STUDY OF BIOFILMED BIOFERTILIZERS TO IMPROVE CROP PRODUCTION AND DISEASE CONTROL IN CHICKPEA

The experiment was conducted during 2013-14 at Department of Agricultural Microbiology and Bioenergy, College of Agriculture, Rajendranagar, ANGRAU, Hyderabad. A biofilm is an aggregate of microorganisms in which cells are stuck to each other and/or to biotic/abiotic surface. These adherent cells are frequently embedded within a selfproduced matrix of Extracellular Polymeric Substance (EPS) is a polymeric jumble of DNA, proteins and polysaccharides. The high population density achieved in biofilms provides the opportunity to perform enhanced biochemical reactions than that of single isolates. Our work was aimed towards the development of biofilms under in vitro conditions, using a combination of agriculturally important potential microorganisms like Bacillus subtilis, Pseudomonas flourescens and Rhizobium leguminosarum with the fungus Trichoderma viride as the matrix. These biofilms were evaluated for their disease management and crop production in chickpea. Optimization of conditions for in vitro development of biofilms involved by determining their population load, biomass, specific growth media and cultural conditions. The biochemical traits of novel Trichoderma based biofilms revealed that PGP traits like phosphorus solubilization, ammonia production, IAA production, protein estimation, HCN production, siderophore production and an enhanced antifungal activity against Fusarium oxysporum, as compared to individual or dual cultures. A field experiment entitled “Study of biofilmed biofertilizers to improve crop production and disease control in chick pea” was conducted during rabi, 2013-14 at College farm, College of Agriculture, Rajendranagar, Hyderabad. The experiment comprised of 9 treatments namely T1 100 % RDF, T2 Trichoderma viride + Rhizobium leguminosarum (Biofilm), T3 Trichoderma viride + Bacillus subtilis (Biofilm) T4, Trichoderma viride + Pseudomonas fluorescence (Biofilm), T5 Trichoderma viride + Rhizobium leguminosarum (Co-inoculation), T6 Trichoderma viride + Bacillus subtilis (Co-inoculation), T7 Trichoderma viride + Pseudomonas fluorescence (Co-inoculation) T8 Trichoderma viride + Rhizobium leguminosarum + Pseudomonas fluorescence+ Bacillus subtilis (Biofilm), T9 Trichoderma viride + Rhizobium leguminosarum + Pseudomonas fluorescence+ Bacillus subtilis (Coinoculation). Results revealed that biofilmed treatments significantly improved plant growth parameters, biomass in soil, germination percentage, yield attributes like number of pods per plant, test weight, seed yield (kg ha). The nutrient content in the shoot of chickpea was also recorded high in biofilm inoculated plants rather than dual cultures and uninoculated plots. In addition, the disease supression against Fusarium oxysporum was seen higher in T8 Trichoderma viride + Rhizobium leguminosarum + Pseudomonas fluorescence+ Bacillus subtilis (Biofilm) with only 1.1% mortality rate. Persistence of biofilms in soils was studied under pot culture. Initial microbial counts were taken before inoculation of biofilms in soil. Microbial populations of both bacteria and fungal partners were recorded at three interval i.e 30, 60 and 90 day after incubation and revealed there is a decrease in population count of both fungi and bacteria. This study illustrates that the biofilms under field conditions, which exhibit multiple PGPR traits, indicative of synergistic interactions among the partners and also for integrated nutrient and disease management strategies in agriculture.