IOSR Journal of Agriculture and Veterinary Science (IOSR-JAVS) e-ISSN: 2319-2380, p-ISSN: 2319-2372. Volume 7, Issue 7 Ver. II (July. 2014), PP 33-37 www.iosrjournals.org www.iosrjournals.org 33 | Page In Vitro Evaluation of Trichoderma Harzianum (Rifai.) Against Some Soil and Seed Borne Fungi of Economic Importance Suraiya Yasmin 1 , Sabiha Sultana 2 , S. K Adhikary 3 , Nusrat Jahan 4 , Sanzida Rahman 5 , Md. Imranur Rahman 6 1, 4, 5 Ex-student, 2 Assistant professor, 3 professor, Agrotechnology discipline, 6 Ex-student, Urban and Rural Planning discipline, Khulna University, Khulna- 9208, Bangladesh Abstract: To investigate the antagonistic potentiality of Trichoderma harzianum against Fusarium oxysporum, Bipolaris sorokiniana and Sclerotium rolfsii. Dual culture technique was followed to evaluate the effect of antagonist. The inhibition percentage of Trichoderma harzianum was substantially affected and differed significantly (p<0.01). In case of antagonist the highest percent inhibition of Trichoderma harzianum was found 89.20% against Bipolaris sorokiniana followed by 88.69% in Fusarium oxysporum but statistically dissimilar with Sclerotium rolfsii 76.76%. In every case inhibition was more than 75%. Key word: Trichoderma harzianum, dual- culture, soil and seed borne fungi I. Introduction The members of genus Trichoderma are free-living fungi that are common in soil and root ecosystems. They are opportunistic, avirulent plant symbionts, as well as being parasites of other fungi (Harman et al.,2004). The T. harzianum are very promising against phytopathogenic fungi like Fusarium oxysporum, Bipolaris sorokiniana and Sclerotium rolfsii (Manczinger et al., 2002). These pathogenic fungi when associated with soil in different way and affect on seed germination, seedling mortality, seedling growth (Mustafa et al., 2004). T. harzianum and several other fungal antagonists are inhibitory to B. sorokiniana causing leaf and seed diseases of rye, wheat, barley (Biles and Hill 1988; Fokkema 1973). T. harzianum also found effective against S. rolfsii (Hadar et al,.(1979), Elad et al., (1980& 1981), Harman et al., (1980), Lewis and Papavizas (1984), Aziz et al., (1997) and F. oxysporum (Sarhan et al., 1999). It colonizes S. rolfsii hyphae, disrupts mycelial growth and kills the organism. Therefore systematic researches are needed to explore the potential of T. harzianum as bio-control agent against seed borne and soil borne fungal pathogens. Considering the above fact the present investigation was undertaken to investigate the antagonistic potentiality of T. harzianum against F. oxysporum, B. sorokiniana and S. rolfsii. II. Materials and Method An isolate of T. harzianum was collected from Bangladesh Agricultural Research Institute (BARI), Joydebpur, Gazipur. Three isolates of B. sorokiniana, F. oxysporum, S. rolfsii were collected from the preserved isolates of Plant Protection Laboratory of Agrotechnology Discipline, Khulna University, Khulna. Preparation of Potato Dextrose Agar (PDA) Medium PDA was prepared following the standard procedure (Anonymous, 1968). 200 gm potato slice was boiled in 1000 ml distilled water. After that it was sieved and 20 gm dextrose was mixed with it. Then 15 gm agar was mixed with slowly and melted on hot plate magnetic stirrer. After preparation of PDA medium, it was poured in to 500 ml conical flasks then the conical flask was plugged with cotton plug and covered by brown paper. Finally the medium was sterilized in an autoclave at 121ºC temperature for 15 minutes. Multiplication of T. harzianum, B. sorokiniana, F. oxysporum and S. rolfsii PDA was poured in sterilized petridishes, 20ml in each plate. After solidification, discs were cut with flame sterilized cork borer (5 mm diameter), then the plates were inoculated by placing 5 mm discs of PDA culture of isolated pathogens. The inoculated petridishes were kept in the growth chamber (25±2 ºC) for observation. All the works were undertaken under aseptic condition. In vitro antagonistic effect of T. harzianum on mycelial growth of B. sorokiniana, F. oxysporum, S. rolfsii Antagonist T. harzianum, was tested against three seed and soil borne fungi following dual culture method (Dennis and Webster, 1971).