Rhizospheric microbes directly or indirectly influence the plant productivity as
their richness in the below ground is the indicator of above-ground wellness in
various environmental conditions. The production of antibiotic compounds bound to
have effect on pathogenic microbes, defence against protozoa, motility, and biofilm
formation.
Several interesting metabolites were produced by these rhizospheric microorganisms such as volatile organic compounds (VOCs) that alter and modulate the crop
growth and involved in signalling process. They help in the long-distance communication because of its high vapour pressure and small in size that diffused through
water and soil pores. These volatiles also proved to arrest the growth of fungal plant
pathogens.
Several research works have been carried out in the rhizosphere that gives a clear
picture and better understanding of the rhizospheric microbes that avid the research
interests of many scientists. The root exudates influence the root zone by changing
the oxidation reduction potential, enhancing the availability of moisture and nutrients, providing better niche for the growth of PGPR organisms, producing antibiotics, other secondary metabolites and growth regulators, microbial interactions,
sheltering the microsymbionts, model system for the study of soil-rhizosphere
biology, drought, avoiding soil erosion, etc.
Science always have two schools of thoughts, crop plants may alter and choose
the microbes needed in the rhizosphere for its own benefit and yield while the other
researches stated that root exudates are kind of products that overflow out of roots,
and further research has to answer postulations.
For growth and reproduction, microbes need water, nutrients, and space that is
enormously available in the rhizospheric region and well utilized for doubling its
population to a greater extent. The primary and the first speech of signals were
exchanged when the seeds start its germination and the seedlings put forth root and
shoot. The developing plant interacts with a wide array of microbes present nearby
and invites through the release of organic materials that act as a driving force for the
development and active growth of microbes. Once after the release of these organic
materials by the root the compounds present in the root were subjected to microbial
attack and make it difficult to separate from the roots. The efficiency of this
exudation is governed by various factors such as nutrient deficiency, temperature,
soil type, light intensity, soil pH, microbial existence, plant species and its developmental stage, etc. (Singh et al. 2006). Even though the rhizosphere is abundant with
all types of nutrients there, the presence and dominance of the individual organism
fluctuate to prove the concept of survival of the fittest. The effect of the root exudates
travels to a certain distance as far as the diffusion and the distribution pattern spreads.
Studies of molecular fingerprints in different root zones showed that the community
composition altered in rhizoplane, emerging roots even in root tips, lateral roots,
older roots, etc.
Alterations in the rhizosphere due to depletion of nutrients cause tidal waves in
the existing population and death, and lysis of bacterial cells occurs. The exponential
growth occurs by the release of nutrients via decay of tissues and cells. Saprophytes
flourish in the rhizospheric soil and do the vital processes of decomposition of
4
M. Gomathy et al.
their richness in the below ground is the indicator of above-ground wellness in
various environmental conditions. The production of antibiotic compounds bound to
have effect on pathogenic microbes, defence against protozoa, motility, and biofilm
formation.
Several interesting metabolites were produced by these rhizospheric microorganisms such as volatile organic compounds (VOCs) that alter and modulate the crop
growth and involved in signalling process. They help in the long-distance communication because of its high vapour pressure and small in size that diffused through
water and soil pores. These volatiles also proved to arrest the growth of fungal plant
pathogens.
Several research works have been carried out in the rhizosphere that gives a clear
picture and better understanding of the rhizospheric microbes that avid the research
interests of many scientists. The root exudates influence the root zone by changing
the oxidation reduction potential, enhancing the availability of moisture and nutrients, providing better niche for the growth of PGPR organisms, producing antibiotics, other secondary metabolites and growth regulators, microbial interactions,
sheltering the microsymbionts, model system for the study of soil-rhizosphere
biology, drought, avoiding soil erosion, etc.
Science always have two schools of thoughts, crop plants may alter and choose
the microbes needed in the rhizosphere for its own benefit and yield while the other
researches stated that root exudates are kind of products that overflow out of roots,
and further research has to answer postulations.
For growth and reproduction, microbes need water, nutrients, and space that is
enormously available in the rhizospheric region and well utilized for doubling its
population to a greater extent. The primary and the first speech of signals were
exchanged when the seeds start its germination and the seedlings put forth root and
shoot. The developing plant interacts with a wide array of microbes present nearby
and invites through the release of organic materials that act as a driving force for the
development and active growth of microbes. Once after the release of these organic
materials by the root the compounds present in the root were subjected to microbial
attack and make it difficult to separate from the roots. The efficiency of this
exudation is governed by various factors such as nutrient deficiency, temperature,
soil type, light intensity, soil pH, microbial existence, plant species and its developmental stage, etc. (Singh et al. 2006). Even though the rhizosphere is abundant with
all types of nutrients there, the presence and dominance of the individual organism
fluctuate to prove the concept of survival of the fittest. The effect of the root exudates
travels to a certain distance as far as the diffusion and the distribution pattern spreads.
Studies of molecular fingerprints in different root zones showed that the community
composition altered in rhizoplane, emerging roots even in root tips, lateral roots,
older roots, etc.
Alterations in the rhizosphere due to depletion of nutrients cause tidal waves in
the existing population and death, and lysis of bacterial cells occurs. The exponential
growth occurs by the release of nutrients via decay of tissues and cells. Saprophytes
flourish in the rhizospheric soil and do the vital processes of decomposition of
4
M. Gomathy et al.