Abstract
Plant growth promoting rhizobacteria (PGPR) can be functional microbial fertilizers and/or biological control agents, contributing to an eco-spirit and safe solution for chemical replacement. Therefore, we have isolated rhizospheric arylsulfatase (ARS)-producing bacteria, belonging to Pseudomonas and Bacillus genus, from durum wheat crop grown on calcareous soil. These isolates harbouring plant growth promoting (PGP) traits were further evaluated in vitro for additional PGP traits, including indole compounds production and biocontrol activity against phytopathogens, limiting the group of multi-trait strains to eight. The selected bacterial strains were further evaluated for PGP attributes associated with biofilm formation, compatibility, salt tolerance ability and effect on plant growth. In vitro studies demonstrated that the multi-trait isolates, Bacillus (1.SG.7, 5.SG.3) and Pseudomonas (2.SG.20, 2.C.19) strains, enhanced the lateral roots abundance and shoots biomass, mitigated salinity stress, suggesting the utility of beneficial ARS-producing bacteria as potential microbial fertilizers. Furthermore, in vitro studies demonstrated that compatible combinations of multi-trait isolates, Bacillus sp. 1.SG.7 in a mixture coupled with 5.SG.3, and 2.C.19 with 5.SG.3 belonging to Bacillus and Pseudomonas, respectively, may enhance plant growth as compared to single inoculants.
Highlights
Our results showed that a selected group of arylsulfatase (ARS)-producing bacterial isolates with biocontrol activity and resistance to salinity stress can stimulate seed germination and enhance plant growth under salinity stress conditions, and in vitro studies demonstrated that compatible mixtures of these multi-trait isolates could promote plant growth as compared to single strains
Sixty-eight arylsulfatase (ARS)-producing bacterial isolates used in this study were isolated from the rhizosphere of durum wheat on calcareous soil after treatment with fertilizer granules containing elemental sulphur (S0 ) and characterized with respect to their phylogenetic affiliation as well as their traits associated with plant nutrition [48]
Strains were tested for their antifungal activity against Rhizoctonia solani and Fusarium oxysporum, as well as against Botrytis cinerea and Colletotrichum sp
Summary
Root beneficial microbiome plays a crucial and significant role in sustainable agriculture. A free-living natural root microbiome, applied as microbial fertilizer and/or as a biological control agent, interacts with the host conferring an eco-friendly balance upon the plant-microbe-soil system. These rhizospheric interactions establish the initial and crucial conditions to improve soil fertility and plant health. Free-living soil bacteria that colonize plant roots and affect plant growth, referred to as plant growth promoting rhizobacteria (PGPR). Many PGPR strains have been used as biofertilizers, successfully contributing to sustainable agriculture [5,6]. Many PGPR promote plant growth and can be biocontrol agents at the same time, but if rhizospheric
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