@ARTICLE{Dehghani Bidgoli, author = {Dehghani Bidgoli, Reza and Azrnejad, Nazanin and Akhbari, Maryam and }, title = {Reducing the effects of drought stress in rosemary (Rosmarinus officinalis L.) plant by using PGPR }, volume = {4}, number = {2}, abstract ={Abstract Introduction: Environmental stresses are one of the most important factors in reducing the yield of medicinal plants and using of plant growth regulators such as PGPR (Plant Growth-Promoting Rhizobacteria) can be a way to reduce the effects of drought stress. Environmental factors, cause changes in the growth of medicinal plants and on the other hand alter the amount and quality of their active substances, such as alkaloids, glycosides, steroids, volatile oils (essential oils). Materials and methods: The experiment was conducted factorial based on a randomized complete block design with 12 treatments in 4 replications at greenhouse of Kashan University. The first factor was irrigation at 3 levels including irrigation at field capacity (FC), mild stress (2.3 FC) and severe stress (1.3 FC), that were applied after establishment of seedlings. The second factor was bacterial growth amount in 4 levels including control (0) and the addition of 10-10, 10-8 and 10-6 molar to the potted soil as a solution before applying drought stress. In order to determine the soil field capacity, soil bulk density was first calculated. Then the soil height was adjusted based on the amount of soil density in the pots. Subsequently, by placing the subfamily on the floor of the pot, saturated water was added to the soil. Then the weight of the pot and the saturated soil was determined by the balance and the pots were covered by plastic. After 48 hours, the pots were weighed again. The weight difference is the amount of gravity water. From the weight fraction of gravity water from the initial water content, the required water for the field capacity was calculated. Results: It was found that the use of PGPR is essential for maintaining the economic performance of plants under stress. The results showed that reduced irrigation had a significant effect on decreasing the growth parameters including dry weight, root length, plant height and essential oil yield. According to the results, the percentage of essential oil with reducing irrigation decreased significantly at 1% level, so that the percentage of essential oil from 0.34% in full irrigation treatment was increased to 0.85% in severe stress and the use of 10-8 molar bacteria. Conclusions: In general, the data of the experiment showed that the use of this bacterium by stimulating the growth parameters and the performance of dry matter of rosemary increased the essential oil yield of this plant and is a suitable strategy for coping with drought stress conditions. Keywords: Bacteria, Stress, Essential oil percentage, Field capacity, Dry weight }, URL = {http://arpe.gonbad.ac.ir/article-1-281-en.html}, eprint = {http://arpe.gonbad.ac.ir/article-1-281-en.pdf}, journal = {2}, doi = {}, year = {2018} }