B. Sreedevi ¹, M. Charitha Devi ¹, D. V. R. Saigopal ¹

Affiliations
1 Department of Virology, Sri Venkateswara University, Tirupati 517 502, Andhra Pradesh, IN

Abstract

Antagonistic activity of Trichoderma harzianum isolated from the rhizosphere of groundnut was determined in vitro. T. harzianum decreased the ischolar_main rot incidence in vivo. Potential of T. harzianum to induce systemic resistance was tested in groundnut against Macrophomina phaseolina. Biochemical changes in T. harzianum treated plants, M. phaseolina inoculated plants and healthy plants were assayed at different stages of infection. Treatment with T. harzianum and challenge inoculation of M. phaseolina enhanced induction of defense enzymes such as peroxidase (PO) and polyphenol oxidase (PPO) and defense compounds like total phenol and ortho-dihydric phenol. Total phenols, ortho-dihydric phenols, peroxidase and polyphenol oxidase activities increased at different stages of infection. T. harizanum treatment along with challenge inoculation of the pathogen significantly increased the activity of peroxidase and polyphenol oxidase by about 28.2 % and 95.5%, respectively, in ischolar_mains at stage 2 compared to untreated plants. Increased levels of peroxidase and polyphenol oxidase were induced in ischolar_main and shoot of treated plants indicating the systemic protection offered to groundnut by T. harzianum. The observations revealed that T. harzianum was capable of inducing systemic resistance against M. phaseolina by eliciting the production of defense enzymes.

Keywords

Trichoderma harzianum, Macrophomina phaseolina,Total Phenols, Ortho-Dihydric Phenols, Peroxidase, Polyphenol Oxidase, Induced Systemic Resistance (ISR).

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M. Charitha Devi ¹, R. D. Prasad ²

Affiliations
1 Department of Virology, Sri Venkateswara University, Tirupati 517502, Andhra Pradesh, IN
2 Directorate of Oilseeds Research, Rajendranagar, Hyderabad 500030, Andhra Pradesh, IN

Abstract

The collor rot incidence in groundnut was reduced by the application of Trichoderma viride as seed treatment along with fungicides. In vitro studies of fungal and bacterial antagonists, viz., Trichoderma spp. and Pseudomonas fluorescens indicated that T. viride was more effective in inhibiting the pathogen A. niger. In pot culture experiment, the combined effect of seed treatment with T. viride and captan resulted in significant reduction of collor rot. Combination of antagonist and fungicide also improved the growth parameters like length of the plant, biomass and yield besides decreasing the disease incidence. Biointensive disease management of collar rot is not only effective but also economical.

Keywords

Aspergillus niger, Biocontrol Agents, Collar Rot, Fungicides and Groundnut.

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M. N. Reddy ¹, M. Charitha Devi ¹, N. V. Sreedevi ¹

Affiliations
1 Department of Applied Microbiology S.P. Mahila Visvavidyalayam Tirupati 517502, Andhra Pradesh, IN

Abstract

Disease suppressive role of the antagonistic microorganisms, Trichoderma harzianum, Trichoderma virens and VAM fungus against rhizome rot of turmeric (Curcuma longa L.) caused by Fusarium solani was established in both pot culture and field studies. VAM treated plants in the infested soil showed reduced disease incidence as compared to F. solani alone treated plants. Trichoderma and Gliocladium treatment resulted in less disease incidence as compared to VAM treated plants. Among the three-biocontrol agents tested, T. harzianum was found to be the most effective in disease control as compared to others. Plants treated with biocontrol agents were healthy with enhanced biomass and also yield to varied extents.

Keywords

Biological Control, F. solani, Rhizome Rot, Turmeric.

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