Document Type : Research Paper

Authors

• O. Heidarpour ¹
• B. Esmaielpour ²
• A. Soltani ³
• zahra aslani ⁴

¹ Faculty of Agriculture Science , Mohaghegh Ardabili University

² -

³ Department of Soil Science, Faculty of Agriculture Science, Mohaghegh Ardabili University

⁴ Department of Horticultural Science, Faculty of Agriculture, Urmia University

Abstract

     Background and objectives: Savory (Satureja hortensis L.) is one of the most important medicinal plants that grows in different parts of the world, including Iran. Water deficit has adverse effects on physiological processes such as photosynthesis, nutrient absorption, development and division of cells, and accumulation and transfer of nutrients, thus reducing the performance of plants. In contrast, biofertilizers play a prominent role in the growth and development of plants by improving the absorption of nutrients and sufficient water through changes in the physicochemical properties of the soil. This study aimed to investigate the effect of drought stress, growth-promoting bacteria (PGPRS) and vermicompost on the yield, amount of nutrients and essential components of the savory plant.
Materials and methods: A factorial experiment based on a randomized complete block design with three replications was conducted at the Research Farm at the Mohaghegh Ardabili University, Iran, from 2016-2017. Treatments included three levels of drought stress (Full irrigation (S1), Water cut at 50% of flowering (S2), and water cut in early stages of flowering (S3), four vermicompost levels (including 0, 1, 1.5 and 2 t. ha-1) and included inoculation with microorganisms at three levels (non-inoculation, inoculation with Streptomyces and Pseudomonas fluorescens p15). Before planting, the seeds were inoculated with biological stimulants. Then, seeds were cultivated in rows at a distance of 25 cm between the rows, 20 cm on rows and at a depth of 0.5 cm. To apply the irrigation treatment, the field's soil was investigated in the horizon of the plant roots up to a depth of 20 cm by digging a profile. The weight method was used to control water. Field capacity (FC) and permanent wilting point (PWP) were measured using intact samples 24 hours after soil saturation for field capacity and placed in a suction device with 15 atmospheres of negative pressure for permanent wilting point. The corresponding values for the soil at a depth of 0 to 30 cm were determined according to the layering of the soil, and from their difference, the amount of usable soil water (AW) was determined. During the test, the usable water (depending on the plant's growth stage) was determined by the soil sampling cylinder and transferred to the oven in the form of moisture percentage by weight. The examined parameters included plant height, shoot dry weight, root dry weight, and concentration of phosphorus, potassium, and essential oil components.
Results: Based on the obtained results, drought stress, vermicompost, and inoculation with PGPRS had a significant effect on the measured parameters. So that the maximum plant height (62.36 cm), shoot dry weight (28.72 grams) and root dry weight (6.35 grams), phosphorus (1.3 percent) and potassium absorption (3.3 percent) were obtained under non-stress conditions, application of vermicompost two tons per hectare of and inoculation with Streptomyces bacteriaand the lowest amount of plant height (22.33 cm), shoot dry weight (18.33 grams), dry weight roots (3.07 grams), phosphorus (0.85 percent) and potassium (1.2 percent)  were observed in the planting beds without vermicompost application and non-inoculation with biological stimulants and in severity drought stress. Also, the highest amount of carvacrol (62%) and gamma-terpinene (26.9%) was obtained in the treatment of severe drought stress and beds containing two tons per hectare of vermicompost in plants inoculated with Streptomyces.
Conclusion: Vermicompost with growth-promoting bacteria can be a sustainable agricultural fertilizer containing beneficial microorganisms that improve the growth performance and essential components of savory plants under drought stress and non-stress conditions.

Keywords

• Essential oil
• plant growth-promoting bacteria
• drought stress
• Satureja hortensis L
• vermicompost

Main Subjects

• Agriculture and horticulture