Use of Bioinoculants in Ameliorative Effects on Radish Plants Under Salinity Stress

The aim of this study was to evaluate the effect of plant growth promoting bacteria (PGPB) on emergence, growth, physiology, and mineral content of radish under salinity stress. The study was conducted in pot experiments using a mixture of soil: sand (1:1 v: v) under greenhouse conditions. Bacillus subtilis EY2, Bacillus atrophaeus EY6, and Bacillus spharicus GC subgrup B EY30 were isolated in highly salty soils in Upper Coruh Valley in Turkey. Seeds were soaked in the bacterial suspension incubated at 27C for 2 h. Emergence percentage (EP) was reduced and mean emergence time (MET) raised with sodium chloride (NaCl) solutions. Inoculated seeds displayed greater EP and less MET compared to the non-inoculated ones. Salinity negatively affected growth of radish; however, plant growth promoting bacteria treatments positively affected growth parameters such as fresh weight (278% for shoot, 371% for root) and dry weights (250% for shoot, 422% for root) compared to non-treated plants that were challenged with salt stress. Furthermore, selected bacteria caused an increase in uptake of minerals except sodium (Na) compared to the non-treated controls in both salt stress and salt stress absence. Sodium concentration of plant leaves was increased by salt stress while bacterial inoculation decreased its concentration. Bacterial treatments increased chlorophyll content and decreased electrolyte leakage of plants in saline conditions. Leaf relative water content (LRWC) of plants in the salt stress condition increased with bacterial application, but reduced without bacterial application. The present study suggests that PGPB seed treatments can ameliorate the deleterious effects of salt stress on radish plants and PGPB could offer an economical and simple application to reduce problems of radish production in an Aridisol caused by high salinity.