Research Information System
in: BACTERIAL PRACTICES IN AGRICULTURE, Fatih Çığ, Editor, İksad Yayınevi, Ankara, pp.169-212, 2021
Beneficial
microorganisms improve plant nutrition and increase plant growth directly and
indirectly through several important mechanisms, including fixation of
elemental nitrogen, solubilization and mineralization of organic/inorganic
phosphate, potassium and zinc, production of siderophores, phytohormones,
ammonia, salicylic acid, hydrogen cyanide and carboxymethyl cellulose, iron
sequestration, producing hydrolytic enzymes like protease, chitinase, lipase,
pectinase, and cellulose, and plant tolerance to abiotic and biotic stress by
lowering host ethylene levels through hydrolysis of 1-
aminocyclopropane-1-carboxylic acid (ACC) by ACC deaminase. In addition, they
act by quorum sensing (QS), rhizosphere engineering, converting organic matter
to biomass, reducing biofilm formation, colonizing the plant root, producing
exopolysaccharides to improve aggregate, improving soil structure, and
indirectly acting as a biocontrol agent by mechanisms such as inducing systemic
resistance. As an alternative, the use of selected and developed effective
bacterial inoculants can contribute to alleviating biotic and abiotic stress
and improve yield and quality in tea by reducing production costs, and
environment and other adverse impacts, as well as reducing and eliminating the
use of chemical fertilizers and pesticides. Due to years of synthetic
fertilizers, soil health has deteriorated, soil acidity has increased and yield
and tea quality have decreased, as well as increased groundwater pollution,
nitrate levels in drinking water, eutrophication, algal blooms, and 'dead
zones' in coastal marine ecosystems as a result of nutrient loss caused by tea
farming systems. Therefore, alternative biotechnological approaches and
different agricultural practices have to be adapted to increase production and
maintain long-term ecological balance in agroecosystem and soil fertility. This
review discusses various microorganisms especially bacteria acting as PGPR,
their ecology, screening strategies, working principles, applications for tea,
and mechanisms and beneficial characteristics exhibited by them. This chapter
is an effort to elucidate the concept of rhizobacteria and their interaction
with tea plants, beneficial properties and mechanisms, with recent updates.