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Indian Journal of Nematology
Year : 2014, Volume : 44, Issue : 1
First page : ( 1) Last page : ( 5)
Print ISSN : 0303-6960. Online ISSN : 0974-4444.

Biochemical Mechanism of Biocontrol Agents in the Management of Citrus Nematode, Tylenchulus semipenetrans on Lemon, Citrus limonia L.

Deepa S.P.*, Subramanian S., Ramakrishnan S.

Department of Nematology, Centre for Plant Protection Studies, Tamil Nadu Agricultural University, Coimbatore-641 003. Tamil Nadu, India

*Corresponding author, E-mail: deepaaarthi@rediffmail.com

Online published on 18 October, 2014.

Abstract

In the field experiment conducted for the biomanagement of citrus nematode Tylenchulus semipenetrans on 9 year old citrus trees, observations were made for the induction of defence enzymes activity. The plant samples were collected at 7, 15 and 45th day after the inoculation (DAI) of test bioagents viz., Pseudomonas fluorescens, Trichoderma viride, T. harzianum and Pochonia chlamydosporia and assayed for Peroxidase (PO), Polyphenol oxidase (PPO), Phenylalanine ammonia lyase (PAL) and Phenols using standard procedure. The analysis of samples revealed that there was significant increase in the enzymatic activity of PO, PPO PAL and Phenols at 7th day after inoculation and found to be decreased or fluctuated steadily at 15 and 45 DAI in all the bioagents inoculated plant samples. Among them P. fluorescens registered highest enzymatic activities of PO (131.76%), PPO (35.21%), PAL (174.39%) and Phenols (156.33%) compared to other bioagents at 7th day after treatment which is found to be the most effective for the management of citrus root nematode. Nematode population was also found to decrease with respect to the induction of defence enzymes. Minimum nematode population was observed on 7th day (200 J2s/250 cc soil) and maximum population was observed on 45th day (250.62 J2s/250 cc soil) after application of P. flourescens when compared to other bioagents treatment. Therefore, the study concludes that the biochemical changes induced by P. fluorescens could be one of the mechanism in the biomanagement of T. semipenetrans.

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Keywords

Biochemical enzymes, biocontrol agents, Citrus limonia L, Tylenchulus semipenetrans.

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