Cacti-associated rhizobacteria from Brazilian Caatinga biome induce maize growth promotion and alleviate abiotic stress

Abstract

The aim of this study was to isolate and characterize the culturable rhizobacteria associated with native cacti from Caatinga biome, testing their potential in plant growth promotion and abiotic stress tolerance. Bacterial isolates were examined for plant growth promotion traits and for in vitro abiotic stress tolerance. Promising isolates were 16S rRNA sequenced, tested under greenhouse conditions for plant growth promotion and induction of water deficit tolerance in maize plants. Analysis of variance was used to assess differences among treatments and, when significant, followed by the Scott-Knott’s test. The highest culturable population density was found in Melocactus zehntneri and the most promissing isolates belonged to the genus Bacillus. Under recommended conditions of irrigation, plants inoculated with the isolates CF12.2, CF8.2, and P12.2 presented an increment in root length, leaf number and root and shoot dry weight. Additionally, isolates CF6.1, CF3.1, CF8.2 and P12.2, increased shoot dry weight under water deficit conditions. In this study we identified bacterial taxa for further validation and application as biostimulants in crops grown in drylands.