Role of microorganisms in bio-control and biofertilizers

Introduction

As the traditional farming methods are becoming a threat to the environment, more and more biological farming techniques are making their way into the modern agriculture. From the past 2decades, as the organic farming is gaining its traction, bio-control is becoming more and more popular. Biocontrol uses biological weapons instead of chemical fertilizers and weedicide sprays. This helps us to keep the environment and health of the consumers in check as many biocontrol mechanisms have a few adverse effects when compared to the conventional farming a. In a biocontrol mechanism, disease-causing microbes are killed by natural predators, for example, many birds are used against insects. Furthermore, biocontrol saves a lot of money being spent in the large-scale insecticide sprays. This article delineates in detail about methods of biocontrol farming and their usage in the modern farming.

 

Microbes as Biocontrol Agents

A number of biocontrol agents are being used depending upon the nature of the disease-causing agent. The use of ladybird and dragonflies help farmers to keep a check against aphids and mosquitoes in many crops. Another example is the Bacillus thuringiensis, experimented against the butterfly caterpillars in a farmland. It is sold in sachets in the form of dried spores. The dried spores can be mixed with water and sprayed over the vulnerable plants like brassicas and fruit trees. The spray must be allowed to dry off and let it stay for 2 hours so in order to kill the insects. The strain of Rhizobium soil bacterium has proved reliable in developing the resistance against root-knot nematode in tomato plants. Caudovirales- a viral colony have effectively controlled columns of salmonella in wastewater. Caudovirales are bacteriophages aid in attacking the salmonella and destroy colonies of the pathogen. Fluorescent pseudomonads have helped to discourage the growth of virulent bacteria in the root system of many plants. Beauveria bassiana is a fungus proved its ability to control malaria-causing mosquito populations. The fungus kills the mosquito larvae.

 

Microbes as biofertilizers

As the plant diseases are showing resistance against the chemical sprays, biofertilizers have slowly evolved to replace the fertilizers. As well know that the consumption of the crops sprayed by chemicals harm the human body systems, biofertilizers have proved to be good alternatives. Biofertilizers boost the plant`s ability to absorb more water and minerals, and they. Biofertilizers are combined with seeds so that they enter into the rhizosphere ( root system) at the time of sowing the seeds.  The artificially multiplied strains of selected combinations of biofertilizers play an essential role in accelerating the microbial processes in soil. Biofertilizers are a cost-effective and renewable source of plant nutrients that replace the chemical fertilizers. Many microbes and their association with crop plants are being exploited in the production of biofertilizers. Some of the biofertilizers and their functional abilities are as follows

 

   Nitrogen-fixing Bio fertilisers

Sl no                   

Groups

Examples

1.

Free-living

Azotobacter, Beijerinkia, Clostridium, Klebsiella, Anabaena, Nostoc, 

2.

Symbiotic

Rhizobium, Frankia, Anabaena azollae

3.

Associative Symbiotic

Azospirillum

 

 Phosphorus  Solubilizing Bio fertilisers

Sl no

Groups

Examples

1.

Bacteria

Bacillus megaterium var. phosphaticum, Bacillus subtilis
Bacillus circulans, Pseudomonas striata

2.

Fungi

Penicillium sp, Aspergillus awamori

 

​​​​​​Phosphorus mobilizers​

Sl          no

Groups

Examples

1.

Arbuscular mycorrhiza

Glomus sp., Gigaspora sp., Acaulospora sp., 
Scutellospora sp. & Sclerocystis sp.

2.

Ectomycorrhiza

Laccaria sp., Pisolithus sp., Boletus sp., Amanita sp.

3.

Ericoid mycorrhizae

Pezizella ericae

4.

Orchid mycorrhiza

Rhizoctonia solani

 

Bio fertilisers as Micronutrients

Sl no

Groups

Examples

1.

Silicate and Zinc solubilizers

Bacillus sp.

 

Growth Promoting Rhizobacteria

Sl no

Groups

Examples

1.

Pseudomonas

Pseudomonas fluorescens

 



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