Isolation, characterization and screening of PGPR capable of providing relief in salinity stress

Abstract

Environmental stresses such as drought, temperature, salinity, air pollution, heavy metals, pesticides, and soil pH are major limiting factors in crop production because they affect almost all plant functions. Soil salinization is a serious stress condition causing major problem for crop productivity. To combat this salinity stress, Plant growth promoting rhizobacteria (PGPR) is considered as innovative, effective and ecofriendly approach. Plant growth promoting rhizobacteria (PGPR) have various direct and indirect mechanisms which can be correlated with their ability to form biofilms, chemotaxis, and the production of exopolysaccharide, indole-3-acetic acids (IAA) and aminocyclopropane-1-carboxylate (ACC) deaminase Investigations on the interaction of PGPR with other microbes and their effect on the physiological response of crop plants under different soil salinity regimes are still at an incipient stage. An experiment was conducted to investigate the effect of PGPR on lowering down the salt stress. Treatments were control (T1), Salt tolerant isolate KH-1 (T2), Salt tolerant isolate KH-2 (T3), Salt tolerant isolate KH-3 (T4), PGPR-I (Pseudimonas) (T5), PGPR-II (Azotobacter) (T6). Rice was sown under saline conditions at Soil Salinity Research Institute, Pindi Bhattian. With the inoculation of salt tolerant PGPR, plant growth and yield was improved. Result showed significant increase in plant height, biomass and yield over control. Inoculation of salt tolerant isolate KH-2 produced maximum grain yield in rice (4267 kg/ha) followed by PGPR-II and it was statistically significant from all other treatments along with control. It is concluded that with the application of salt tolerant isolate (KH-2), there is significant increase in rice production.

Salt-Tolerant PGPR Confer Salt Tolerance to Maize Through Enhanced Soil Biological Health, Enzymatic Activities, Nutrient Uptake and Antioxidant Defense

“…Rhizobacterial inoculation improved the growth as well as yield of maize under salinity stress in comparison with their uninoculated unstressed control. These results are in line with the previous reports (Hussein and Joo, 2018;Upadhyay et al, 2019;Javed et al, 2020). The increase in plant growth might be correlated with the production of auxin by inoculated rhizobacterial strains that may have enhanced the cell division as well as elongation in the seedlings (Kadmiri et al, 2018).…”

“…Moreover, excessive production of abscisic acid (ABA) under salinity stress induces stomatal closure that leads to low or no water uptake by the roots entailing low relative water contents of the plants (Polash et al, 2018). Microbially mediated improvement in the relative water contents (RWCs) of plants has already been documented (Ji et al, 2020;Li et al, 2020). Increment in the RWC under inoculated treatments might be due to microbially induced enhancement in the root length and diameter that may have helped the plant to uptake more water under the exact salinity situation (Ali et al, 2017).…”

Sugar Beet Extract Acts as a Natural Bio-Stimulant for Physio-Biochemical analysis of Hordeum Vulgare L. under Induced Salinity Stress

“…Salinity causes many abnormal changes in the morphological and physiological functioning of plant cells due to sodium and chloride ions in cells, disturbs the level of minerals and reduces the water potential of the soil for sowing by a high osmotic potential causing high osmotic stress (Zhu et al 2020). Due to salinity, synthesis of lipids and protein along with photosynthesis are badly affected in plants (Javed et al 2020). To respond to such reactive oxygen species (ROS), plants immediately regulate their antioxidant defense mechanism by activating antioxidant enzymes activities; such as SOD, POD, CAT (Amirjani 2011).…”

“…About 6.30 million of lands is affected with salinity (Economic survey of Pakistan 2017). According to an estimate about 20% of all irrigated and cultivated lands (equivalent to 62 million ha) are negatively affected by salt stress at present time (Javed et al 2020). Production of barley fluctuated substantially in the history of Pakistan.…”