Agriculture Reference
In-Depth Information
Chapter 3
Factors Affecting Phosphate-Solubilizing
Activity of Microbes: Current Status
Javed Musarrat and Md. Saghir Khan
Abstract
Phosphorous (P) plays an important role in regulating the vital meta-
bolism and concomitantly the health of plants. The use of phosphate-solubilizing
microorganisms (PSM) in P-deficient soils has been found effective in transforming
insoluble P into soluble forms and, hence, enriching the soil P pool. The structure,
composition, and physiological functions of soil dwellers depend, however, on the
variable soil constituents and other environmental factors. Moreover, the establish-
ment and performance of these microbes are affected severely by environmental
stressors such as high temperature, pH, and salt, etc. prevalent in degraded eco-
systems such as alkaline/saline soils. Therefore, any alteration in normal environ-
mental factors leads to poor growth and survival of PSM. Also, PSM, when
introduced exogenously into soil as inoculant, encounter a furious competition
from the indigenous soil microflora. The success of the inoculants, therefore,
depends on how quickly and efficiently such microbes overcome the stressful
environmental variables. This chapter focuses on the effects of different factors
on the overall functioning of the PSM, which is likely to help in developing
environment-friendly bio-inoculants, especially for P acquisition by plants under
environmentally challenged conditions.
Keywords
PSM • Temperature • Salts • Alkalinity • pH
3.1
Introduction
Phosphorus is one of the 16 known major plant nutrients that plays a significant role
in plant metabolism (Vikram and Hamzehzarghani
2008
; Padmavathi and Usha
2012
). On global basis, 40 % of the arable soil is P deficient (Vance
2001
) because
