Effect of indole acetic acid producing bacteria and hormone applications on growth, yield and essential oil components of savory (Satureja hortensis L.)

The objective of this study was to evaluate possible effects of mineral fertilizer (NPK), two plant growth regulators (Indole 3-acetic acid + benzylaminopurine IAA+BAP and benzylaminopurine BAP) and five N2-fixing, P-solubilizing, and IAA-producing bacteria (Pseudomonas fluorescens RC26, Pseudomonas putida RC48, Micrococcus luteus RC17A, Bacillus subtilis RC17C, and Bacillus subtilis RC631) strains, which isolated from the wild oregano and red raspberries, as biofertilizer on growth, yield and quality characteristics of the plant, essential oil content and major component of the essential of summer savory (Satureja hortensis L.). During growth, the plants are sprayed with 100 ppm (100 mg/L) of each plant growth regulators (IAA+BAP and BAP), the first spray was applied two weeks after the transplantation, the second spray fifteen day after the 1st one wetting agent. The hydro-distillated essential oils were analyzed by GC-MS. BAP and IAA+BAP caused an increase in the yield of essential oil (8.2% and 40.5% respectively). Bacterial efficiency were variable and depended on the inoculants strain and growth parameters evaluated. Trial results show that inoculation with IAA-producing, N2-fixing and P-solobilizing bacterial strain especially Pseudomonas fluorescens RC26, Micrococcus luteus RC17A and Bacillus subtilis RC17C stimulated overall plant growth, including plant height, trunk diameter, drug and fresh herb yield, dry leaf ratio, fresh and dry leaf and root weight, essential oil ratio and yield, essential oil components such as carvacrol of savory. The main monoterpenes found were p-cymene, carvacrol and their precursor γ-terpinene. The presence of at least thirty one compounds were identified in the samples analysed, representing 99% of the total oil contents. In terms of general categories, monoterpene hydrocarbons dominated the chemical profile of the oils with carvacrol (48.18-53.96%), γ-terpinene (23.76-31.11%), p-cymene (4.25-7.85%), and α-terpinene (3.91-6.24%) as the main components. The other constituents were found to be myrcene (1.56-2.73%), β-bisabolene (0.67-3.13%), α-thujene (0.79-2.13%), α-pinene (0.58-2.13%), β-pinene (0.41-2.25%), β-caryophyllene (0.41-1.87%), α-phellandrene (0.38-0.70%) and spathulenol (0.26-0.67%), the amount of all remaining oil components was less than 1% or not found in all samples. Of the effective bacteria tested usually gave growth and yields of summer savory equal to or higher than chemical fertilizers application. In this research, the effective and efficient bacteria in plant growth has decreased the need for chemical fertilizer, volatile oil and carvacrol and also has changed the volatile oil in savory, using this method as a biological fertilizer in organic farming has been proved.