Changes in growth parameters and essential oil content of Satureja bachtiarica Bunge under the effects of 28-Homobrassinolid and drought stress

Environmental stresses, particularly drought stress, are considered as one of the major obstacles in the production of horticultural crops in many parts of the world, especially in arid and semiarid regions like Iran. Brassinosteroids are of plant steroidal compounds with broad biological activities that are able to increase plant performance through changes in plant metabolism and protectecting them against environmental stresses especially drough stress. In a greenhouse study, the impact of three levels of irrigation at field capacity (FC), mild stress (FC2/3) and severe stress (FC1/3) and four concentrations of plant growth regulators of Article 28-Homobrassinolid including zero, 10-10 M, 10-8 M and 10-6 M were investigated on some traits of Satureja Bachtiarica Bunge. The results showed that reducing irrigation had a significant effect on the reduction of growth parameters, including root length, root dry weight, stem diameter, branch number, plant height, shoot yield and total yield. Concentration of 10-8 M 28-Homobrassinolid significantly increased root dry weight, stem diameter, branch number, plant height, and total yield. Oil percentage showed a significant increase at 1% level of probability by reducing irrigation as it increased from 0.36% in full irrigation upto 0.87% in severe stress and use of 10-8 M hormone. Generally, our results showed that the use of 28-Homobrassinolid could increase dry matter yield through stimulating growth parameters and it was considered as as a good strategy to deal with water stress conditions.