Journal of Environmental Biology

Antifungal properties of native Trichoderma isolates against Sclerotium rolfsii and Pythium aphanidermatum infecting tobacco

K.L.N. Mallikharjuna Rao¹, K. Siva Raju²* and H. Ravisankar²

¹AKRG College of Pharmacy, Nallajarla, West Godavari-534 112, India

²AKMU, Central Tobacco Research Institute, Rajahmundry-533 105, India

*Corresponding Author E-mail: rajuks2002@yahoo.co.in

Publication Data

Paper received:

18 June 2014

Revised received:

21 November 2014

Re-revised received:

05 February 2015

Accepted:

20 March 2015

Abstract

Isolates of Trichoderma native to tobacco rhizosphere, were evaluated for their antifungal properties? against Sclerotium rolfsii and Pythium aphanidermatum, fungal pathogens causing collar rot and damping off diseases in tobacco. Isolate TvJt1 showed maximum HCN production (0.14 OD) followed by ThHt1 and minimum by isolates ThJnt and ThRt1 (0.08 and 0.09 OD). Indole acetic acid (IAA) production among the isolates varied from 6.48 to 14. 82 ?g ml^-1. Isolate ThJO1 produced maximum siderophore (13.48 m mol ml^-1), whereas isolate TvJt1 produced minimum content (6.24 m mol ml^-1). Isolate ThJt1 showed maximum and significantly higher chitinase activity (62.12 p kat ml^-1) as compared to other isolates, followed by isolate TvHt2. Isolate TvHt2 showed maximum and significantly higher β-1, 3-glucanase activity (9.94 n kat ml-1) when compared? to all other isolates. Isolate ThJt1 showed second highest activity of β-1, 3-glucanase (6.75 n kat/ml). In dual culture, inhibition of mycelial growth of Pythium by isolate TvHt2 was maximum (72.45%) followed by ThJt1 whereas inhibition of mycelial growth of S. rolfsii by these two isolates was at a par (78.36% and 76.17%) and significantly higher than some isolates. Isolates TvHt2 and ThJt1 showed maximum and significantly higher inhibition of Pythium and Sclerotium growth (80.24% and 76%) by production of non-volatiles. Inhibition of Pythium and Sclerotium growth by production of volatile compounds by Trichoderma isolates ranged from 54.36 to 72.6% and 66.24 to 84.24% respectively.? Hence, further investigation with potential isolates ThJt1 and TvHt2 in tobacco nursery may help to explore these bioagents for control of collar rot and damping off diseases in tobacco. ?????  

 Key words

Antifungal properties, Fungal pathogens, Tobacco rhizosphere, Trichoderma isolates 

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