Studies on the Population Dynamics of Trichoderma Spp. In Soil and Its Antagonistic Activity Against Fusarium Oxysporum F. Sp. Ciceris

Abstract

Chickpea is an important pulse crop cultivated all across the globe. It is a major pulse crop in terms of its nutrient composition and is consumed by a large population all around the world. Fusarium oxysporum f. sp. ciceris is a major pathogen of chickpea causing wilt in the crop. The average annual yield losses due to wilt have been estimated to 10 to 90 percent and sometimes reach up to 100 percent. Trichoderma spp. are an effective bio control agent for the management of pathogens affecting various crops. The present study was conducted to understand the population dynamics of the bio agent in soil and to study the antagonistic activity of the bio agent against Fusarium wilt of chickpea under pot conditions. For this purpose SV3 strain of T. harzianum was used. The strain was multiplied on five different substrates viz. sorghum grains, vermicompost, sugarcane bagasse, paddy straw and groundnut cake before applying to the soil. The sorghum grains proved to be the best in supporting the growth and the viability of the bio agent in soil for a longer time. The sugarcane bagasse was found to be the next best substrate for supporting a good colony count of the bio agent followed by paddy straw. The sorghum grains and vermicompost as substrate for T. harzianum (SV3) reduced the wilt disease incidence of chickpea significantly. Sugarcane bagasse was found to be the next best substrate in terms of reducing the disease incidence in the crop. In addition to maintaining a good population count, soil application of SV3 mass multiplied on sorghum grains also significantly increased the yield, shoot length, root length, plant height and fresh weight of chickpea plants. This was followed by soil application of T. harzianum (SV3) mass multiplied on vermicompost and talc (positive control). The paddy straw exhibited a good performance as substrate for SV3 strain of T. harzianum in terms of maintaining population levels of the bio agent in soil and reducing the wilt incidence in chickpea. The biometric parameters of chickpea also didn’t show much improvement in soil treated with T. harzianum (SV3) mass multiplied on groundnut cake. Overall, it was seen that the substrates on which the bio agent was multiplied had a significant effect over the population dynamics of the bio agent in soil, disease incidence, biometric parameters and yield of the crop. Thus, the performance of the bio agent could be improved with the use of substrates suitable for its growth and development.