Journal of Medicinal Plants Biotechnology

Abstract To investigate the effect of proline and gamma-aminobutyric acid on the quantitative and qualitative traits of medicinal plant chamomile (Matricaria chamomilla L.) under water deficit stress, an experiment was conducted according to split plots design with a completely randomized block arrangement with four replications during the spring and summer of 2024 in the research greenhouse at the University of Zanjan. The main factor consisted of two irrigation levels (70 and 100% of field capacity) and the subplots included foliar applications of two levels of proline (0.5 and 1 mM), gamma-aminobutyric acid (0.5 and 1 mM) and control treatment (distilled water).
The results showed that the highest chlorophyll a content (1.40 mg/g fresh weight) was achieved under 100% field capacity irrigation combined with 1 mM proline. Foliar application of 0.5 mM proline under 70% irrigation level resulted in the highest phenolic content (4.78 mg gallic acid/g dry weight) and the greatest total antioxidant activity (51.75%). The maximum flavonoid content (1.49 mg quercetin/g dry weight) was observed with 0.5 M GABA treatment. Additionally, the highest thousand-seed weight (148 mg) was recorded under full irrigation (100% field capacity) with 1 mM proline, compared to the control. Overall, the combined application of 0.5 mM proline and GABA was most effective in mitigating the adverse effects of drought stress on chamomile.

Abstract Thyme is one of the most important medicinal plants which grows naturally in wide areas of range lands in Iran and simultaneously is cultured widely in Iran and other parts of the world. As Iran has placed in arid and semi-arid regions of the world, with actually low precipitation, doing projects in order to reveal the mechanisms or increase the drought tolerance of crop and medicinal plants has great value. Drought stress decreases the yield and quality of medicinal plants as well as crops. To investigate the mechanisms of drought tolerance of thyme plants and to evaluate the possibility of increasing of drought tolerance in these valuable medicinal plants, activity of some antioxidant enzymes and total soluble proteins were been analyzed in Thymus vulgaris L.in a complete randomized design experiment. After reaching to the adequate stage of growth, seedlings were grown in pots containing suitable soil, were subjected to different levels of drought stress (80% as control, 60% and 40% irrigation of field capacity(FC) as treatments). Results show that, drought stress had significant effect on total protein content as well as the activity of antioxidant enzymes. At 60% FC treatment and especially at 40% FC the amount of total soluble proteins drastically decreased. However; the activity of catalase increased at 60% FC treatment. The activity of peroxidase did not change significantly at 60% treatment but its activity decreased at 40% treatment. As a conclusion; it can be suggested that, one of the drought tolerance mechanisms of thyme is increasing of the activity of antioxidant enzymes especially the activity of catalase.  

Abstract In order to investigate the effect of drought stress on vegetative growth and physiological characteristics of Damask rose, a factorial potted experiment was conducted in a randomized complete block design with three replicates. Treatments include three levels of Nanozeolite and four Irrigation intervals, which were performed in a roofed space with sufficient light. After determining the field capacity and soil wilting point, the reference weight was determined in terms of field capacity, and drought treatments were applied based on soil moisture. Various morphological factors, including diameter growth, seedling height, leaf number, leaf area, and aerial and terrestrial biomass were determined after applying stress. The results indicated that the highest total plant weight and shoot dry weight were obtained in 10g Nanozeolite treatment and irrigation interval  four days. The interaction effect of Nanozeolite and irrigation intervals on fresh and dry leaf weight was significant and reached its maximum in 10g Nanozeolite and irrigation interval four days treatments. Nanozeolite affected the number, length, volume, and dry weight of Damask rose root significantly, and consumption of 10g of Nanozeolite improved these traits. Irrigation intervals significantly affected all measured traits except shoot dry weight, the number of roots, plant height, and leaf relative water content. In general, it can be concluded that the use of Nanozeolite in low concentrations has improved growth indices and the application beyond the desired limit for the drought-tolerant Damask rose plant has adverse effects.

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