Improvement ofTrichodermaspp. Strain for Integrated Control of Soilborne Plant Pathogens

Fusarium udum, Fusarium oxysporum f. sp. ciceri and F.oxysporum f.sp.lentis cause severe economic loss to pigeonpea, chickpea and lentil crops. Forty three isolates of Trichoderma were screened for their antagonistic ability against the test pathogens. Potent strains were identified on the basis of in vitro antagonistic ability and fungicide tolerant capability. They were subjected for mutagenesis using NTG for improvement of their antagonistic potential. Two stable mutants who exhibited enhanced bioefficacy against the soilborne fungi and tolerated carbendazim and copper sulphate were subjected for protoplast fusion in order to achieve superior strain. Protoplasts were obtained from the mutants with novozyme 234 and were fused in the presence of PEG and hybrids were isolated on selective medium. Selected fast growing stable fusants were tested for fungicide tolerant capability and bioefficacy in dual culture experiments. The fusant TPTF3 exerted high degree of antagonistic ability in controlling the radial growth of test pathogens which was between 90–94% and also tolerated carbendazim and copper sulphate up to 125 μm and 120mM respectively. The fusant strain produced higher level of chitinase and â-1, 3 glucanase as compared to the mutants and wild type parent strains. Hence, in present study, superior strain with broad spectrum distinct antagonistic and fungicide tolerant abilities was developed which could be used in IPM programme for the control of soilborne diseases of pulse crops.