Growing vegetables
Nasrin Farhadi; Mojgan Abdeshahian; Samane Mottagi
Abstract
Introduction
Currently, salinity stress is one of the most important challenges in the agriculture and is the main growth limiting factor of many plant species. Saline stress adversely affects the plant's physiological and biochemical process which leads to a considerable reduction of plant growth ...
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Introduction
Currently, salinity stress is one of the most important challenges in the agriculture and is the main growth limiting factor of many plant species. Saline stress adversely affects the plant's physiological and biochemical process which leads to a considerable reduction of plant growth and yield. Shallot (Allium hirtifolium Boiss.) is a perennial plant from the Alliaceae family, which is one of the native and valuable plants of Iran and wildly grows in the slopes of the Zagros Mountain range. The nutritional and medicinal value of shallots is due to the presence of sulfur compounds, especially allicin in the bulbs. The present study was conducted to investigating the effect of foliar application of salicylic acid on the changes of growth, physiological and biochemical traits of shallot under different levels of salinity stress in factorial design based on a completely randomized design with three replications. The investigated treatments were four levels of salinity (0, 30, 60 and 90 mM NaCl) and four levels of salicylic acid (0, 1, 1.5 and 2 mM). Distilled water (control) and salicylic acid (1, 1.5 and 2 mM) were foliar sprayed on the whole plants at 4, 6 and 8 weeks after sowing date. At the end of the growing season (beginning of yellowing of the leaves of the plants), growth, physiological and biochemical traits were evaluated. Evaluation of lipid peroxidation, osmolality compounds and activity of antioxidant enzymes was carried out in the leaves of treated plants and the amount of pyrovat and allicin was measured in harvested shallot bulbs.
Results and discussion
Various abiotic stresses restrict plant productivity, and many efforts have been done to reduce plant growth inhibition by alleviating the disorder’s effects of these stresses. Exogenous application of plant growth regulators has been reported as an economic procedure to improve plant resistance to environmental stresses. It has been previously reported that salicylic acid as a signaling molecule alleviated the adverse effect of different stress condition. In this experiment, shallot resistance to saline condition was enhanced by the foliar spray of salicylic acid. The results showed a significant link between salicylic acid treatment and improvement of bulb biomass under saline conditions. Lipid peroxidation regards to accumulation of malondialdehyde and hydrogen peroxide increased with increasing the salinity intensity. Also, saline stress significantly enhanced the proline and glycine betaine content in stressed plants of shallot. The plant antioxidant activity induced under stress condition by increased the total phenol content as well as the activity of catalase, peroxidase, ascorbate peroxidase and superoxide dismutase enzymes. The pyrovat and allicin content of shallot bulb was increased with increasing salinity stress. The decreased in the photosynthetic pigments (total chlorophyll and carotenoids) led to a decrease in plant growth with the intensifying of stress level. So that the lowest leaf area, fresh and dry weight of bulbs were obtained in severe salinity stressed plants (90 mM NaCl). Foliar application of salicylic acid through increasing the antioxidant compounds (total phenol, pyrovat and allicin) and the activity of antioxidant enzymes (CAT, POX, APX and SOD) limited the of hydrogen peroxide accumulation and lipid peroxidation. The induced accumulated osmolyte compounds proline and glycine betaine was decreased in treated plant with salicylic acid. The treatment of salicylic acid considerably improved the chlorophyll and carotenoids content especially in salinity stressed plants. So that the applied of salicylic acid, especially at concentration of 2 mM, reduced the harmful effects of salinity stress on plant growth and bulb yield by increasing the photosynthesis pigments and consequently photosynthesis efficiency. Also increased growth in the treated plants with salicylic acid has been attributed to changes in the concentration of plant hormones, especially auxins and cytokinins (the most important plant growth stimulating hormones). Nevertheless, the growth reactions of treated plants to salicylic acid are different depending on the used concentration, the plant species and the growth stage at the treatment time.
Conclusion
In the several literatures the salicylic acid effects on plant growth enhancement under unfavorable environmental condition attributed to salicylic acid-induced changes in plant biochemical and physiological processes. Based on the obtained results, the salinity resistance of the shallot plant in response to salicylic acid is related to the increased antioxidant capacity of the stressed plants, which leads to the improvement of the photosynthetic pigments, and consequently plant growth and bulb biomass under saline condition. Although the present study was performed in the glass greenhouse, the obtained finding showed that salicylic acid application could also be a promising treatment for improving salinity tolerance of A. hirtifolium under field conditions.
Ornamental plants
M. Ayaseh; M. Kafi; M. Khansefid; M. Shokrpour; R. Naderi
Abstract
Introduction
Today, a significant factor limiting plant growth is the rising salinity of soil and water, which poses challenges to food security, ecological stability, and agricultural systems. Numerous studies indicate that salinity hampers seed germination and early plant development by inducing osmotic ...
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Introduction
Today, a significant factor limiting plant growth is the rising salinity of soil and water, which poses challenges to food security, ecological stability, and agricultural systems. Numerous studies indicate that salinity hampers seed germination and early plant development by inducing osmotic stress, ion toxicity, and oxidative stress. Utilizing salinity-tolerant aromatic plants in saline areas can effectively enhance landscapes. Therefore, cultivating valuable plant species that meet high ecological demands may be the best strategy to mitigate salinity stress in agriculture and natural resources. These species can serve as alternative crops for oil seed production, food products, fodder, and both medicinal and ornamental uses. Tanacetum parthenium, Achillea millefolium, and Zygophyllum eurypterum are examples of medicinal and aromatic herbaceous perennials with low input requirements. They can be grown for various purposes, including ornamental use in dry and saline climates, as well as in the food, perfumery, cosmetics, and medicinal industries. Successful cultivation of these valuable plants in stressful ecosystems necessitates investigating their early growth responses to salinity stress. This research aims to identify suitable conditions for the successful establishment of these plants, ultimately leading to increased production.
Materials and Methods
In order to investigate the physicochemical responses and the early growth of seedlings in the shoot and root of three plants, T. parthenium, A. millefolium and Z. eurypterum to different levels of zero salinity stress (control), 1.5, 3 and 6 dS.m-1, an experiment was conducted as factorial based on completely random design with three replications using a completely randomized design in a greenhouse under pot conditions in Department of Horticultural Science and Green Space Engineering at the University of Tehran. Seeds from three plant species—T. parthenium, A. millefolium, and Z. eurypterum—were obtained from the Research Institute of Forests and Rangelands (RIFR) in Karaj province, Iran. Prior to planting, the seeds were sterilized for one minute in a 2% sodium hypochlorite solution and then washed three times with sanitized water. The seeds were then planted in plastic pots (45, 66, and 23 cm) filled with a mixture of clay, sand, and perlite, at a depth of three centimeters, under greenhouse conditions. Sodium chloride was used to create salinity stress, exposing all studied plants to four salinity levels for a duration of six weeks. The greenhouse maintained a temperature of 20°C at night and 25°C during the day, with a relative humidity of 60-80%. All physiological and biochemical measurements were conducted after six weeks, once the plants were fully established. It is important to note that all samples were washed with distilled water post-sampling, the surface water was removed using filter paper, and samples were immediately stored at -80°C until measurements were taken.
Results and Discussion
The results of this study indicated that the concentration of photosynthetic pigments (chlorophyll a, chlorophyll b, carotenoids, and total chlorophyll) decreased with increasing salinity levels, which correlated with a reduction in the growth length of both shoots and roots. The results indicated that under severe salinity stress, oxidative damage increased, leading to higher levels of fat peroxidation (MDA) and reduced cell membrane stability. This decrease in stability was linked to a reduction in photosynthetic pigments, ultimately disrupting optimal plant early growth. At all salinity levels, the total antioxidant capacity of A. millefolium leaves was greater than that of its roots. Among all three plants and salinity levels, the highest total antioxidant capacity of 78.57% was observed in the roots of Z. eurypterum under a salinity condition of 3 dS.m-1. Conversely, the lowest total antioxidant capacity, at 25.38%, was found in the leaves of T. parthenium under non-saline conditions. The results indicated that the potassium to sodium ratio at equilibrium varied significantly depending on the plant species, plant organ, and salinity concentration and the highest ratio was found in the aerial parts of T. parthenium.
Conclusions
Overall, based on the biochemical and physiological responses to salinity stress, all three plants exhibited a relatively high tolerance. However, the T. parthenium plant demonstrated the greatest tolerance to salinity stress among them. Therefore, the cultivation of these three species, which possess ornamental, aromatic, and medicinal value, can serve as a viable solution for the ecological sustainability of saline ecosystems and their integration into urban landscaping.
Acknowledgement
The authors are grateful for the scientific assistance of Dr. Behrouz Malekpour
Growing vegetables
Z. Khalili; F. Nekounam; T. Barzegar; Z. Ghahremani; M. Farhangpour
Abstract
IntroductionTomato (Solanum lycopersicum L.) belongs to the Solanaceae family, which is one of the most widely cultivated and economically important vegetables in the world, which is an excellent source of ascorbic acid and has high antioxidant capacity against oxidative damage caused by free radicals. ...
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IntroductionTomato (Solanum lycopersicum L.) belongs to the Solanaceae family, which is one of the most widely cultivated and economically important vegetables in the world, which is an excellent source of ascorbic acid and has high antioxidant capacity against oxidative damage caused by free radicals. Ascorbic acid (AsA) is a water-soluble vitamin that plays a key physiological role in scavenging reactive oxygen species (ROS), and enzyme cofactor. Ascorbic acid is antioxidant and anti-stress agent, and also acts as a signaling molecule in some plant physiological processes and defense mechanisms. Positive roles of such antioxidants in scavenging or chelating the free radicals and activating the natural resistance against different biotic and abiotic stresses have been reported in several fruit trees. Calcium has a vital role for normal growth and development of plants due to an important role in balancing membrane structures, increasing nutrient uptakes and activates of metabolic processes. Calcium plays a vital role in maintains cell wall stability, integrity and determining the fruit quality. To our knowledge, however, little information is available regarding the interaction effect of ascorbic acid and calcium chloride on tomato. Thus, the aim of this study was to investigate the foliar application of ascorbic acid and calcium chloride on quality and antioxidant capacity of tomato fruit. Materials and MethodsTo study the effect of foliar application of calcium chloride (Ca) and Ascorbic acid (AsA) on growth, yield and fruit quality of tomato, the field experiment was carried out from June to September 2021 at Research farm of faculty of Agriculture, at the University of Zanjan, Iran. Each treatment was carried out with three replicates. Different concentrations of Ca (0, 0.3, 0.6 and 0.9 %) and AsA (0, 100, 200 and 300 mg.l-1) were sprayed three times (0, 15, 30 days after full bloom). Fruits were harvested at two harvests stage (orange and red color) and transferred to the laboratory on the same day. Flesh firmness was determined with penetrometer (model Mc Cormic FT 32), using an 8 mm penetrating tip. Results were expressed in kg cm-2. The pH values of solutions were monitored with pH meter. TSS was measured in the extract obtained from three fruit of each replicate with a digital refractometer Atago PR-101 (Atago Co., Ltd., Tokyo, Japan) at 20◦C. Total ascorbic acid content was expressed as mg per 100 g of juice. Antioxidant activity was measured using the free radical scavenging activity (DPPH) and calculated according to the following formula: RSA%= 100(Ac-As)/Ac. Statistical analyses were performed with SPSS software package v. 20.0 for Windows, and means comparison were separated by Duncan’s multiple range tests at p< 0.05. Results and DiscussionThe results showed that fruit harvested at red color stage had higher vitamin C, total soluble solid (TSS), total phenol, flavonoids contents and antioxidant capacity compared to fruit harvested at orange color stage. Foliar application of AsA and Ca had significantly improved tomato fruit quality. The highest value of TSS (4.9 °B), vitamin C (46.1 mg.100 ml-1), total phenol and flavonoids contents and antioxidant capacity (36%) was achieved with application of 300 mg.l-1 AsA and 0.9% Ca in fruit harvested at red color harvest time. The lowest value of pH and highest TA was observed in red color fruit treated with 300 mg.l-1 AsA and all Ca levels. Ca had significant effect on fruit firmness, which the highest fruit firmness was obtained from 0.9% Ca. The fresh tomato is an important source of ascorbic acid for human consumption. AsA significantly increased the amount of vitamin C in the plum and sweet pepper fruits. Increasing vitamin C content in fruits after treatment with Ca could be related to inhibiting action of calcium on the activities of ascorbic acid oxidase that use ascorbate as a substrate. The results indicated that treatment of Ca produced fruits with higher firmness compared to control and other treatments. Firmness and resistance to softening can be increased by the addition of Ca, due to interaction of calcium with pectate acid in the cell wall to form calcium pectate and retarding polygalacturonase activity. Differences in the percentage of TSS content at the time of harvest indicated the AsA and Ca effects on carbohydrate accumulation in fruits, which had different potential on respiration rates and consequently storability of plants. The antioxidant activity has positive correlation with total phenolic content, flavonoids and content of ascorbic acid. ConclusionsThe results of our research indicated that per-harvest foliar application of AsA and Ca improved fruit quality attributes including vitamin C, fruit firmness, TSS and antioxidant activity. These results suggest that AsA and Ca treatments, especially AsA 300 mg.l-1 and Ca 0.9%, may be proposed to improve fruit quality.
Growing vegetables
M. Ghoreyshi; F. Nekounam; T. Barzegar; J. Nikbakht
Abstract
Introduction
Water stress is the most prominent abiotic stress limiting agricultural crop growth and productivity. Deficit irrigation stress as a consequence of the progressive decrease in water availability has been a hot topic regarding food security during the last two decades. Growth and development ...
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Introduction
Water stress is the most prominent abiotic stress limiting agricultural crop growth and productivity. Deficit irrigation stress as a consequence of the progressive decrease in water availability has been a hot topic regarding food security during the last two decades. Growth and development of plants is influenced by reduction in turgor that results in decreased nutrient acquisition from dry soil. When water supply is limited, plant growth and yield is reduced and plant structure is modified by decreasing in leaf size. The effect of deficit irrigation on fruit yield and quality has been reported by numerous researchers with different results. In melon, deficit irrigation reduced marketable fruit number and yield, average fruit weight, fruit diameter and did not affect rind thickness and seed cavity, but increased total soluble solids content. Although the effects of water stress have been studied on growth and yield of different crops during the last years, recent information on the response of African horned cucumber yield and quality to deficit irrigation remains limited, particularly about the results of restricted water distributions in arid and sub-arid environments. The main goal of this study was to evaluate the effect of controlled deficit irrigation on growth, physiological parameters and yield and fruit quality of African horned cucumber.
Material and Methods
Field experiment was performed based on a completely randomized block design with three irrigation regimes (60, 80 and 100 %ETc), whit three replications at Research Farm of University of Zanjan during the 2019. The African horned cucumber seeds were sown on 1th July 2020 at recommended spacing of 50 cm in row with 120 cm between rows. The irrigation system consisted of one drip line every crop row. The three irrigation levels were calculated based on actual evapotranspiration (ETc): (1) control, irrigated 100% crop water requirement, (2) deficit irrigation 80% ETc and (3) deficit irrigation 60% ETc. The Water requirement of the plant for control treatment was estimated using long-term average daily data of meteorological parameters recorded at Zanjan Meteorological Station and following relation. Before starting the differential irrigation at five-leaf stage, all treatments were supplied with similar amount of water to maximize stands and uniform crop establishment. During plant growth, the relative water content, proline content, electrolyte leakage, chlorophyll and carotenoids, P and K contents were measured. After fruit harvest, vine length of each plant, leaf dry weight and stem diameter were measured. The fruits were harvested when color changed from green to yellow. Fruit weight, fruit number per plant and fruit yield per plant was measured. Immediately after harvest, fruit firmness, total soluble solid, total phenols content, antioxidant capacity and vitamin C were determined.
Results and Discussion
As the results showed water deficit stress significantly reduced plant length, chlorophyll content, and increased carotenoids content. Based on the findings, deficit irrigation caused a significant reduction in leaf relative water content. According to the results, phosphorus and potassium contents in African horned cucumber leaves decreased with deficit irrigation treatments. The highest P and K contents were found under irrigation 100 %ETc treatment. Drought stress and associated reduction in soil moisture can decrease plant nutrient uptake by reducing nutrient supply through mineralization. The proline content increased with the deficit irrigation treatments; in particular with sever deficit irrigation (60 %ETc). Mean comparisons of data showed that deficit irrigation led to a significant increase in electrolyte leakage compared to control.
Water deficit stress caused significant reductions in yield. The highest fruit number per plant and yield were obtained under irrigation 100% ETc. The average fruit weigh significantly increased in response to increase water deficit stress. Deficit irrigation treatments significantly decreased vitamin C and fruit firmness. Significant differences among irrigation treatments were observed for total phenols and total soluble solid contents. The phenols and total soluble solid contents increased with the decrease of irrigation water applied. Antioxidant capacity was affected significantly by the irrigation treatments, and water deficit stress increased antioxidant capacity, which no significant difference was observed between irrigation 100 and 80 %ETc.
Conclusion
Water deficit has been shown to adversely affect plant growth, fruit yield, and leaf water status of African horned cucumber, but led to increase the TSS and antioxidant capacity. According to the results, fruit yield reduced 13.9 % under irrigation 80% ETc compared to irrigation 100% ETc, However, water consumption was saved by 20% and improved fruit weight and fruit quality with increasing soluble solids and antioxidant capacity.
Postharvest physiology
M. Ghafouri; F. Razavi; M. Arghavani; E. Abedi Gheshlaghi
Abstract
Introduction Nowadays, the application of chemical compounds is limited due to their harmful effects on human and the environment health. The benefits of seaweeds as sources of organic matter and fertilizer nutrients have been known to agriculture for centuries, especially in coastal areas extracts ...
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Introduction Nowadays, the application of chemical compounds is limited due to their harmful effects on human and the environment health. The benefits of seaweeds as sources of organic matter and fertilizer nutrients have been known to agriculture for centuries, especially in coastal areas extracts of these seaweeds have been used for decades as foliar- and soil-applied treatments in crop production systems due to the presence of a number of plant growth-stimulating compounds. Unlike chemical fertilizers, extracts derived from seaweeds are biodegradable, non-toxic and non-hazardous to humans, animals and birds. Therefore, it is required to find a safe compound that is utilized in the postharvest technology of fruit and vegetables. Pre-harvest application of nutrient solutions such as seaweed increases the quality and quantity of crop and also enhance their storage life and marketability. Various researchers reported that aqueous extracts of seaweed increased the yield and quality of tangerine and orange, strawberry, grape, apple, and watermelon fruit. Thus, the aim of the current study was to investigate the effect of pre-harvest foliar application of Seaweed extract on quality and quantity values, antioxidant properties, and storage life of kiwifruits.Material and Methods This experiment was carried out on 10-year-old kiwifruit vines, in a commercial orchard located in Gilan Province. Vines were selected with uniform size in terms of growth, yield and fruit load, then sprayed with seaweed extract at four levels of 0, 1, 2 and 3 g.l-1 as a foliar spray and control vines only received water. Foliar spraying was performed in three stages, (110, 125 and 140 days after full bloom stage) and Tween 20 was used as a surfactant. This experiment was designed as factorial based on randomized complete block design with three replications. The fruits were harvested in November with soluble solids content (TSS) of 6.5-6.2% and then transferred to the post-harvest physiology laboratory of the University of Zanjan. The treated fruits were stored for 90 days at 1 ° C with 90% RH. Sampling was done at harvest time and after 30, 60 and 90 days of storage and some quantity and quality traits such as weight loss, tissue firmness, TSS, ascorbic acid, total phenol and flavonoids, antioxidant capacity and the activity of superoxide dismutase (SOD) and phenylalanine ammonia-lyase (PAL) enzymes were evaluated.Results and Discussion The ANOVA results showed that seaweed extract, storage time, and interaction of seaweed extract × storage time had a significant effect (p≤0.01) on evaluated traits. All treatments maintained the antioxidant capacity, total phenol and flavonoids content and PAL activity at a higher level compared with control. The amount of fruit tissue firmness, TA and ascorbic acid decreased by increasing the storage time, and at the third month of storage, the lowest amount was observed in the control fruit. Also, comparing the interaction of the mean of treatments and storage time showed that pH, weight loss, TA, TSS, antioxidant capacity, total phenol, flavonoids and PAL enzyme activity increased by increasing the storage time. At the end of the storage time, the highest level of TSS, weight loss and pH were observed in the control fruit. The lowest antioxidant capacity (48.14 %) was observed in the control treatment at harvest time and the highest antioxidant capacity was observed in 3 levels of brown algae extract treatment at the end of storage period. Comparison of means showed that at the first 30 days of storage, the highest PAL enzyme activity was observed in the treatment of 3 g / l of brown algae. PAL enzyme activity significantly increased after the experiment. At the end of storage period, the lowest PAL enzyme activity was observed in control fruit. Treatment of 3 g / l brown algae had higher PAL activity. PAL, as a key enzyme in phenylpropanoid metabolism, catalyzes the conversion of phenylalanine to trans-cinnamic acid, which is the first step in the biosynthesis of phenylpropanoids and leads to the production of secondary metabolites such as lignin, phytolaxoids, and flavonoids. The direct and positive relationship of this enzyme with the synthesis of phenols and flavonoids has been discovered in the fruits of blood orange, strawberry and blueberry. The results of the comparison of the mean showed that the total phenol and flavonoids increased by increasing the storage time. The lowest phenol (23 mg GAE.100 g-1 FW) was observed in control fruit at harvest and the highest (8.88 mg GAE.100 g-1 FW) content of total phenol was observed in 3 levels of brown algae extract at the third month of storage. Plants release phenolic compounds in response to some messenger compounds that play an important defense role. Studies show that there is a positive relationship between total phenol content and their antioxidant activity. Flavonoids are also polyphenolic compounds and are the most important secondary compounds of plants. Under oxidative stress, in plants, the activity of propanoid pathway increases, especially the pathway of flavonoids biosynthesis. Flavonoid compounds are abundant in plants and show antioxidant activity. Seaweed extract enhances the antioxidant capacity of the fruit and thereby inhibits oxygen-free radicals Treatment of 3 g/l seaweed extract had the best effect among the treatments applied in maintaining firmness, fruit weight loss, TA, antioxidant capacity, total phenol and flavonoids and PAL enzyme activity. All three levels of seaweed extract increased the amount of total phenol, flavonoids and antioxidant capacity all over the storage time, but no significant difference was observed among the treatments levels. Based on the results, the application of 3 g/l seaweed extract effectively increased the antioxidant capacity and PAL enzyme activity during 90 days of storage time. As a result, seaweed extract treatment had positive effects on maintaining the quality and increasing the shelf life of kiwifruit during 90 days of storage.ConclusionSeaweed extract is one of the natural compounds and compatible with human health and nature has medicinal and nutritional value that can increase the shelf life and maintain fruit quality in the postharvest period. In summary, foliar application of seaweed extract has a significant effect on fruit firmness, total soluble solids, total acid, vitamin C, phenol and total flavonoids, total antioxidant activity and the enzyme phenylalanine ammonialyase. The appropriate treatment for kiwifruit cultivar ‘Hayward’ is introduced. Among the applied treatments, 3 g/l of seaweed extract had the best effect on firmness (40.40%), fruit weight loss percentage (41.87%), titratable acid (25.37%), vitamin C (33.26%), antioxidant capacity (26.70%), total phenol (81.17%), total flavonoids (103.67%) and PAL enzyme activity (153.75%) compared to the control in 90 days of storage.
Mohsen Mozaffari; Farhang Razavi; Vali Rabiei; Azizollah Kheiry; Akbar Hassani
Abstract
Introduction: Demand for healthy and high-quality fruits has increased in the markets, and compositions such as vitamins, sugars, and anti-oxidant properties of fruits have attracted many consumers. Grapes contain phenols, flavonoids, anthocyanins, tannins and vitamins with high antioxidant properties. ...
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Introduction: Demand for healthy and high-quality fruits has increased in the markets, and compositions such as vitamins, sugars, and anti-oxidant properties of fruits have attracted many consumers. Grapes contain phenols, flavonoids, anthocyanins, tannins and vitamins with high antioxidant properties. Antioxidants support biological systems such as proteins, amino acids, lipids, and DNA against oxidative damage produced by active oxygen species of ROS, resulting in reduction of cell damage and death, cardiovascular disease and cancers in the human body. Selenium is essential for humans and animals and should be fed through a diet, for this reason, FAO recommends entering selenium to agricultural products (especially fruits and vegetables). In recent years, selenium has been recognized as a useful element for plants that have been toxic at high concentrations but at desirable concentrations, it has positive antioxidant effects, increases growth and significantly affects seed germination. Selenium protects plants from several abiotic stresses such as heavy metal and arsenic, ultraviolet radiation, and biotic stress such as pathogens and pests. Selenium neutralizes oxidative stress interfering with lipid peroxidation, and accelerates gluthatione peroxidase (GSH-Px) activity, this phenomenon delay plant senescence and diminish postharvest losses. This element increases the yield and improves the quality of the fruits and vegetables. When Camelia oleifera plants were treated with selenium, cellular content of linoleic acid and sterol were elevated but oleic acid content diminished. Selenium treatment had a significant effect on preserving the sensory and the postharvest quality by decreasing respiration rate and ethylene biosynthesis in broccoli by diminishing phenylalanine ammonia-lyase (PAL) activity and ethylene production in lettuce and chicory. Foliar application of peach and pear trees with selenium, decelerated fruit softening rate and elongated shelf-life. Therefore, treatment of agricultural products with the appropriate amount of selenium can have a positive effect on the increase of the quality and enrichment of selenium in fruits and also play an important role in human health.
Materials and Methods: In order to investigate the effect of selenium as foliar application (0, 1, 2 and 3 mg L-1) on quality traits, antioxidant compounds and enrichment of grape cv. Fakhri, an experiment based on randomized complete block design with three replications in a vineyard (Kurdistan Povince, Ghorveh town) was performed. The 15-year-old vines were sprayed with selenium solution plus 0.1% of Twin 20 as surfactant until the leaves were completely wet (for each vine about 0.5 liter) at three stages of berry growth and development: Berry formation, Lag phase and veraison. A 1000 mg L -1 stock solutions (Made by the Belgian company CHEM-Lab, containing selenium ion Se+6) was used to prepare the desired solutions. At commercial fruit maturity stage (20° Brix), samples of fruits and leaves randomly were collected from treated and control vines and were immediately transferred to the postharvest physiology laboratory. Traits such as total chlorophyll, carotenoid, nitrogen, potassium, selenium content of leaves and fruits, and also, total soluble solids, soluble sugars, titrable acidity, acidity (pH), vitamin C, phenol and flavonoids, antioxidant capacity in fruits and the berry weight were evaluated. Data were analyzed using SAS statistical software (SAS V.9.4), and means were compared by Duncan’s multiple range tests at the 5% of probability level.
Results and Discussion: Results showed positive effects of selenium treatment on evaluated traits. As a result, 2 mg L-1 of selenium increased photosynthetic pigments, nitrogen and leaf potassium, soluble solids, soluble sugars, vitamin C, total phenol, antioxidant capacity of fruits in comparison with untreated vines. The highest amount of titrable acidity, total fruit flavonoid and leaf selenium was recorded in vines treated with 3 mg L-1 selenium, whereas, this treatment had less effect on other traits. The highest amount of berry weight was obtained in 1 mg L-1 of selenium. However, none of the selenium treatments had significant effect on the juice acidity (pH). In general, the results showed a positive effect of selenium on improvement of antioxidant properties, quality and enrichment of grape, and 2 mg L-1 selenium with the highest effect on traits was identified as the best treatment. According to other researchers, foliar application of selenium in "Starking Delicious" apple cultivar was effective in enhancement of fruit selenium content and nutritional properties, postponing the flesh firmness decrease, and delaying fruit ripening resulting from less ethylene production, therefore significantly affecting apple fruit quality and storage life.
Zahra Khazaei; Mohammad Sayyary; Mehdi Seydi
Abstract
Drought, withnegative impacts on plant growth and development, isa major abiotic stress. In order to decreasing drought stress injuries and recognizing red peppers tolerance physiology against drought stress in greenhouse conditions, an experiment with three levels of drought stress (irrigation at 100, ...
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Drought, withnegative impacts on plant growth and development, isa major abiotic stress. In order to decreasing drought stress injuries and recognizing red peppers tolerance physiology against drought stress in greenhouse conditions, an experiment with three levels of drought stress (irrigation at 100, 60 and 30% of field capacity) and four concentrations of 5-aminolevolinic acid ((ALA; 0, 0.25, 0.5, and 1 mM)with four replications in an experimental was 3×4 factorial experiments in a randomized completely design was conducted in greenhouse of Agricultural Faculty of Ilam University. In the end of experiments, parameters such as ascorbate peroxidase activity, total antioxidant activity, malondialdehyde content, ascorbic acid, relative water content, plant height and number of lateral buds was evaluated. The results showed that with increasing drought stress severity the growth parameters decreased significantly but ascorbate peroxidase activities, total antioxidant capacity, malondialdehyde and ascorbic acid content increased. Foliar application of AHA reduced malondialdehyde content and improved other evaluated traits. ALA protected cell membranes by reducing malondialdehyde content and lipid peroxidation. In addition, ALA with increasing ascorbate peroxidase activity, total antioxidant capacity and ascorbic acid contents in plants improved physiological traits and drought stress resistance.
