STUDIES ON THE MYCOFLORA AND SOME PHYSICAL CHARACTERISTICS OF GHANAIAN MAIZE (Zea mays L) VARIETIES AND THE EFFECT OF EXTRACTS OF ZANTHOXYLUM XANTHOXYLOIDES LAM AND KIGELIA AFRICANA BENTH ON

ABSTRACT Mycoflora of mixed maize grains and the newly developed Abeleehi and Obaatanpa varieties and airspora in the Warehouse o f the Ghana Food Distribution, GFDC, at Balduzzi, Kumasi have been studied under normal and simulated ambient Environmental Relative Humidities (ERH ’s) representative of the Ghanaian conditions. Some important physical and processing characteristics of £. and normal stackbumed white and yellow maize (seed water absorption, swelling index, 1000-seed weight, fermentation parameters) and gem ination capacity of grains were also examined. To ascertain the ability of Abeleehi and Obaatanpa varieties to absorb and desorb moisture in relation to the development of attendant resident fungi, the moisture sorption isotherm at ERH’s 55-95% were determined in simulated humidity chambers. Finally results o f the use of aqueous, acetone and methanolic extracts of the dry leaves of Zanthoxylum xanthoxyloides and the dry leaves and dry fruit o f Kigelia africana as biofungicides to control vegetative growth and sporulation of important potential pathogenic fungi (Paecilomyces carneus, P.puntoni, P.varioti, Curvularia lunata, Fusarium moniliforme and Penicillium digitatum) resident in Abeleehi and Obaatanpa varieties are reported. Fifteen different fungal species (Aspergillus flavus, A.niger, A.sulphureus, A.tamarii, Penicillium brevicompactum, P.chrysogenum, P.citrinum, P.cyclopium, P. digitatum, P.glabrum, P.oxalicum, Cladosporium herbarum, Fusarium moniliforme, F.roseum andM ucor haemalis) were isolated from maize grains obtained from the GFDC Warehouse at Balduzzi, Kumasi. Aspergillus species (A.flavus, A.niger, A. sulphur e-US', A.tamarii) and Penicillium species (Penicillium brevicompactum, P.chiysogenum, P.citrinum, P.cyclopium, P.digitatum) predominated. The initial fungal population in the mixed grain variety was 4.8 - 5.4 log |0 CFU/g but this decreased by 0.4 -1.3 log cycle after 2 months. There was no statistical difference (P< 0.05) between the population of fungi isolated from grains sampled from the top, middle and bottom of the bagstacks. Aspergillus flavus was Hie most predominant fungi encountered constituting 41.7- 44.0% of the species followed by Mucor haemalis (4.0 - 20.5%). Both A.flavus and M. haemalis occurred at all positions sampled. Twenty four different airspora of fungi (Aspergillus flavus, A.clavalus, A.fiumigatus, A.niger, A.ochraceus, A.parasiticus, A.sulphureus, A.tamarii, Penicillium chrysogemim, P.citrinum, P.cyclopium, P.digitatum, P. expansum, P.italicum, P.oxalicum Paecilomyces carneus, Ppuntonii, P.varioti, Cladosporium herbarum, Curvularia lunata, Fusarium moniliforme, M ucor haemalis, Neurospora sitophila, Rhizopus oryzae) were isolated from the Balduzzi W arehouse. Species of airspora that were not foundinthe grains wereA.clavatus, A.ochraceus, Aparasiticus, A.fumigatus, P.expansum, Paecilomyces carneus, P puntonij P.varioti, Curvularia lunata and Rhizopus oryzae. Generally mycological media used and the method used in isolation influenced the profile o f fungal species encountered. Thirty and 28 fungal species belonging to 13 genera were isolated from Abeleehi and Obaatanpa varieties respectively, and they are being recorded for the first time in Abeleehi and Obaatanpa varieties. The species diversity was influenced by grain variety, method of isolation, mycological media used, storage humidity and whether the grains were exposed in petri dishes or in woven polypropylene sachets. A.flavus was ubiquitous and was isolated from both Abeleehi and Obaatanpa stored at 55-95% ERH in both open Petri dishes and in woven polypropylene sachets; Fusarium moniliforme was encountered atE R H ’s 65-95% in open Petri dishes but not at 65 and 75 ERH in woven polypropylene sachets. Xerophilic species, like Aspergillus giganteus, P. carneus, P.puntoni and P.varioti were isolated at 55-65% ERH in both grain varieties. There was no statistical difference (analysis of variance P.< 0.05) between germination capacity of Abeleehi grains stored in woven polypropylene sachets at ERH 55- 85%; seed germination was drastically reduced at 90 and 95% ERH after 2 months storage period. Data on grains kept exposed in Petri dishes to the same ERH’s were similar. The same trend as above was observed for Obaatanpa grains. The storage ERH influenced the length of the emerging radicles of the germinating grains such that the higher the incubating ERH, the shorter the length o f the emerging radicle. At ERH 95% radicle length was reduced by 39-69% (depending on the maize variety used). There was however a significant (P< 0.05) difference between the higher radicle length recorded in grains of both varieties stored in woven polypropylene sachets than same grains exposed in Petri dishes under the same ERH conditions.