Characterization of Soil Fungi Capable of Striga Seed Bank Depletion Under in Vitro Conditions
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Date
2020-06-06
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Addis Ababa University
Abstract
Striga hermonthica (Del.) Benth is an obligate hemi-parasitic plant which severely threatens cereal production. Therefore, the use of soil-borne antagonists for Striga seedbank depletion is one of the useful control methods suggested for integrated pest management (IPM). The objectives of this study were to preliminary screen and evaluate effective soil fungi that are capable of decaying Striga seed using seed trap method. From the soil samples showing seed decay, fungi were isolated and characterized using standard methods. The effect of fungal spores to inhibit Striga seeds germination was also tested using synthetic stimulant GR-24 and was further studied using sorghum variety Teshale. Besides, effects of fungal spore on Striga seeds viability were also studied. Soil samples collected from Tahtay Adiabo (E22) showed the highest Striga seed decay (19.8%) whereas soil samples collected from Raya-Kobo (E46) showed the lowest activity (3.6%). A total of 43 fungal isolates were collected from the soil of which 20 isolates decayed more than 50% of the Striga seeds. Genus Fusarium was the dominant and only ten further characterized. All isolates were showed maximum mycelium dry weight at 25oC and different mycelium dry weight at different hydrogen ion concentration (pH). Effects of fungal isolate on Striga seeds germination inhibition using sorghum variety Teshale as test crop revealed that there were significant (p<0.05) differences among fungal isolates. The results indicated that inoculation of the Striga seeds with isolate (F-254) significantly (p<0.05) have showed the highest percentage of Striga seed germination inhibition of 74.4%, 82.8% and 92.8% of all the fungal isolates upon 15, 21 and 30 days of incubation, respectively. In terms of Striga seed viability analysis, the highest number of Striga seed mortality (70%, 86% and 92%) were obtained when the Striga seeds treated with isolate (F-254) at 15, 21 and 30 days of incubation, respectively which were statistically significant (p<0.05) difference from all fungal isolates. However, the lowest results (16.4%) and (29.6%) were obtained from isolate (F-301) at 15 and 21 days of incubation while 39.6 ±8.98 was recorded at 30-DOI with isolate (F-040). This study therefore provides preliminary information on the existence of potential fungal isolates as candidates for biocontrol against Striga seeds in the soil that could be further tested in the management of Striga seedbanks.
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Biocontrol, Haustoria, Strigolactone, Sorghum, Viability