A field study was conducted at Atonsu, Sekyere Central District, Ghana from 2013 to 2014, to (i) determine the effects of Moringa oleifera, Chromolaena odorata and Panicum maximum as ex-situ mulches, on soil nematodes population after two years of yam cropping and (ii) assess the effects of the soil nematodes on the yield and physical tuber quality of yam. The field experiment was a 3×3 factorial arrangement in a randomized complete block design with three replications. The first factor was ex-situ mulch types at three levels; Panicum maximum (farmers’ choice), Chromolaena odorata and Moringa oleifera. The second factor was natural fallow aged systems at three levels: 3, 5 and 7 years old. Data collected included nematode population changes, total tuber yield of yam and tuber physical quality assessment. Generally, Meloidogyne spp., Pratylenchus spp. and Scutellonema spp. were the nematode genera identified. However, Scutellonema spp. was found to be the most pathogenic nematode affecting yam tuber yield and physical quality. Chromolaena and Moringa mulches suppressed Scutellonema spp. populations by 80.7% and 76.2% respectively as compared to the Panicum maximum mulch. The suppressed Scutellonema spp. population significantly contributed to higher tuber yields and good tuber physical quality under the M. oleifera and C. odorata mulches in comparison to the P. maximum mulch.
Dr. Anthony A. Mainoo
Adventist Development and Relief Agency (ADRA Ghana), P.O.Box 1435, Accra, Ghana.
Prof. Ben K. Banful
Faculty of Agriculture, Kwame Nkrumah University of Science and Technology, University Post Office, Private Mailbag, Kumasi, Ghana.
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Yam is an important crop in Nigeria, where it is produced both as food and cash crop. Fusarium rots of yam are among the most important postharvest pathogens of yam worldwide, causing a lot of postharvest losses in stored yam tubers. Lactic acid bacteria (LAB) lower the pH and create an environment that is unfavorable to pathogens and spoilage organisms. In vitro inhibition of fusarium species by LAB was investigated; mono-culture and multi-cultures were used. The inhibition tests were carried out with pure cultures of LAB and fusarium spp. The pure culture of actively growing Fusarium was inoculated into Potato Dextrose Agar medium aseptically and then incubated at room temperature for 72 h. The diameter of the growing Fusarium was measured, after which less than a loop full of actively growing (18-24 h) LAB isolates were used to inoculate the medium containing the growing Fusarium at a known distance in the same plate. The whole set up was incubated at 300C and inhibition zones on Fusarium by the LAB were observed 24 hourly for 96 h. The tests were carried out for mono-culture and multi-cultures in triplicate. The inhibition zone ranged from 43 to 100% in mono-culture plates and from 40 to 113% in multi-culture plates. The slightly larger inhibition in the multi-culture plate may be due to much pressure on the Fusarium. Hence LAB may be used to control rot caused by Fusarium in in stored yam, which can improve yam tuber storage for better economic growth.
R. M. Omodamiro
Department of Postharvest Technology Programme, National Root Crops Research Institute, Umudike, Nigeria.
P. C. Ojimelukwe
Department of Food Science and Technology, Micheal Okpara University of Agriculture, Umudike, Nigeria.
Dr. R. Asiedu
Yam Barn Unit, International Institute of Tropical Agriculture, Ibadan, Nigeria.
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