B. C. Das ¹, B. K. Das ¹, Pranab Dutta ¹, D. K. Sarmah ¹

Affiliations
1 Department of Plant Pathology, Assam Agricultural University, Jorhat, 785 013, Assam, IN

Abstract

In vitro osmoticant (manitol) amended and osmoticant free media of potato dextrose broth (PDB), modified Richard's broth (MRB) and Czapek dox broth (CDB) were tested for biomass production of Trichoderma harzianum Rifai. Osmoticant amended MRB was found best for production of maximum sporulation, cfu and dry weight of biomass of the antagonist, Osmoticant amended media produced higher biomass of T. harzianum than osmoticant free media. Growth and sporulation of T. harzianum was assessed in different carrier viz. starch, talc and molasses enriched charcoal powder (MECP) based formulation. Starch and MECP based formulation of T. harzianum showed increased trend in sporulation of the antagonist upto 60 days, but after this, viability of T. harzianum was abruptly decreased. Talc based formulation-exhibited gradual declining trend in multiplication and sporulation of T. harzianum after 30 days onwards. Among the nine formulation evaluated for growth and sporulation, starch based formulation alone performed best upto 60 days, followed by MECP based formulation. But after 60 days onwards, talc based formulation @ 3: 1 dose showed highest sporulation and maximum cfu, followed by starch formulation @ 1: 1 dose. The overall performance of talc-based formulation was better for growth and sporulation of the antagonist. Potentiality of T. harzianum as seed treatment with talc based T. harzianum and chemical were assessed field condition against Rhizoctonia solani causing stem rot disease of soybean. Lowest disease index and highest % seed germination was observed when seeds were treated with formulation of T. harzianum + talc + osmoticant formulation with enhanced plant vigour and yield of the crop.

Keywords

Biomass, Osmoticant, Rhizoctonia solani, Soybean, Stem Rot, Trichoderma harzianum.

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S. Mech ¹, B. C. Das ¹, D. K. Sarmah ¹

Affiliations
1 Assam Agricultural University, Jorhat 785013, Assam, IN

Abstract

In the present investigation, carbendazim tolerance in Trichorderma harzianum was induced by exposing the culture to UV radiation for different periods (viz. 0, 2, 4, 6 and 8 h) and then the same were grown in PDA amended with different concentration of carbendazim viz. 0.01, 0.05, 0.1 and 1.0 per cent, respectively. In each concentration, colonies developed after 5 days were isolated, purified with serial dilution and sub-cultured thrice on PDA without carbendazim and tested their stability. These resulted in the development of 18 stable mutants, which could tolerate up to 0,1 per cent of carbendazim while wild T. harzianum (Th-w) failed to tolerate the same. Based on radial growth of above 18 stable mutants grown on fungicide free PDA, only three stable mutants were selected, which were designed as Th-M₁, Th-M₂ and Th-M₃, In vitro antagonistic activities of these three mutants tested against Sclerotinia sclerotiorum, the causal agent of white mold of French bean on PDA showed maximum reduction of radial growth of pathogen by Th-M₂ In another test, all the mutants arrested sclerotial production of S. sclerotiorum, significantly. However, the mutant Th-M₂ showed maximum reduction when it was inoculated seven days prior to inoculation with S. sclerotiorum in MSM (4%) as compared to wild T. harzianum (Th-w).

Keywords

Carbendazim, Mutant, Sclerotinia sclerotiorum, T. harzianum, UV Radiation, White Mold.

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K. C. Puzari ¹, D. K. Sarmah ¹, L. K. Hazarika ²

Affiliations
1 Mycology Research Section, Assam Agricultural University, Jorhat 785 013, Assam, IN
2 Department of Entomology, Assam Agricultural University, Jorhat, IN

Abstract

A medium was developed with rice hull, saw dust and rice bran at a ratio of 75:25:100, respectively, to mass culture Beauveria bassiana (Balsamo) Vuillemin, a potential biocoritrol agent against the rice hispa, Dicladispa armigera (Olivier) (Coleoptera:Chrysomelidae). It produced 39.33 × 10⁷ conidia/ml of water 24 days after inoculation. The mortality of the adult could be achieved up to 78.6 per cent at spray concentration of 106 spores/ml of water.

Keywords

Beauveria bassiana, Dicladispa armigera, Rice Hull, Rice Bran, Saw Dust.

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