Abstract
The study of morphology and bioefficacy of Trichoderma was undertaken to select the effective isolates against soil-borne pathogens. Fifty one (51) isolates (23 isolates of Trichoderma virens and 28 isolates of Trichoderma harzianum) were morphologically characterised based on the growth characteristics on PDA medium, the size and shape of phialides and conidia.These isolates were screened for bioefficacy against soil borne plant pathogens (Fusarium oxysporum, Rhizoctonia solani and Sclerotium rolfsii) based on their percent inhibition observed during dual culture, volatile and non-volatile methods. Eight T. virens isolates and 12 T. harzianum isolates were proven to be potential isolates against the soil-borne pathogens tested. No correlation was found between bioefficacy and morphology in both species isolates. Key words: Trichoderma virens, Trichoderma harzianum, morphology, dual culture, biocontrol and bioefficacy.
Highlights
Trichoderma spp. is cosmopolitan and abundant fungi in soil in a wide range of ecosystems and climatic zones. They are characterized by rapid growth, capability of utilizing diverse substrates and resistance to noxious chemicals (Klein and Eveleigh, 1998). Their economic importance includes their role as primary decomposers, producers of antibiotics and enzymes as well as biocontrol agents against a wide range of plant pathogens (Hjeljord and Tronsmo, 1998; Kubicek and Penttila, 1998; Rossman, 1996; Sivasithamparam and Gisalberti, 1998)
In the direct interaction between Trichoderma spp. and the phytopathogenic fungi, mycoparasitism is one of the mechanisms observed in which the antagonist coils around the hyphae of the pathogen, develops hook-like structures known as appressoria coupled with production of lytic enzymes and penetrates the pathogen hyphae (Chet, 1987; Kubicek et al, 2001)
The photographs were taken under 100x magnification and under 10x magnification were measured in micrometer by using ImageJ
Summary
Trichoderma spp. is cosmopolitan and abundant fungi in soil in a wide range of ecosystems and climatic zones. They are characterized by rapid growth, capability of utilizing diverse substrates and resistance to noxious chemicals (Klein and Eveleigh, 1998). Their economic importance includes their role as primary decomposers, producers of antibiotics and enzymes as well as biocontrol agents against a wide range of plant pathogens (Hjeljord and Tronsmo, 1998; Kubicek and Penttila, 1998; Rossman, 1996; Sivasithamparam and Gisalberti, 1998). Coiling of the phytopathogenic fungal hyphae by Trichoderma spp. is one of the parameters used to characterize the mycoparasitism (Howell, 2003; Rocha-Ramirez et al, 2002)
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