Quantification of changes in morphophysiological and biochemical criteria of Satureja rechingeri Jamzad under salinity stress using nonlinear models

Satureja rechingeri Jamzad, a member of the Lamiaceae family, is a species endemic to Iran, which has a wide distribution in southern Iran (mainly Khuzestan and Ilam). This plant has many medicinal properties and the main composition of its essential oil is carvacrol (48 to 95%). Carvacrol is mainly involved in biological activities and used in the production of substances such as antibiotics and antioxidants. Drought and salinity stress are the main limiting factors for successful production and yield of crops in Iran and the world. Salinity alters metabolic processes and the activity of enzymes. One of the biochemical changes that occur in plants when exposed to saline environments is the increase in the production of oxygen free radicals. Little is known about the tolerance of this plant to salinity stress. Therefore, this study was performed to quantify the morphophysiological and biochemical responses of Satureja rechingeri to salinity stress using nonlinear models.

This experiment was conducted in a completely randomized design with four replications in greenhouse conditions during 2016-2017. Rooted cuttings were prepared from Khorman Pharmaceutical Company located in Khorramabad (Lorestan) and transferred to the research greenhouse for the Department of Horticulture and Landscape Engineering, Campus of Agriculture and Natural Resources, University of Tehran, located in Karaj (Alborz). Rooted cuttings were kept under favorable conditions for about a month and then transplanted into pots. Six weeks after full establishment, the plants were exposed to different concentrations of sodium chloride (0, 2, 4, 8, and 16 dS / m). Parameters including membrane stability, malondialdehyde level, activities of superoxide dismutase and ascorbate peroxidase, proline content, total phenol, plant height, leaf length and width, stem diameter, herbal fresh and dry weight, and percentage and yield of essential oil were measured. Logistic, sigmoid, and peak models were used to quantify these parameters.Findings and

The effect of salinity stress on most of the parameters was significant (except for stem diameter and essential oil percentage). With increasing NaCl salt concentration, in plants under salinity stress, membrane leakage (250%), proline content (430%), catalase (360%), ascorbate peroxidase (550%), superoxide dismutase (320%), total phenol (350%), and malondialdehyde (280%) increased. Salinity decreased plant height (14%), leaf length and width (21% and 23%), fresh weight of shoot (35%), dry weight of shoot (15%), and essential oil yield (15%). Moreover, changes in morphological characteristics under salinity stress were logistic and in biochemical properties (except those in ascorbate peroxidase, which was peak) were sigmoid.

Satureja rechingeri tolerated salinity up to 4 dS / m, but at higher salinities, herbal fresh and dry weight and plant height significantly reduced.