16
control treatments. Serw-4 variety of canola plant with 60 kg N/fed showed high
seed yield/plant and seed yield/hectare (73.70 g and 4211.24 kg, respectively) compared to other tested varieties (El-Howeity and Asfour 2012). Various mechanisms
are associated with lowering plant stress from different contaminants (Tripathi et al.
2015a, b), one of which may be the lowering of ethylene concentration under heavy
metal stress which supports plant growth. Another mechanism can also be the accumulation of toxic metals by the microbial strains at the cellular level, hence reducing availability to the crop (Nadeem et al. 2014). Microorganisms such as arbuscular
mycorrhizal (AM) fungi, viz. Glomus mosseae, promote maize plant growth under
heavy metal-contaminated soils. The fungi produce an insoluble glycoprotein glomalin that acts as a chelating agent for heavy metals. Furthermore, the co- inoculation
of AM fungi and certain bacterial strains such as Brevibacillus spp. promotes the
growth of the red clover plant in contaminated soils (Nadeem et al. 2014).
2.8 Microorganisms for Phyto-Bioremediation, Carbon
Sequestration, Biomass, and Bioenergy Production
The present scenarios indicate that food, energy, and emission of trace gases (CO 2 ,
CH 4 , N 2 O, fluoride gases) are the key global challenges of the twenty-first century.
The rapidly increasing population has resulted in accelerated consumption of fossil
fuels, resulting in warming of the planet Earth and climate change (Dubey et al.
2016b; Edrisi and Abhilash 2016). In such a situation, renewable energy options
from microbial sources (PGPR, PGPF, microalgae, cyanobacteria) could be green,
sustainable, and carbon-neutral solutions (Ragauskas et al. 2006). Microbial biomass is a potent renewable energy source that has the capability to replace fossil
fuels. Soil pollution by heavy metals, organic pollutants, and industrial effluents, as
well as the energy crisis, are challenging issues. Besides the energy crisis, in India,
approximately 1391.09 km
2
, 58 km
2
, and 593.65 km
2
land area are degraded by
strong alkali, industrial contaminants, and mining pollutants, respectively (NRSC
2011). Thus, it is imperative to develop technologies for restoring degraded lands.
Microbe-assisted phyto-remediation is a low-input sustainable technology in comparison to the conventional physicochemical and biological treatments and thermal
desorption remediation methods. In degraded lands, rapid growth and high biomass/
bioenergy crops such as Zea mays, Brassica napus, and Glycine max associated
with microbes may address the issue of increased global atmospheric CO 2 concentration by capturing it in the plant biomass (Witters et al. 2012). This method has a
variety of benefits as it can capture carbon, hyper-accumulate heavy metals, remediate organic pollutants, and offer biofuel and raw materials for paper and pulp industry, as well as the revitalization of degraded land. Restored areas also balance
increased demand for arable lands for energy and food production (Meers et al.
2010). Therefore, the practices of energy crop production can maximize agricultural
land area by restoring contaminated lands with microbe-assisted phyto-remediation
and sufficient food for the increasing human population. For better utilization of
biomass produced through microbe-assisted phyto-remediation, it becomes
2 Belowground Microbial Communities: Key Players for Soil and Environmental…
control treatments. Serw-4 variety of canola plant with 60 kg N/fed showed high
seed yield/plant and seed yield/hectare (73.70 g and 4211.24 kg, respectively) compared to other tested varieties (El-Howeity and Asfour 2012). Various mechanisms
are associated with lowering plant stress from different contaminants (Tripathi et al.
2015a, b), one of which may be the lowering of ethylene concentration under heavy
metal stress which supports plant growth. Another mechanism can also be the accumulation of toxic metals by the microbial strains at the cellular level, hence reducing availability to the crop (Nadeem et al. 2014). Microorganisms such as arbuscular
mycorrhizal (AM) fungi, viz. Glomus mosseae, promote maize plant growth under
heavy metal-contaminated soils. The fungi produce an insoluble glycoprotein glomalin that acts as a chelating agent for heavy metals. Furthermore, the co- inoculation
of AM fungi and certain bacterial strains such as Brevibacillus spp. promotes the
growth of the red clover plant in contaminated soils (Nadeem et al. 2014).
2.8 Microorganisms for Phyto-Bioremediation, Carbon
Sequestration, Biomass, and Bioenergy Production
The present scenarios indicate that food, energy, and emission of trace gases (CO 2 ,
CH 4 , N 2 O, fluoride gases) are the key global challenges of the twenty-first century.
The rapidly increasing population has resulted in accelerated consumption of fossil
fuels, resulting in warming of the planet Earth and climate change (Dubey et al.
2016b; Edrisi and Abhilash 2016). In such a situation, renewable energy options
from microbial sources (PGPR, PGPF, microalgae, cyanobacteria) could be green,
sustainable, and carbon-neutral solutions (Ragauskas et al. 2006). Microbial biomass is a potent renewable energy source that has the capability to replace fossil
fuels. Soil pollution by heavy metals, organic pollutants, and industrial effluents, as
well as the energy crisis, are challenging issues. Besides the energy crisis, in India,
approximately 1391.09 km
2
, 58 km
2
, and 593.65 km
2
land area are degraded by
strong alkali, industrial contaminants, and mining pollutants, respectively (NRSC
2011). Thus, it is imperative to develop technologies for restoring degraded lands.
Microbe-assisted phyto-remediation is a low-input sustainable technology in comparison to the conventional physicochemical and biological treatments and thermal
desorption remediation methods. In degraded lands, rapid growth and high biomass/
bioenergy crops such as Zea mays, Brassica napus, and Glycine max associated
with microbes may address the issue of increased global atmospheric CO 2 concentration by capturing it in the plant biomass (Witters et al. 2012). This method has a
variety of benefits as it can capture carbon, hyper-accumulate heavy metals, remediate organic pollutants, and offer biofuel and raw materials for paper and pulp industry, as well as the revitalization of degraded land. Restored areas also balance
increased demand for arable lands for energy and food production (Meers et al.
2010). Therefore, the practices of energy crop production can maximize agricultural
land area by restoring contaminated lands with microbe-assisted phyto-remediation
and sufficient food for the increasing human population. For better utilization of
biomass produced through microbe-assisted phyto-remediation, it becomes
2 Belowground Microbial Communities: Key Players for Soil and Environmental…