Effects of biofertilizers on growth criteria, quantitative and qualitative yield of summer savory (Satureja hortensis L.)

In order to investigate the effects of Plant Growth Promoting Rhizobacteria (PGPRs) inoculation on the growth, yield and quality of essential oils of summer savory (Satureja hortensis L.), an experiment were conducted based on randomized complete block design with three replications at Research Institute field of Forests and Rangelands, Karaj, Alborz during growing season of 2012-2013. The experimental treatments included suspension of three species of rhizobacteria namely Azotobacter, Azospirillum, Pseudomonas in single and combination application of these bacteria included Azotobacter- Azospirillum, Azotobacter –Pseudomonas, Azospirillum-Pseudomonas, Azotobacter- Azosperillium-Pseudomonas and control (without any inoculation with bacteria), which applied as root inoculation on summer savory plants. Assessed traits included plant height, canopy diameter, dry weight and yield of shoot, leaf area and leaf dry weight, inflorescence number, dry weight and yield, percentage and yield of essential oil and component of essential oil content such as α-terpinene, and thymole. Results revealed that inoculation of plants with PGPRs had significant effect on all of assessed parameters such as vegetative growth criteria and essential oil yield and quality. The highest value for traits such as plant height (45.67 cm), canopy diameter (40.54 cm), dry weight of shoot (33.82 g.plant-1), aerial part yield (3578 kg.ha-1), leaf yield (451 kg.ha-1), inflorescence yield (1398 kg.ha-1), essential oil percentage (2.33 %) and essential oil efficiency (2.43 %) were obtained by application of Azotobacter- Azosperillium-Pseudomonas combination and the lowest amount for all of mentioned traits were achieved in control treatment. The highest amount of α-terpinene(53 mg.L-1) thymole (48.5 mg.L-1) were obtained by inoculation with Azotobacter – Pseudomonas combination and Azotobacter, respectively. In general the highest plant dry weight and essential oil yield can be obtained by combination of three assessed PGPRs. Inoculation of summer savory by PGPRs enhancing root growth and development supplying favorable condition for plant growth with respect to supplying better condition for water and nutritional elements absorption from soils.