اثرات بیولوژیکی گونه‏های تریکودرمای ریزوسفر گوجه‏فرنگی و قارچ‌کش بیولوژیکی trichomax-hv علیه بیماری پژمردگی فوزاریومی گوجه‏فرنگی در شرایط آزمایشگاهی

پژمردگی فوزاریومی گوجه‏فرنگی از مهم‌ترین و شایع‏ترین بیماری‏های گوجه‏فرنگی در مناطق زیر کشت این گیاه در سراسر جهان می‏باشد. کنترل بیولوژیک بیماری های گیاهی با استفاده از میکروارگانیسم های غیر بیماری‌زا توجه بسیاری از پژوهشگران را به خود جلب نموده است. از موفق‏ترین و پرکاربردترین میکروارگانیسم‏هایی که باعث جلوگیری از خسارت قارچ‏ها در گیاهان می‏شوند، گونه‏های مختلف جنسtrichoderma  می‏باشند. در این تحقیق اثر دو جدایه trichoderma harzianum و trichoderma virens و سم بیولوژیک trichomaxhv علیه fusarium oxysporum f. sp. lycopersici عامل بیماری پژمردگی فوزاریومی گوجه فرنگی در آزمایشگاه و گلخانه مورد ارزیابی قرار گرفت. فعالیت آنتاگونیستی این جدایه ها علیه این بیمارگر در آزمایشگاه به روش کشت متقابل مورد مطالعه قرار گرفت. به ‌منظور بررسی اثر این جدایه های آنتاگونیست در گلخانه، ابتدا مایه تلقیح قارچ بیمارگر به یک‌سوم تحتانی خاک گلدان‏ها افزوده شد و به‌ محض انتقال دادن گیاهچه‏ها به گلدان، آنتاگونیست‏های قارچی به گلدان ها اضافه شد و پس از 60 روز برهم‏کنش بین بیمارگر و آنتاگونیست، مورد ارزیابی قرار گرفت. نتایج بررسی‏های آزمایشگاهی نشان داد که t. harzianum به میزان 9.48 درصد، trichomaxhv به میزان 6.45 درصد و t. virens به میزان 22.36 درصد از رشد بیمارگر (در مقایسه با شاهد) جلوگیری کردند و باعث کلونیزه کردن پرگنه‏های بیمارگر شدند. عوامل آنتاگونیست در آزمایش‏های گلخانه‏ای موجب افزایش ارتفاع ساقه، وزن تر و خشک اندام های هوایی و ریشه در غیاب بیمارگر شدند. فقط t. harzianum در برهم‏کنش‏ با بیمارگر باعث افزایش ارتفاع ساقه، وزن تر و خشک اندام های هوایی و ریشه نسبت به شاهد آلوده شد.

Biological Effects of Trichoderma spp. Isolated from Tomato Rhizosphere and Trichomax-HV Biofungicide against Tomato Fusarium Wilt in Vitro

Introduction: Fusarium wilt of tomato is one of the most important and common tomato diseases growing in the cultivated areas of this plant around the world. Biological control of plant diseases using nonpathogenic microorganisms has attracted the attention of many researchers. Trichoderma is one of the most successful and widely used microorganisms that prevent fungal damage in plants. Trichoderma spp. have different mechanisms to deal with plant pathogens, such as increasing plant resistance and activating defense reactions, direct confrontation with the pathogen through mycoparasitism, antibiosis, competition, plant growth stimulation, regulation and induction of plant growth factors including auxins, cytokinins and ethylene that stimulate growth Plants are involved. Totally, they destroyed biological reproductive organs, survival and reproduction, weakening and expelling pathogens from plant debris and preventing the formation of contaminants are the three basic methods by which biological control is achieved. Trichoderma is one of the living fungi that can perform the above three mechanisms simultaneously and as a result it is used as a biological fungus that increases plant growth and activity of beneficial microorganisms.Material and Methods: In this study, the effects of two isolates; Trichoderma harzianum and Trichoderma virens, and biological toxin of TrichomaxHV against Fusarium oxysporum f. sp. lycopersici which is the agent of Fusarium wilt disease in tomato was evaluated in the laboratory and greenhouse. TrichomaxHV is a biofungicide that use as commercially. During summer and autumn, tomato plants with obvious signs of Fusarium wilt were collected from tomato fields in different parts of Lorestan province and transferred to the laboratory. Isolation of pathogenic fungi was performed according to Bani Hashemi and Dezeeuw methods using acidic PDA culture medium. Antagonistic activity of these isolates against this pathogen was studied by dual culture method in the laboratory. In order to investigate the effect of these antagonist isolates in the greenhouse, first the inoculum of pathogenic fungus and fungal antagonists were added to the pots as soon as the seedlings were transferred to the pots and then after 60days, the interactions between the pathogen and antagonist was evaluated. This test was performed in a completely randomized design with 10 treatments and three replications. The data obtained from the experiment were statistically analyzed using SPSS 16 software and the average of the treatments were compared using Duncan’s multiple range test at 5% probability level.Results and Discussion: In this study, a total of three isolates of F. oxysporum f. sp. lycopersici were isolated from tomato plants infected with Fusarium wilt disease from Robat and Chegeni Dore tomato fields (Khorramabad city) and Cham fig fields (Poldokhtar city) that was assigned them codes FOM, FOK and FOS respectively. A total of 27 fungal isolates were isolated from soil samples of tomato rhizosphere collected from tomato fields of two cities in Lorestan province. By evaluating the inhibitory effect of these isolates on pathogenic growth, two isolates prevented the growth of pathogenic mycelium by creating an inhibitory aura. The results of laboratory studies showed that T. harzianum by 48.9 percent, TrichomaxHV by 45.6 percent and‏ T. virens to 22.36 percent prevented the growth of pathogen and colonized the pathogen’s colonies (in comparison with the control). Antagonist agents in greenhouse experiments increased stem height, wet and dry weight of shoots and root in the absence of pathogen. Comparing with the control sample, only the isolate T. harzianum in the interaction with the pathogen increased the plant height, wet and dry weight of shoots and root. According to study, in the greenhouse biological tests of biofungicide (TrichomaxHV) and Trichoderma spp. had shown good control on causal agent of the disease (Fusarium oxysporum f. sp. lycopersici). Among these treatments, T. harzianum had the best effect on the control of pathogenic fungi, which is due to the complex system of soil biology and ecology and the presence of antagonists in the rhizosphere and the power of root colonization and antagonist survival, soil pH and soil texture.Conclusion: Based on the this study results, T. harzianum had the highest percentage of inhibition of pathogenic fungal growth as well as increase in height, fresh and dry weight of the plant and decrease in disease severity among the different treatments tested. In greenhouse conditions, T. harzianum prevented from tomato Fusarium wilt disease (caused by Fusarium oxysporum f. sp. lycopersici) in very large extent. Also this results showed that TrichomaxHV could be a viable alternative to chemical fungicides in controlling this disease.