The role of microbes in tea cultivation

The adoption of biological techniques for sustainable tea cultivation is a pertinent strategy for
an efficient and ideal agricultural growth with minimal generation of adverse environmental
impacts that may affect water resources, ecosystems or the quality of human life. Modern
agriculture offers immense opportunity to exploit beneficial soil microbial resources such
as nitrogen fixers, phosphate solubilizers, potash mobilizers, cellulose degraders, AM
fungi, etc., as well as biopesticides (microbial biocontrol agents and entomopathogens),
to optimize crop benefit and maintain soil quality. According to Raja (2013) there is a rising
trend towards organic agriculture using biological-based organics as an alternative to
agrochemicals.
Organic farming ensures food safety as well as aiding biodiversity conservation and
functioning in the soil. It is highly likely to be dependent on the native soil microflora
which constitutes all kinds of useful bacteria and fungi including the AMF and PGPR. A
synergistic interaction of PGPR and AMF is recorded as highly suitable to fertilizer use
patterns in agricultural soil. An enhanced plant nutrient-use efficiency with PGPR and AMF
in an integrated nutrient management system has been achieved by Adesemoye et al.
(2008), and thereby suggested the application of microbes with reduced doses of fertilizer
in agricultural soil. Microbial inoculants are of paramount significance in integrated nutrient and pest
management schedules and thereby assist in the generation of healthy agricultural practices
(Adesemoye and Kloepper, 2009). Microbial biofertilizers and biopesticides fulfil diverse
beneficial interactions in tea soil and thereby lead to promising solutions for sustainability.
As the rhizosphere is an ideal habitat for the isolation of beneficial microorganisms (Mendes
et al., 2013), considerable effort has been made to explore the microbial diversity of the
surface and sub-surface soil of tea plants under cultivation in diverse topographical regions.
Different species of microbial inoculants are now known to antagonize tea pathogens via
mycoparasitism, producing volatile and non-volatile antibiotics, competing for nutrients
and space, as well as their diverse beneficial activities contributing towards enhanced
crop production. The use of microbials such as viruses (NPV/GV), spore-forming bacteria
(Bacillus strains) and fungi (Beauveria, Metarhizium, Verticillium, Paecilomyces), holds great
promise in this regard. Most of the tea estates, however, refrain from risking crop loss due
to pest attack and liberally use synthetic pesticides under ‘no threshold category of pest
management’ (Pedigo, 2002), and as microbial insecticides are pest specific, the potential
market for these products is rather limited.