research article nutritional value and utilization of yams ... publication...air yam ( d. bulbifera...

Research ArticleNutritional Value and Utilization of Yams (Dioscorea steriscus)by Residents of Bindura Town High Density Suburbs Zimbabwe

S Washaya1 J F Mupangwa1 and E Muranda2

1Department of Livestock and Pasture Science Faculty of Science and Agriculture University of Fort HarePrivate Bag Box X1314 Alice King Williams Town 5700 South Africa2Hermann Gmeiner High School Private Bag Box 998 Bindura Zimbabwe

Correspondence should be addressed to S Washaya jabulaniwashayayahoocom

Received 25 June 2015 Revised 14 October 2015 Accepted 15 October 2015

Academic Editor Othmane Merah

Copyright copy 2016 S Washaya et al This is an open access article distributed under the Creative Commons Attribution Licensewhich permits unrestricted use distribution and reproduction in any medium provided the original work is properly cited

The objective of this study was to assess utilization levels availability nutritional value and magnitude of sales by vendors ofDioscorea steriscus by residents of Bindura A multistage sampling procedure was used to select respondents Data were subjectedtoChi-square logistic regression and correlation to determine the effects of demographic determinants onutilization ofD steriscusQuestionnaires were used to collect data Results show that education status and period of stay significantly affect the consumptionof D steriscus (119875 lt 005) It was also observed that consumption is frequent between lunch and supper (47) compared tobreakfast D steriscus has high iron (68) ash (206) and CF (168) contents but it is low in protein (083) Irrespective ofgender of respondent suburb of residence size of family period of stay education level employment status and source of incomerespondents will growD steriscus for use as food supplement (odds ratio = 0475)The period of stay (119903 = 008) and education level(119903 = 008) positively affect the growing of D steriscus D steriscus can be used as source of energy and can also be used possibly formedicinal purposes Further study is required on possibility of phytochemicals and cytotoxic components to justify its use

1 Background

Yams are herbaceous climbing twining perennial mono-cots they are the starchy tuberous root of any of thevarious climbing vines of the genus Dioscorea cultivated oroccurring naturally in warm regions [1] They are native totropical regions of Asia and Africa Due to widespread earlycultivation and transport of yams exact origins for somespecies are unknown in other parts of the world Neverthelessother species have been linked to certain areas and portionsof the world Chinese yam (D bulbifera) is native to easternAsia Five-leaf yams (D pentaphylla) are native to tropicalAsia or eastern Polynesia Zanzibar yam (D steriscus and Dsansibarensis) is native to Africa Water yam (D alata) hasbeen reported as native to Southeast Asia [2] These are thefew characterized species of yams across the world that areknown so far [3] There is however evidence which indicatesthat water yam is unknown in the wild state anywhere inthe world but was first cultivated in Assam or Burma [4]

Air yam (D bulbifera) is known from both Asia and Africa[1] but it is unclear if air yam is native to both continentsor was introduced from one to the other Indigenous airyam populations were also reported on Australiarsquos northerncoastline [1]

In tropical areas of Asia and Africa yams occur at theedges or in the canopy gaps of rainforests and woodlandsYams grow by trailing and twining other trees above groundVines are without tendrils and use dead stems from theprevious yearrsquos growth to climb into the other vegetation [5]Most occurring yams grow below ground tubers annuallywhile others can be perennial Yams also produce aerialtubers (bulbils) [5] Both belowground tubers and bulbilsare comprised of stem tissue [6] Yams regenerate exclusivelyasexually from tubers or bulbils Yams are dioecious and pro-duce very small flowers if any [1] Yam vines twine clockwiseor counter-clockwise and may grow to 30m long dependingon species [1] Leaves may reach 26 cm wide and long withpetioles generally shorter than the leaf blade [5] Yam size

Hindawi Publishing CorporationAdvances in AgricultureVolume 2016 Article ID 5934738 7 pageshttpdxdoiorg10115520165934738

2 Advances in Agriculture

Figure 1 Dioscorea steriscus tubers

and appearance are also highly variable Variability in bulbilsand tubers gives a distinct characteristic in classification andidentification Plants grow rapidly in summer than in wintersimilarly for tuber growth D steriscus is a tropical climateyam which prefers 30∘C as optimal temperature for growthand rainfall of about 1500mm per annum Yams grow bestin loose deep free-draining fertile soil Generally yams areregarded as underutilized species in Africa and all over theworld

Underutilized or neglected crops are those plant speciestraditionally used for their food fiber fodder oil or medici-nal properties but have been overlooked by scientific researchand development workers (ICUC 2006)The term ldquounderuti-lizedrdquo means that they were once grown more extensively ormight be more widely grown in the future but for economicagronomic or genetic reasons they are now cultivated in lim-ited areas [2]These plant species have significant food andorindustrial potential which remain underutilized through lackof a coherent strategy for their evaluation and development[7] They can help to meet the increasing demand for foodand nutrition medicines and industrial needs These plantsrisk falling into disuse yet they lay a crucial role in foodsecurity income generation and culture of the rural poorAccording to [8] these crops have a great potential to provideincome to rural micro entrepreneurship Unfortunately thelack of attention has meant that their potential value isunderexploited and they are in danger of continued geneticerosion ultimately leading to disappearance

Many underutilized crops are collected rather than cul-tivated constituting a significant share of income for thosewho do not have other alternatives [2] Dioscorea steriscus(Figure 1) is one of the underutilized plant species and itis sold in residential areas by vendors There is no enoughinformation documented on this crop implying that itscurrent and potential contribution to peoplersquos livelihood isunknown

Approximately 12 billion people in the world do nothave enough food to meet their daily requirements [7] Indeveloping countries farmersrsquo dependence on a few highlyselective crops has caused food and nutrition insecurity andpoverty in communities due to narrow food baskets Modernagriculture practices encourage the use of wild edible plantsas a supplementary food resource [9] These underutilizedspecies are gathered as a source of food or cash especially

during ldquolean periodsrdquo of the agricultural cycle [2] Dioscoreasteriscus is one such species in Zimbabwe Indeed Dioscoreaspp are listed under priority underutilized root and tubercrops for Africa Asia and Latin America by Wagner etal [10] According to Izquierdo [8] there are major gapsin our knowledge about these neglected and underutilizedspecies and their ecology Consequently the capacity toconserve them and improve their yield is also limited Inurban areas the tuber is sold by vendors who move aroundresidential suburbs The purpose of this study is to assessutilization levels of D steriscus by Bindura high densitysuburbs residents and to assess its availability nutritive valueand magnitude of sales

2 Research Methodology

21 Description of the Study Area The study was carriedout in Bindura high density suburbs which are located inagroecological region II b which receives annual rainfall of750ndash1000mm Bindura high density suburbs are composedof Chipadze Chipadze Extension commonly known as Aero-drome and Chiwaridzo phases I and II (Municipality ofBindura Engineering Department 2003)

Habitats ofD steriscus areas studied were DawMill Farmwhich is 3 km from town and is located north-east of BinduraTrojan Nickel Mine which is also 3 km and is located inthe southwest of Bindura and lastly SOS Maize-lands Farmwhich is 13 kmaway and is located in the east of Bindura townThese sites were studied for fieldrsquos observations as shown inFigure 2

Geologically Trojan area is typically a greenstone con-figuration composed mainly of basaltic rocks (komati-itictholeitic basalts and gabbro) coupled with banded ironformations and volcanic tuffs (Trojan Mine 2007) At SOSMaize-lands the soils are from the parent rocks greenstonebanded ironstone and conglomerates of the Shamva seriesThese give a very wide range of soils form the heavy vlei claysto the sandy loams mixed with gravel of the river deposits(Farm Planning Scheme 1958)

At Daw Mill Farm the soils are mainly moderate deepclays to clay loams and are derived from the Shamva Gritseries (Farm Planning Scheme No 5 1342 June 1960)

22 Sampling Procedures A multistage sampling procedurewas done in selecting respondents from the four Bindurahigh density suburbs In this study two suburbs namelyChipadze and Chipadze Extension (Aerodrome) were ran-domly selected from the four suburbs Aerodrome is furthersubdivided into Aerodrome high and Aerodrome suburbs

Chipadze Extension has a total of 730 houses whileChipadze has a total of 1995 houses (Municipality of BinduraEngineering 2003) Therefore the entire population was 2705houses A sample of 60 households was selected from theentire population of the two suburbs (30 households pereach suburb) Proportionate sampling of the houses was donein order to achieve a fair representation of houses in eachsuburb Households were therefore systematically selectedquestionnaires administered to each of the 10th householdIn this case the household head was the target

Advances in Agriculture 3

1 0 1 2

(km)

31∘20

998400

31∘20

998400

31∘25

998400

31∘25

998400

17∘20998400

17∘20998400

17∘15998400

17∘15998400

N

To Musana

To HarareTrojan Mine

SOS Farm To Shamva

Study area

To Mt Darwin

Daw Mill Farm

Bindura Town

Manyanya source areaMinor roadMajor road

Figure 2 BUSE GIS Department location of source areas for Dioscorea steriscus

Vendors were interviewed as they were met especiallyduring the weekends and a sample size of 30 was interviewedThese vendors are also households in their own right Sitesselected were based on vendor direction that is where theycollected D steriscus and three sites nearest to Bindura townwere selected

23 Data Collection Personal interviews were used for datacollection from the residents of Bindura high density suburbsand vendors Questionnaires were completed through face toface contact with the respondents Samples of the tuber weredried crushed into powder and sent for a nutritional valueanalysis (proximate analysis) at the Government AnalystLaboratory in Harare Zimbabwe

24 Data Analysis TheStatistical Package for Social Sciences(SPSS) Version 170 was used to analyze data PearsonrsquosChi square test was used to analyze relationships betweensocioeconomic characteristics of respondents and whetherthey eat D steriscus or not A binomial regression analysiswas used to rank factors that would lead to cultivation of Dsteriscus

25 Factors Affecting the Growing of D steriscus A binomiallogistic regressionwas used to rank demographic factors (agegender education level marital status employment statusperiod of stay size of family and source of income) thatwouldlead respondents to growing D steriscus using the followingmodel

ln [119901

1minus 119901] = 120573

119900+ 12057311199091+ 12057321199092+ 12057331199093sdot sdot sdot 120573119896119909119896+ 120576 (1)

where 119901 = probability of respondents ranking yes to growingof D steriscus first 120573

119900= intercept 120573

1sdot sdot sdot 120573119896= regression

coefficients of ranked factors on ln[1199011 minus 119901] [1199011 minus 119901] oddsratio referred to the odds of ranking location (suburb) first asa factor affecting growing of D steriscus computed for eachestimator [120573

1sdot sdot sdot 120573119896] and 120576 = random residual error

26 Nutritional Value of D steriscus The proximate con-tent of samples was conducted by the Government AnalystLaboratory in Harare Zimbabwe The procedure used wasaccording to the AOAC of 1995


Table 1 Demographic data of Bindura high density residents (119873 =60)

Demography factor Percentage TotalGender

Male 133 100Female 867

Age24ndash35 400

10036ndash45 31746ndash60 233gt60 50

Size of familylt2 83

1003-4 4335ndash7 367gt8 117

Marital statusMarried 583

100Widowed 283Divorced 33Single 10

Table 2 Chi square results for dependent variables which wouldlead to the consumption of D steriscus in Bindura high densitysuburbs

Variables Consumption of D steriscus (119899 = 60)Yes No Chi square Sig

Residence 661 339 4028 0133Education status 983 17 9153 0027lowast

Age 983 17 1525 0822Gender of resp 667 333 072 0788Marital status 667 333 387 0527Employment status 667 333 0696 0706lowastSignificant at 119875 = 005

3 Results and Discussion

31 Demographic Data of Bindura High Density ResidentsGenerally each community is different from any other onethe perceptions by that community will favor or discourageutilization of wild plants Table 1 is demographic data forBindura high suburb community

The results in Table 1 show that there were more females(867) than males (133) in the sample Most respondentswere married (583) The larger group of the samplebelonged to the 24ndash35 years of age group (40) and very fewpeople were above 60 years of age (50)

Chi square test of association on whether people eat Dsteriscus or not and residence (DF 119875 value 4 119875 gt 005) sex(DF 119875 value 1 119875 gt 005) marital status (DF 119875 value 4 119875 gt005) and employment status of respondent (DF 119875 value 2119875 gt 005)was not significantHowever therewas a significantdifference with respect to level of education (DF 119875 value 3119875 lt 005) (see Table 2)

Chipadze Aerodrome high Aerodrome

NoneOncemonthEveryday

TwiceweekOnceweek

0

5

10

15

20

25

30

35

40

45

50

Figure 3 Frequency of eating D steriscus for Bindura high densityresidents (119873 = 60)

Table 3 Frequency of D steriscus meals for Bindura high densityresidents

Meal PercentBreakfast 103Lunch 385Dinner 256Lunchdinner 77Breakfastlunch 179Total 100

32 Frequency of Eating D steriscus Frequency with whichthe plant is used within residences was determined andFigure 3 shows these results

Results show that 15 of the sample eats D steriscus atleast once a week and 20 does so every day Dioscoreasteriscus is a popular food crop which is taken by 45 ofthe sample at least once a week The crop is therefore anintegral component of the traditional food system and isreadily accepted

Results of Table 3 show that 64 of the respondents takeD steriscus during dinner and lunch

33 Sources of D steriscus for Bindura High Density SuburbsResidents Since D steriscus is not a common tuber manyusers cannot easily find it because of its habitat characteristicstherefore the source of the tuber was also determined againstthis background and Figure 4 shows the results

Most people who eatD steriscus (744) obtain the tuberfrom vendors around high density suburbs Very few peopleobtain D steriscus from the market (155) and from areas ofgrowth (103)

34 Selling of D steriscus and Its Availability D steriscus issold by vendors in and around Bindura residence when thevendors were contacted they also indicated their margin of


05

101520253035

Vendors Fresh marketproduce

Area of growth Other sources

Figure 4 Sources of D steriscus for Bindura high density suburbsresidents

Table 4 (a) Selling of D steriscus and its availability (119873 = 30) (b)Availability of D steriscus tuber in Bindura local market

(a)

Quantity sold Frequency of selling D steriscuskg Frequency 10ndash15 20 1-2 times per week 76316ndash20 367 1-2 times monthly 6721ndash25 367 Once every 3 weeks 33ge26 67 Once a month 33Total 1000 1000

(b)

Availability of D steriscus throughout the yearPercentage (119873 = 30)

Seasontime

JunendashDecember 567JulyndashDecember 93MayndashDecember 67JunendashNovember 233

Throughout the year 33

sales over time Much of the crop finds its way to eitherconsumers or the vegetable market through vendors a resulton the quantities sold is shown in Table 4(a) and time ofavailability is shown in Table 4(b) of this tuber in Bindura

Vendors who sell D steriscus come every week (763)The frequency of selling and the quantity sold indicate clearlythe potential D steriscus has as a substitute for energy sourceespecially in Chipadze area it is also possible that if onlyChipadze was to be sampled the rates of utilization of thistuber would be high (763) All vendors concurred that Dsteriscus is available from July to November (90)

Nutritional value forD steriscuswas determined focusingmainly on dry matter contents and the results were obtainedin Table 5

D steriscus is primarily used as an energy source for thestudy area and it seems to provide more than is necessaryenergy for an adult human being (936 calkg) if both CF andcarbohydrate contents are considered However the amountof protein available (0083 gkg) falls way below human dailyrequirement for an adult human being (08 gkg)

Table 5 Nutrient composition of D steriscus

Nutrient PercentageProtein 083Ash 206CF 168Iron 68Carbohydrate 902Moisture 725

Table 6 Logistic regression for willingness to grow D steriscus inChipadze Aerodrome high and Aerodrome

Predictor 119861 SE Wald df Sig Exp(119861)a2 minus029 048 374 1 541 971a3 168 1022 027 1 869 1183a4 446 343 1691 1 193 1562a5 1570 1765 791 1 374 4805a8 minus020 031 421 1 517 980a9 647 537 1453 1 228 1911a10 minus269 591 207 1 649 764a11 minus142 537 070 1 791 867Constant minus184 2255 667 1 414 158a2 age of respondent a3 gender of respondent a4 marital status a5 sizeof family a8 period of stay a9 education level a10 employment status a11source of income

35 Willingness to Grow D steriscus Respondents wererequested to indicate if they would want to grow the plantand the results are shown in Table 6

The odds ratio of growing D steriscus for this populationis 0475 if respondents are given an opportunity to do soThis means that close to half the population would want toproduce their own D steriscus for their consumption Thecorrelationmatrix indicates that period of stay and educationlevel positively affect the growing ofD steriscus However thecontribution was meagre (0008) to warrant any relianceon these factors as drivers for willingness to grow the plantwithin the study area

4 Discussion

41 Demographic Characteristics Most respondents (Table 1)were females because most men go to work in the Zimbab-wean setupThis is in linewith Jaenicke andHoschle-Zeledon[11] in Levinson Folly and Holland who state that men areoften in jobs with frequent overtime Because of this theresponses represent the opinion of women rather than menHowever it is also important to note thatmore than half of therespondents are married Men spend average of nine hoursper week on family care as compared to women who spendan average of 29 hours per week [11] The respondents fallwithin the economically active age group (le65 years) Theminimum retirement age is 55 years and the maximum is 65years (Government of Zimbabwe)


42 Consumption of D steriscus Most people (72) areinterested in growing D steriscus which shows that it is apopular food crop for the community under study Indeedsome farmers in Zimbabwersquos Rushinga District have domes-ticated the plant (personal communication 2011) The highlevels of interest in D steriscus confirm its importance to thecommunity and hence it is worthwhile to channel resourcesfor the development of the crop It appears that people withhigher levels of education (secondary school to tertiary) aremore cautious of the danger posed bywild plantsThis impliesthat if the plant is to be accepted across the whole educationlevel spectrum there is need for detailed scientific analysesof the cytotoxic and antinutritional properties of D steriscusThis should be followed by training of communities on howto safely prepare food from the crop

43 Frequency of Consumption Eating D steriscus is irre-spective of the socioeconomic characteristics of the respon-dents considered in this study such as sex marital statussource of income and employment status According toMorisawa [12] underutilized species are traditionally food forthe poorThis is in partial agreement with results of this studysince the study was conducted in high density suburbs wherelargely the low income class resides Izquierdo [8] also showsthat indigenous vegetables are mostly a poor manrsquos food

Although the majorities (64) of the respondents takethe crop as lunch or dinner the crop can also be taken asbreakfast In this respect the crop shows desirable versatilityas people with different eating habits can take it when theywantThe crop therefore has a huge potential to contribute todietary requirements of the community (Table 5)

Consumption of D steriscus is more common inChipadze than in either of the Aerodrome residences (43)(Figure 3) It is also within the same residence that people eatD steriscus on a daily basis (35) Aerodrome is primarilya medium density suburb in which the residence wouldnot prefer the use of D steriscus for food It is withinthis residence where the response rates were very low andvery little information could be derived from this group ofpeople nevertheless there are still some people who utilizeDsteriscus This disqualifies the fact that it is generally the poorwho use neglected plants in their daily living

44 Nutritional Value of D steriscus The average energyrequirements for an adult human being can be coveredbeyond measure by consumption of only 100 g of D steriscus(since it contains 936 calkg DM) of energy However theprotein content is lower than human requirements per day(Table 5) An adult human being requires 8mgday of iron(male) and 18mgday (females) The results of this study(Table 5) indicate that the yam can sustain the daily ironrequirements for all age groups (68 gI100 g) However ele-vated iron levels have been linked to cardiovascular diseaseinflammatory conditions like arthritis and cancermost likelybecause of ironrsquos propensity to oxidize (produce free radicals)in a liquid environment

45 Sources of D steriscus Much of the plant is providedby vendors who seem to be conversant with the area most

liked by the plant to grow It is interesting to note that someconsumers do not even knowwhere the plant grows (personalcommunication 2014) but still they consume it from thehands of vendors Typically for this community vendorsknow much about the plantrsquos habitats more than anyone elsedoes This is particularly important as it provides incometo vendors however respondents indicated that given anopportunity they would want to grow D steriscus for theirconsumption and reducing expenses Most residents (75)purchase D steriscus from vendors who move around thesuburbs selling the crop Therefore D steriscus providesemployment to low income earners Some people may notbe able to identify the plant in the wild so it is difficultfor them to obtain it from the source areas others simplydo not have time to do so due to other commitments Theresults are in line with Ahmad and Javed [7] and Hughes[13] who established that early people vendor and Hakeemrsquoswere more experienced and had more knowledge aboutunderutilized crops

46 Availability of D steriscus throughout the Year Dioscoreasteriscus is a source of income for vendors who area mostlypeople from areas surrounding Bindura town They sell amean weight of 213 kg per trip and the standard deviationis 662 kg The quantity sold is just about what an individualcan carry on the head This also suggests that there aretransport bottlenecks for the vendors The results agree withthe assertion by Izquierdo [8] that access to markets is aproblem for all rural farmers

Dioscorea steriscus is available during the dry periodfrom July to November (Table 4(b)) In Zimbabwe thisperiod coincides with the period when people have finishedharvesting This long window of availability implies thatpeople can rely on the crop for at least half a year thusmakingit a reliable rescue crop Since D steriscus is available duringa longer period it is possible to dry the crop for future useduring lean periods

47 Willingness to Grow D steriscus Urban dwellers arewilling to grow D steriscus for their own consumptionWald statistic (which is a conservative test of the uniquecontribution of each predictor) indicates that marital statuseducation level and size of family (169 145 and 144)respectively are the main contributors to growing of Dsteriscus in Bindura The logistic regression indicates thatirrespective of gender of respondent suburb of residence sizeof family period of stay in Bindura education level employ-ment status and sources of income respondent will grow Dsteriscus for use as food supplementThis should significantlyimprove nutrition of the population since we observed thatthe plant is highly nutritious especially in terms of energyand mineral components Although residence (45) wouldwant to cultivate D steriscus it is difficult especially takinginto consideration the fact that they are urban residencesthat only have their residential area occupied by the houseHowever with the current situation in the country where thelocal councils allow residence to farm open pieces of land itis possible for some to cultivate this plant


5 Conclusions and Recommendations

51 Conclusion Themajority of respondents (65) indicatedthat they eat D steriscus This was regardless of the socioe-conomic characteristics of the respondents except educationlevel Frequency of use of eating of the crop is also relativelyhigh with 45 of the respondents taking the crop at leastonce a week Generally the crop is available on the marketfrom May to December and vendors sell the crop at leastonce a week carrying just over 20 kg on each trip D steriscusis high in DM content particularly iron dietary fiber andcarbohydrates and these are important nutrients requiredin significant quantities by the human body There is asignificant difference in the consumption of D steriscus inBindura high density suburbs with respect to education level119875 lt 005

52 Recommendations Since the crop is popular and canbe used during lean periods (dry season) there is need toinvest resources to develop the crop At the same time councilshould provide land that has been designated for periurbanfarming by the government to residence willing to cultivatethis underutilized plant More research is required in orderto establish the nutritional composition of the crop so asto provide information to the skeptical category that com-prises those with higher education levels The plant growthcharacteristics habitats and climatic requirements are allnot known for Zimbabwe plant development institutionslike CIMMYT and ICRISAT should partner government infulfilling this endeavorThere is need to domesticate the cropso that larger quantities of the crop are made available forthe benefit of both vendors and the consuming public Thiswill also help in conserving the plant species The conditionsthat favour the growth of the crop can be provided in homegardens

Conflict of Interests

The authors declare that there is no conflict of interestsregarding the publication of this paper

References

[1] G Gruele A Giuliani andM Smale ldquoMarketing underutilizedplant species for the benefit of the poor A conceptual frame-workrdquo Paper 154 Environment and Production Division 2006

[2] E J Czarapata Invasive Plants of the Upper Midwest AnIllustrated Guide to Their Identification and Control Universityof Wisconsin Press Madison Wis USA 2005

[3] C L Gucker ldquoDioscorea spprdquo in Fire Effects InformationSystem US Department of Agriculture Forest Service RockyMountain Research Station Fire Sciences Laboratory 2009httpwwwfsfedusdatabasefeis

[4] S S Ahmad and S Javed ldquoExploring the economic value ofunderutilized plant species in Ayubia National Parkrdquo PakistanJournal of Botany vol 39 no 5 pp 1435ndash1442 2007

[5] M Sundriyal and R C Sundriyal ldquoUnderutilized edible plantsof the Sikkim Himalaya need for domesticationrdquo CurrentScience vol 85 no 6 pp 731ndash736 2003

[6] B A Levinson D E Foley andD C HollandTheCultural Pro-duction of the Educated Person Critical Ethnographies of School-ing and Local Practice University of New York Press New YorkNY USA 1990

[7] AOAC Official Methods of Analysis Association of OfficialAnalytical Chemists Washington DC USA 15th edition 1995

[8] J Izquierdo ldquoUnder-utilized Andean food crops status andprospects of plant biotechnology for the conservation andsustainable agricultural use of genetic resourcesrdquo Tech RepAA 6347 Centro Internacional de Agricultura Tropical (CIAT)Cali Colombia 1998

[9] H Shiwachi T Ayankanmi and R Asiedu ldquoEffect of day lengthon the development of tubers in yams (Dioscorea spp)rdquoTropicalScience vol 42 no 4 pp 162ndash170 2002

[10] W L Wagner D R Herbst and S H Sohmer EdsManual ofthe Flowering Plants of Hawairsquoi vol 1 of Bishop Museum SpecialPublication 97 University of Hawairsquoi Press Bishop MuseumPress Honolulu Hawaii USA 1999

[11] H Jaenicke and I Hoschle-Zeledon Eds Strategic Frameworkfor Underutilized Plant Species Research and Development withSpecial Reference to Asia and the Pacific and to Sub-SaharanAfrica International Centre for Underutilized Crops ColomboSri Lanka Global Facilitation Unit for Underutilized SpeciesRome Italy 2006

[12] T L Morisawa ldquoWeed notesmdashDioscorea species Dioscoreabulbifera D alata D sansibarensisrdquo in Control MethodsmdashPlants Global Invasive Species Team (GIST) Ed The NatureConservancy Arlington Va USA 1999

[13] J Hughes ldquoJust faminefoods What contributions can under-utilised plants make to food security Scientific AmericanrdquoSpecial Issue Diet Health and Food Supply 2007

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Figure 1 Dioscorea steriscus tubers

and appearance are also highly variable Variability in bulbilsand tubers gives a distinct characteristic in classification andidentification Plants grow rapidly in summer than in wintersimilarly for tuber growth D steriscus is a tropical climateyam which prefers 30∘C as optimal temperature for growthand rainfall of about 1500mm per annum Yams grow bestin loose deep free-draining fertile soil Generally yams areregarded as underutilized species in Africa and all over theworld

Underutilized or neglected crops are those plant speciestraditionally used for their food fiber fodder oil or medici-nal properties but have been overlooked by scientific researchand development workers (ICUC 2006)The term ldquounderuti-lizedrdquo means that they were once grown more extensively ormight be more widely grown in the future but for economicagronomic or genetic reasons they are now cultivated in lim-ited areas [2]These plant species have significant food andorindustrial potential which remain underutilized through lackof a coherent strategy for their evaluation and development[7] They can help to meet the increasing demand for foodand nutrition medicines and industrial needs These plantsrisk falling into disuse yet they lay a crucial role in foodsecurity income generation and culture of the rural poorAccording to [8] these crops have a great potential to provideincome to rural micro entrepreneurship Unfortunately thelack of attention has meant that their potential value isunderexploited and they are in danger of continued geneticerosion ultimately leading to disappearance

Many underutilized crops are collected rather than cul-tivated constituting a significant share of income for thosewho do not have other alternatives [2] Dioscorea steriscus(Figure 1) is one of the underutilized plant species and itis sold in residential areas by vendors There is no enoughinformation documented on this crop implying that itscurrent and potential contribution to peoplersquos livelihood isunknown

Approximately 12 billion people in the world do nothave enough food to meet their daily requirements [7] Indeveloping countries farmersrsquo dependence on a few highlyselective crops has caused food and nutrition insecurity andpoverty in communities due to narrow food baskets Modernagriculture practices encourage the use of wild edible plantsas a supplementary food resource [9] These underutilizedspecies are gathered as a source of food or cash especially

during ldquolean periodsrdquo of the agricultural cycle [2] Dioscoreasteriscus is one such species in Zimbabwe Indeed Dioscoreaspp are listed under priority underutilized root and tubercrops for Africa Asia and Latin America by Wagner etal [10] According to Izquierdo [8] there are major gapsin our knowledge about these neglected and underutilizedspecies and their ecology Consequently the capacity toconserve them and improve their yield is also limited Inurban areas the tuber is sold by vendors who move aroundresidential suburbs The purpose of this study is to assessutilization levels of D steriscus by Bindura high densitysuburbs residents and to assess its availability nutritive valueand magnitude of sales

2 Research Methodology

21 Description of the Study Area The study was carriedout in Bindura high density suburbs which are located inagroecological region II b which receives annual rainfall of750ndash1000mm Bindura high density suburbs are composedof Chipadze Chipadze Extension commonly known as Aero-drome and Chiwaridzo phases I and II (Municipality ofBindura Engineering Department 2003)

Habitats ofD steriscus areas studied were DawMill Farmwhich is 3 km from town and is located north-east of BinduraTrojan Nickel Mine which is also 3 km and is located inthe southwest of Bindura and lastly SOS Maize-lands Farmwhich is 13 kmaway and is located in the east of Bindura townThese sites were studied for fieldrsquos observations as shown inFigure 2

Geologically Trojan area is typically a greenstone con-figuration composed mainly of basaltic rocks (komati-itictholeitic basalts and gabbro) coupled with banded ironformations and volcanic tuffs (Trojan Mine 2007) At SOSMaize-lands the soils are from the parent rocks greenstonebanded ironstone and conglomerates of the Shamva seriesThese give a very wide range of soils form the heavy vlei claysto the sandy loams mixed with gravel of the river deposits(Farm Planning Scheme 1958)

At Daw Mill Farm the soils are mainly moderate deepclays to clay loams and are derived from the Shamva Gritseries (Farm Planning Scheme No 5 1342 June 1960)

22 Sampling Procedures A multistage sampling procedurewas done in selecting respondents from the four Bindurahigh density suburbs In this study two suburbs namelyChipadze and Chipadze Extension (Aerodrome) were ran-domly selected from the four suburbs Aerodrome is furthersubdivided into Aerodrome high and Aerodrome suburbs

Chipadze Extension has a total of 730 houses whileChipadze has a total of 1995 houses (Municipality of BinduraEngineering 2003) Therefore the entire population was 2705houses A sample of 60 households was selected from theentire population of the two suburbs (30 households pereach suburb) Proportionate sampling of the houses was donein order to achieve a fair representation of houses in eachsuburb Households were therefore systematically selectedquestionnaires administered to each of the 10th householdIn this case the household head was the target


1 0 1 2

(km)

31∘20

998400

31∘20

998400

31∘25

998400

31∘25

998400

17∘20998400

17∘20998400

17∘15998400

17∘15998400

N

To Musana


SOS Farm To Shamva

Study area

To Mt Darwin

Daw Mill Farm

Bindura Town







ln [119901

1minus 119901] = 120573

119900+ 12057311199091+ 12057321199092+ 12057331199093sdot sdot sdot 120573119896119909119896+ 120576 (1)


119900= intercept 120573









Age24ndash35 400

10036ndash45 31746ndash60 233gt60 50


1003-4 4335ndash7 367gt8 117













TwiceweekOnceweek

0

5

10

15

20

25

30

35

40

45

50











05

101520253035





(a)


(b)


Seasontime













4 Discussion



















References
















Journal of




Agronomy





Microbiology




Volume 2014

























1 0 1 2

(km)

31∘20

998400

31∘20

998400

31∘25

998400

31∘25

998400

17∘20998400

17∘20998400

17∘15998400

17∘15998400

N

To Musana


SOS Farm To Shamva

Study area

To Mt Darwin

Daw Mill Farm

Bindura Town







ln [119901

1minus 119901] = 120573

119900+ 12057311199091+ 12057321199092+ 12057331199093sdot sdot sdot 120573119896119909119896+ 120576 (1)


119900= intercept 120573









Age24ndash35 400

10036ndash45 31746ndash60 233gt60 50


1003-4 4335ndash7 367gt8 117













TwiceweekOnceweek

0

5

10

15

20

25

30

35

40

45

50











05

101520253035





(a)


(b)


Seasontime













4 Discussion



















References
















Journal of




Agronomy





Microbiology




Volume 2014




























Age24ndash35 400

10036ndash45 31746ndash60 233gt60 50


1003-4 4335ndash7 367gt8 117













TwiceweekOnceweek

0

5

10

15

20

25

30

35

40

45

50











05

101520253035





(a)


(b)


Seasontime













4 Discussion



















References
















Journal of




Agronomy





Microbiology




Volume 2014

























05

101520253035





(a)


(b)


Seasontime













4 Discussion



















References
















Journal of




Agronomy





Microbiology




Volume 2014









































References
















Journal of




Agronomy





Microbiology




Volume 2014


























Journal of




Agronomy





Microbiology




Volume 2014
























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