Root knot nematode, Meloidogyne incognita, is an important nematode parasite of tuberose. A study was undertaken to assess the evaluation of plant growth promoting rhizobacteria (PGPR) against Meloidogyne incognita infestation on tuberose in vitro, pot culture and field conditions.
Tuberose fields were surveyed for the nematode incidence in different districts of Tamil Nadu. Among the nematodes associated with the crop M. incognita caused severe damage to crop.
Plant growth promoting rhizobacteria were isolated from soil samples collected from field and subcultured for further studies. The isolates were tested for their efficacy for plant growth promotion by roll towel and pot culture studies with rice plants. Among them, three isolates, viz. BT3, BT8 and BT21 were found to be effective in increasing the plant growth promotion when compared to other isolates.
Biochemical characterization of the isolates revealed that the cultures were found to be the group of Bacillus spp. Liquid formulation were prepared for the three isolates with nutrient amendments, viz. glycerol (10 Mm), trehalose (5 mM) and the stickers, viz. starch (2%) and PVP (2%) and the antagonistic effect of different Bacillus isolates were studied against M. incognita in vitro. Effect of liquid formulation of the Bacillus strains were tested against M. incognita under greenhouse and field condition. Histopathological studies were carried out for the B. subtilis treated and untreated plants.
Table of Contents
I Introduction
II PGPR in nematode management
III Diversity of Bacillus
IV Biocontrol potential of Bacillus on nematodes
V Isolation and characterization of Bacillus subtilis
VI Bacillus subtilis in nematode management
VII Overview
Research Objectives and Key Themes
The primary objective of this study is to assess the efficacy of liquid bioformulations of native antagonistic Bacillus subtilis strains against the root knot nematode Meloidogyne incognita in tuberose (Polianthes tuberosa L.) crops. The research explores the isolation of native Bacillus from diverse geographical locations in Tamil Nadu, characterizes their biocontrol potential, and evaluates their role in plant growth promotion and the induction of systemic resistance in infected plants.
- Isolation and identification of native Bacillus strains from rhizosphere soil samples.
- In vitro efficacy testing of Bacillus culture filtrates against nematode egg hatching and juvenile mortality.
- Evaluation of liquid formulations on plant growth, yield, and nematode management under pot and field conditions.
- Analysis of histopathological changes in tuberose roots and induction of defense-related enzymes (Peroxidase, Polyphenol oxidase, PAL) following bacterial application.
Excerpt from the Book
Introduction
Floriculture is a fast emerging venture throughout the world and is recognized as a lucrative profession with higher potential for returns per unit area. In India, 1,91,000 ha are under cultivation of flower crops (2010- 2011) with the production of 7000 millions of cut flowers and 10.40 lakh metric tons of loose flowers and 7000 million cut flowers (NHB Database 2011).
Among the important ornamental bulbous plants grown in India, tuberose (Polianthes tuberosa L.) occupies a prime position due to its popularity and economic potential as a cut flower, loose flower and its potential in perfume industry. Tuberose belongs to the family Amaryllidaceae and is native of Mexico. Among the single flowered types, Calcutta single variety is extensively used as loose flower and for extraction of essential oil. Prajwal, a cross between Shringar and Mexican single cultivar is used as cut flower. Among the double flowered types, Calcutta double is preferred as cut flower, loose flower and also for oil extraction. Abiotic and biotic stress play a major role which affect the yield. Among abiotic factors, temperature is the most important one affecting growth, flower initiation and subsequently flower and bud development. Optimum temperature range for growth and development of tuberose is 20-30 °C (Sadhu and Bose, 1973).
Among the biotic stresses, nematodes are one of the major limiting factors reducing the yield of the crop both in quantity and quality. Most of the growers of tuberose are not aware of the menace since the nematodes are unseen enemies. The crop harbours many nematode pests, viz., root knot, spiral, reniform, lance and stunt nematodes. Monoculture of the crop increases the population of nematode fauna. The technologies such as cropping system approach, new fertilizer regime and irrigation schedule generally provide a congineal environment for the preponderance of the nematode species. Among the nematodes, root knot nematode, Meloidogyne incognita is the key nematode pest of the crop which causes serious damage and affects the flower yield of the crop. Root knot nematodes, viz. M. incognita, M. javanica and M. arenaria have been considered as the major limiting factors in the successful cultivation of
Summary of Chapters
I Introduction: Provides an overview of the tuberose industry, the economic importance of the crop, and the significant threat posed by nematodes like Meloidogyne incognita.
II PGPR in nematode management: Reviews the role of Plant Growth Promoting Rhizobacteria (PGPR) and their mechanisms in biological control and sustainable agriculture.
III Diversity of Bacillus: Discusses the genus Bacillus, its biological characteristics, endospore formation, and its distribution in natural environments.
IV Biocontrol potential of Bacillus on nematodes: Examines various Bacillus strains and their reported nematicidal activities, focusing on extracellular toxins and antibiotics.
V Isolation and characterization of Bacillus subtilis: Details the methodologies used for surveying, isolating, and molecularly confirming the identity of native Bacillus strains from field samples.
VI Bacillus subtilis in nematode management: Presents findings from in vitro, pot culture, and field experiments regarding the efficacy of liquid formulations in managing nematode populations and enhancing plant growth.
VII Overview: Summarizes the major research findings and provides concluding remarks on the practical application of B. subtilis for integrated nematode management.
Keywords
Bacillus subtilis, Meloidogyne incognita, Tuberose, Nematode management, PGPR, Biological control, Liquid formulation, Systemic resistance, Peroxidase, Polyphenol oxidase, Phenylalanine ammonia lyase, Rhizosphere, Crop yield, Sustainable agriculture, Nematicidal activity.
Frequently Asked Questions
What is the primary focus of this research?
The research focuses on utilizing native Bacillus subtilis as a biological control agent to manage Meloidogyne incognita (root knot nematode) in tuberose crops.
What are the central thematic areas?
The work covers isolation of beneficial bacteria, characterization of their nematicidal properties, development of shelf-stable liquid formulations, and assessment of plant-microbe interactions.
What is the research's main objective?
The primary goal is to provide an eco-friendly and economically viable alternative to chemical nematicides for tuberose growers in Tamil Nadu.
Which scientific methods are employed?
The study utilizes random soil surveys, microbial isolation and biochemical characterization, PCR-based molecular identification, in vitro screening, and randomized pot/field trials to measure plant parameters.
What does the main content cover?
The chapters detail the isolation processes, the efficacy of specific bacterial strains (BT3, BT8, BT21), and the biochemical analysis of plant defense responses like enzyme induction and phenol accumulation.
What keywords characterize the work?
Key terms include Bacillus subtilis, Meloidogyne incognita, biocontrol, liquid formulation, PGPR, and systemic resistance.
Which strain of Bacillus showed the most significant results?
The strain BT3 demonstrated the highest efficacy in suppressing nematode populations and promoting plant growth across the various tests conducted.
What are the advantages of liquid formulations mentioned?
Liquid formulations offer higher cell counts, zero contamination, increased shelf life, and better protection against environmental stresses compared to traditional carrier-based methods.
How does the treatment affect the plant's defense system?
Application of the bacterial isolates significantly induced defense-related enzymes, specifically peroxidase, polyphenol oxidase, and phenylalanine ammonia lyase, enhancing the plant's natural resistance.
- Arbeit zitieren
- V. Veerasakthi (Autor:in), Sankari Meena (Autor:in), SA. Ramyabharathi (Autor:in), N. Ardhanareeswaran (Autor:in), E. I. Jonathan (Autor:in), 2014, Bacillus subtilis. A bioagent in nematode management, München, GRIN Verlag, https://www.grin.com/document/284615
