Management of aflatoxine producing fungi in peanut (Arachis hypogeae) varieties in central tigray through soil solarization and planting time

Ref ID: 19372

Author:

K. T. Mawcha

Author address:

Aksum University, Ethiopia

Full conference title:

6th Trends in Medical Mycology 2013

Date: 11 October 2014

Abstract:

Objectives Peanut is invaded before harvest mainly by Aspergillus
flavus and A. parasitics, which are potential aflatoxin producers. How-
ever, no research efforts have been directed to develop suitable man-
agement options against aflatoxigenic fungi in Northern Ethiopia.
Therefore, this study was undertaken to determine the effect of soil
solarization on A. flavus inocculum in the soil and to evaluate the
effect of soil solarization and planting time on peanut seed invasion
by Aspergillus spp. and yield of peanut varieties.
Methods Soil samples were taken from 5 and 10 cm soil depths in
three rounds and analyzed for aflatoxigenic population. Soil solariza-
tion reduced fungal inoculum and increased groundnut yields. Individ-
ual and total cfu g!1 of soil was determined before, after solarization
and at harvest. Four Aspergillus species namely, A. flavus, A. parasiticus,
A. niger and A. terreus were plated on Rose Bengal Agar media (selec-
tive medium for Aspergillus spp.) and morphologically identified. To
determine the natural seed infection by Aspergillus spp. and other
fungi, undamaged pods from the middle two rows were carefully hand-
shelled and 100-seed of each plot were surface sterilized by soaking in
5% aqueous solution of sodium hypochlorite (NaOCl) for 3 minutes
and immediately rinsed with sterile distilled water, and plated on Cza-
pek-Dox agar medium and incubated at room temperature. After
7 days the growing colonies of fungi were visually recorded. Finally,
fungi identification was carried out based on macro- morphological
(reverse and surface coloration of colonies, presence of pigment, and
colony texture) and micro- morphological characteristics (conidia size,
conidial head, shape of vesicle). Standard text (Klich, 2002) was used
in the identification process.
Results Their densities were significantly (P < 0.05) reduced at after solarization. In the solarized plots, A. flavus and A. parasiticus were found reduced by 53.8 and 45% cfu g!1 at Ramma and 36.4 and 44% cfu g!1 at 5 and 10 cm soil depths at Mayweyni, respectively, after soil solarization in the solarized plots than the nonsolarized plots. At harvest, Fusarium spp., A. flavus and A. terreus were detected. Pod yields were found increased by 265.6 and 182.22 kg ha!1 on solarized plots at Mayweyni and Ramma, respec- tively. Increase in yield related parameters (14.8% increase in num- ber of seed per plant and 7.4% increase in number of pods per plant) were found from early planting dates as compared to later planting time at Mayweyni. Conclusions Generally, yields varied across locations; mean pod yield in Mayweyni was 360.9 kg ha!1higher than the yield in Ram- ma. Three Aspergillus species namely, A. flavus, A. niger, and A. para- siticus were isolated from seed samples plated on Czapek-Dox Agar medium. Early planting of the varieties showed the lowest level of seed infection by A. flavus (22.8%). Four Aspergillus species namely, A. flavus, A. parasiticus, A. niger and A. terreus were isolated before soil solarization and after solarization. Both the total propagule den- sity and individual fungi cfu g!1 were counted and A. niger was found as the most dominant.

Abstract Number: p001

Conference Year: 2013

Link to conference website: NULL

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