Intensification of sodic soil due to increasing pH is an emerging environmental issue. The present study aimed to isolate and characterise alkaline stress-tolerant and plant growth-promoting bacterial strains from moderately alkaline soil (pH 8-9), strongly alkaline soil (pH 9-10), and very strongly alkaline soil (> 10). Total 68 bacteria were isolated, and screened for multiple plant growth promoting (PGP) attributes. Out of total, 42 isolates demonstrating at least three plant growth promoting PGP traits selected for further assays. Then out of 42, 15 bacterial isolates were selected based on enhanced maize plant growth under greenhouse experiment, and 16S rRNA gene sequencing revealed Bacillus spp. as a dominant genus. Furthermore, based on improved seed germination percentage and biomass of maize (Zea mays L.) under alkaline stress conditions Alcaligenes sp. NBRI NB2.5, Bacillus sp. NBRI YE1.3, and Bacillus sp. NBRI YN4.4 bacterial strains were selected, and evaluated for growth-promotion and alkaline stress amelioration under greenhouse condition. Amongst the selected 3 plant growth promoting rhizobacterial (PGPR) strains, Bacillus sp. NBRI YN4.4 significantly improved the photosynthetic pigments and soluble sugar content, and decreased proline level in inoculated maize plants as compared to uninoculated control under stress conditions. Moreover, significantly enhanced soil enzymes such as dehydrogenase, alkaline phosphatase and betaglucosidase due to inoculation of Bacillus sp. NBRI YN4.4 in maize plants grown in alkaline soil attributes to its role in improving the soil health. Therefore, alkaline stress-tolerant PGPR NBRI YN4.4 can be useful for developing strategies for the reclamation of saline/sodic soils and improving the plant growth and soil health in sustainable manner.

中文翻译：

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表征植物生长的碱性耐碱碱菌和芽孢杆菌菌株，用于缓解玉米中的碱性胁迫。

由于pH值升高而导致的碱土集约化是一个新兴的环境问题。本研究旨在从中度碱性土壤（pH 8-9），强碱性土壤（pH 9-10）和极强碱性土壤（> 10）中分离并鉴定耐碱胁迫和促进植物生长的细菌菌株。总共分离出68种细菌，并针对多种植物生长促进（PGP）属性进行了筛选。在总数中，有42个分离株表现出至少三种植物生长促进PGP性状的选择，用于进一步测定。然后在温室试验中，基于增强的玉米植物生长，从42种细菌中分离出15种，并通过16S rRNA基因测序揭示了芽孢杆菌。作为优势属。此外，基于改善的玉米种子发芽率和生物量（Zea mays L. ）在碱性胁迫条件下 NBRI NB2.5，芽孢杆菌属。NBRI YE1.3和芽孢杆菌 选择NBRI YN4.4细菌菌株，并在温室条件下评估其生长促进和碱性胁迫的改善。在选定的3种促进植物生长的根际细菌（PGPR）菌株中，芽孢杆菌属（Bacillus sp。）。与在胁迫条件下未接种的对照相比，NBRI YN4.4显着提高了接种玉米植物的光合色素和可溶性糖含量，并降低了脯氨酸水平。此外，由于接种了芽孢杆菌属（Bacillus sp），土壤酶大大增强，例如脱氢酶，碱性磷酸酶和β-葡萄糖苷酶。在碱性土壤中生长的玉米植物中的NBRI YN4.4归因于其在改善土壤健康中的作用。因此，耐碱性PGPR NBRI YN4。