AUTHOR=Shabaan Muhammad , Asghar Hafiz Naeem , Zahir Zahir Ahmad , Zhang Xiu , Sardar Muhammad Fahad , Li Hongna 

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

JOURNAL=Frontiers in Microbiology

VOLUME=13

YEAR=2022

URL=https://www.frontiersin.org/journals/microbiology/articles/10.3389/fmicb.2022.901865

DOI=10.3389/fmicb.2022.901865

ISSN=1664-302X

ABSTRACT=<p>Salt-tolerant plant growth-promoting rhizobacteria (PGPR) can improve soil enzyme activities, which are indicators of the biological health of the soil, and can overcome the nutritional imbalance in plants. A pot trial was executed to evaluate the effect of inoculation of different salt-tolerant PGPR strains in improving soil enzyme activities. Three different salinity levels (original, 5, and 10 dS m<sup>–1</sup>) were used and maize seeds were coated with the freshly prepared inocula of ten different PGPR strains. Among different strains, inoculation of SUA-14 (<italic>Acinetobacter johnsonii</italic>) caused a maximum increment in urease (1.58-fold), acid (1.38-fold), and alkaline phosphatase (3.04-fold) and dehydrogenase (72%) activities as compared to their respective uninoculated control. Acid phosphatase activities were found to be positively correlated with P contents in maize straw (<italic>r</italic> = 0.96) and grains (<italic>r</italic> = 0.94). Similarly, a positive correlation was found between alkaline phosphatase activities and P contents in straw (<italic>r</italic> = 0.77) and grains (<italic>r</italic> = 0.75). In addition, urease activities also exhibited positive correlation with N contents in maize straw (<italic>r</italic> = 0.92) and grains (<italic>r</italic> = 0.91). Moreover, inoculation of <italic>Acinetobacter johnsonii</italic> caused a significant decline in catalase (39%), superoxide dismutase (26%) activities, and malondialdehyde contents (27%). The PGPR inoculation improved the soil’s biological health and increased the uptake of essential nutrients and conferred salinity tolerance in maize. We conclude that the inoculation of salt-tolerant PGPR improves soil enzyme activities and soil biological health, overcomes nutritional imbalance, and thereby improves nutrient acquisition by the plant under salt stress.</p>