leave Yam, water yam and yellow yam recorded from 129.56 to 138.11, from 133.58 to 163.21 and from 128.34 to 143.88 respectively. Furthermore, white yam, purple yam, three leave yam, water yam and yellow yam respectively recorded swelling power range from 11.84 to 12.63, from 11.14 to 11.82, from 11.28 to 12.66, from 12.19 to 12.38 and from 11.68 to 11.96. The three leave yam recorded the highest water absorption capacity which makes it likely to have least shelf life stability as compared to others because of the ability of absorbing water from a humid atmosphere. Results of the analysis of variance (ANOVA) on the effect of drying methods on the functional properties of the yam varieties showed significant difference at 5% and 1% probability level while the yam varieties did not show any significant different on the functional properties of the yam flour varieties.

A comparative assessment of nutrients and anti-nutrients contents of varieties of fried yam (<i>Dioscorea specie</i>) commonly consumed in Nigeria

There is limited information on nutrients composition of Nigerian foods. As a result, nutrients intake from Nigerian foods is in most cases estimated using foreign food composition tables. This research determined and compared proximate composition, minerals and anti-nutrients in pre- boiled fried New and old White Yam ( Dioscorea rotundata ), Water Yam ( Dioscorea alata ) and Yellow Yam ( Dioscorea cayenensis ) purchased at Yankura market, Kano, Northwestern Nigeria. Samples were peeled, boiled and fried. Fried yam samples were analysed for moisture, protein, carbohydrate, fat, ash, fiber and mineral contents using methods of the Association of Official Analytical Chemist. Phytate and cyanide were estimated bytitration. Results were analyzed using ANOVA in GraphPad Instat software. New White Yam exhibited significantly (P<0.05) higher content in moisture (52.5 ± 8.40 g/100g), fiber (2.0 ± 0.02 g/100g), calcium (13.7 ± 0.5 mg/100g); lower concentration of phytate (11.3 ± 0.08 mg/kg) and moderate concentrations of other parameters studied. Water yam contains significantly (P<0.05) higher protein (5.77 ± 0.2 %), potassium (683 ± 3.6 mg/100g) and moderate amount of other parameters studied. Yellow Yam contains significantly (P<0.05) higher magnesium (16.3 ± 1.52 mg/100g), phytate (31.2 ± 0.40 mg), lower fiber (0.9 ± 0.03 g/100g) and moderate amount of other parameters. Old White Yam contains significantly (P<0.05) higher carbohydrate (37.47 ± 0.5 g/100g), lower cyanide (3.2 ± 0.15 mg/kg) and moderate amount of other parameters studied. The fried yam samples studied have variable amount of nutrients and anti-nutrients. Apart from being excellent energy sources, all yam samples studied could contribute to intake of micronutrients. Keywords: Fried yam, proximate content, micronutrients, anti-nutrients

Abstract 197: Anti-cancer activity of extract from the Jamaican round-leaf yellow yam (RLY2) (Dioscorea cayenensis)

Abstract The Jamaican Round-Leaf yellow yams (RLY2), Dioscorea cayenensis, are edible tubers, bulbils or rhizomes that are of considerable economic value and possess several health benefits. These RLY2 are a rich source of anti-oxidants, vitamins and phytochemicals. In addition to its nutritional value, the Jamaican populace regards RLY2 as an herbal medicine useful in treatment of diabetes mellitus, hypertension and certain kind of cancers. Chemical analysis of RLY2 revealed the presence of a myriad of bioactive ingredients that are likely to be lost due to the method of preparation for consumption. Thus, we hypothesized that mild extraction of RLY2 will preserved the bioactive analytes that give RLY2 its anti-cancer property. To test this hypothesis, different ethanolic extracts of RLY2 were prepared, and their bioactivity demonstrated in two models of prostate cancer. The present study demonstrates dosage and time-dependence inhibition in both the androgen sensitive LNCaP and androgen insensitive DU-145 prostate cancer cell lines. We observed that DU-145 was three-times more sensitive to RLY2 ethanol extract than LNCaP. Growth of LNCaP for 3-days with varying concentration of RLY2 ethanol extract resulted in an IC50 of 750 ppm (95% C.I. 726-791ppm), whereas DU-145 resulted in an IC 50 of 250 ppm (95% C.I. 236-281ppm). The maximum growth inhibition by RLY2 extract occurs within twenty-four hours for both LNCaP and DU-145 with no significant changes after 5-days. To determine the mechanism of toxicity by RLY2, we induced both LNCaP and DU-145 with RLY2 for 0-24h and prepared cells for flow cytometer analysis. The effect of RLY2 on cell cycle and degree of apoptosis will be discussed. Our data indicated that the ethanol extract of RLY2 was more sensitive toward androgen-insensitive prostate cancer. Thus, this study suggests that RLY2 contain bioactive chemical that may be used in grade II prostate adenocarcinoma represented by the DU-145 phenotype. Citation Format: Sasha-Gay A. Wright, Wesley G. Gray, Helen Asemota. Anti-cancer activity of extract from the Jamaican round-leaf yellow yam (RLY2) (Dioscorea cayenensis) [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2017; 2017 Apr 1-5; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2017;77(13 Suppl):Abstract nr 197. doi:10.1158/1538-7445.AM2017-197

Effects of processing methods on nutrient and antinutrient composition of yellow yam (Dioscorea cayenensis) products

There is dearth of documented information on nutrient retention of Dioscorea cayenensis products. This study was carried out to evaluate effects of processing methods on nutrient and antinutrient retention of yellow yam products. Fresh Dioscorea cayenensis tubers were purchased from Bodija market in Ibadan, peeled, cut into small pieces, divided into nine portions. One portion was treated as raw sample, and others processed into local delicacies. All nine samples were analysed for proximate, mineral, vitamin and antinutrient composition using AOAC methods. Data were analysed using ANOVA at p=0.05. Raw yam contained 66.79g moisture, 2.62g crude protein, 0.27g lipid, 0.17g fibre, 0.63g ash, 29.69g carbohydrates, 262.30mg potassium, 61.53mg magnesium, 0.79mg iron, 0.39mg zinc, and yielded 108.26kcal energy with insignificant vitamin content/100g edible portion. Processing significantly improved macronutrients and energy content with significant reduction in all antinutrients of products (p<0.05). The yam products can serve as staple source of energy to consumers.

English

Genetic improvement of major food yams is constrained by a number of factors, such as the scarcity of flowers and lack of synchronization between male and female flowering. Consequently, somaclonal variation including somatic polyploidization has been considered as a useful tool in yam breeding. Somatic polyploidization and its effect on phenotypic traits of Dioscorea species such as D. alata, D. japonica and D. zingiberensis has been reported; however, optimization of this method in two major yam species, D. rotundata and D. cayenensis, is yet to be achieved and the effect of polyploidization on phenotypic traits of this species yet to be elucidated. In the present study, a high rate of somaclonal polyploid variation was successfully achieved by in vitro colchicine treatment of D. rotundata and D. cayenensis. In most cases, except TDc 3704, the highest rate of polyploid induction appeared after 0.1% colchicine treatment. However, in triploid yellow yam accessions the induction rate was relatively low. Tetraploid variants of D. rotundata tended to display somewhat rounder leaves than their diploid parents. The size and shape of D. rotundata stoma were also affected by levels of ploidy, with tetraploid variants exhibiting larger stomata at a lower density compared to their diploid parents. The efficient method of in vitro polyploidy induction reported here is therefore a highly useful tool for obtaining polyploid variants for use as genetic resources in D. rotundata breeding. Key words: Leaf, nodal segment culture, ploidy level, somaclonal variation, stoma, white guinea yam, yellow Guinea yam.

Physicochemical and Organoleptic Properties of Dried Synbiotics Yoghurt from Lesser Yam Tubers (DioscoreaesculentaL.)

There are many variations of Yam ( Dioscorea spp.) which spread out in the world including Indonesia. Those variations could be categorized based on their shape, size, colour, and flavour of their tuber. The genus of Dioscorea spp. has more than 600 species, such as Dioscorea hispida , Dioscorea esculenta (lesser yam), Discorea bulbifera , Dioscorea alata (purple yam), Dioscorea opposita (white yam), Dioscorea villosa (yellow yam), Dioscorea altassima , and Dioscorea elephantipes. At the present, the utilization of yam tubers is seen to be limited. The purpose of the research was to evaluate the properties/characteristics of dried synbiotics yoghurt from lesser yam tubers. The treatment on this study was performed by the number of substitution of lesser yam tubers and the fermentation time. The results show that the dried synbiotics yoghurt that most preferred by consumers was G 2 F 3 (lesser yam 40% and fermentation time 22 hours) with an average value 3.65. It is followed by the total LAB (lactic acid bacteria) 8,15 log cfu/g, pH 4.27, total lactic acid 1.02%, yield of dried synbiotic yoghurt 32.30%, and total soluble protein 4.53%.

Diversity of Yam (&amp;lt;i&amp;gt;Dioscorea spp&amp;lt;/i&amp;gt;.) Populations in South Western Region of Cameroon

Yams are Dioscoreaceae grown in the tropics and sub-tropics and used as food and for related pharmaceutical properties. The South Western Region of Cameroon is a major yam producing zone. This study which evaluates morphological variability between ten linguistically different yam types grown in South Western Cameroon will serve as a necessary step for subsequent genetic study of the species. The yams, collected from nine sites, were planted in a completely randomized design in four locations. Analysis of data on nine morphological vines traits reveals that, the yam types constituted five main clusters. Cluster 1 with 61.3% similarity consists of five accessions of D. rotundata - Ikom, Calabar, White, Agar and Igbo yams. This cluster has three sub-groups with 84.9% similarity. Cluster 2 consists of Yellow yam (D. cayenensis) with 48.5% similarity to members of Cluster 1. Ghana Water yam and Swệt yam constitute Cluster 3 with 83.4% similarity while Sugar yam and Water yam constitute the 4th and 5th clusters respectively. The ten yam types are actually five cultigens –rotundata, rotundata-cayenensis complex, cayenensis, dumetorum and alata; and the significant variability (P<0.05) observed with respect to the morphological characters evaluated may be the basis for the linguistic polymorphism noticed in the naming of the different yam types. Although genetic analysis is recommended to determine firm similarities, the establishment of clear links remains problematic because of the high hybridisation noticed among members of the Dioscoreaceae; and considering that yams types were introduced in the zone from different lands over many centuries.

Assessment of sweet potato [Ipomoea batatas (L.) Lam] for bioethanol production in southern Italy

The potential of sweet potato as an alternative crop for bioethanol production has been assessed. We evaluated the amount of soluble sugars, starch and cell wall polysaccharides in tubers of three sweet potato cultivars characterized by different pulp and peel colouration: “Yellow yam” with yellow flesh and brown peel, “White yam” with white flesh and white peel and “Orange yam” with orange flesh and brown peel. The results confirm the high concentration of carbohydrates in sweet potato tubers, especially “Yellow yam”, mainly in the form of starch (67%) and soluble sugars (26%). “Yellow yam”, which is the most widespread cultivar in Salento, appeared the best choice as biomass for bioethanol production. It is characterized by high productivity (20–40 tons/ha year). Results also suggest that “Yellow yam” cultivar has great potential as a bioethanol source in southern Italy with an estimated agroindustrial production yield higher than 2032 l/ha year.

Effects of annealing, acid hydrolysis and citric acid modifications on physical and functional properties of starches from four yam (Dioscorea spp.) cultivars

The effects of annealing, acid hydrolysis and citric acid modification on the physical and functional properties of starches of four Nigerian yam cultivars were studied. Loose (0.3636–0.7658 g/cm3) and packed (0.5606–1.0165 g/cm3) bulk densities and CIE L* of native, and modified starches decreased significantly (p < 0.05) with annealing, but increased significantly with acid hydrolysis and citric acid modification. The CIE a* value and %W (whiteness degree) increased, while b* value reduced with all modifications. The CIE L*, a* and b* values of extracted starches ranged between 74.8–98.3, −4.21–4.80 and 4.40–12.9, respectively. Among the native starches, L* ranked: bitter yam > white yam > water yam > yellow yam. Starch granule shapes varied with cultivar but not with the modifications. Starch granule sizes reduced significantly with the modifications, with increased incidence of small and medium sized granules, and decrease in large sized granules. Short and long length of native white, yellow, water and bitter yam starches ranged from 19.5–54.9 and 15.6–42.9 μm, 27.30–58.50 μm and 15.60–42.90 μm, 23.4–58.5 μm and 15.6–35.1 μm, and 2.50–7.50 μm and 2.50–5.0 μm, respectively. Chemical modifications caused etching, fragmentation and roughening of some granules' edge. The WAC (0.63 g/g–1.047 g/g) increased significantly with acid hydrolysis and citric modification, but reduced significantly on annealing while OAC (0.437 g/g–1.053 g/g) was not significantly affected by the modifications. Generally, alkaline water retention (1.017 g/g–0.670 g/g) and foam capacity of the starches decreased with all the modifications. Annealed yam starches showed better foam stability than citric modified and acid hydrolysed yam starches. Generally, emulsion index (0.337–0.621) increased insignificantly with citric acid modification, while annealing and acid hydrolysis had variable effect.

High-Quality Draft Whole-Genome Sequences of Three Strains of Enterobacter Isolated from Jamaican Dioscorea cayenensis (Yellow Yam)

Here we report the whole-genome sequences of three endophytic bacteria, Enterobacter sp. strain DC1, Enterobacter sp. strain DC3, and Enterobacter sp. strain DC4, from root tubers of the yellow yam plant, Dioscorea cayenensis. Preliminary analyses suggest that the genomes of the three bacteria contain genes involved in acetoin and indole-3-acetic acid metabolism.

Molecular and morphological characterisation of Scutellonema bradys from yam in Costa Rica and development of specific primers for its detection

The yam nematode, Scutellonema bradys, which can cause dry rot disease of yam (Dioscorea spp.), was recorded for the first time from Costa Rica in four species of yam occurring in the Atlantic and north regions. Morphometric measurements from two populations from each region using ten female and 11 male characters corresponded with previous descriptions of this species. Canonical discriminant analysis of the female morphometric data separated the populations by region, whereas no separation by region was evident using the male data. Analysis of DNA sequences from the ITS region indicated that populations from Costa Rica were monophyletic with S. bradys from West Africa and clearly distinct from other Scutellonema species. No genetic separation by geographic region or Dioscorea species host was observed between Costa Rica populations. Species-specific primers were developed from the ITS region and supported the identity of 17 populations from 15 locations in Costa Rica as S. bradys: 14 populations from D. alata (greater or water yam) and one each from D. trifida (white yampee), D. cayenensis (yellow yam) and D. rotundata (white yam). Yam production in Costa Rica began in the Atlantic region, where the yam nematode was likely introduced from the Caribbean, progressively spreading to other locations through the use of infected vegetative planting material.

Functional, thermal and molecular behaviours of ozone-oxidised cocoyam and yam starches

Ozone-oxidised starches were prepared from the native starches isolated from white and red cocoyam, and white and yellow yam cultivars. The native and oxidised starches were evaluated for functional, thermal and molecular properties. The correlations between the amount of reacted ozone and carbonyl and carboxyl contents of the starches were positive, as ozone generation time (OGT) increased. Significant differences were obtained in terms of swelling power, solubility, pasting properties and textural properties of the native starches upon oxidation. The DSC data showed lower transition temperatures and enthalpies for retrograded gels compared to the gelatinized gels of the same starch types. The native starches showed CB-type XRD patterns while the oxidised starches resembled the CA-type pattern. As amylose content increased, amylopectin contents of the starches decreased upon oxidation. Similarly, an increase in Mw values were observed with a corresponding decrease in Mn values upon oxidation.

Analysis of Selenium Content in Root and Tuber Plants in Central Nigeria

Some common staple roots and tubers (cassava, yam, sweet potato and yellow yam) were analyzed for selenium content level using hydride generation—atomic absorption spectrophotometry (HG-ASS) technique. Results for duplicate analysis revealed that sweet potato has the highest mean selenium content (19.2 ± 5.20 μg/kg), followed by yellow yam (18.3 ± 6.97 μg/kg), then yam (13.6 ± 7.12 μg/kg) and cassava the least (13.0 ± 5.84 μg/kg). In comparing our results with the literature values, most of the results obtained in this work such as 54.2, 72.3 and 81.8 μg/kg were higher than literature values. The variations could be due to the type of species/variety, geographical location, total selenium concentration in the soil and its bioavailability. In view of the importance of Se to human health and considering the levels found in the staples investigated, we recommend that sweet potato be popularized as a staple, much more than cassava as it is now the case in Central Nigeria.

Effect of Bauxite Mineralized Soil on Residual Metal Levels in Some Post Harvest Food Crops in Jamaica

The concentrations of nine residual metals in some Jamaican foods were determined using inductively coupled plasma mass spectrometry technique. Cadmium concentration was highest in yellow yam (0.21 mg/kg). Sweet potato had the highest concentrations of lead (0.31 mg/kg), arsenic (0.70 mg/kg) and mercury (0.35 mg/kg). Samples from Grove Place exceeded the regulatory limits of 0.1 mg/kg for cadmium, lead and arsenic and 0.05 mg/kg for mercury. Significant correlations were found between soil and agricultural produce concentrations for cadmium and lead (r(2) ≥ 0.5). These results suggest that the elements were available in soluble forms in the soil for absorption by food crops.

Effects of two processing methods on some nutrients and anti-nutritional factors in yellow yam (Dioscorea cayenensis)

Raw and processed tubers from eight genotypes of yellow yam (Dioscorea cayenensis) were evaluated for their contents of iron, zinc, calcium, phosphorus, total carotenoids, vitamin C, phytic acid and tannin. The mean values obtained (in mg/kg on dry weight basis) were 7.2 for iron, 9.2 for zinc, 169.3 for calcium, 1331.3 for phosphorus, 181.8 for phytate and 353.6 for tannin. Similarly, 6.31 µg/g of total carotenoids and 37.3 mg/kg of ascorbic acid were obtained on fresh weight basis. The genotypes differed significantly (P < 0.05) in tuber contents of zinc, calcium, phosphorus, total carotenoids and vitamin C but they were similar with respect to iron, phytate and tannin contents. Genotype TDc 95-65 had the highest levels of zinc, calcium, total carotenoids and phytate while TDc 95-294 had the highest levels of iron and phytate. Tubers of TDc 95-65, TDc, 95-294, TDc 04-168 and TDc 98-136 are good sources of iron, zinc and phosphorus. The two cooking methods had little effect on the minerals but significantly reduced the levels of total carotenoid, vitamin C, phytate and tannin contents. Key words: Antinutrients, boiling, Dioscorea cayenensis, phytic acid, pounding and tannin.

The effect of tillage systems and mulching on soil microclimate, growth and yield of yellow yam (Dioscorea cayenensis) in Midwestern Nigeria

Yellow yam (Dioscorea cayenensis) is one of the major varieties of yam produced in Midwestern Nigeria mainly by traditional farmers. Most of these traditional farmers employ zero tillage system and mulching after planting. But, is this the best practice for optimising yield? This paper examines the effect of tillage systems and mulching on soil microclimatic conditions, growth and yield of yellow yam. To generate the needed data, the physiological approach was employed. An experimental farm that measured 35 x 47 m was established at Agbor, Delta State, Nigeria, for two planting seasons 1997/98 and 1998/99. The microclimatic parameters monitored include air and soil temperatures and relative humidity while the physiological parameters measured were emergence, growth rate, leaf area accumulation and yield. Time series, multiple correlations, chi-square, ANOVA, least square range test and stepwise regression analysis were the statistical tools employed in analysing the data. The results showed that soil moisture at 0-15 cm depth was significantly higher in zero tillage (40 g/g), followed by ridge (30 g/g) and mound (24 g/g) but the reverse was the case with soil temperature where mound tillage (34.2°C) had the highest temperature followed by ridge (31.4°C) and zero (29.5°C). Mulching also significantly influenced the soil microclimatic condition. While soil moisture enhanced yam emergence, soil temperatures favoured the growth, leaf area accumulation and yield. Mound tillage significantly gave the highest yam tuber yield (12.0 t/ha-1), followed by ridge (8.8 t/ha-1) and zero (5.0 t/ha-1). Partially mulched treatment significantly produced the highest yam tubers (10.3 t/ha-1), followed by the unmulched (8.1 t/ha-1) and mulched (7.4 t/ha-1) treatments. The best practice recommended for the production of ware yams is mound tillage that is partially mulched. This recommended practice yielded more than the local practice by 44.6%. Key words: Tillage systems, yellow yam, Midwestern Nigeria, soil microclimate, mulching, yam yield.

Relationship between the physicochemical properties of starches and the glycemic indices of some Jamaican yams (Dioscoreaspp.)

Starch granules from round leaf yellow yam (RY), Lucea yam (LY), white yam (WY), and Chinese yam (CY) grown in Jamaica were isolated and the relationship between starch amylose content, crystallinity, microscopic properties, in vitro digestibility, and the glycemic index (GI) of the tubers was investigated. The results indicate that RY had the highest amylose content (265.30 +/- 0.09 g/kg starch) while CY the lowest (111.44 +/- 0.03 g/kg starch). A corresponding variation in starch digestibility and GI was also observed, as CY which had the highest in vitro digestibility had the highest GI (21.27 +/- 0.01 and 97.42 +/- 0.62%, respectively), while RY, LY, and WY starches with low digestibility had lowest GI. Differences in the crystalline pattern of the different starches were observed, where RY, LY, and WY displayed the type B crystalline pattern while CY had the intermediate crystallite (type C).

The interplay between yam ( Dioscorea sp.) starch botanical source, micromeritics and functionality in paracetamol granules for reconstitution

A comparative investigation of the interplay between starch botanical source, micromeritics and their functionality in formulated paediatric paracetamol granules for reconstitution was conducted using starches extracted from five local yam ( Dioscorea spp. ) species. Significant differences were observed in the physicochemical properties of the different starches studied ( p < 0.05). The observed differences in paracetamol dissolution correlated well with the physicochemical properties of the starches. Granules formulated with Chinese yam and Bitter yam starches showed the fastest rate of paracetamol dissolution with T 80 of 2.2 and 2.6 min, respectively, at 2.5%w/w, and 3.75 and 4.00 min, respectively, at 10% w/w binder concentrations. Those formulated with Round leaf yellow yam starch had the slowest dissolution rate with T 80 of 4.5 and 8.75 min, respectively, at 2.5% and 10% binder concentrations. The results generally indicate a significant dependence of the rate of paracetamol dissolution from granules on starch surface tension, viscosity, swelling power and water binding capacity, particle size distribution, specific surface and porosity. These, in turn, were found to be starch botanic source-dependent suggesting careful consideration of botanic source when substituting one starch product for another in granule formulation.

The effect of tillage systems and mulching on soil microclimate, growth and yield of yellow yam ( Dioscorea cayenensis ) in Midwestern Nigeria

Yellow yam (Dioscorea cayenensis) is one of the major varieties of yam produced in Midwestern Nigeria mainly by traditional farmers. Most of these traditional farmers employ zero tillage system and mulching after planting. But, is this the best practice for optimising yield? This paper examines the effect of tillage systems and mulching on soil microclimatic conditions, growth and yield of yellow yam. To generate the needed data, the physiological approach was employed. An experimental farm that measured 35 x 47 m was established at Agbor, Delta State, Nigeria, for two planting seasons 1997/98 and 1998/99. The microclimatic parameters monitored include air and soil temperatures and relative humidity while the physiological parameters measured were emergence, growth rate, leaf area accumulation and yield. Time series, multiple correlations, chi-square, ANOVA, least square range test and stepwise regression analysis were the statistical tools employed in analysing the data. The results showed that soil moisture at 0-15 cm depth was significantly higher in zero tillage (40 g/g), followed by ridge (30 g/g) and mound (24 g/g) but the reverse was the case with soil temperature where mound tillage (34.2°C) had the highest temperature followed by ridge (31.4°C) and zero (29.5°C). Mulching also significantly influenced the soil microclimatic condition. While soil moisture enhanced yam emergence, soil temperatures favoured the growth, leaf area accumulation and yield. Mound tillage significantly gave the highest yam tuber yield (12.0 t/ha-1), followed by ridge (8.8 t/ha-1) and zero (5.0 t/ha-1). Partially mulched treatment significantly produced the highest yam tubers (10.3 t/ha-1), followed by the unmulched (8.1 t/ha-1) and mulched (7.4 t/ha-1) treatments. The best practice recommended for the production of ware yams is mound tillage that is partially mulched. This recommended practice yielded more than the local practice by 44.6%.

The Rainmaker’s Mistake

Reviewed by: The Rainmaker’s Mistake Kelly Baker Josephs (bio) Brodber, Erna. The Rainmaker’s Mistake. London: New Beacon, 2007. “If who know, nah talk, you haffi work it out child. You just haffi work it out” (59). Erna Brodber’s fourth work of fiction attempts to “work out” the question of present day black diasporic identity. The text offers readers a challenge that, in form and content, is simultaneously novel and not novel. In general, Brodber’s writings consider the importance of the past in shaping the present and the future of blacks in the Caribbean and North America. [End Page 938] Her new offering turns to fantasy, fairy tale, folk tale, and myth to creatively imagine a past for the New World present. It focuses more closely than her previous works (both fiction and non-fiction) on historical links between various populations of the African Brodber fans will first recognize the characteristic Errol Lloyd cover, with its layered and suggestive images that, like the text it bounds, can reveal new meanings upon successive viewings. The textual layers are evident in the beginning as readers encounter what seems to be an omniscient narrator only to find they have been “listening” to Queenie’s recounting of the creation myth/mystery that drives the novel. Queenie, whose interest in education and social science corresponds to Brodber’s other fictional heroines, carries most of the narration, but she is joined by other “I”—s six others, in fact—who, like Queenie, search for answers to their present with questions about their past. The Rainmaker’s Mistake begins in an unspecified time and place. Mr. Charlie, landowner, looks out on his “patent” and decides he needs labor. He plants his seed in the earth, raises yams from this planting, and cultivates these brown yams into brown people who are “young and old, big and small, male and female, brothers and sisters, children of one father dug from an everlasting underground source” (2). After Mr. Charlie’s planting is revealed as an oft-told tale within a tale, readers are introduced to the Eden-like existence of the people who believe they were once brown yams. Each time readers feel as though they have grasped the direction of Brodber’s storyline, or deciphered some meaningful historical or contemporary connection, a new voice or idea enters the narrative, unbalancing any appearance of stable metaphorical correlations. For example, early in the text Mr. Charlie announces from his verandah, “It is 1834: You are under six years old and you are free” (10). This first concrete evidence of time is comforting and the reference to freedom indicates that the “brown yams” are slaves on Mr. Charlie’s patent of land. The previous mentions of labor, naming, missing women, and new babies begin to fall into place as evidence of life on a plantation. With this clue, readers can now settle in with the innovative metaphor, reveling in the conflicts created by impending freedom and the appearance of a yellow yam baby, Sallywater, who has unusually soft and straight hair. But in the very next paragraph, Mr. Charlie reappears to announce, “It is 1838 . . . you are free” (11). Thus, just as it is offered to the reader, the gift of chronological certainty is revoked. But the reference to these specific years still indicates that the story is set in a West Indian British colony and that the relationship between Mr. Charlie and his “children” is one of master and slaves. However, as Queenie grapples with this idea of freedom “And what was this he was saying: ‘You are free’ and behaving so strangely because of this thing called ‘free’” (11)—one of her brothers, Woodville, laughs Mr. Charlie’s house off its base. The house disappears into the sky, leaving the former slaves (though this word is never used) to fend for themselves in a changing landscape. And readers are once again left with as much foundation as Mr. Charlie’s house. The ensuing neglect of the land causes the rivers to run and separate the land into three continents: Woodville on one, Sallywater and her “caretaker” I-Sis on another, and the rest in the middle. These...