مجله تحقیقات گیاهان دارویی و معطر ایران
سال چهلم شماره 1 (پیاپی 119، بهار 1403)

Light is one of the environmental factors influencing the growth and development of plants. In recent years, the attention of agricultural experts has been directed to plant growth regulators in order to improve the quality and stability of the cultivation system. The current research was carried out in the year 2021 in the greenhouse of Shahid Fozveh Biological Research Center in a factorial format in the form of a completely randomized design in 5 replications. For this purpose, the effect of test factors including four concentrations of abscisic acid (0, 5, 10 and 20 mg/liter) and 5 day lengths (16, 14, 12, 10 and 8 hours of light) on the growth characteristics and content of photosynthetic pigments. The cannabis plant was evaluated. The results showed that the highest plant height, stem diameter, number of leaves, root length, fresh and dry weight of roots, fresh and dry weight of aerial parts and fresh and dry weight of leaves were obtained under the lighting duration of 14 hours, while the lowest amount of this the traits were observed during the lighting period of 16 hours. Also, the highest amounts of chlorophyll a, b, total and carotenoid were obtained in the treatment of 16 hours of light duration without the use of abscisic acid hormone. While the highest amount of anthocyanin was observed in the treatment of 16 hours of light duration under the treatment of abscisic acid hormone with concentrations of 10 and 20 ppm. Also, the highest amount of total phenol was obtained during the lighting period of 16 hours under the treatment of abscisic acid with a concentration of 20 ppm. Considering the importance and many uses of secondary metabolites in today's human life, investigating the existence of a relationship between environmental conditions and the production and accumulation of secondary metabolites in plants can be very useful. Therefore, it is recommended to use LED light with lighting durations of 14 and 16 hours to increase the growth characteristics and content of photosynthetic pigments of hemp plant.

Teucrium polium L. is a herbaceous plant from the mint family that has many uses in traditional medicine. In recent years, numerous medicinal effects such as anti-diabetes, anti-cancer, anti-spasm, and reducing fat and blood pressure have been reported. Therefore, cultivation of this plant under laboratory conditions is necessary to preserve its survival, reproduction, and increased secondary metabolites. Among the solutions, elicitors in the plant tissue culture technique are one of the most widely used methods to increase secondary-medicinal metabolites. Chitosan, as a biopolymer, induces defense responses, increases antioxidant enzyme activity, and accumulates phenolic compounds. In the present study, the effect of chitosan bio-elicitor was studied on some phenolic compounds of T. polium under in vitro culture to optimize secondary metabolites and increase antioxidant capacity. Leaf explants were prepared from preserved T. polium in hydroponic conditions and fed with Hoagland's solution. After sterilization with sodium hypochlorite 5% (v/v) and ethanol 70% (v/v), middle slices were prepared from the leaf explant and cultured on Murashige and Skoog (MS) culture medium containing separate and combined concentrations of benzyl amino purine (BAP)(1 and 1.5 mg.L-1) and naphthalene acetic acid (NAA)(0.5 mg.L-1). The samples were kept for four weeks in the dark at 25 degrees Celsius. With callogenesis, the samples were transferred to light conditions of 16 hours of light and 8 hours of darkness. At the end of the sixth week, the induced calli were subcultured. The calli were treated with chitosan at different concentrations (0, 50, 100, and 150 mg.L-1). After eight weeks, green calli were collected. Finally, to prepare the final extract for biochemical assays, extraction was done from green calli. The content of phenolic compounds (phenol, flavonoid, flavone, and phenolic acids), antioxidant activity, and phenylalanine ammonialyase (PAL) activity was measured. According to the results, the application of different concentrations of chitosan (0, 50, 100, and 150 mg.L-1) and all hormonal treatments (BAP1, BAP1.5, and BAP1.5+NAA 0.5 mg.L-1) caused a significant increase in the content of phenolic compounds, antioxidant capacity, and PAL activity compared to the control samples. So the application of the simultaneous and combined treatment of BAP at a concentration of 1.5 mg.L-1 with NAA at a concentration of 0.5 mg.L-1, along with the treatment of 100 mg.L-1 of chitosan induced green calli of T. polium in in vitro culture, results in the maximum content of phenolic derivatives (1884.95 for phenol, 936.65 for o-diphenol, 1462.28 for flavonoid, 631.07 for flavone, and 662.41 for phenolic acids). As compared to the control, the antioxidant capacities (measured by DPPH and FRAP assays) increased by 68.34 percent and 71.92 percent, respectively. A significant increase in PAL activity (65.81%) was observed in induced calli. Considering the importance of T. polium as a medicinal plant, chitosan, a successful elicitor, promotes the synthesis of phenolic secondary metabolites. As a result, the increase of antioxidant power and PAL activity in the callus of T. polium.

The Peganum hamala L. medicinal plant belongs to the Nitrariaceae family and is a native species of the Peganum genus in Iran. P. hamala possesses a wide range of unique biological and medicinal properties due to its valuable secondary metabolites like flavonoids, alkaloids, anthraquinones, and volatile oil compounds. Despite the widespread distribution of P. hamala in northern Iran, limited studies were conducted on this plant species adapted to arid and semi-arid ecological conditions. Therefore, in this regard, one of the goals of this research is to evaluate the ecological impact and the effect of fixed latitude and different geographical longitudes of the growing place along with the rhizosphere on some structural and yield traits of P. hamala under nine altitude gradients located in Mazandaran.

To investigate the effect of ecological factors on the structural traits (wet and dry weight of vegetative organs, fresh and dry weight of root, dry matter percentage of vegetative organs, dry matter percentage of root, arch, plant height, plant canopy area, diameter and length of root, and maximum length of stem and crown) and yield traits (fruit diameter, fruit yield, fruit weight, seed weight, average number of seeds, number of fruits, and percentage of seeds in the fruit) of P. hamala, samples of whole plants in the seeding stage were collected from nine different altitude gradients in regions of Khatirkoh (700 and 1000 m), Chahardangeh (1300, 1500, 1700, and 1900 m), and Gadook (2100, 2300, and 2500 m), with three replications along with the substrate soil in a completely random design.

Based on the results of the analysis, yield traits show a positive correlation with atmospheric Based on the analysis, yield traits are positively correlated with atmospheric factors. Furthermore, among the structural traits, stem vegetative traits are positively correlated with precipitation, evaporation, and radiation at the probability level of 5%. They also have a negative correlation with relative humidity at 1%. The increase in height above sea level causes an increase in humidity and a decrease in temperature in the Gadook and Khatirkoh areas. In contrast, it causes decreased humidity and temperature in the Chahardangeh area. Also, crop yield decreases with increasing altitude in all three regions. The maximum yield of the product is observed at 2100 m and 1500 m altitudes. The increase is due to increased silty materials, moisture, EC, and pH. The altitude slope shows a positive correlation with grain yield at 1%. In each region, as height above sea level increases, the root length and diameter increase and decrease, respectively. Stem and root vegetative traits show a negative correlation with seed traits. Also, canopy level with plant height and maximum plant stem arch were positively correlated with plant yield at the 1% probability level. In general, based on the results, by increasing the height gradient from sea level, decreasing the temperature, and increasing the humidity and nutrients of the soil, there is a decrease in vegetative growth and an increase in crop yield. According to the performance feature regression model, as elevation increased, the amount of sand and clay, organic matter, and evaporation increased. This led to an increase in yield with a 60% determination factor. According to the regression model used, the effect of soil factors is higher than weather and climate. Therefore, climate factors change for this plant at a fixed latitude.

According to the results of examining the structural and yield traits of the collected P. hamala ecotypes, yield traits increase with the increase in altitude gradient, the amount of sand and clay, organic substances, evaporation, and decrease in temperature. On the other hand, vegetative traits decrease. Therefore, the Gadook region population is introduced as the superior ecotype with maximum yield traits among these studied regions in Mazandaran province.

The beneficial effects of the chamomile plant have been attributed to its essential oil, so any factor that affects the quantity of its essential oil will be of interest to researchers. To investigate the effect of plant growth regulators salicylic acid and methyl jasmonate on the production of secondary metabolites in chamomile plants, this experiment was conducted under the native in vitro conditions of Sharbian City. To conduct this research, chamomile seeds were collected from Sharbian (N ʺ52 58 37 and E ʺ06 ʹ11 ˚), East Azerbaijan province. After transfer, the seeds were sterilized for 15 minutes in a detergent. Their surfaces were disinfected with 70% alcohol for 45 seconds and then with sodium hypochlorite for 30 minutes. After surface disinfection, they were washed twice with distilled water. The basic culture medium in this study was the MS culture medium. All cultures were placed in the growth chamber at a temperature of 24±2°C and 16 hours of light and 8 hours of darkness. A factorial experiment was performed in a complete random design with three replications. Test treatments included salicylic acid (SA) and methyl jasmonate (MeJA) at five levels (0, 50, 100, 200, 400 μM). Minguez-Mosquera and Perez-Galvez methods were applied to determine photosynthetic pigment amounts. The amount of phenolic compounds in the plant extract was measured with a slight modification based on the Slinkard and Singleton method with the Folin-Ciocalteau reagent. The data related to this research were analyzed using SAS V.9.g.1 statistical software. The comparison of treatment averages was done with Duncan's test at 5% and 1%. Graphs were drawn using Microsoft Excel software. The analysis of variance showed that the interaction effect of the applied treatments on the traits of stem weight, root weight, stem length, and root length is significant at the 1% probability level. In addition, it is significant on the number of stems at the 5% probability level. The comparison of the averages showed that the highest amount of stem weight was obtained in the interaction effect of (50 µM) SA and (200 µM) MeJA, and the lowest amount of stem weight was obtained in the interaction effect of (400 µM) SA and (400 µM) MeJA treatment. The comparison of the means shows a significant difference in this trait. The highest amount of root weight was obtained in the interaction effect of (100 µM) SA and (100 µM) MeJA, and the lowest amount of root weight was obtained in the interaction of (400 µM) SA and (400 µM) MeJA treatment. Came. A comparison of the averages showed that the highest number of stems was obtained in the interaction of (100 µM) SA and (50 µM) MeJA, and the lowest number of stems was obtained in the interaction of (400 µM) SA and (200 µM) MeJA. The comparison of the means showed the significance of the stem and root length traits. The highest value of these two traits was due to the interaction of (50 µM) SA and (100 µM) MeJA treatments, and the lowest value of stem length was in the combination of (400 µM) SA and (µM) treatments. 400) MeJA and root length were measured from the combination of SA (400 µM) and MeJA (200 µM) treatments. In the biochemical traits, variance analysis of the data showed that the effect of SA levels on the amount of chlorophyll a, b, carotenoid, total chlorophyll, phenol, and flavonoid in all three wavelengths was significant at the 1% probability level. In this experiment, it was shown that metabolite production depends not only on enzyme activity but also on stimulant concentration. Increasing the stimulus more than usual not only increases metabolism but also reduces or stops the production of metabolites through the reduction of enzyme activity (probably through the reduction of the corresponding gene expression).

Elicitors are used more frequently to promote plant growth and secondary metabolites. One of the main challenges for tea producers is the slow growth and poor quality of green tea leaves (Camellia sinensis) in tea-growing regions of Iran. In many plants, foliar application of chitosan or nano-chitosan (NC) enhances secondary metabolite production. It has a positive impact on plants' physiological and biochemical indicators. This study investigated the impact of nano-chitosan on some biochemical and physiological parameters with and without mineral nutrition (NPK), as well as assessing the quality of green leaves by comparing the relative expression levels of three enzymes involved in the flavonoids pathway in the Kashef cv. tea plant in northern Iran. For this, two scenarios were used: four different concentrations of nano chitosan solution (0, 25, 50, and 100 mgL-1) were prepared and combined with NPK (1%-1%-0.5%), and without NPK were prepared. At the Lahijan Tea Research Center in Iran, two experiments were conducted as foliar treatments applied twice at two-week intervals, after the first season's harvest in 2021. Twenty days following the initial foliar treatment, plant sampling was conducted to examine physiological, biochemical, metabolic, and molecular characteristics. The first and second leaves, as well as the buds, were gathered for metabolic and molecular testing. The third and fourth leaves were collected for physiological and biochemical analyses. Chlorophyll content and relative water content were measured in physiological experiments. Protein content and the antioxidant enzymes CAT, SOD, and PPO were investigated biochemically. Additionally, metabolic properties were determined using the folin-sio-catheo method as well as HPLC to determine catechins, epigallocatechins, and gallocatechins. Molecular analysis was also performed by examining the relative expression of three critical enzymes in the flavonoid biosynthesis pathway, F3H, DFR, and LAR. The results showed that utilizing NC along with NPK significantly increased the content of total polyphenols in tea compared to the control (without NC and NPK). All treatments reduced catechin content 4- to 6-fold. With an increase in NC concentration, epigallocatechin content increased. Gallocatechin content also revealed a slight increase in 100 mg.L-1 NC concentration. Chlorophyll content indicated a significant difference with a falling trend in treatments with low concentrations of NC; however, a significant difference with a growing trend was seen in treatments with 100 mgL-1 of nano chitosan. In comparison to the control, various NC treatments had similar protein content. Except for the 50 mg.L-1 NC+NPK treatment, there was an apparent significant difference in the SOD enzyme activity in each NC treatment, with a positive trend. With increasing NC concentrations, CAT enzyme activity also rose in various treatments. In treatments with insignificant NC concentrations, PPO enzyme activity significantly decreased. In different treatments, leaf water content rose. Only at a dose of 100 mg.L-1 NC+NPK did the relative expression of the F3H enzyme rise nearly three times compared to the control; in contrast, other treatments had no meaningful effect on relative expression. Different NC+NPK treatments raised DFR relative expression, and 100 mg.L-1 NC demonstrated the highest expression (4 times). Compared to the control, LAR relative expression increased at 0, 50, and 100 mg.L-1 NC and NPK. The treatment without NC and with NPK displayed the highest level of LAR expression, with an expression almost 2.5 times higher than the control. In Kashef cultivar tea plants, chitosan nanoparticles in various concentrations coupled with NPK increased the production of catechin compounds. This effectively reduced oxidative stress and enhanced green tea leaf quality. In addition to addressing oxidative stress, NC may play a practical role in green tea quality. Due to its biodegradable properties, nano chitosan can be used instead of chemicals to improve tea plants' green leaves quality and lower environmental pollution.

Basil (Ocimum basilicum L.) is an annual herbaceous plant belonging to the mint family (Lamiaceae). Its fresh and dried leaves and essential oils are used in the food, pharmaceutical, and cosmetic industries. In recent years, the use of symbiosis with plant beneficial rhizospheric microorganisms including rhizobacteria and endophytic fungi has been considered as a cost-efficient and sustainable strategy to alleviate the adverse effects of environmental stresses such as salinity. Therefore, the present study was conducted in the research greenhouse of Urmia University. It evaluated the effect of inoculation with growth-promoting microorganisms on some growth, physiological, and phytochemical characteristics of basil plants under salt-stress conditions. This research was conducted as a factorial experiment in a completely randomized design with three replications. The experimental factors were inoculation with microorganisms at three levels (control without inoculation, inoculation with Serendipita indica, and inoculation with a mixture of Pseudomonas areuginosa, P. putida, and P. fluorescens) and salinity stress at four levels (0, 40, 80 and 120 mM of NaCl). For inoculation, the germinated seeds were separately inoculated with S. indica suspension (5×105 spores per ml) and inoculum containing a mixture of Pseudomonas bacteria (1.61×109 cells per ml) and planted in prepared pots. The pots were irrigated with ordinary tap water until the plants were eight-leafed, and from this stage onwards, salinity stress treatments were applied by dissolving different concentrations of NaCl in the irrigation water and continued until the full flowering stage. In the full flowering stage, plant samples were collected and root colonization percentage by fungus, growth parameters (plant height, stem diameter, number and total length of lateral branches, leaf number and area, inflorescence length, fresh and dry weight of leaf and stem), leaf relative water content (RWC), photosynthetic pigments, concentration of leaf nutrients (N, P, K, Na and Cl), essential oil content and yield were evaluated. For essential oil extraction, shade-dried samples were hydro-distilled using a Clevenger-type apparatus. The results showed that due to salinity stress, the percentage of root colonization by S. indica, growth parameters, RWC, photosynthetic pigments, essential oil content, yield, N, P, and K content, and K/Na ratio decreased while Na and Cl content increased. In addition, all evaluated parameters in inoculated plants were higher than in non-inoculated plants except Na and Cl content. The highest and lowest rates of growth parameters, RWC (74.47 and 72.39%), essential oil yield (0.23 and 0.17 ml/pot), and N content of leaves (1.36 and 1.14%) were obtained in plants inoculated with S. indica and non-inoculated plants, respectively. The highest and lowest amounts of chlorophyll a (0.87 and 0.74 mg/g fw), chlorophyll b (0.41 and 0.37 mg/g fw), essential oil percentage (1.24 and 1.05%), K content (5.15 and 3.97%), P content (0.29 and 0.24%) and the K/Na ratio (10.05 and 4.07), were observed in plants inoculated with a mixture of Pseudomonas bacteria and non-inoculated plants, respectively. Also, the lowest Na (1.34%) and Cl (2.93%) accumulation was observed in plants inoculated with Pseudomonas bacteria and S. indica fungus, respectively. According to the results of this study, the use of plant growth-promoting microorganisms (S. indica fungus and a mixture of Pseudomonas bacteria) can alleviate adverse effects of salinity stress on the growth and essential oil production of the basil plant by increasing the absorption of water and nutrients, preserving photosynthetic pigments and reducing the accumulation of toxic ions.

Stress affects the body's systems and can lead to many disorders, including depression. To deal with stress and depression, the use of medicinal plants that have fewer side effects than chemical drugs has attracted the attention of researchers. Melilotus officinalis L. contains compounds such as coumarin, flavonoids, triterpene, saponin, and volatile oils with anti-inflammatory and antioxidant effects. The present study investigated the effect of the hydroalcoholic extract of the M. officinalis plant on depression caused by chronic immobility stress in adult male rats.

In this experimental study, 48 male Wistar rats weighing 250-300 grams were used. The rats were randomly divided into 6 groups of 8 (n=8) including control (intact), sham (under chronic immobility stress and receiving normal saline), experimental groups (under chronic immobility stress and subjected to doses 25, 50, and 100 mg.kg-1 of M. officinalis extract), and the positive control group (under chronic immobility stress and receiving fluoxetine). To establish an animal model of chronic immobility stress, the rats were placed in the restraint device daily for 2 hours, for 3 weeks. Injections were made intraperitoneally (IP), 30 minutes before stress induction. The depression model was evaluated by the Forced Swimming Test (FST) and motor activity by the Open Field Test (OFT). Then with deep anesthesia in the animals, blood was taken from the heart. By separating the serum, the amount of corticosterone in the rats’ blood was evaluated and measured using special kits and the ELISA method.

The results of this research showed that in the sham group, the duration of immobility in the FST increased significantly in comparison to the control group (P<0.001). In the experimental groups, a high dose of M. officinalis extract led to a significant increase in the duration of immobility in the FST (P<0.01). However, the lower doses of the extract led to a significant decrease in immobility duration compared to the sham group (P<0.001) (P<0.01). The fluoxetine-receiving group also showed a significant reduction in immobility duration compared to the sham group (P<0.01). Lower doses of M. officinalis extract caused a significant increase in blood corticosterone relative to the sham group (P<0.001). Administration of fluoxetine also caused a significant increase in corticosterone levels in the blood in comparison to the sham group (P<0.001). In the OFT, the number of crossing lines in the sham group showed a significant increase relative to the control group (P<0.01) in the experimental groups, a high dose of M. officinalis extract resulted in a significant decrease in the number of times the rats crossed the lines in comparison to the sham group (P<0.01).

Phytochemical studies have shown some active substances, such as quercetin and phenolic acids in M. officinalis, which have antioxidant and antidepressant activity by inhibiting monoamine oxidase and increasing dopamine and serotonin. Therefore, due to active biological molecules, M. officinalis can play a vital role in preventing depression. The results have also shown that M. officinalis extract, particularly in lower doses, has better antidepressant effects in rats under chronic stress.

Deficiency or excess of any growth factor leads to morphological, anatomical, physiological, and growth disorders in plants. Drought stress means a lack of water in the plant. This situation occurs when the amount of transpiration exceeds the amount of water absorption. Low irrigation (watering less than the optimal water requirement of the plant) is a strategy to save water, but it affects the plant at a particular stage of growth or the entire season. Biofertilizers develop the root system, changing host plant water relations and plant metabolism. They also activate the defense system, improving access to minerals and tolerance to drought in the host plant, making it environmentally friendly and natural. To manage the prevailing water crisis, one should look for solutions such as reducing water consumption and stopping irrigation at all stages of growth. This is without harming the plant's final performance. In addition, due to the importance of medicinal plants and increasing their biomass, biological fertilizers and the adjustment of drought stress effects have a special place. This experiment was carried out to investigate the effectiveness of Satureja bachtiarica Bunge. against dehydration at different stages of growth. It also investigated the consumption of mycorrhizal fungi and growth-stimulating bacteria to manage plant production with high quality and quantity.

The experiment was carried out in the form of split plots in the form of a randomized complete block design in three replications in the research farm of Islamic Azad University, Tabriz branch, in 2018. The main and sub-factors were included in 4 water stress (I1: without stress, I2: cut irrigation in stem elongation stage, I3: cut irrigation at the budding stage and I4: cut irrigation at 50% flowering stage) and 5 biofertilizer levels (b1: without inoculation, b2: inoculation with Funneliformis mosseae, b3: inoculation with Rhizophagus irregularis, b4: Funneliformis mosseae + Rhizophagus irregularis and b5: Azosprillium+Pseudomonas+Azetobacter), respectively. The harvest was in full flowering stage.

The comparison of the average of irrigation interruptions showed that the most number of leaves, stem diameter, canopy extent, root weight, leaf yield, flowering stem yield, and flowering branch yield belonged to the irrigation interruption at the 50% flowering stage. Inoculation with Funneliformis mosseae mycorrhizal fungus achieved the highest leaf yield (912.06 kg/ha), flowering stem yield (1071.25 kg/ha) and flowering branch yield (1983.32 kg/ha) in inoculation with Azosprillium + Pseudomonas + Azotobacter was observed. The highest percentage of essential oil was found in inoculation with Funneliformis mosseae with an average of 1.76%. The maximum average yield of essential oil at 30.50 kg/ha was observed in the inoculation treatment with Azosprillium + Pseudomonas + Azotobacter. The results of the comparison of the average of the interaction effect showed that the maximum height of the plant and the number of inflorescences with an average of 61.72 cm and 30.46 per plant were found in the interaction effect of the treatment of interruption of irrigation at the stemming stage and inoculation of Rhizophagus irregularis + Funneliformis mosseae, which is about 31 and 39 The percentage increased compared to their lowest value. Stopping irrigation in the budding stage ×Funneliformis mosseae had the highest percentage of essential oil with an average of 2.33%. Stopping irrigation in the stemming stage ×Rhizophagus irregularis had the lowest essential oil percentage. The highest leaf yield (1212.83 kg/ha), flowering stem yield (1494.75 kg/ha), flowering branch yield (2707.58 kg/ha) and essential oil yield (44.39 kg/ha) in the interaction effect of cutting × Azosprillium + Pseudomonas + Azotobacter irrigation was observed at the 50% flowering stage, which increased by 70, 82, 81 and 87% compared to the lowest ones.

The correct management of soil fertility, improvement, and maintenance of soil fertility in modern agricultural systems will provide the nutrients needed by the plant and thus enhance the yield. Therefore, in recent years, many studies have been conducted on biological fertilizers. Mycorrhizal fungi are essential factors in the stable plant-soil system, which coexists with more than 85% of plants. Drought stress is one of the most influential environmental factors in plant growth and causes morphological, physiological, and metabolic changes. In addition, biofertilizers increase plant access to nutrients and produce and direct hormones involved in the growth of the root environment. They also increase stress tolerance and enhance yield. Considering the arid and semi-arid conditions of the country and the increase in demand for medicinal plants and Satureja bachtiarica spices, it is recommended to stop irrigation at the 50% flowering stage and use Azotobacter, Azospirillium, and Pseudomonas biofertilizers to obtain the maximum yield of leaves, flowering branches, and essential oil.

Cumin (Cuminum cyminum L.) is one of the oldest aromatic plants in the world, known medicinally as the second domesticated medicinal plant in Iran. Drought stress, as oxidative stress, affects plant biochemical, physiological, and morphological responses. One of the ways to increase plants' resistance to environmental stress is to use plant growth regulators such as brassinosteroids and melatonin. These hormones increase plant performance in both stress and non-stress conditions. Plant growth regulators, by affecting plant metabolites, stimulating phytohormone biosynthesis, enhancing nutrient absorption, improving defense mechanisms, stimulating root growth, and improving gas exchange, contribute to plants' quantitative and qualitative performance in stress and non-stress conditions. Although some research shows that the use of plant growth regulators such as brassinosteroid and melatonin, which are of natural origin and compatible with the environment, has a significant effect on reducing adverse effects caused by environmental stresses; however, the combined use of these plant hormones is less reported. Therefore, in this research, the influence of the foliar application of brassinosteroid and melatonin on some physiological traits, including amount of malondialdehyde, hydrogen peroxide, electrolyte leakage, activity of antioxidant enzymes, accumulation of carbohydrates and proline, malondialdehyde, hydrogen peroxide as well as quantitative and qualitative yield of cumin was examined under water deficit conditions.

This research was conducted in the research greenhouse of the Faculty of Agriculture, Shahid Bahonar University, Kerman, Iran. A factorial experiment in a randomized complete block design with six replications was carried out in 2022. The experimental treatments included different levels of drought stress (100 % and 50 % field capacity; F.C.), melatonin (0 and 100 μM), and brassinosteroid (0 and 0.75 μM).

The results showed that water deficit increased the amount of malondialdehyde, hydrogen peroxide, electrolyte leakage, activity of antioxidant enzymes (peroxidase (POD), catalase (CAT), and ascorbate peroxidase (APX) and superoxide dismutase (SOD)), as well as raised the accumulation of carbohydrates and proline in cumin plants. Indeed, brassinosteroids and melatonin significantly increased antioxidant enzyme activities and the concentrations of osmolytes. It also decreased the levels of malondialdehyde, hydrogen peroxide as well and electrolyte leakage in drought-stressed plants. Drought stress resulted in reduced cumin grain yield. In contrast, under these conditions, the percentage of cumin seed essential oil was increased. Foliar application of brassinosteroid and melatonin in stress and non-stress conditions improved cumin yield.

Overall, it was concluded that the use of brassinosteroid and melatonin increased the resistance of cumin plants against drought stress by increasing the activity of antioxidant enzymes, increasing the accumulation of compatible osmolytes such as proline and carbohydrate, and maintaining the stability of the membrane and ultimately enhancing the yield of cumin seeds. The application of melatonin and brassinosteroid also affected the quality of the product and increased the percentage of cumin essential oil; however, the positive effects of brassinosteroid and melatonin were greater than those of brassinosteroid or melatonin applied separately.

Awareness of changes in medicinal plant yield quantity and quality over time is one of the most important goals in agricultural management. Satureja mutica is one of the valuable medicinal species growing in Iran. This study was conducted to evaluate the effects of different planting beds on changes in vegetative characteristics and essential oil components over the years of growth in S. mutica under rainfed conditions. The experiment was conducted in the form of split plots in a randomized complete block design for three years (2018-2020) in the rainy conditions of Feridounshahr city, Isfahan province. Planting beds as the main plot included cow manure (30 tons per hectare), wheat straw (10 tons per hectare), and control (without cow manure and wheat straw). After the preparation of the field, the seedlings were planted at the bottom of the wells created at a distance of 50 x 50 cm from each other. During the growing season and at the time of 50% flowering, the studied traits including total plant dry weight, leaf and stem dry weight, plant height, crown diameter per plant, canopy area per plant, and in each square meter of land and the number of stems per plant were measured. For essential oil extraction, the flowering branches of the plants were harvested at the full flowering stage. After drying in the shade, the essential oil was extracted by the water distillation method. After determining the yield of essential oils based on the dry weight of the plant, the essential oils were analyzed and identified by gas chromatography, and gas chromatography was connected to a mass spectrometer in the phytochemistry laboratory of the Research Institute of Forests and Rangelands. Considering that the plant is several years old and measurements are carried out every year on fixed plots, the design analysis was done on divided plots at the time of implementation. The SAS computer program was used to perform statistical calculations, and the LSD test was applied to compare the means. For essential oil extraction, the flowering branch of the plant was harvested at the full flowering stage. After drying in the shade, the essential oil was extracted by the water distillation method. After determining the yield of essential oils based on the dry weight of the plant, the essential oils were analyzed and identified by gas chromatography, and gas chromatography was connected to a mass spectrometer in the phytochemistry laboratory of the Research Institute of Forests and Pastures. The SAS computer program was used to perform statistical calculations, and the LSD test was used to compare the means. The variance analysis of the data showed that the effects of bed, year, and their interaction effects on the measured traits were significant in many cases. Results showed that the highest values of plant height, crown diameter, canopy area, and number of stems per plant in the first year were seen in manure treatment. In the last year, they were in control. The highest rates of total dry weight, leaf dry weight, essential oil yield, and essential oil percentage were observed in control in the last year. These rates were 1427, 891, 42 kg ha-1, and 4.67%, respectively. The main essential oil components are thymol, carvacrol, p-cymene, and gamma-terpinene. These essential oil components are affected by the planting bed and the growth year. So in the case of p-cymene, the highest amount obtained in the first year was in the straw treatment. The highest amounts of gamma-terpinene were observed in all three planting bed treatments in the last year of growth. S. mutica had significant amounts of thymol, and the trend of changes among planting bed treatments and during growing years was very small. The highest amounts of carvacrol were observed in straw treatment and animal manure in the second year of growth. The results of the correlation coefficients showed that the most vital traits affecting essential oil yield were total dry weight, leaf and stem, and essential oil percentage. Thymol and p-cymene were inversely correlated with carvacrol and gamma-terpinene. On the whole, to produce S. mutica under rainfed conditions similar to this study, manure or straw could affect yield and essential oil over the first and second years; however, in the third year, this effect diminished, and control treatment was superior to straw and manure treatments.

Drought stress is the most critical factor limiting agricultural and medicinal plants' performance in arid and semi-arid areas. Silybum Marianum L. is a medicinal plant with antioxidant properties. In addition to the plant's genetic nature, flavonolignan production and accumulation are affected by various environmental conditions. The accumulation of secondary metabolites under drought stress was studied concerning the antioxidant defense system at the biochemical level. The purpose is to evaluate the secondary metabolites of milk thistle under non-stress conditions and different levels of drought stress and different growth conditions, as well as to identify the best level of moisture stress and the time of harvesting the plant to increase the effective compounds. Milk thistle seeds were disinfected and transferred to a Petri dish containing filter paper and placed in a germinator at 25°C for germination. The germinated seeds were transferred to the pots and put under controlled temperature and humidity in the greenhouse of Hirmand city, Shandel village, located 25 km from Zabul city, Sistan, and Baluchistan province. Evaluation of the effect of drought stress at four different levels of irrigation (25, 50, 75, and 100% of water requirement respectively severe stress, moderate stress, mild stress, and non-stress) and in 3 growth stages (6, 13 and 20 weeks after planting) on biochemical traits including proline content (PC), carbohydrates content (CC), total phenol content (TPC), total flavonoid content (TFC), antioxidant activity and activity of antioxidant enzymes such as catalase (CA), ascorbate peroxidase (AP), guaiacol peroxidase (GP), superoxide dismutase (SOD) and polyphenol oxidase (PO) was carried out. The experiment was done as a factorial based on a completely randomized design with three replications. Data and errors were examined for normality. After confirming the normality of the data and errors, analysis of the variance of the traits and comparing the mean of the traits (LSR) was done at the 5% level. The variance analysis of traits showed that the effect of different levels of irrigation, harvest time, and their interaction on all traits was significant. Comparison of the average interaction effect of irrigation treatment and harvest time of traits: proline content, carbohydrates content, phenol and flavonoid content, and antioxidant activity increased in all growth stages and the lowest and highest values were respectively observed in the growth stage 6 weeks after planting in 100 Percentage of water requirement and growth stage 20 weeks after harvesting in the condition of 25% water requirement. Therefore, the drought stress factor can be used to improve the effective substances of this plant. In addition, the final growth stage is the most appropriate time to harvest this plant due to the accumulation of secondary metabolites at this stage. The interaction effect of irrigation treatment and harvest time was not significant for the activity of guaiacol peroxidase enzyme, and for other antioxidant enzymes it showed that the highest activity of catalase enzyme was at the growth stage 6 weeks after planting in conditions of 25 and 50% water requirement, for ascorbate peroxidase enzyme, it belonged to the growth stage 6 weeks after planting in the condition of 100% water requirement, and for polyphenol oxidase and superoxide dismutase enzymes, it belonged to the growth stage 20 weeks after planting in the condition of 25% water requirement. These results indicate that antioxidant enzymes act differently at different growth stages and under various moisture stress conditions. The evaluation results of milk thistle in 4 irrigation regimes and three growth stages showed that most biochemical traits increased under stress conditions. This indicates that the milk thistle plant responds to drought stress through an enzymatic and non-enzymatic antioxidant defense system. Milk thistle plants had the highest total phenolic and flavonoid content at the final development stage (20 weeks after planting). Therefore, the best time to harvest is at the final stage of development, which has the most polyphenolic compounds.