The earth, the soil is a fertile land and a rich
source of various types of naturally occurring fungi, bacteria, protozoa
and viruses. The narrowest region of the soil known as the rhizosphere
is greatly affected and influenced by root secretions and microbial
activity.
There are various Plant Growth Promoting Bacteria that occupy the very
same rhizosphere. These growth promoting bacteria have beneficial
effects on the growth of the plant. The breeder goes about inducing the
bacteria in either a direct or indirect manner. A direct method means to
increase the growth of the plant by injecting the plant with various
nutrients and hormones. The indirect method includes reduction of
vulnerable to diseases and beginning a form of defense also known as
induced systematic resistance.
The benefits of Plant promotion are many. Here are a few listed below:
- Nutirents in more supply: The Rhizobacteria can substantially increase the growth of the plant in the absence of pathogenic microorganisms. One way in which they can enhance plant growth is by solubilizing normally poorly soluble nutrients with either bacteria siderophores or lowering the pH by secreting acidic organic compounds.
- Phytohormones: Plant growth can be controlled by the production of hormones and other compounds related to plant development. Auxin, a plant hormone is important for the promotion of lateral root formation.
- Ethylene levels: a low level of ethylene is a sure shot way to promote plant growth. But high ethylene levels may inhibit root elongation. In plants, 1-aminocyclopropane-1-carboxylate (ACC) and 5’-deoxy-5’methylthioadenosine (MTA) is converted to ACC by ACC synthase [9]. A number of plant growth-promoting bacteria have been found to contain the enzyme ACC deaminase, which cleaves and sequesters the plant ethylene precursor ACC and thus lowers the level of ethylene in a developing or stressed plant [1]. The presence of plant growth-promoting bacteria thereby moderates concentration of ACC so that it does not reach a level where it begins to impair root growth.
These are just few of the various methods through
which plant promotion can be done. PGPB is today an important method in
the production of plants. While there may not be many takers for PGPB,
the use of plant growth-promoting bacteria in agriculture and solving
environmental problems seems promising, there is not enough knowledge
about these bacteria for them to be put into use. However, there’s
nothing to lose when it comes to the growth of your plants.
