The Response of Maize to Inoculation with Arthrobacter sp. and Bacillus sp. in Phosphorus-Deficient, Salinity-Affected Soil.

Tchuisseu Tchakounté Gylaine Vanissa,Fankem Henri,Silke Ruppel,Ondřej Novák,Danuše Tarkowská,Beatrice Berger,Matthias Becker,Sascha Patz,Veronika Turečková

doi:10.3390/microorganisms8071005

Abstract

Salinity and phosphorus (P) deficiency are among the most serious soil factors constraining crop productivity. A proposed strategy for alleviating these stresses is supporting plants by inoculation with growth-promoting rhizobacteria (PGPR). Here, a comparison of the ability of two maize composite and two F1 hybrid varieties to tolerate a P deficiency in either a saline or a non-saline environment showed that the uptake of nutrients by all four entries was significantly reduced by the imposition of both soil salinity and P deficiency, and that their growth was compromised to a similar extent. Subsequently, the ameliorative effect of inoculation with three strains of either Arthrobacter sp. or Bacillus sp. in an environment, which suffered simultaneously from salinity and P deficiency, was investigated. Inoculation with each of the strains was found to limit the plants’ uptake of sodium cations, to increase their uptake of potassium cations, and to enhance their growth. The extent of the growth stimulation was more pronounced for the composite varieties than for the F1 hybrid ones, although the amount of biomass accumulated by the latter, whether the plants had been inoculated or not, was greater than that of the former varieties. When the bacterial strains were cultured in vitro, each of them was shown as able to produce the phytohormones auxin, abscisic acid, gibberellins, and cytokinins. The implication is that since the presence in the rhizospere of both Arthrobacter sp. and Bacillus sp. strains can support the growth of maize in salinity-affected and P deficient soils in a genotype-dependent fashion, it is important to not only optimize the PGPR strain used for inoculation, but also to select maize varieties which can benefit most strongly from an association with these bacteria.

Highlights

Salinity and phosphorus (P) deficiency represent two of the most serious soil constraints to crop production
While breeding for adaptation to either saline and/or P deficient soils has the potential to raise yield potential [6], the yield can be enhanced by exploiting the ability of plant growth-promoting rhizobacteria (PGPR) to solubilize phosphate in the soil and to mitigate salinity stress [7]
Root elongation was not inhibited by neither salinity stress or combined P and salt stress treatments and was even promoted by P deficiency

Summary

Introduction

Salinity and phosphorus (P) deficiency represent two of the most serious soil constraints to crop production. While breeding for adaptation to either saline and/or P deficient soils has the potential to raise yield potential [6], the yield can be enhanced by exploiting the ability of plant growth-promoting rhizobacteria (PGPR) to solubilize phosphate in the soil and to mitigate salinity stress [7]. Some of these bacteria are known to produce a number of key phytohormones, notably auxin (indole-3-acetic acid, IAA), cytokinins (CKs), abscisic acid (ABA), and gibberellins (GAs), to convert atmospheric nitrogen into a form assimilable by plants and to enhance tolerance against certain pests [8]

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