Phyto-Microbiome in Stress Regulation by Manoj Kumar & Vivek Kumar & Ram Prasad

Author:Manoj Kumar & Vivek Kumar & Ram Prasad
Language: eng
Format: epub
ISBN: 9789811525766
Publisher: Springer Singapore

The weathering of K-bearing minerals may be the result of carbonic acid formation from the respiratory CO2 release of the microorganisms and its subsequent reaction with water (Barker et al. 1998). Bacterial IAA can attract more rhizosphere bacteria in the rhizosphere by increasing more amount of root exudation, resulting in more production of CO2. In addition, CO2 can directly release K from K-bearing minerals (Rosenqvist et al. 2014). For example, CO2 can convert K feldspar into muscovite and release K (Fig. 9.10). In general, K-solubilizing PGPR can dissolve K-bearing minerals by production of organic acids, IAA, siderophore, and polysaccharides. Previous studies showed K-solubilizing PGPR with other PGP traits. For example, Zhao et al. (2008) isolated bacterial strains with multiple beneficial activities such as IAA production, K solubilization, and siderophore production. Prajapati et al. (2013) reported that inoculation with IAA-producing PGPR strain Enterobacter hormaechei enhanced the root and shoot length of okra and mobilized K efficiently in plant when feldspar was added to the soil. The plants with more fibrous, branching roots increase nutrient (K)-absorbing surface. Nadeem et al. (2009) reported that ACC deaminase-containing rhizobacteria improved the uptake of K in maize under salinity stress. They observed that these strains were strong colonizers of plant roots. The increased colonization by the K-solubilizing PGPR made the plants capable to explore more soil that might have improved the uptake of K indirectly. Previous studies showed that the solubilization and release of K through organic acids by K-solubilizing PGPR resulted in plant growth promotion leading to enhanced yield and production, which have been well reviewed (Ahmad et al. 2016; Bahadur et al. 2014; Das and Pradhan 2016; Meena et al. 2016; Sharma et al. 2016; Sindhu et al. 2014a, 2016; Velázquez et al. 2016; Zahedi 2016). The above discussion shows that bacterial strains have a number of potential mechanisms to solubilize K from insoluble sources and the contribution of these mechanisms in weathering of K-bearing minerals is variable. Among these mechanisms, the production of organic acids is one of the major mechanisms used by K-solubilizing PGPR. It has also been observed that K solubilization by the bacteria is affected by a large number of soil and environmental factors (Uroz et al. 2009).

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