Growing vegetables
Farhad Shakarami; sadegh Mousavi-Frad; Abdolhossein Rezaei Nejad; Farhad Beiranvand
Abstract
Introduction
Salinity in water and soil stands as a crucial environmental factor that significantly hampers global agricultural production. Over recent decades, the escalating demand for irrigation in arid and semi-arid regions has intensified this issue, making it a major agricultural challenge. Salinity ...
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Introduction
Salinity in water and soil stands as a crucial environmental factor that significantly hampers global agricultural production. Over recent decades, the escalating demand for irrigation in arid and semi-arid regions has intensified this issue, making it a major agricultural challenge. Salinity stress, characterized by reduced water absorption, heightened salt uptake (especially sodium, chlorine, and boron), and the generation of reactive oxygen species, induces oxidative stress in plants, severely impacting their growth and overall performance. To enhance plant tolerance to salinity stress, elicitors are employed as a short-term and viable solution to mitigate the adverse effects of stress. Copper, serving as a cofactor and essential element for numerous enzymes involved in photosynthesis and respiration processes, plays a crucial role in sustaining natural plant growth and metabolism. Copper ions function as cofactors in enzymes like superoxide dismutase (Cu/Zn SOD) and polyphenol oxidase, contributing to the removal of reactive oxygen species. However, the absence of this element in plants cultivated in alkaline and saline soils of arid and semi-arid regions can lead to nutritional disorders. In this context, copper nanoparticles emerge as a suitable alternative to chemical fertilizers due to their quicker and more efficient impact. Their use not only mitigates the negative consequences of excessive fertilizer application but also reduces the frequency of application. The Persian leek (Allium ampeloprasum subsp. Persicum) is a valuable edible-medicinal plant native to Iran, belonging to the Amaryllidaceae family. It holds significance in Iran as a key leafy vegetable, valued for its freshness and high processing potential among horticultural plants. Given the nutritional and medicinal importance of Persian leek and the prevalence of salinity stress, this study aims to explore the impact of copper nanoparticle spray in modifying the effects of salinity stress on the morphophysiological and biochemical characteristics of Persian leek.
Materials and methods
A factorial experiment was conducted using a completely randomized design with three replications in the research greenhouses of Lorestan University's Faculty of Agriculture. The experimental conditions included daytime temperatures ranging from 20 to 28 °C, nighttime temperatures from 15 to 20 °C, relative humidity set at 60-70%, and a light intensity of 400-500 µmol m-2 s-1. The first factor involved foliar spraying of copper nanoparticles at control levels (zero), 150, and 300 mg/liter, while the second factor comprised salinity stress at control levels (zero), 50, 100, and 150 mM sodium chloride. F1 seeds were obtained from Pakan Bazr Company and planted in 1.5-liter pots, with each pot containing three plants. The copper nanoparticles were applied through foliar spraying twice on the shoot parts at the four-leaf and six-leaf stages. Salinity stress was introduced one week after the foliar application, implemented through irrigation once every three days at a level corresponding to 90% of the field capacity. The soil mixture comprised an equal ratio of agricultural soil, cow manure, and sand, maintaining a clay-sand loam texture. Following three months of applying salt stress, a comprehensive assessment of morphophysiological characteristics was carried out. This included the measurement of plant height, stem and bulb diameter, leaf count, fresh and dry weights of stem, root leaf, root volume and length, shoot/root ratio, dry matter (%), stress tolerance index, relative water content (RWC), electrolyte leakage, malondialdehyde content, photosynthetic pigments, chlorophyll stability index, as well as the activity of peroxidase and ascorbate peroxidase.
Results and Discussion
The results indicated that salinity stress had a detrimental impact on various aspects of plant growth, including a decrease in plant height, stem and bulb diameter, leaf number, and the fresh and dry weights of the stem, bulb, and root. Additionally, there was a reduction in root volume and length, along with decreased levels of photosynthetic pigments. The percentage of electrolyte leakage, malondialdehyde content, and the activity of antioxidant enzymes, namely peroxidase and ascorbate peroxidase, also increased, highlighting the adverse effects of salinity stress on plant development. The decline in plant growth can be attributed to multiple factors, including diminished cell division, ionic imbalance, reduced water absorption, impaired uptake of essential elements, and the impact of toxic ions, particularly sodium and chlorine. Other contributing factors include impaired absorption, regeneration, and metabolism of nitrogen and protein, as well as stomatal closure, collectively resulting in reduced photosynthetic efficiency. Salinity stress further leads to a reduction in soil water potential and an increase in the osmotic pressure of the soil solution. Consequently, the plant requires more energy to absorb water from the soil, leading to increased respiration and alterations in the hormonal balance of plant tissues, ultimately causing a decrease in growth and negative effects on the plant. The application of copper nanoparticles at both concentrations demonstrated positive effects on various growth components, including plant height, stem and bulb diameter, leaf count, and the fresh and dry weights of the stem, bulb, and root, as well as increased root volume and length. Additionally, the use of copper nanoparticles resulted in a decrease in the percentage of electrolyte leakage and malondialdehyde content, coupled with an increase in the concentration of photosynthetic pigments and the activity of antioxidant enzymes, including peroxidase and ascorbate peroxidase. Notably, the concentration of 150 mg/liter exhibited a more pronounced effect in enhancing plant growth, with a diminishing impact observed at higher concentrations. Copper \nanoparticles improve plant growth under stress conditions by influencing the content of cellular antioxidants and modulating the hormonal balance of plant tissues.
Conclusion
The findings of this study indicated that increased salinity stress led to higher electrolyte leakage and malondialdehyde content, along with a reduction in RWC and photosynthetic pigments. These changes caused a decline in the morpho-physiological characteristics of Persian leek. However, salinity stress also increased the activity of peroxidase and ascorbate peroxidase enzymes. Foliar application of copper nanoparticles under these conditions had beneficial effects on the plants. Specifically, at a concentration of 150 mg/liter, the negative effects of salinity stress on the morpho-physiological indices of Persian leek were alleviated. This improvement was due to an increase in the activity of antioxidant enzymes, RWC, and the concentration of photosynthetic pigments.
Postharvest physiology
Z. Pakkish; S. Mohajerpour; S. Saadati
Abstract
Introduction
Fresh fruits and vegetables are physiologically active and perishable after harvest. Continued metabolic processes such as transpiration or respiration may significantly affect their quality and thus shorten their useful life. Since keeping at low temperatures and without freezing for ...
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Introduction
Fresh fruits and vegetables are physiologically active and perishable after harvest. Continued metabolic processes such as transpiration or respiration may significantly affect their quality and thus shorten their useful life. Since keeping at low temperatures and without freezing for a long time effectively reduces the physiological activity of the products, it can be used as a strategy to maintain the quality of the products and increase their life after harvesting. Among the most economically important tropical fruits, ripe green bananas are very sensitive to cold and when stored below the threshold temperature, they show all the symptoms of frost damage. While banana cultivars, maturity stage, and ripening all influence cold sensitivity, there's a growing interest in extending the shelf life of produce using natural, plant-friendly compounds. Gamma-aminobutyric acid (GABA), a naturally occurring four-carbon, non-protein amino acid found in plants, animals, and bacteria, is a promising candidate in this area.Abiotic stresses such as cold, heat, drought, ultraviolet rays and low oxygen can cause the accumulation of GABA in plants. Generally, the purpose of this research was to investigate the effect of gamma-aminobutyric acid treatment to improve freezing and antioxidant properties of Cavendish banana at 5 degrees Celsius for 24 days in 90% relative humidity.
Materials and Methods
Cavendish banana fruits (Musa acuminata cv. Cavendish) at the time of commercial maturity (ripe green) were obtained from a banana garden in Kerman and immediately transferred to the horticultural science laboratory of Shahid Bahoner University, Kerman. Healthy and uniform fruits were selected in terms of size, shape, color, and degree of ripening, and after washing with water and drying them, frost tolerance, malondialdehyde, and antioxidants were measured for zero day. GABA (Sigma-Aldrich, USA) required after weighing was dissolved in water and prepared in two concentrations of 2.5 and 5 mM. The fruits were divided into three groups of 54 and each repetition included 18 fruits. The first and second groups were immersed in GABA solution of 2.5 mM and 5 mM for 5 minutes, respectively. The third group was immersed in distilled water for 5 minutes and was used as a control (Khaliq et al., 2023). Each treatment was repeated three times. Then, all the fruits were dried in the air for one hour and kept for 24 days at 5 degrees Celsius and relative humidity of 85-90%. Biochemical observations were measured on days 0, 4, 8, 12, 16, 20 and 24 of storage.
Results and Discussion
The results of this research showed that frost damage gradually increased during the storage period and the control fruits showed significantly more frost damage symptoms than the fruits treated with GABA. GABA treatments of 2.5 and 5 mM at the end of the storage period reduced the amount of frost damage by 55.64 and 69.95%, respectively, compared to control fruits. As shown in Figure 1b, MDA content as an index of membrane lipid peroxidation in the control and GABA-treated fruit showed an upward trend, which was associated with the destruction of banana fruit membrane under cold stress. Compared to control, banana fruits treated with GABA showed lower MDA accumulation during the entire storage period at 4 degrees Celsius. On the last day of storage, GABA treatment with a concentration of 2.5 mM and 5 mM reduced the amount of MDA in banana fruits by 30.99% and 59.80%, respectively, compared to the control. Post-harvest treatment with GABA reduced frostbite, ion leakage and MDA levels in banana fruits, thereby maintaining fruit quality during low temperature storage. GABA treatment increased the activity of catalase (CAT), ascorbate peroxidase (APX), peroxidase (POD) and superoxide dismutase (SOD) enzymes in banana fruit compared to the control under low temperature storage. The activity of antioxidant enzymes CAT, APX, POD and SOD increased significantly until the 20th day of storage at low temperature, especially in the 5 mM GABA treatment compared to the other two treatments, and then decreased slightly at the end of the storage period. An increase in the concentration of oxygen free radicals, including hydrogen peroxide, leads to an increase in catalase enzyme activity. Catalase enzyme is often present in the peroxisome and causes the decomposition of hydrogen peroxide into water and oxygen. The specific activity of catalase enzyme increased during cold storage, especially in GABA treatments, so it seems that this enzyme is an efficient scavenger for removing hydrogen peroxide and thus causes better protection of cells against peroxidation. In the ascorbate-glutathione cycle, the ascorbate peroxidase enzyme reduces the amount of hydrogen peroxide by using ascorbate as an electron donor. In the present study, the activity of ascorbate peroxidase enzyme in GABA treatment was significantly higher than the control, which indicates the importance of the role of ascorbate peroxidase in plant tissues against oxidative damage. Guaiacol peroxidase enzyme is another antioxidant enzyme that decomposes hydrogen peroxide into water and oxygen. Peroxidase enzyme plays a role in the oxidation of precursors of phenolic compounds, lignin production, and removal of free radicals. The activity of peroxidase enzyme showed a similar trend in all three treatments, although its activity in GABA treatments was more than the control. Therefore, this enzyme effectively eliminated free radicals in banana fruits. In confirmation of these findings, it was reported in research that the activity of peroxidase enzyme increased in fir cuttings during the cold period. In research, post-harvest treatment of GABA with a concentration of 5 mM reduced frostbite and increased the activity of antioxidant enzymes such as CAT, APX, POD and SOD in peach fruits.
Conclusion
The results of this research showed that the applied post-harvest treatments reduced the signs of frostbite and preserved the antioxidant properties of banana fruits. Among the treatments, 5 mM concentration of GABA was the most effective treatment in the storage period. Therefore, GABA treatment can be used as a practical solution to reduce frostbite and preserve the antioxidant properties of Cavendish bananas during long-term storage.
Ornamental plants
Afsaneh Hooshmand; Mitra Aelaei; Masoud Arghavani; Fahimeh Salehi
Abstract
Introdaction
Heavy metals are one of the most important environmental contaminants, particularly in soil and water sources. Mining and metal mining activities are major factors in soil contamination and generally surface soil around mines contain high amounts of these metals. Lead (Pb) is one ...
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Introdaction
Heavy metals are one of the most important environmental contaminants, particularly in soil and water sources. Mining and metal mining activities are major factors in soil contamination and generally surface soil around mines contain high amounts of these metals. Lead (Pb) is one of the heavy metals and important pollutant in arid ecosystem. The use of plants to remove contaminated soil or phytoremediation is an economical method. Today, due to increasing the pollution of soil sources and resultant problems, identification of the resistant plant species against soil pollution is essential. Using lead-contaminated soils requires their decontamination and improvement. There are different methods to remove these pollutions, one of them is the use of phytoremediation to remove pollutants from water and soil or to reduce them. Among the plants that as an ornamental plant can have a covering role in the green space and also perform the work of phytoremediation is the ornamental cabbage plants (Brassica oleracea L.). In this regard, this study was conducted with the aim of investigating the effect of lead heavy metals and the use of brown algae (Polycladia indica) and spirulina (Arthrospira platensis) as biofertilizers on ornamental cabbage plants in the direction of plant treatment. In addition, due to the presence of polysaccharide compounds such as carrageenan and alginate in the cell wall, algae (seaweeds) have a higher ability to absorb many heavy metals.
Materials and Methods
The experiment was conducted as factorial based on a completely randomized design in 2020 at the research greenhouse of Zanjan University. The studied factors including lead from lead nitrate source Pb(No3)2 with three concentrations (0, 25 and 50 mg/kg) were applied to the potting soil in four replications in two stages with an interval of two weeks. The second factor was included no algae, brown algae (Polycladia indica) and spirulina (Arthrospira platensis), which occurred in four replications. The measured traits included morphological traits: number of leaves, leaf surface index. Wet and dry root weight, and physiological traits included total chlorophyll content, total leaf antioxidant, peroxidase enzyme, glycine betaine, malondialdehyde, and leaf lead and phosphorus content. Data analysis was performed using SAS software and means were compared by LSD method.
Results
The results of the variance analysis showed that different levels of lead and the application of algae had a significant effect on the number of leaves per plant, leaf area index, weight, and drying of roots, total chlorophyll, and antioxidants. Moreover, the interaction effect was significant for leaf area, root fresh and dry weight, antioxidants, and leaf lead content. The simple effect of lead at p≤0.01 significantly affected glycine betaine, malondialdehyde, and leaf phosphorus. When comparing the average mutual effects of lead and algae application, it was found that the treatment with no use of lead and spirulina algae resulted in the highest weight and dry weight of the root, with an average of 11.19 and 3.625 grams, respectively. Additionally, despite the decrease in dry weight of the root due to increased lead concentration, using algae, especially for ornamental cabbage (Brassica oleracea L.), increased the dry weight of the root. The presence of natural plant hormones, organic substances, carbohydrates, fiber and amino acids in algae accelerates rooting, reduces stress caused by heavy metals and absorbs more water due to the presence of o developed root system. Also according to the results of comparing the amount of leaf lead with increasing lead, algae as an auxiliary factor can reduce the amount of uptake in the plant. Leaf phosphorus was also significant due to the simple effect of lead and algae. The highest amount of phosphorus with an average of 0.56% was observed in spirulina and the lowest with 0.48% was observed in control.
Conclusion
In general, due to the toxicity of lead metal even in low concentrations, sufficient attention should be paid to the sources of this pollutant entering the environment. In this study, the effective parameters on the uptake of heavy metal lead from the soil by spirulina and brown algae were investigated. The findings of this study indicate that the ornamental cabbage plant is capable of sustaining its growth in the presence of lead and has a high resistance to this heavy metal while simultaneously absorbing it from the soil. Furthermore, the addition of algae as an auxiliary factor can improve the growth of ornamental cabbage under adverse conditions. Therefore, it is recommended that this plant be further examined for its potential to absorb other heavy metals.
Growing vegetables
Z. Darabi; F. Ghanbari; J. Erfani moghadam
Abstract
Introduction
Low temperature is one of the most important environmental stresses that cause damage to plants and limit the geographical distribution of plant species. Plants of tropical and sub-tropical origin, such as cucumbers, are sensitive to cold stress and severely damaged at low temperatures. ...
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Introduction
Low temperature is one of the most important environmental stresses that cause damage to plants and limit the geographical distribution of plant species. Plants of tropical and sub-tropical origin, such as cucumbers, are sensitive to cold stress and severely damaged at low temperatures. Plants have evolved a set of defense mechanisms to adapt to low temperatures. These mechanisms include the regulation of gene expression and physiological and biochemical changes that increase plant resistance to chilling stress. Cinnamic acid (CA) is one of the most important phenolic acids present in all plants and has antimicrobial properties against fungi and bacteria. The application of this compound in some plants causes oxidative stress and leads to the activation of antioxidant enzymes. Therefore, in the present study, the effects of exogenous cinnamic acid treatment on cold stress tolerance in cucumber seedlings have been investigated.
Materials and Methods
This research was conducted in the greenhouse and laboratory of the Department of Horticultural Sciences of Ilam University in 2019. Cucumber seeds (Super Daminus cultivar) were planted in a 1: 1: 1 ratio of field soil, manure, and sand. In the fully developed two-leaf stage, seedlings produced were sprayed using cinnamic acid (at concentrations of 0, 50, 100, and 200 μM). Foliar spraying treatments were applied at the mentioned concentrations until the surface of the leaves was completely wet. 24 hours after foliar application, all plants were exposed to cold stress at 3 ° C for 6 hours in six consecutive days. After applying the cold treatment, the seedlings were transferred to the greenhouse and 72 hours later, the traits were measured.
Results and Discussion
The results showed that exogenous CA application increased the growth characteristics of cucumber seedlings subjected to chilling stress. Improving the growth and development of plants under stress conditions by cinnamic acid treatment has been reported in other studies, which is consistent with the results of the present study. It has been reported that cinnamic acid treatment, by causing oxidative shock in plants, leads to plant defensive responses to stress conditions, and through this, plants can better withstand stress conditions. These defense responses include increasing compatible solutions and improving the antioxidant system. In the present study, the use of cinnamic acid treatment increased proline, chlorophyll, and total phenol and reduced of membrane lipid peroxidation, and these changes led to a decrease in the apparent effects of cold on cucumber seedlings.
The use of chemicals that can mitigate the effects of cold on the plant can also help maintain plant growth under cold stress. In the present study, the application of cinnamic acid improved the growth of cucumber seedlings under cold stress conditions. Cinnamic acid pretreatment by inducing antioxidant compounds reduced the effects of cold on cucumber seedlings and improved plant growth in chilling conditions. Also, cinnamic acid treatment increased the growth of pepper plants under salinity stress, cucumber under drought stress, and wheat under drought conditions, which is consistent with the results of the present study. Therefore, it can be said that cinnamic acid improves plant growth under stress by changing physiological and biochemical processes. The results showed that the application of cinnamic acid improved the growth of cucumber seedlings under chilling stress conditions. Cinnamic acid pretreatment caused a significant increase in relative water content (25 to 32%), chlorophyll (108 to 125%), proline (152 to 244%), and total phenol (31%) compared to the control, therefore improving the adaptabilities of cucumber seedlings to chilling stress. The application of cinnamic acid also reduced the damage to cell membranes. The electrolyte leakage and malondialdehyde accumulation of cinnamic acid-treated seedlings were lower than that of control seedlings.
Conclusion
In general, the results of this study showed that the application of cinnamic acid reduced the effects of cold stress on cucumber seedlings. These results were associated with increased proline, chlorophyll, phenol and relative water content, in this way, the rate of ion leakage and accumulation of malondialdehyde in cucumber seedlings were reduced under cold stress. In general, the results showed that cinnamic acid treatment (especially concentration of 200 μM) can effectively reduce the effects of chilling on cucumber seedlings and improve their growth under cold stress.
F. Ghanbari; S. Akbari
Abstract
Introduction: Melon, like other members of cucurbitaceae family, is sensitive to cold stress. Applying different cultivation techniques in the nursery can provide some degree of tolerance to environmental stresses in the plants. In the other words, applying stress conditions on plants may cause them ...
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Introduction: Melon, like other members of cucurbitaceae family, is sensitive to cold stress. Applying different cultivation techniques in the nursery can provide some degree of tolerance to environmental stresses in the plants. In the other words, applying stress conditions on plants may cause them to withstand subsequent stresses, this is so called a cross-adaptation or cross-tolerance. For example, Whitaker (1994) showed that cold stress damage can be mitigated by temperature pretreatment. This technique was then used to improve stress tolerance in different plants. In this regard, heat treatment has been used to increase the chilling tolerance in fruits and vegetables. Therefore, in this study, the possibility of increasing cold stress tolerance in melon seedlings using heat shock was investigated. Materials and Methods: The experiment was conducted in a completely randomized design (CRD) with three replications and five treatments (including control and spraying with water at temperatures of 20, 45, 50 and 55 °C for 90 seconds) in Faculty of Agriculture of Ilam University in 2019. Heat treatments where used as foliar spray by heated water. After applying different levels of heat treatment and recovery at 24 hours, seedlings were exposed to chilling stress at 3 °C for 6 h in 6 consecutive days. All seedlings were transferred to greenhouse and after 72 hours, the related traits were measured. Results and Discussion: Results showed that pre-treated seedlings had higher growth rate than control seedlings at the end of chilling period. Heat shock pretreatment significantly increased the content of chlorophyll, proline and hydrogen peroxide and reduced the amount of malondialdehyde compared to the control. The lowest amount of malondialdehyde (1.14 nmol g-1 fresh weight) was observed in the 50 °C treatment, which was 50% lower than the control. Similar to other environmental stresses, low temperature usually leads ROS production and oxidative stress. Malondialdehyde content is an index to measure membrane lipid peroxidation and its measurement is a criterion of damage to plants in stress conditions. Reduction of malondialdehyde has been reported to increase cell membrane stability and increase stress tolerance in plants. In the present study, heat shock reduced the accumulation of malondialdehyde compared to the control, indicating a decrease in cold effects on the plant. Mei and Song (2010) investigated the effect of heat pretreatment on increasing high temperature tolerance in barley, and reported that using this method by stimulating the synthesis of antioxidant enzymes prevented the increase of malondialdehyde in the plant under heat stress. Therefore, maintaining the membrane structure and decreasing the accumulation of malondialdehyde in melon seedlings under cold conditions indicates an improvement of plant defense responses induced by heat shock. Environmental stresses including cold stress by producing hydrogen peroxide and other free radicals lead to oxidative stress and damage plant cells. Hydrogen peroxide is converted to water by ascorbate peroxidase, peroxide redoxin, glutathione peroxidase and guaiacol peroxidase groups. Therefore, increasing the activity of antioxidant enzymes in plants is one of the most important mechanisms of the plant to cope with stress conditions. In the present study, heat shock pretreatment significantly increased peroxidase (POD) and poly phenol oxidase (PPO) activity and increased the amount of proline and hydrogen peroxide. In this regard, it has been reported that hydrogen peroxide has a dual role in plants and its increase in stress conditions by regulating the production of antioxidant enzymes helps plants to enhance their tolerance to the stress conditions. Our results is in consistent with Ao et al. (2013) report that stated hardening pretreatment of Jatropha curcas seedlings caused to increase the antioxidant enzymes activity, plant glutathione and ascorbate content. The increases in antioxidant enzymes activity by heat shock might be a positive mechanism, which facilitate the scavenging of ROS and induce plant growth and development under chilling stress. These results indicate that antioxidant defense system has a specific role in enhancing plant tolerance to stress conditions and hydrogen peroxide play an important signaling role in plant adaptive responses. Conclusion: In general, the results showed that heat shock (especially at 50 and 55 oC) caused positive physiological changes in melon seedlings and could increase their tolerance to cold stress conditions.
A. Moshashaei; M.M. Jowkar
Abstract
Introduction: Dianthus barbatus L. from Caryophyllaceae is an important herbaceous landscape ornamental plant in the temperate regions throughout the world. Although this ornamental plant is used as bedding plant, it also has other extensive applications such as cut flower and pot plant. Besides, in ...
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Introduction: Dianthus barbatus L. from Caryophyllaceae is an important herbaceous landscape ornamental plant in the temperate regions throughout the world. Although this ornamental plant is used as bedding plant, it also has other extensive applications such as cut flower and pot plant. Besides, in some countries the leaves of Dianthus barbatus are used for treatment of digestive disorders in their traditional medicine. Landscape and its quality, plays an essential role in human life. Nowadays, maintenance and development of urban landscape in many regions such as Iran is facing major challenging issues. Soil and water salinity are the most important challenges of urban landscape. Considering the challenges which landscape development faces in many parts of the country and the importance of this plant in landscape, the effect of salinity on D. barbatus during in vitro condition was studied in order to obtain some basic physiological information for future stress studies on this plant.
Materials and Methods: In vitro sterile plants were initially obtained from seeds by culturing them on basal MS medium. Calli were obtained by culturing leaf, stem and root explants on previously reported callogenesis optimization medium which was MS medium supplemented with 2µM BAP + 6µM NAA. Calli proliferation was then conducted on the same media. Proliferated calli with same size were subjected to MS medium supplemented with the mentioned plant growth regulators and various NaCl concentrations (0, 1, 3, 6, 9, 12 gl-1) in order to induce salinity stress. Various physiological aspects and stress related mechanisms such as growth, osmo-protection and oxidative stress mechanisms were consequently studied in the stressed Dianthus barbatus calli. Studied growth features were calli growth, final growth rate, fresh and dry weight. Total protein content, glycine-betaine content, and the activity of betaine aldehyde dehydrogenase (BAD) were studied as a part of osmo-protection mechanism. On the other hand, the activity of free radical scavenger enzymes such as sccccuperoxide dismutase (SOD), catalase (CAT), peroxidase (POX) and malondialdehyde damage biomarker content were studied in stressed calli as a part of oxidative stress mechanism. Total protein was measured using Bradford method. Glycine-betaine content was measured using spectroscopy method by KI-I2 reaction agent. The activity of betaine aldehyde dehydrogenase was evaluated using spectroscopy method by reduction with NAD+. SOD activity was measured using spectroscopy method and formation as an indicator. CAT activity was measured using spectroscopy method by measuring hydrogen peroxide breakdown. POX activity was measured using spectroscopy method by nitro-blue tetrazolium reduction activity. Malondialdehyde content was also measured by using spectroscopy method.
Results and Discussion: Results indicated that by increasing salinity level, calli growth and consequently fresh and dry weight reduced. Calli growth was dramatically reduced as salinity level reached above 1 gl-1. This slow growth was also observed at high stress levels such as 12 gl-1. By salinity increment, total protein content of the stressed calli significantly reduced. On the other hand, BAD activity increased as a result of salinity stress and consequently glycine-betaine content also increased significantly. The highest level of glycine-betaine content and also the activity of BAD activity were observed in 12gl-1 NaCl treated calli. A significant correlation between glycine-betaine content and BAD activity was observed. The activity of free radical scavenger enzymes such as SOD, CAT, POX also significantly increased by salinity stress increment. The highest activity of the mentioned free radical scavenger enzymes were observed in 12 gl-1 NaCl treated calli. CAT had the most activity among the mentioned studied free radical scavenger enzymes. The highest increase in POX activity was half of the control and also half of the activity increment of other studied free radical scavenger enzymes. Although the activity of free radical scavenger enzymes increased, the level of malondialdehyde damage biomarker also increased as the result of salinity stress increment. The highest amount of malondialdehyde content was seen in the 12gl-1 NaCl treated calli. A significant correlation between malondialdehyde content and the activity of free radical scavenger enzymes was observed.
Conclusion: In general, the calli of Dianthus barbatus cultured in vitro are sensitive to salinity stress induced by more than 1 gl-1 NaCl; indicating the stress tolerance threshold. The tolerance and resistance mechanisms performed well under stress condition and the stress calli resisted to salinity up to 12 gl-1 NaCl and survived without chlorosis.
seyyed mousa mousavi; mehrangiz chehrazi; Esmaeil Khaleghi
Abstract
Introduction: With regard to decrease of precipitation and poor distribution of rainfall during the dry phenomenon of urban, green spaces face problems. In fact, one of the most important environmental stress is drought stress at different stages of plant growth such as seed germination, seedling establishment ...
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Introduction: With regard to decrease of precipitation and poor distribution of rainfall during the dry phenomenon of urban, green spaces face problems. In fact, one of the most important environmental stress is drought stress at different stages of plant growth such as seed germination, seedling establishment and crop production. The effect of drought stress, plants photochemical activity ceased Calvin cycle enzymes and chlorophyll content also varies in the process of photosynthesis under drought stress. Under drought stress, reactive oxygen species (ROS) such as hydrogen peroxide (H2O2), superoxide radicals (O2 • -) and hydroxide (OH •) increase their accumulation in cells that can lead to oxidative stress. To neutralize ROS, antioxidant enzymes systems in plant such as superoxide dismutase (SOD), peroxidase (POD), catalase (CAT) and ascorbate peroxidase (APX) are active. The response of antioxidants depends on the lack of water, the intensity of the stress and the type of plant species. Also, it is well known that photosynthetic systems in higher plants are most sensitive to drought stress. Indeed, drought is one of the factors affecting photosynthesis and chlorophyll content. Some of researchers reported that chlorophyll might estimate influence of environmental stress on growth because these parameters were closely correlated with the rate of carbon exchange. The aim of this study was an investigation of effect of water deficit different levels on antioxidant system and lipid peroxidation in two species of marigold. Therefore, an experiment was carried out as factorial in a randomized complete block design with three replication at Shahid Chamran University of Ahvaz in 2014 year.
Materials and methods: Experimental treatments were irrigation with three levels: 100% ETcrop (no stress), 75% ETcrop (moderate stress) and 50% ETcrop (severe stress) and two species of marigold (African and French). Catalase activity decreased absorption at a wavelength of 240 nm through catabolizing on the basis of H2O2 according to Beers and Sizer (1952). Peroxidase activity decreased absorption at a wavelength of 470 nm that was measured by using Hemeda and Kelin (1990). Ascorbate peroxidase enzyme extracted from leaf based on defects in the wavelength of 290 nm that was measured by Nakano and Asada (1987). The final product of membrane lipid peroxidation malondialdehyde concentration as the reaction thiobarbituric acid (TBA) was measured. Also, chlorophyll a, b and total chlorophyll were calculated by Arnon’s equations and chlorophyll content index (C.C.I) was measured by chlorophyll content meter (SPAD-502).
Results and discussion: Results of analysis of variance showed that irrigation treatment had significant effect on chlorophyll a, total chlorophyll (Chl a+b), chlorophyll content index and catalase peroxidase, ascorbate peroxidase enzymes activity and malondialdehyde while there was not significantly difference between two species of marigold on any of the measured biochemical characteristics. Also, results revealed that amount of leaf chlorophyll a and total chlorophyll (chl a+b) were reduced by increasing water deficit. In fact, amount of total chlorophyll, chlorophyll a, b and chlorophyll content index were higher in plants that were received 100% ETcrop than 75 and 50% ETcrop. ,The results of enzyme activity were similar to total chlorophyll and chlorophyll a and b. Amount of decreased chlorophyll a and total chlorophyll in plants were received 50% ETcrop were 24% and 47.46%, compared with 100% ETcrop, respectively.
Conclusion: Result showed that different levels of irrigation were significantly different at 5% level on catalase, peroxidase, ascorbate peroxidase enzymes activity and malondialdehyde concentration. Catalase, peroxidase, ascorbate peroxidase enzymes activity and malondialdehyde concentration were increased by reducing the amount of irrigation while there were no different between two species of marigold and interaction between species and irrigation was not effective on measured indexes.
Nasser Abbaspour; Lavin Babaei; Alireza Farrokhzad
Abstract
Introduction: Water stress is considered as a main environmental factor limiting crop growth and yield, including grape in Mediterranean areas.Selection for drought-tolerantvarieties is possible through investigation of their performance under stress conditions. The estimation of physiological characteristics ...
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Introduction: Water stress is considered as a main environmental factor limiting crop growth and yield, including grape in Mediterranean areas.Selection for drought-tolerantvarieties is possible through investigation of their performance under stress conditions. The estimation of physiological characteristics as reliable indices can be used as a tool to select tolerant plants. For this reason, varieties and genotypes of one plant species are usually investigated through physiological characteristics and its relation to drought tolerance. Investigation of the effects of water stress on some growth and physiological characteristics in grape plants has revealed that plant height, number of leaves and nodes, leaf area and the percentage of dry weightdecreased under increasing drought stress. Salicylic Acid is a naturally occurring plant hormone whichinfluences various morphological and physiological functions in plant. It can act as an important signaling molecule and has diverse effects on biotic and abiotic stresses tolerance capacity.
Materials and Methods: In this research, two-yearold grapesplanted in plastic pots containingingredients of humus, soil and sand (1:2:1) were used. The experiment was conducted using a factorial based on randomized complete block design with three factors including irrigation periods (every 5, 10 and 15 days), salicylic acid concentrations (0, 1 and 2 mM) and grape cultivars (Rasheh andBidanesefid) with 3 replications in thegreenhouse of faculty of agricultureinUrmia University. Plant height, stem diameter and leaf area and chlorophyll indicesweremeasuredby usingruler, digital caliper (Model22855 NO: Z), leaf Area Meter (ModelAM200) and SPAD-502 chlorophyll meter (Minolta Crop, Japan),respectively. In order to determine proline content, malondialdehyde (MDA), total protein and total soluble sugars, spectrophotometric methods [51,25,6and28] were utilized,respectively.
Results and Discussion: Based on comparing the averages related to the interaction of various levels of drought and salicylic acid, increasing watering intervals resulted in significant decrease in parameters of plant height, stem diameter, leaf area, leaf number and chlorophyll index,and increase inproline content, malondialdehyde, total protein and total soluble sugars.Furthermore, according to the obtained results, plant height, stem diameter, leaf number, chlorophyll index, accumulation of prolineandtotal protein in grape cv. Rashehwere higher than Bidanesefidone.Drought effected the mitotic division, andelongation and expansion of cells, leading to reduced growth and crop yield. It was concluded that plant height, stem diameter, and leaf area decreased noticeably byincreasing water stress. The reduction in plant height could be attributed to decline in the cell enlargement and higher rate ofleaf senescence in the plant under water stress. The reduction in leaf number under severe water deficit was partially due to leaf senescence. Reduction inthe number of leaves could be a response by plants to minimize the transpiration surface. Sorghum plants have also been reported to have a similarbehaviorthroughwhichthey conserve water by reducing the number of leaves. When exposed to chronic water deficit, they showed an initial decrease in the daily increment of leaf area and eventually a decrease due to accelerated senescence. Dropping of the leaves during severe stress markedly reduces the evaporative surface and allows the plant to conserve water.It is well known that proline contents in leaves of many plants are enhanced by several stresses including drought stress. The efficiency of exogenous SA depends on multiple causes such as the species, developmental stage of the plant, manner of application and concentration of SA.Plant height, stem diameter, leaf number, leaf area, leaf total soluble sugar and chlorophyll index increased by applying 2 mM salicylic acid comparedwith 0 and 1 mM doses. The findings of this study showed that salicylic acid was able to enhance the tolerant capacity of the grape plant to the drought stress. According to theobtained results, Rashehcultivar showed a greater resistance to drought stress. Salicylic acid prohibits auxin and cytokinin loss in plants and thus enhances cell division and plant growth. Salicylic acid maintainsphotosynthetic aspects like chlorophyll content at proper level and thus helps plants to grow and developwell. In this study, the drought stress increased the amount of MDA.MDA and other aldehydes in the dry conditions are the result ofactive oxygen species (ROS) such as super oxide radical, peroxide, hydrogen and radical hydroxide, whichareproduced underoxidative stress conditions. The species of active oxygen leads to lipids' per oxidation as a result of injury or damage to the cellular membrane, especially chloroplast membrane.Salicylic acid increases the activity of antioxidant enzymes such as CAT, POD and SOD which in turn protect plants against ROS generation and lipid peroxidation. Salicylic acid treatment also providesa considerable protection from the enzyme nitrate reductase, thereby maintaining the level of diverse proteins in leaves.Mohammadkhani and Heidari (48) found that the initial increase in total soluble proteins during drought stress was due to the expression of new stress proteins.
