Antagonistic properties of Trichoderma viride and Trichoderma harzianum against storage fungi

Introduction Agriculture is the backbone of the Indian economy and villages are the life lines of growth of India. It is a very important sector for the sustained growth of the Indian economy. About 70% of the rural households and 8% of urban households are still principally dependent on agriculture for employment. India has undergone a series of successful agricultural revolutions-starting with the ‘green’ revolution in wheat and rice in the 1960’s and 1970’s, the ‘white’ revolution in milk to the ‘yellow’ revolution in oilseeds in 1980’s. As a result, India has achieved self-sufficiency in agriculture. India is one of the largest producers of oilseeds in the world and this sector occupies an important position in the agricultural economy covering an area of 38 million hectares, and accounting for the production of about 32 million tonnes of oilseeds annually. India contributes about eight per cent of the world oilseeds production after China, EU-15 and USA (Kakde, 2011). India has a wide range of oilseeds crops grown due to the different agro-climatic zones. In Maharashtra state seed for sowing is available at seed industries and Government Agriculture institute. Whereas, poor farmer keep the reserved seeds with him for his consumption and sowing purpose in next season. High nutritive value makes oilseeds prime target of attack of various microorganisms like bacteria, viruses, fungi and insects. Among these, fungi play a dominant role in decrease in quality and longitivity of oilseeds (Christensen and Kaufman,1969). Therefore, such seeds are not fit for human consumption and are also rejected at industrial level. Hence, emphasis has been given on to investigate fungi associated with different varieties of oilseeds and ten fungi were selected on the basis of their quantitative occurrence of dominance. Importance of biocontrol has been enhanced for the sustainable agricultural practice and environmental protection. The adaptation of a sustainable agricultural practice, using strategies that are environmentally friendly, less dependent on agricultural chemicals is gaining worldwide recognition. One of the key elements of such sustainable agriculture is the application of biocontrol agents. Trichoderma spp. is antagonistic by nature with rich resource and a broad action scope. In this regard experiments were carried out to screen the antagonistic nature of Trichoderma harzianum and Trichoderma viride against storage fungi. Materials and Methods Isolation of storage fungi of oilseeds Collection of oilseed samples Oilseeds samples of groundnut, soybean, sesame, safflower and sunflower of different varieties were collected from market places and store houses from different parts of Marathwada region of Maharashtra state. These seeds were then packed in pre-sterilized polythene bags and kept in laboratory conditions until use. Isolation of oilseed mycoflora For detection of seed mycoflora associated with seed samples, the method recommended by ISTA (1966), Neergaard (1973) and Agarwal (1976) were adopted. 10 seeds per presterilized petriplates were equispaced asceptically on autoclaved Potato Dextrose Agar (PDA) and Glucose Nitrate Agar (GNA) media. Plates were then allowed to incubate at room temperature for seven days. Antagonistic activity of Trichoderma viride and Trichoderma harzianum against storage fungi Trichoderma harzianum and Trichoderma viride were isolated from the sesame on PDA. A mycelial disc (1.2 cm diam), obtained from the peripheral region of 5-7-day-old cultures of Alternaria dianthicola, Curvularia lunata, Curvularia pellescens, Fusarium oxysporum, Fusarium equiseti, Macrophomina phaseolina, Rhizopus stolonifer, Penicillium digitatum and Penicillium chrysogenum was placed on a fresh PDA plate (3 cm from the center) and incubated at 28C for 48 h to initiate growth. Then a 1cm diameter mycelial disc, obtained from the periphery of a 5-7day old culture of Trichoderma harziaum and Trichoderma viride was placed 3 cm away from the inoculum of the pathogen, the plates were incubated at 28 0 C and measurements were taken after 7 days. In the control