r. khademian

To evaluate the silicon effects on morphological characteristics as well as the percentage and composition of basil (Ocimum basilicum L.) essential oil under cadmium stress, a factorial greenhouse experiment was conducted in a completely randomized design. The treatments included cadmium metal (Cd) as the first factor at three levels of 0, 25, and 50 mg kg-1 soil and silicon (Si) as the second factor with concentrations of 0, 1, and 2 mM. The characteristics including root length, fresh and dry weight of roots, plant height, fresh and dry weight of stems, stem diameter, number of leaves, fresh weight of leaves, number of buds, number of sub-stems, and percentage and composition of essential oil were evaluated. The results showed that Cd had negative effects on all studied morphological characteristics and significantly decreased their values compared to the control. However, Si treatment improved all these traits and with increasing the concentration of this element, a significant increase in the values of these traits was observed. Application of Si in the concentration of 2 mM caused 63.8, 81, 61, and 61% increase in the number of sub-stems, root fresh weight, stem fresh weight, and number of buds compared to the control, respectively. The amounts of five major constituents of basil essential oil including 1,8-cineole, linalool, estragole, methyl eugenol, and eugenol were affected significantly with the Cd and Si treatments. However, the interaction of these two treatments showed a significant effect only on the three compounds 1,8-cineole, linalool, and methyl eugenol. The maximum amounts of 1,8-cineole (5.06%) and methyl eugenol (6.21%) were observed in the plants which simultaneously exposed to the highest concentrations of Cd and Si. The amount of linalool was also decreased with the presence of Cd and increased with the Si treatment. The Cd treatment increased the amount of estragole by 12.8% and decreased the amount of eugenol by 25.2%. The Si treatment also increased the amount of estragole by 23.9% and decreased the amount of eugenol by 18.3%.

To investigate the effect of mycorrhiza inoculation on increasing the resistance of medicinal plant dill (Anethum graveolens L.) to salinity stress, a factorial experiment was conducted in a randomized complete block design with three replications at the research greenhouse of Imam Khomeini International University, Qazvin province, Iran. The first factor was ecotype at two levels (Isfahan and Varamin), the second factor was salinity at three levels (0, 5 and 10 dS/m), and the third factor was mycorrhiza at three levels (0, 75 and 150 g fungi). The results showed that mycorrhizal inoculation improved all the quantitative traits studied so that under salinity conditions, the plants inoculated with mycorrhiza showed better growth than non-inoculated plants. The highest dry weight, plant height, number of seeds plant-1, and 1000-seed weight were obtained in ecotype Isfahan, salinity level 5 dS/m and 150 g of mycorrhiza. Eleven compounds were identified in dill essential oil. The highest percentage of limonene (7.5%) was obtained from ecotype Varamin plants treated with 5 dS/m salinity and 150 g mycorrhiza. The highest percentage of carvone (86.3%) was obtained in ecotype Isfahan treated with 150 g mycorrhiza and non-salinity.

Safflower (Carthamus tinctorius L.), is an important medicinal plant of Asteraceae family, which is a rich source of pharmaceutically active compounds including phenols, flavonoids and fatty acids. In traditional medicine this plant has been used as an herbal medicine to treat various diseases.

The aim of this study was to evaluate the role of jasmonic acid to protect safflower against drought damages.

The greenhouse experiment was conducted as a factorial experiment in a completely randomized design with three replications. The first factor was irrigation regime, which was applied at four levels: field capacity (FC), 0.8 FC, 0.6 FC and 0.4 FC. The second factor was application of jasmonic acid in three concentrations (0, 0.5 and 1 mM).

According to the obtained results activities of antioxidant enzymes including catalase, superoxide dismutase and glutathione peroxidase, and also the amount of compounds like abscisic acid, proline, malondealdehyde, protein, phenols and flavonoids contents were significantly increased in safflower by enhancement of water stress. Conversely, relative leaf water content (RWC) exhibited a significant decrease due to water deficit. According to the obtained results, application of jasmonic acid can mitigate the adverse effect of drought stress on the mentioned attributes. Also, the amount of main fatty acids in the oil were significantly changed due to water deficient.

The results illustrated that jasmonic acid has an important role in increasing safflower ability to cope against drought stress through improvement of antioxidant enzymes activities and enhancement of secondary methabolites.