Evaluation of substrates for multiplication of bio-agent , Trichoderma viride

An experiment was conducted using locally available substrates to mass multiply Trichoderma viride on different substrates. Experiment was conducted during June to August for 2 years (2011 and 2012). Result revealed that sporulation was observed after 5 days of incubation in cowdung, followed by all other substrates after 7 days of incubation. Maximum sporulation (51.50 × 10 cfu g) was observed in cowdung on 15 day, which is followed by rice bran, talc powder, rice straw, banana leaf, arecanut leaf, coconut leaf, neem cake and vermicompost with 48.12 × 10, 44.5 × 10, 39.00 × 10, 29.00 × 10, 21.4 × 10, 18.2 × 10, 15.5 × 10 and 10.45 × 10 cfu g, respectively. Nevertheless, up to 90 days of observation, significantly superior growth (39.1 × 10 cfu g) was noticed on cowdung in comparison to other substrates.


INTRODUCTION
Out of various strategies for management of diseases, chemicals have been so far found to be most dominating.Although this has resulted in increase in production of agricultural commodities but there is deleterious effects of chemical pesticides on crop ecosystems.Increase in public awareness about these problems, has stimulated research on biocontrol agents.Also, biological control of plant diseases has got momentum as it offers many advantages over the conventional methods of control (Mukhopadhyay, 1994).Among the biocontrol agents, Trichoderma spp.have shown exceptionally good promise in the management of a wide range of plant pathogens (Cook and Baker, 1983) and are acclaimed as effective, eco-friendly and cheap, nullifying the ill effects of chemicals.However, it is also known that these biocontrol agents should be native for their good efficacy against their target pathogens.But the utilization of these bioagents has been hampered mainly because of nonavailability of effective methods of mass production technology.Different workers have used different substrates such as composted coir pith, coffee (Rukmani and Mariappan, 1993), coffee wastes and poultry manures (Sawant et al., 1995), neem cake, coir pith, farmyard manure (FYM), and decomposed coffee pulp (Saju et al., 2002), well-decomposed FYM, dried cowdung, gobar gas slurry (GGS), sorghum grain floor, 0.15 0.17 0.17 0.17 0.17 0.17 wheat bran, groundnut shell, molasses, saw dust, wheatstraw, mushroom bed straw, neem cake, peat soil, fly ash and talc (Sangle and Bambawale 2005), cowdung, neem cake, coir pith, sorghum grain, saw dust, and rice bran (Rini and Sulochana, 2007), vegetable wastes, fruit wastes, crop wastes, FYM and poultry manure (Simon, 2011), vegetable waste, fruit juice waste, sugarcane baggase, rotten wheat grains (Babu and Pallavi, 2013) for mass production of Trichoderma spp.The present study was therefore carried out to identify a suitable, cheaper and locally available substrate for mass multiplication of Trichoderma viride.

MATERIALS AND METHODS
The trial was conducted in the laboratory of Central Plantation Crops Research Institute, Research Centre, Kahikuchi, Guwahati.Nine substrates viz., arecanut leaf, banana leaf, coconut leaf, cowdung, rice bran, rice straw, neem cake, vermicompost and talc powder were evaluated for mass multiplication of T. viride using the procedure of Kousalya et al. (1990).Rice straw, arecanut, coconut and banana leaves were chopped into small bits (2 to 3 cm) and then pre-soaked for overnight as per the procedure of Kousalya et al. (1990).The treatments were maintained following a completely randomized block design with 20 numbers of packets for each treatment for 3 months.After incubation, the samples were drawn and population of T. viride was enumerated in Trichoderma selective medium (Elad and Chet, 1983).Colony forming units (cfu 10 8 /g) were estimated by dilution plate technique (Pramer and Schimidt, 1956) after every 15 days interval and the data was analyzed statistically.The study was conducted during the period from June to August for 2 years (2011 and 2012).

RESULTS AND DISCUSSION
The growth of T. viride on different substrates is enumerated in the Table 1.Sporulation was observed after 5 days of incubation in cowdung as compared to 7 days after incubation, in all other substrates.Maximum sporulation (51.50 × 10 8 cfu g -1 ) was observed in cowdung on 15 th day, which was followed by rice bran (48.12 × 10 8 cfu g -1 ).The result is in consistent with the findings of Saju et.al. (2002).Other substrates in order of merit were; by talc powder, rice straw, banana leaf, arecanut leaf, coconut leaf, neem cake and vermicompost with 44.5 × 10 8 , 39.00 × 10 8 , 29.00 × 10 8 , 21.4 × 10 8 , 18.2 × 10 8 , 15.5 × 10 8 and 10.45 × 10 8 cfu g -1 , respectively.A significant difference was observed among all the substrates tried throughout the experiment period that is, starting from 15 to 90 days of incubation.The enhanced effect of cowdung might be due to the supplementation of NPK and other nutrients to the substrate.FYM was reported to be an effective substrate for growth and multiplication of both Trichoderma harzianum and T. viride (Kousalya and Jeyarajan, 1988).Sethuraman (1991) reported that the increase in Trichoderma population was due to application of organic amendments viz., rice bran and FYM in soil.Nevertheless, up to 90 days of observation, significantly superior growth (39.1 × 10 8 cfu g -1 ) was noticed on cowdung followed by rice bran (35.2 × 10 8 cfu g -1 ), talc powder (34.7 × 10 8 cfu g -1 ) and rice straw (25.4 × 10 8 cfu g -1 ).Vermicompost recorded continually lower population as compared to other substrates (Table 1).The study also indicated that there is decreasing trend of population of T. viride.The decrease in population of T. viride was observed after 15 days onwards.In all the substrates, invariably, there was a reduction in the population at 90 days after incubation from initial level, which ranged between 22.02% in talc powder to 59.89% in coconut leaf.
The result of study indicated that the locally available substrates viz., cowdung, rice bran, rice straw, banana leaf and arecanut leaf has got immense potential for growth and sporulation of the antagonistic fungi, T. viride,

Table 1 .
Effect of different substrates on the population of Trichoderma viride.