Dr. Parviz Moradi,
Volume 6, Issue 19 (3-2018)
Abstract
Thyme is one of the best known genera within Labiatae family, because of its more than 250 species and its antimicrobial and antispasmodic uses. At the present time, demand for thyme products are increasing and hence research demand is increasing. Environmental factors such as drought can affect plant growth and production. Phytohormones take a crucial role in this stress. Indicated T. serpyllum as the most tolerant and T. vulgaris as the most susceptible genotypes to water deficit stress been used. At the end of stress period, shoot dry weight , water content, water potential and soil moisture were measured. Based upon these traits, tolerant plants known as water saver plants, while, sensitive plants behaved as water spender plants. This experiment was conducted at the University of Birmingham, School of Biosciences in 2013. During the stress, leaf samples were harvested and analyzed through mass spectrometry based metabolomics approach. The results of tolerant plants indicated significant increase in drought-stressed plant rather than control plants as follows: 173% increase in salysilic acid, 133% increase in neoxantin (abscisic acid substrate), 166% of auxin and 180% of gibberellic acid. Nevertheless, sensitive plants showed significant increase in jasmonic acid 132%, salysilic acid 242% and decrease in neoxanthin 62% and gibberellic acid 36%. Auxin had non-significant difference between stressed and control plants of sensitive populations. Increasing of neoxanthin in tolerant plants occurred with water content maintenance and decreased shoot dry weight. This experiment confirmed the key role of abscisic acid and salysilic acid in drought stress tolerance mechanism. Even though, it seems overall response of plant to drought stress is the result of all the phytohormones interaction. Increasing ABA precursor caused growth inhibition in drought tolerant plants, which eventually provided less water usage. Since, sensitive plants didn’t exhibit neoxantin elevation, which seems it is due to being lower than water potential threshold.
Kolsoom Sattar, Tahmaseb Asemaneh,
Volume 12, Issue 57 (12-2023)
Abstract
Garden Thyme (Thymus vulgaris L.) is a medicinal plant belonging to the Lamiaceae. The natural distribution and effective substances of some thyme species have been related to the amounts of calcium and magnesium in the soil. Accordingly, in this study, the effects of different calcium to magnesium quotients (0.28, 0.8, 2, 3 (control) and 8), which contain 1 to 3.5, 2 to 2.5, 3 to 1.5, 1.5 to 0.5 and 4 to 0.5 mM calcium to magnesium concentrations, were investigated on the vegetative and physiological charactristics of garden thyme in a hydroponic culture in a completely randomized design. The results showed that the high amounts of calcium and magnesium in the nutrient solution resulted in a significant increase in the leaf chlorophyll, carotenoids and anthocyanins, soluble carbohydrates and total protein content and a decrease in the root and shoot potassium content of the plant compared to the control. On the other hand, at the 8 calcium to magnesium quotient in the nutrient solution, the root and shoot calcium concentrations increased and the magnesium concentration reduced. The highest amount of phenolic compounds of garden thyme was observed at the 8 quotient of calcium/magnesium treatment. The amount of phenolic compounds in the plant decreased compared to control by increasing available magnesium. The calcium to magnesium quotients applied in this study, especially the ratio of 0.8, resulted in a significant increase of average leaf area, fresh and dry weight of root and shoot compared to the control. In general, it can be stated that 8 and 0.8 calcium to magnesium quotients in nutrient solution were the best for the growth of the plant species, and an 8 quotient was the best for phenolic compounds production.
Hadis Zaremanesh,
Volume 13, Issue 60 (5-2024)
Abstract
A factorial experiment using a randomized complete block design with three replications was carried out at Payame Noor University of Lorestan Province to study the effects of potassium sulfate sprays on the traits of Thymus daenensis under salinity stress. The factors were salinity stress (0, 50 and 100 mM sodium chloride) and potassium sulfate sprays (0, 1 and 2 g/L). In the 100 mM sodium chloride treatment, total chlorophyll and chlorophyll a and b contents and leaf relative water content were at their lowest levels (6.7, 4.3 and 11 mg/g fresh weight and 57.8%, respectively). Application of potassium sulfate sprays, especially at 2 g/L, significantly improved these traits. In the 100 mM sodium chloride treatment, carotenoid and proline contents increased by 94% and 195%, respectively, compared to the treatment with no salinity stress, whereas carotenoid and proline contents increased by 17% and 16%, respectively, compared to the control when potassium sulfate was applied at 2 g/L. The highest hydrogen peroxide content was recorded in the treatment in which the plants were under salinity stress (100 mM sodium chloride) and potassium sulfate was not applied. However, application of potassium sulfate (1g and 2 g/L) decreased hydrogen peroxide contents by 22% and 44%, respectively. The highest rates of superoxide dismutase and ascorbate peroxidase activity (9.60 and 0.910 units/mL enzyme extract) were observed under the treatment of salinity stress (100 mM sodium chloride) and the application of potassium spray (2 g/L). In general, salinity levels, especially the 100 mM sodium chloride treatment, led to a decrease in chlorophyll content and relative leaf water content and an increase in carotenoid and proline content traits, hydrogen peroxide, malondialdehyde content, and the activity of superoxide desmutase and ascorbate peroxidase enzymes. On the other hand, the application of potassium sulfate foliar application could greatly reduce the negative effects of stress.
