Medicinal Plants
Mohammad Bagher Razavinia; Nasibeh Pourghasemian; Farzad Najafi
Abstract
IntroductionHeavy metals, like cadmium, lead, and arsenic, harm air, soil, agriculture, and human health. Plants suffer from reduced growth, chlorophyll production, and enzyme activity due to heavy metal exposure. Reactive oxygen species are produced, damaging biological molecules. However, plants ...
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IntroductionHeavy metals, like cadmium, lead, and arsenic, harm air, soil, agriculture, and human health. Plants suffer from reduced growth, chlorophyll production, and enzyme activity due to heavy metal exposure. Reactive oxygen species are produced, damaging biological molecules. However, plants have developed resistance mechanisms, including antioxidant stimulation. Flavonoids, complex compounds in plants, enhance resistance to heavy metals. Medicinal plants, rich in secondary metabolites like flavonoids, phenolic compounds, and alkaloids, show resistance to heavy metals. Origanum majorana as a medicinal plant, contains compounds that contribute to its heavy metal resistance. Based on limited studies, medicinal plants, particularly marjoram, have shown greater resistance to environmental stresses due to their secondary metabolites and the ability to produce uncontaminated essential oils in response to heavy metals like cadmium and lead. This study aimed to investigate the biochemical responses and growth of marjoram plants when exposed simultaneously to cadmium and lead, as well as the mutual effects of these two elements on marjoram behavior. Materials and Methods A factorial randomized complete block design experiment with four replications was used to study the effect of Cd in four concentrations (0, 6, 12 and 24 mg.kg-1 soil) as well as Pb in four concentrations (0, 150 300 and 450 mg. Kg-1 soil). The concentrations were determined based on previous reports and a preliminary experiment. Soil was prepared with appropriate amounts of cadmium chloride and lead chloride were added according to the desired concentrations. The contaminated soil was then incubated at field capacity moisture for two months. Seeds have been sown in germination trays. Seedlings at the three to four leaf stage were transferred to pots containing the contaminated soil. Plant harvest took place 42 to 52 days after the transfer to pots, specifically when the plants had just entered the flowering stage. The aboveground parts of the plants were harvested separately, and the roots were carefully removed from the soil. Half of the plants were dried at 105 °C for 24 h to determine the dry weight, Pb and Cd concentrations. The other half of the plants were used to measure biochemical traits including flavonoids, anthocyanins, malondialdehyde, protein, proline and some enzymatic antioxidants. The data was analyzed using a two-way analysis of variance (ANOVA), and the means were compared using the LSD test. A significance level of 95% was applied using SAS 9.2. Results and DiscussionIn this study, various parameters were measured including the dry weight of aerial parts and roots, concentrations of lead and cadmium in the aerial parts and roots, lipid peroxidation (MDA), flavonoids, anthocyanins, total phenols, proline, protein, and antioxidant enzymes including guaiacol peroxidase (GPX), ascorbate peroxidase (APX), and catalase (CAT). The results of the analysis of variance showed that all the mentioned traits were influenced by the individual effects of lead and cadmium. However, there was no significant interaction between cadmium and lead on proline, protein, GPX, polyphenols, flavonoids, and anthocyanins. The dry weight of aerial parts and roots decreased in the presence of cadmium and lead, while the concentrations of lead and cadmium increased. However, this damage was more pronounced in the presence of cadmium compared to lead. The presence of cadmium in a lead-containing environment had an inhibitory effect on lead uptake by the plant, and vice versa. The highest level of MDA was reported in the combination of lead and cadmium concentrations of 450 and 24 mg/kg, respectively. The analysis of enzyme activity showed that the maximum catalase activity was observed in the combination of 6 and 450 mg/kg of cadmium and lead, respectively, while the minimum activity was found in the control group. Similarly, the highest APX activity was reported in the combination of 24 mg/kg of cadmium and zero lead, while the lowest activity was observed in the control group. The use of cadmium and lead at the highest consumption level compared to the control group resulted in a 204% and 40% increase in GPX activity, respectively. In the analysis of total phenols, flavonoids, anthocyanins, and protein, an increase in cadmium concentration from zero to 24 mg/kg led to a decrease of 52%, 42%, 208%, and 81%, respectively, while protein decreased by 39%. These traits showed an increase of 14%, 14%, 58%, and 40%, respectively, with an increase in lead concentration from zero to 450 mg/kg, while protein decreased by 24%. Based on the results, it appears that the increase in secondary metabolites with the increase in heavy metals has accompanied the plant's response to the prevailing conditions. Conclusion The study found that both cadmium and lead negatively affect the dry weight of plants, with cadmium having a greater impact. This reduction is particularly noticeable in photosynthesis, pigments, electron transport chain, and energy production. The highest concentrations of lead and cadmium (24-450 mg/kg) show the maximum decrease. As the concentrations of these elements increase in the growth medium, their concentration in the plants also increases. Lead has lower mobility and tends to accumulate in the roots compared to cadmium. Interestingly, the presence of cadmium inhibits the uptake of lead by the plant, and vice versa. This leads to an average inhibition of 39% for lead uptake by cadmium and 35% for cadmium uptake by lead in the aerial parts. The study also observed an increase in secondary metabolites, which act as antioxidants and help the plant cope with the stresses caused by cadmium and lead. These metabolites may also contribute to osmotic regulation along with the increase in proline. Based on these findings, it seems that these plants can be used in green spaces contaminated with moderate to low levels of cadmium and lead, particularly in mining areas.
Seyyed Mohammad Bagher Razavi nia; Nasibeh Pourghasemian; Farzad Najafi
Abstract
Introduction: Pollution of the biosphere with toxic levels of metals has accelerated dramatically since the beginning of the industrial revolution. Soil pollution by heavy metals including cadmium (Cd) and lead (Pb) is a global problem, which can cause agricultural lands to become hazardous for wildlife ...
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Introduction: Pollution of the biosphere with toxic levels of metals has accelerated dramatically since the beginning of the industrial revolution. Soil pollution by heavy metals including cadmium (Cd) and lead (Pb) is a global problem, which can cause agricultural lands to become hazardous for wildlife and human populations. Accumulated Cd and Pb in their roots and shoots may also be negatively affect their photosynthesis, growth, and reproduction. Cd and Pb uptake and their effects on plants may be influenced by a variety of factors, e.g. the plant species, cultivar, soil characteristics and etc. Heavy metals such as Cd and Pb may cause the formation of reactive oxygen species (ROS), damage plant tissue membranes, and inhibit photosynthesis, carbon dioxide assimilation, and growth. Photosynthesis is the fundamental process of energy metabolism and therefore, closely related to the plants growth and productivity. However, it is a sensitive process and an important target of environmental stresses. Plants counteract the harmful effects of heavy metals by a variety of protective mechanisms including immobilization, exclusion, chelation, compartmentalization, osmotic regulation and elevating antioxidant system.
Lemon balm (Melissa officinalis L.) is a widely grown aromatic and medicinal plant of the Labiatae family. The plant has various therapeutic properties and is also used to flavor different food products due to its particular taste. Little scientific data exist on the response of this medicinal plant to Cd and Pb stress. Therefore, the objective of this work was to investigate the biological and physiological responses of lemon balm (Melissa officinalis L.) under cadmium and lead stress conditions.
Materials and Methods: A factorial randomized complete block design experiment with four replications was used to study the effect of Cd in four concentrations (0, 6, 12 and 24 mg.kg-1 soil) as well as Pb in four concentrations (0, 150 300 and 450 mg. Kg-1 soil). Before harvesting, chlorophyll fluorescence, photosynthetic and transpiration rates were measured with fluorescence meter and photosynthetic meter, respectively. Thereafter, plants were harvested and the roots were washed in distilled water. Then, half of the plants were separated into roots and shoots, which were dried at 105 °C for 24 h to determine the dry weight, Cd and Pb concentrations, Cd transfer factor and essential oil content. The other half of the plants were separated into roots and shoots, kept in liquid nitrogen, and then stored in freezer for one week to determine proline and shoot MDA concentrations. Data were subjected to two-way analysis of variance (ANOVA) and the difference between means was compared using LSD test. A significance level of 95% was applied by SAS 9.2.
Results and Discussion: According to the results, root and shoot dry weight, protein content, photosynthetic rate, transpiration rate and chlorophyll fluorescence were decreased by increasing Cd and Pb concentrations. However, Cd concentration decreased these traits more than Pb. The shoot MDA concentration, essential oil and proline content were enhanced by increasing Cd and Pbconcentrations. The combination of two pollutants (Cd and Pb) together reduces the negative impact of each element alone. Shoot and root Cd and Pb concentrations were increased by increasing Cd and Pbconcentrations. The interaction effect of Cd×Pbapplication showed that increasing Cd concentration decreased root and shoot Pb concentrations and increasing Pb concentration decreased root and shoot Cd concentrations. Cd and Pb were not detected in essential oil. Moreover, the Cd transfer factor was increased with increasing Pb concentration under high Cd concentration levels (12 and 24 mg.kg-1).
Conclusion: This study demonstrated that Cd toxicity is more than Pb toxicity due to its high mobility. There was an antagonistic relationship between Cd and Pb. Furthermore, due to the absence of Cd and Pb in the essential oil, lemon balm may be a suitable plant for areas contaminated with heavy metals especial Cd and Pb.
Nasibeh Pourghasemian; Mehdi Naghizadeh; Rooholla Moradi; Mohammad Salari
Abstract
Introduction: Successful greenhouse and nursery production of plants is largely dependent on the chemical and physical properties of the growing substrate. An ideal potting substrate should be free of weeds and diseases, heavy enough to avoid frequent tipping over and yet light enough to facilitate handling ...
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Introduction: Successful greenhouse and nursery production of plants is largely dependent on the chemical and physical properties of the growing substrate. An ideal potting substrate should be free of weeds and diseases, heavy enough to avoid frequent tipping over and yet light enough to facilitate handling and shipping. The substrate should also be well drained and yet retain sufficient water to reduce the frequency of watering. Other parameters to consider include cost, availability, consistency between batches and stability in the media over time. Greenhouse crops in general, have higher nutrient demands than field grown crops. Therefore, in order to optimize production it is essential to focus on the growing substrate and fertilization. The physical properties of the growing medium are important parameters for successful plant growth, as these are related to the ability to adequately store and supply air and water to plants. Humic acid is a principal component of humic substances, which are the major organic constituents of soil (humus), peat and coal. It is also a major organic constituent of many upland streams, dystrophic lakes, and ocean water. It is produced by biodegradation of dead organic matter. It is not a single acid, but it is a complex mixture of many different acids containing carboxyl and phenolate groups so that the mixture behaves functionally as a dibasic acid or occasionally as a tribasic acid. Humic acids can form complexes with ions that are commonly found in the environment creating humic colloids. Humic and fulvic acids (fulvic acids are humic acids with lower molecular weight and higher oxygen content than other humic acids) are commonly used as a soil supplement in agriculture. Humic Plus contains humic acid, fulvic acid, macro micro nutrients and proprietary constituents essential for plant growth. Organic matter soil amendments have been known by farmers to be beneficial to plant growth for longer than recorded history. However, the chemistry and function of the organic matter have been a subject of controversy since humans began their postulating about it in the 18th century. Selection of the proper media components is critical to the successful production of plants. So, the objective of this study was to assess the effect of humic acid foliar application and various substrate on quantitative and qualitative characteristics of tomato seedling.
Material and Methods: The experiment was conducted in a greenhouse at Bardsir Faculty of Agriculture , Shahid Bahonar University of Kerman in 2015, as a factorial arrangement based on completely randomized design with five replications. The experimental treatments were substrate in 7 levels (peat, coco-peat, leaf-soil, compost, vermi-compost, manure and clay soil), humic acid in two levels (foliar application and non- foliar application). After preparation of substrates, plastic boxes with 12 cm diameter and 10 cm height were chosen. After extracting gravity water, tomato (cv. Canyon) seeds were sown in pots. Rain irrigation was done daily. Foliar application of humic acid with concentration of 0.001 liter was performed from seedling emergence to transplanting every two days. The germinated seeds was daily counted and number and rate of seed emergence was estimated. Plant height, stem diameter, number of internodes, leaf area, shoot and root dry matter and chlorophyll contents were calculated at transplanting time of seedling.
Results and Discussion: The substrate treatment had a significant effect on rate and percent of germination, plant height, shoot dry matter, leaf area, number of internodes and, chlorophyll a and carotenoid contents. According to the results, the greatest and smallest rate and percent of germination was found in peat and manure treatments, respectively. Also the greatest shoot dry matter (1.17 g), leaf area (125.9 cm plant-1), number of internodes (6.19), plant height (13.51 cm) and chlorophyll a concentration (2.55 µg/ml) were observed for peat substrate. Manure and clay soil substrates showed the smallest of these measurements and carotenoid contents. It seems that physical characteristics of peat was better than other substrates. Plant height, shoot dry matter, leaf area, number of internodes, chlorophyll a and carotenoid contents showed a significant effect by humic acid application. Foliar application of humic acid significantly increased the mentioned traits.
Conclusion: The results illustrated that between substrates in this study, peat was the best for seedling production of tomato. Foliar application of humic acid had a positive effect in improving growth characteristics of tomato seedling.
