The genus Stachys is a member of the Lamiaceae family. These are important medicinal plants which grow all over the world and are known for their flavoring and therapeutic effects and Stachys lavandulifolia is an endemic species of Iran. To acquire high‐quality essential oil (EO), drying technique was implemented which is an essential part of this process. The present study designed to evaluate the influences of different drying techniques (fresh sample, shade, sunlight, freeze‐drying, microwave, and oven‐drying (40, 60, and 80°C) on EO yield and composition of S. lavandulifolia. The results indicated that the maximum EO yield was obtained by the shade‐drying method. The main compounds found in the fresh samples were spathulenol, myrcene, β‐pinene, δ‐cadinene, and α‐muurolol, while spathulenol, cyrene, δ‐cadinene, p‐cymene, decane, α‐terpinene, β‐pinene, and intermedeol were found to be the dominant compounds in the dry samples. Drying techniques were found to have a significant impact on the values of the main compositions, for example, monoterpene hydrocarbons such as α‐pinene, β‐pinene, myrcene, and β‐phellandrene were significantly reduced by microwave drying, oven‐drying (40, 60, and 80°C), and sunlight‐drying methods. Drying techniques increased the antioxidant activity of S. lavandulifolia EOs especially those acquired by freeze‐drying with the half‐maximal inhibitory concentration (IC₅₀) values 101.8 ± 0.8 mg/ml in DPPH assay and 315.2 ± 2.1 mg/ml in decreasing power assay. As a result, shade‐, sun‐, and oven‐drying (40°C) were found to be the most important techniques for attaining maximum yields of EO.

Salinity is a major environmental stress that limits crop production worldwide. It is well-understood that environmental adaptations, physiological and biochemical traits adjust salinity tolerance in plants, but imparting the knowledge gained towards crop improvement remain arduous. Utilizing the potentially of beneficial microorganisms present in the rhizosphere is an alternative strategy to improve crop production under optimal or stress conditions. The current study aims at examining the ability of plant growth-promoting rhizobacteria (PGPR) in improving coriander growth under salt stress condition. Coriander seeds were inoculated via dual culture of Azospirillum brasiliense and Azotobacter chroococcum, and therefore subjected to four levels of salt stress (0, 40, 80 and 120 mM NaCl) with three replications in a research greenhouse. Seventy-five days after sowing, when leaves fully developed, leaf samples were collected and the traits were measured. The results indicated that the dual inoculation improved chlorophyll a and b content, in comparison to the un-inoculated plants. The dual inoculation increased grain yield, stem fresh and dry weights by 11.6, 11.3 and 17.2%, respectively; it also enhanced total plant fresh and dry weights by 6.1 and 10.2%, respectively, as compared to control. As a result, the dual inoculation significantly improved catalase (CAT), but decreased ascorbate peroxidase (APX) and guaiacol peroxidase (GPX) enzymes activities, as compared to control plants. Salt stress significantly increased (CAT) activity in the leaves, whereas it resulted in significant reduction in (APX) and (GPX) activity, especially in inoculated plants. Furthermore, dual inoculation decreased Na and subsequently increased K concentration in coriander leaves comparing with untreated plants. Overall, these results indicate that the PGPRs has improved coriander growth under control as well as salt stress conditions. Thus, PGPR can could significantly contribute to solve the coriander plant production problems caused by high salinity.

Strigolactones (SLs) have been implicated in many plant biological and physiological processes, including the responses to abiotic stresses such as drought, in concert with other phytohormones. While it is now clear that exogenous SLs may help plants to survive in harsh environmental condition, the best, most effective protocols for treatment have not been defined yet, and the mechanisms of action are far from being fully understood. In the set of experiments reported here, we contrasted two application methods for treatment with a synthetic analog of SL, GR24. A number of morphometric, physiological and biochemical parameters were measured following foliar application of GR24 or application in the residual irrigation water in winter wheat plants under irrigated and drought stress conditions. Depending on the concentration and the method of GR24 application, differentiated photosynthesis and transpiration rate, stomatal conductance, leaf water potential, antioxidant enzyme activities and yield in drought conditions were observed. We present evidence that different methods of GR24 application led to increased photosynthesis and yield under stress by a combination of drought tolerance and escape factors, which should be considered for future research exploring the potential of this new family of bioactive molecules for practical applications.

The objective of this study was to evaluate the production, contents, and essential oil (EO) components of sage as a function of the diurnal variation. The EOs from the aerial parts of the plant harvested at different day/night times were extracted by hydro-distillation. Plants were harvested in 2 h intervals (twelve harvesting times during each 24-h day). Harvesting between 4:00 and 6:00 p.m. revealed the highest EO percentage (1.14%), whereas harvesting between 04:00 and 06:00 a.m. indicated the minimum EO percentage (0.599%). The analysis of the EO identified 32 components. The major identified EO compounds were cis-thujone (34.38–46.18%), 1,8-cineol (8.70–11.07%), camphor (9.65–14.38%), and trans-thujone (9.43–14.19%). The highest value of cis-thujone (46.18%) was related to the harvest time of 04:00–06:00 a.m., and the lowest value (34.38%) was recorded at the harvest time of 00:00–02:00 a.m. The highest value of trans-thujone (14.19%) was obtained between 10:00–00:00 p.m., and the lowest value (9.43%) was obtained between 10:00–12:00 a.m. Camphor was another dominant compound where the highest (14.38%) was observed at 00:00–2:00 a.m. Our findings in sage, for the first time, may pave the route towards the optimization of sage EO quality and quantity by selecting the best harvesting time of the plants.

Salinity stress is one of the main limiting factors of medicinal plant growth and may affect their characteristics and chemical composition. In order to evaluate the response of different species of Iranian mint to salinity stress, an experiment was designed in greenhouse conditions. In this experiment, six Iranian mint species were cultivated in pots under different salinity stress including 0, 2.5, 5, and 7.5 dS/m. The chlorophyll indices (a, b, total, and a/b ratio), carotenoids, total anthocyanin, total phenolic and flavonoid content, antioxidant activity, dry matter yield, and essential oil content were measured in two different harvest stages. Salinity stress affected various measured traits. The results showed that despite the negative effect of salinity stress on photosynthetic pigments, in some ecotypes and species, photosynthetic pigments were not affected by salinity stress. The amount of total phenolic content, total flavonoid content, and total anthocyanin increased in response to salinity stress. The dry matter decreased under salinity stress, but the content of essential oil increased as a result of salinity stress increment. The results of PCA biplot showed that the E16 and E18 ecotypes were separated by a large distance. Among the various ecotypes, E18 had the most desirable traits which can be recognized as a salt‐tolerant ecotype. Also, piperita species was the best among the species in all salinity stress levels.