root zone by changing the oxidation reduction potential, enhancing the availability
of moisture and nutrients, providing better niche for the growth of plant growth
promoting 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. Exploring these rhizospheric microorganisms by unravelling their possible
relationships with plants has launched a new and fascinating area of investigations
in the rhizosphere research. Moreover, the rhizospheric microbes are considered as
bioindicators of soil quality that are affected by much of the pollutant that makes the
soil infertile. Rhizosphere region that harbours abundant microbes can remediate the
polluted soils in a much greener way. Microorganisms and their metabolites like
enzymes were involved in bioremediation process. Hence, bioremediation is a much
auspicious method to overwhelm the pesticide pollution that can surely solve the
problem of pollution in soil.
Keywords Rhizosphere · Microorganisms · Rejuvenation · Bioremediation
1.1 Rhizosphere
Rhizosphere is the nutrient-rich soil region surrounding the root. The term was
coined by Hiltner in the year 1904, and he only introduced the concept of rhizosphere first to describe the narrow zone of soil surrounding the root where microbes
and their populations are stimulated by root activities. This rhizosphere seems to be a
complex environment where the interaction between the plant and the soil microbes
are interdependent and highly interacting. However, the original concept has now
been extended to include the soil surrounding a root in which physical, chemical and
biological properties have been changed by root growth and activity. The discharges
of roots will attract many microbes and help the microbes to colonize around the root
system is known as rhizosphere effect (Hiltner 1904), and he also observed direct
proportional relationship between the population of microorganism around the root
system to the yield. Many microbes such as bacteria, fungi and actinomycetes
rhizosphere include mycorrhizal fungi, PGPR, biocontrol agents, mycoparasitic
organism and antibiotic produces among which many of them play important role
as N fixers, P solubilizers, K mobilizers, etc. are onus for the rhizosphere dynamics.
Rhizosphere also known as the warehouse of microbes where the biochemical
secretions are influenced by the roots. Rhizospheric bacteria help the plants in
various ways through the secretions (Kundan et al. 2015). The composition of the
root exudates varies depending on the plant species and physicochemical properties
that help the plants to attract many microbes (Kang et al. 2010). Three niches were
identified to be the hot spots of root exudates, namely rhizospheric soil, rhizoplane
(surface of the root) and the root itself. These regions were profound to have root
2
M. Gomathy et al.
of moisture and nutrients, providing better niche for the growth of plant growth
promoting 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. Exploring these rhizospheric microorganisms by unravelling their possible
relationships with plants has launched a new and fascinating area of investigations
in the rhizosphere research. Moreover, the rhizospheric microbes are considered as
bioindicators of soil quality that are affected by much of the pollutant that makes the
soil infertile. Rhizosphere region that harbours abundant microbes can remediate the
polluted soils in a much greener way. Microorganisms and their metabolites like
enzymes were involved in bioremediation process. Hence, bioremediation is a much
auspicious method to overwhelm the pesticide pollution that can surely solve the
problem of pollution in soil.
Keywords Rhizosphere · Microorganisms · Rejuvenation · Bioremediation
1.1 Rhizosphere
Rhizosphere is the nutrient-rich soil region surrounding the root. The term was
coined by Hiltner in the year 1904, and he only introduced the concept of rhizosphere first to describe the narrow zone of soil surrounding the root where microbes
and their populations are stimulated by root activities. This rhizosphere seems to be a
complex environment where the interaction between the plant and the soil microbes
are interdependent and highly interacting. However, the original concept has now
been extended to include the soil surrounding a root in which physical, chemical and
biological properties have been changed by root growth and activity. The discharges
of roots will attract many microbes and help the microbes to colonize around the root
system is known as rhizosphere effect (Hiltner 1904), and he also observed direct
proportional relationship between the population of microorganism around the root
system to the yield. Many microbes such as bacteria, fungi and actinomycetes
rhizosphere include mycorrhizal fungi, PGPR, biocontrol agents, mycoparasitic
organism and antibiotic produces among which many of them play important role
as N fixers, P solubilizers, K mobilizers, etc. are onus for the rhizosphere dynamics.
Rhizosphere also known as the warehouse of microbes where the biochemical
secretions are influenced by the roots. Rhizospheric bacteria help the plants in
various ways through the secretions (Kundan et al. 2015). The composition of the
root exudates varies depending on the plant species and physicochemical properties
that help the plants to attract many microbes (Kang et al. 2010). Three niches were
identified to be the hot spots of root exudates, namely rhizospheric soil, rhizoplane
(surface of the root) and the root itself. These regions were profound to have root
2
M. Gomathy et al.