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Effects of abiotic and biotic factors on Trichoderma strains with biocontrol potential

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IOBC
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Disciplines
  • Biology

Abstract

Microsoft Word - KUSADABS.DOC Effects of abiotic and biotic factors on Trichoderma strains with biocontrol potential László Kredics1, László Manczinger2, Zsuzsanna Antal1, Annamária Molnár2, Ferenc Kevei2, Erzsébet Nagy1 1Hungarian Academy of Sciences and University of Szeged, Microbiological Research Group, PO Box 533. H-6701 Szeged, Hungary, E-mail: [email protected], fax 36 62 544 823 2Department of Microbiology, University of Szeged, Hungary The effects of low temperature, low water potential, pesticides, heavy metals and antagonistic bacteria on Trichoderma strains with biocontrol potential were examined in vitro. Cold-tolerant strains growing well at 5°C were isolated from soil samples. In dual culture tests at 10°C, most strains antagonized plant pathogenic fungi. The activities of extracellular enzymes important for mycoparasitism were significant at 5°C in the cold-tolerant strains. Nearly linear correlation was found between water potential and colony growth rate with higher growth rates at higher water potential. Secretion of the enzymes also depended on the water potential of the liquid media. However, significant in vitro activities were measured for most of the enzymes even at water potential values below the limit of mycelial growth, suggesting the possibility of using mutants with improved xerotolerance for biocontrol purposes in dry soils. The effects of three fungicides and four herbicides on the growth and in vitro activities of extracellular enzymes of the Trichoderma strains were also examined. In the case of the examined herbicides the IC50 concentrations were found to be so high, which values can not be present in the soil during their application. However, the fungicide susceptibility of the strains may cause problems during their combined application with antifungal compounds. For such purposes fungicide resistant mutants should be applied. The examined heavy metals showed inhibition of mycelial growth, but the ex

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