Effect of Carrier Media on Population Fluctuation of Trichoderma harzianum (MTCC5179) in Black Pepper ( Piper nigrum L.) Rhizosphere and their Interaction with Soil Microflora and Fauna

Trichoderma harzianum is used as a biocontrol agent to manage Phytophthora foot rot of black pepper (Piper nigrum L.) in India. Several organic materials such as sorghum, neem cake, decomposed coir pith and farmyard manure are used both as multiplication and carrier media for T. harzianum. The effect of these carrier media on the population build up of T. harzianum in black pepper rhizosphere and their effect on microflora and fauna was studied. The organic materials increased the population of introduced T. harzianum and also increased populations of fungi, bacteria, microarthropods and nematodes. In case of sorghum, there was a sudden spurt in the population of saprophytic nematodes and mycophagous mites within 15 days followed by a succession of predatory mites and nematodes. The unspent carbohydrate and mycelial form of T.harzianum in sorghum perhaps helped in the population build up of soil microarthropods and nematodes, which in turn affect the biocontrol efficiency of the introduced organism.