Arulraj, S.

Rajappan, K.

Surulirajan, M.

English

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158Coconut palm (Cocos nucifera L.), a perennialhorticultural crop, is a symbol of national andinternational integration involving more than 93producing countries with an area of 12.8 million haand production of 10.9 million tones of copraequivalent and more than 140 consuming countries(Madhavan et al., 2010). Coconut is mainly grownfor the high oil content of the endosperm (copra)which is an important source of vegetable oil usedin the manufacturing of edible oils, margarine,cooking fat and soaps (Van Dam, 2005; Rajarajanet al., 2009). A number of value added products aremanufactured from coconut. At present, India is thelargest producer of coconut in the world with anannual production of 1,49,40,000 MT (2011-12)(http:/www.coconutboard.gov.in/stat.htm). Coconutoil accounts for about 7.8 per cent of the total edibleoils production in the country with a production of4.4 lakh tones. In addition, India imports around2000-7000 tonnes of crude coconut oil. Beforeextracting oil form the copra, it has to be dried, butdrying in the winter poses problems like the growthof molds and subsequent rotting of the copra.Common salt is widely used to smear the copra toarrest the mold growth. In the present study, attemptwas made to assess the effect of some chemicalpreservative and biocontrol agents on the growthof mycoflora of copra. The outcome of this studywill largely benefit the resource poor small farmersand small sized copra processing and oil extractingunits throughout the coconut producing countriesin the world.Copra samples were collected from the farmof Coconut Research Station, Veppankulam, TamilNadu, India. The samples were collected from thecultivar, East Coast Tall (ECT). The mycofloraassociated with copra were isolated using potatodextrose agar (PDA) medium. Copra was sliced intosmall pieces, washed in sterile distrilled water andplated in Petri dishes containing PDA medium. Theplates were incubated at 26±2 oC for 7 days inincubator.Fungal growth from the copra slices weretransferred to PDA plates and were identified onthe basis of colour of hyphae, shapes of the sporesand morphology of the spores and morphology ofthe mycelium produced, using light microscope.Pure cultures of the fungi were prepared andpreserved in PDA slants in the refrigerator forfurther studies.Mycelial dics of 6 mm diameter of mycofloraof copra were placed in Petri dishes (90 mm dia)containing PDA medium using flame sterilized corkborer in one end and the same diameter myceliadisc of Trichoderma viride was placed at theopposite end of the plate and incase ofPseudomonas fluorescens a loopful of culture wasstreaked. Plates without biocontrol agents servedas control. Five replications were maintained forJournal of Plantation Crops, 2015, 43(2): 158-161Short Scientific ReportManagement of mycoflora in copra using chemicals andbiocontrol agentsK. Rajappan*, M. Surulirajan and S. Arulraj1Coconut Research Station, Tamil Nadu Agricultural University, Veppankulam-614 906,Tamil Nadu, India1ICAR-Indian Institute of Oil Palm Research, Pedavegi-534 450, Andhra Pradesh, India(Manuscript Received:29-03-14, Revised:21-05-15, Accepted: 02-07-15)Keywords: Copra, mycoflora, chemical preservatives, biocontrol agents, managementCorresponding Author: rajappankasilingam@yahoo.co.in159each mycoflora and for each biocontrol agent.The plates were incubated at room temperature(28 + 2 oC) for 7 days and the growth of mycofloraand biocotnrol agents were measured. Per centinhibition was worked out using the followingformulaPer cent inhibition = Control – Treated   x 100        ControlTwenty five milli litre of one week old culturefiltrate (106 spores  mL-1) of T. viride was pouredinto conical flasks (250 mL capacity) containing100 mL of sterilized molasses yeast extract brothfor testing the efficacy of culture filtrate of T. viridein arresting the biomass production of mycofloraof copra and for P. fluorescens 25 mL of three daysold bacterial suspension (2x108 cfu mL-1) waspoured into conical flasks (250 mL capacity)containing 100 mL of sterilized King’s Broth. Sixmillimeter mycelial discs of one week old mycofloraof copra were inoculated into the flasks andincubated at room temperature for one month. Flaskswithout inoculation of culture filtrate of T. viride andbacterial suspension of P. fluorescens and inoculatedwith mycelial discs of mycoflora of copra served ascontrol. Five replications were maintained for eachmycoflora and for each biocontrol agent. Thebiomass was filtered, dried and the dry weight wasrecorded and the per cent inhibition was workedout.Citric acid, acetic acid and sodium chloridewere incorporated in PDA medium at 1000 ppmconcentration and poured into the Petri plates.Six millimeter diameter mycelia discs of oneweek old mycoflora of copra were placed in thecentre of the plates and incubated at roomtemperature. Plates without the incorporation ofpreservatives and inoculated with respectivemycoflora served as control. The plates wereincubated until the control plates were fullygrown by the mycoflora, the growth wasmeasured and the per cent inhibition was workedout. Five replications were maintained for eachpreservative and for each fungus. All theexperiments were conducted in a factorial mannerin completely randomized design (CRD). Theresults were analysed by means of analysis ofvariance (ANOVA).The results on the management of mycofloraof copra with the help of biocontrol agents andchemical preservatives are presented in Tables 1, 2and 3. Aspergillus flavus, A. niger, Botryodiplodiatheobromae, Penicillium sp and Rhizopus stoloniferwere the common mycoflora isolated from copra.The fungal biocontrol agent, T. viride inhibited thegrowth of all the mycoflora isolated from copra inthe present study. The inhibitory effect was morepronounced in liquid medium than in solid medium.In solid medium, the highest inhibition of 67.8 per centwas observed with respect to Penicillium sp. asagainst the lowest of 55.6 per cent in case of B.theobromae (Table 1). However, the inhibition ofgrowth of various mycoflora of copra by T. viridedoes not differ significantly from each other. Onthe other hand, the inhibitory effect is statisticallysignificant with regard to various mycoflora.Maximum of 93.5 per cent inhibition of growth ofA. flavus was observed in liquid medium by T.viride.Table 1. Effect of T. viride on the growth of mycoflora of copraName of the mycoflora Solid medium Liquid mediumMycelial growth (mm) Inhibition Dry weight biomass (g) InhibitionTreated Control (%) Treated Control (%)A. flavus 38 90 57.8 0.06 0.92 93.5A. niger 33 90 63.3 0.16 1.08 85.2B. theobromae 40 90 55.6 0.07 0.89 92.1Pencillium sp. 29 90 67.8 0.19 1.34 85.7R. stolonifer 32 90 64.4 0.15 0.91 83.7CD (P=0.05) NS NS NS 0.02 ** 0.12 ** 2.2 **Management of mycoflora in copra160Rajappan et al.Table 2. Effect of P. fluorescens on the growth of mycoflora of copraName of the mycoflora Solid medium Liquid mediumMycelial growth (mm) Inhibition Dry weight biomass (g) InhibitionTreated Control (%) Treated Control (%)A. flavus 21 55 60.5 0.20 1.80 88.7A. niger 22 56 60.8 0.11 2.34 95.2B. theobromae 19 60 67.5 0.23 0.92 74.6Pencillium sp. 22 57 61.3 0.17 1.99 91.5R. stolonifer 20 50 60.0 0.15 0.37 59.3CD (P=0.05) NS NS NS 0.02 0.11 4.6Table 3. Effect of chemical preservatives on the growth of mycoflora of copraName of the mycoflora Mycelial growth (mm) Growth inhibition (%)Citric Acetic Sodium Control Citric Acetic Sodiumacid acid chloride  acid  acid chlorideA. flavus 53 66 70 90 41.1 26.7 22.2A. niger 51 60 73 90 43.3 33.3 18.9B. theobromae 41 55 72 90 54.4 38.9 20.0Pencillium sp. 48 70 78 90 46.7 22.2 13.3R. stolonifer 60 64 80 90 33.3 28.9 11.1CD (P=0.05) NS 9.20 NS NS NS 10.2 NSThe effect of the bacterial biocontrol agent,P. fluorescens is depicted in Table 2. The inhibitoryeffect was more in liquid medium compared to solidmedium. In solid medium, 67.4 per cent inhibitionwas noticed in the growth of B. theobromaewhereas; in liquid medium 95.2 per cent inhibitionwas recorded in A. niger. The above results indicatethat these two biocontrol agents can be effectivelyused for managing the mycoflora of copra. All thethree chemical preservatives namely citric acid,acetic acid and sodium chloride showed inhibitoryeffect (Table 3). Per cent inhibition of growth ofvarious mycoflora by citric acid ranged from 33.3per cent (R. stolonifer) to 54.4 per cent (B.theobromae). Acetic acid caused a maximum of38.9 per cent inhibition of B. theobromae while,sodium chloride showed 22.2 per cent inhibitionof A flavus. Onuegbu and Ihuanne (1994) showeda reduction in growth of A. niger, Pencillium sp.and Clalosphorium sp., isolated from palm oil, bycommon salt. Similar to the observations made inthe present study, acetic acid and citric acidexhibited varying degrees of inhibitory actionagainst A. niger, A. flavus, Rhizopus sp. andPenicillium sp. under in vitro conditions (CPCRI,2009).A. flavus, A. niger, B. theobromae, Penicilliumsp and R. stolonifer are the common mycofloraassociated with copra. Biocontrol agents, P. fluorescensand T. viride were found to be promising ininhibiting the growth of mycoflora of copra.Chemical preservatives viz., acetic acid, citric acidand sodium chloride can be used for themanagement of mycoflora of copra.AcknowledgementThe authors are highly grateful to AICRP onPalms for providing financial assistance in carryingout this work.ReferencesCPCRI. 2009. Annual Report-All India Co-ordinated Researchprojects on Palms (ICAR), CPCRI, Kasargod-671 124,Kerala, India. p. 72.161http:/www.coconutboard.gov.in/stat.htm.(Date accessed17.02.2015).Madhavan, K., Arumuganathan, T. and Mathew, A.C. 2010.Commercial production of coconut chips. CPCRITechnical Bulletin No: 62; 14 p.Onuegbu, B.A. and Ihuanne, H.A. 1994. Effect of commonsalt on stored oil palm Elaeis guineensis. Indian Journalof Agricultural Sciences 64(9): 647-649.Rajarajan, G., Sureshkumar, S. and Rajkala, A. 2009. Effectof enriched organic waste on available nutrients in soiland yield of coconut trees. Published by the NationalLaw School of India University (NLSIU) Centre forEnvironmental Law Education Research and Advocacy(CEERA) 10: 12p.Van Dam, J.E.G. 2005. Coir Processing Technologies-Imrpovement of Drying, Softening, Bleaching andDyeing Coir Fibre / Yarn and Printing Coir FloorCoverings. Department of Fibres and CelluloseAgrotechnological Research Insittute (ATO bv).Wageningen, the Netherlands. Technical Paper No. 6.Management of mycoflora in copra

Management of mycoflora in copra using chemicals and biocontrol agents

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