Research Article
Atiyeh Oraee; Ali Tehranifar; Ahmad Nezami; Mahmood Shoor
Abstract
Introduction: Climate change is expected to have impacts on ecosystems worldwide. During the last 50 years, the greatest warming trends have been observed in winter months and significant increases in both the occurrence and duration of winter warming have already been reported. In general, predicted ...
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Introduction: Climate change is expected to have impacts on ecosystems worldwide. During the last 50 years, the greatest warming trends have been observed in winter months and significant increases in both the occurrence and duration of winter warming have already been reported. In general, predicted future climate change scenarios will result in less than optimal cold acclimation conditions, leading to decreases in freezing tolerance and predisposition of plants to winter injury. Nonetheless, it is not clear whether water stress induced during cold hardening is of high importance in inducing freezing tolerance in plants or it is an integral part of typical cold hardening process. Since rapid and effective assessment of plant cold tolerance is important for researchers and also field trials have no regular process and have high error, different kinds of artificial freeze tests such as survival percentage test and regrowth after imposing stress have been developed.
Materials and Methods: In order to evaluate the effect of drought stress on plant freezing tolerance of viola, a factorial experiment was conducted based on completely randomized design with three replications in faculty of Agriculture, Ferdowsi University of Mashhad. Experimental factors include three water treatments (80% FC, 60 % FC and 40% FC) and 10 temperature levels (Control, from zero to -24 with 3 °C intervals). Pansy seeds sown in a nursery in the summer of 2015 and after reaching the five-leaf stage in the fall plants were transferred to the pots. After the potted plants spend cold acclimation in nature conditions, plants were subjected to water stress including control (80% FC), 60% and 40% FC for two weeks. After drought stress, whole plants were sampled for freezing tolerance assessment and they were transferred to the freezer thermos-gradient. After applying the stress, electrolyte leakage, lethal temperature 50 according to the electrolyte leakage percentage (LT50el) were measured. One months later, survival percentage, lethal temperature 50% of plant according to the survival percentage (LT50su), leaf area, number of flower and bud, dry weight (dry weight of vegetative, reproductive, root and total) and reduced dry matter temperature 50 (RDMT50) were evaluated.
Results and Discussion: Electrolyte leakage percentage (EL %) and survival (%) were significantly (p ≤ 0.01) affected by irrigation treatments in the freezing conditions. By lowering the temperature from 20 to -24 °C, the EL% significantly increased in three irrigation treatments and it increased in 80% FC compared to 60% (by 16%) at -24°C. plants under 60% FC treatment exhibited higher baseline freezing tolerance (LT50 of −18.4 °C) compared to 80% FC (LT50 of −11.8 °C).Treated plants (except 80% FC) were able to tolerate lowering the temperature to -21°C. Lowering the temperature to -24°C caused the total mortality. According to the LT50su index, 60% FC treatment was less than compared to other treatments. Leaf area significantly increased by 16%, respectively, when plants were under water deficit (60% FC) compared to 80% FC at 0 °C. The maximum number of flower were seen in 60% FC at – 3 °C and the maximum number of bud were observed at 0 °C. The results showed that dry weight was significantly (p ≤ 0.01) increased by drought stress in the freezing conditions. Plants under 60% FC at 0 °C had the highest increase (55, 62 and 64%, respectively) dry weight of vegetative, reproductive and total growth, respectively compared to control. By lowering the temperature to -18 °C in 80% FC vegetative, reproductive and root growth decreased (36, 38 and 42%, respectively) compared to control plants. RDMT50 significantly affected by drought stress. There were significantly correlation between EL with LT50el and RDMT50 (r =0.25* and r = 0.72**, respectively). In total, plants under 60% FC showed highest freezing tolerance compared to the other treatments.
Conclusions: In the current study, we found that the greatest gain in freezing tolerance was associated with cold and that the effect of drought stress on freezing tolerance varied with temperature. Drought stress resulted in an improvement in freezing tolerance of viola (lower LT50). Among the different parameters evaluated, 60% FC treatment at 0 °C most consistently induced increases in survival percentage, reproductive and vegetative growth which suggested a synergistic effect between drought exposure and low temperature. Higher dry weight of viola plants may contribute to better plant overwintering capacity. In addition, future research should explore the effect of repeated mild drought events on freezing tolerance of acclimated plants, by using strategies such as wilt-based irrigation scheduling, partial root zone drying, and deficit irrigation.
Research Article
Lamya Vojodi Mehrabani
Abstract
Introduction: Ocimum basilicum L. is an herbaceous annual plant from Lamiaceace family. Ocimum basilicum is more valued for its essential oil components, vitamins and elemental content. Nowadays, using soil covers is a major trend in modern agricultural systems mainly due to their water saving potential, ...
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Introduction: Ocimum basilicum L. is an herbaceous annual plant from Lamiaceace family. Ocimum basilicum is more valued for its essential oil components, vitamins and elemental content. Nowadays, using soil covers is a major trend in modern agricultural systems mainly due to their water saving potential, prevention of soil erosion, soil temperature equilibrium, nutrients availability, soil structure improvement, positive effect on plant quality attributes, weed control and yield improvement. Organic fertilizers, regulate pH, adjust soil CEC and improve the micro-organisms activity. Dekap® and Estimplex® improves the plant nutrition and the application of these organic sources would be so promising in order to meet the sustainable agricultural system needs mainly to cut the overuse of chemical fertilizers. High pH and calcareous soils greatly impact the quality and yield of plants dominantly due to nutritional imbalances in the most regions of the country. Therefore, the foliar application of nutrients would be an efficient way to overcome the problem. Moreover, water deficiency is another constraint encourages the using bed-covers to combat the water scarcity in many parts of the country.
Materials and Methods: In order to study the effects of soil cover (control, black and white) and different levels of Dekap® [Dekap fertilizer is containing 33% P (P2O5) and 42%K (K2O)] and Estemplex (see algae extract) (0, 1.5, 3 and 4.5 mlL-1) on growth and some physiochemical characteristics of Ocimum basilicum L. an experiment was conducted as factorial based on completely randomized block design with three replications at Azarbaijan Shahid Madani University, Iran.
Results and Discussion: The results showed that there were interaction effects of soil cover and foliar applications on phenolics content. The highest data for phenolics content was recorded with black soil cover × 4.5 mlL-1Dekap (105 mgg-1 DWt), black soil cover × 1.5 and 3 mlL-1 (98 mgg-1 DWt) Estemplx. The results showed that the highest data for plant dry weight (51 g) were obtained from black soil-cover and the highest plant height and axillary shoots number were recorded in both plastic soil cover. Foliar application of Dekap and Estemplex increased plant height and axillary shoots number. The highest data for N and Mg contents were obtained from black soil-cover and for K and Zn were obtained from black and white soil cover. The foliar application of Dekap and Estemplex increased P and K contents in plant. 1.5, 3 and 4.5 mlL-1 Estemplex increased N, K and Mg contents in Ocimum basilicum. The results showed that the highest data for chlorophyll a, flavonoid, total soluble solids and protein content were obtained from black soil-cover. IC50 and superoxide dismutase content of plant influenced by black and white soil cover. Foliar application of Dekap and Estemplex increased flavonoid contents in plant. Foliar applications with three concentrations of Estemplex increased chlorophyll a, IC50 and protein content in plant. 1.5, 3 and 4.5 mlL-1Estemplex increased superoxide dismutase, total soluble solids content (2.1 0 brix) and Zn content (28.9 and 30.3 mgKg-1).
Conclusion: Adequate and balanced nutrition of plants result in environmental protection mainly by the reduced application of chemical fertilizers, soil erosion prevention, and increased input efficiency. Foliar application is an environmental friendly method to reduce the production changes. The overall results revealed the positive effects of black mulch and Estemplex fertilizer on nearly all the desired traits. It seem that Estemplex fertilizer effects on the growth indices was greater than Dekap fertilizer. Seemingly, with the more detailed studies, this fertilizer has the potential to be employed with the extension section.
Research Article
Sepideh Taghizadeh; Hossein Sadeghi; Mehdi Hadadinejad
Abstract
Introduction: Influx of Siberian cold air masses into the northern parts of Iran causes severe decrease in temperature, heavy snowfall and freezing of citrus every few years. Depending on the temperature drop, in some years only fruits and in some years, citrus trees suffer severe damage too. One of ...
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Introduction: Influx of Siberian cold air masses into the northern parts of Iran causes severe decrease in temperature, heavy snowfall and freezing of citrus every few years. Depending on the temperature drop, in some years only fruits and in some years, citrus trees suffer severe damage too. One of the sudden drops in temperature was in January 2007, when the temperature dropped from -7 degrees Celsius to -13 degrees Celsius. Consecutive damage to citrus trees and crops in the north of the country has caused citrus gardeners to despair of its economic viability and to refrain from rehabilitating destroyed orchards. The mechanisms of frost resistance and relative tolerance to cold in citrus include physiological adaptation and metabolic changes. These changes will lead to the production of various cellular osmolytes, the accumulation of soluble substances, changes in lipid metabolism (with an increase in unsaturated fatty acids), an increase in supercooling temperature, and ultimately an increase in plant resistance. The use of passive and active methods can also partially prevent frost damage or reduce the severity of the injury, but spraying with compounds that may provide physical protection of trees against freezing or spraying chemicals that reduce the freezing point of the cellular fluid by altering the concentration of the cell sap could be more promising.
Materials and Methods: Experimental factors include freezing temperatures at three levels (-5, -8 and -11° C) and spraying with two types of experimental material including carnauba wax in two concentrations of zero and four percent (manufactured by Orange Saft SL, Spain) and glycol potash in two concentrations of zero and 10% (prepared by Pooshesh sabze Company, Iran), carnauba + glycol potash (carnauba wax in 4% concentration and 10% glycol potash concentrate) and control (distilled water solution).
Results: Electrolyte leakage is the uncontrolled leakage of organic ions from the cell membrane due to stress and damage to the membrane. The lowest electrolyte leakage was observed at -5° C and the highest one was at -8° C. As a messenger molecule, proline is effective in regulating mitochondrial activity, cell proliferation, and cell death. Proline also expresses certain genes that are essential for improving plant conditions under stress. Proline concentration increased with decreasing temperature but it decreased again at -8 ° C. Using carnauba wax at -5 ° C has reduced the concentration of total soluble sugars (66.92 micro g / g by weight) but did not significantly differ from the control treatment (83/23) and -11 ° C. Frost tolerance and frost resistance vary in different organs of citrus trees. Young shoots and twigs are very sensitive to cold and frost, so their tissues change color due to the cold. If the intensity of cold and frost increases, it will cause the shoots to dry out. freezing temperature has a significant effect on Shoot dying back, so that the highest dryness of the shoots was observed at -11 ° C (91.66%) and the lowest at -5° C (10.41%). The highest percentage of leaf abscission was observed at -11 and the lowest with significant difference at -5° C. Symptoms of freezing such as leaf abscission and tree Shoot dying back are not seen up to -5 ° C but they are well visible at -8 ° C. Experimental treatments also failed to prevent shoots from drying out at -11° C.
Conclusion: Thomson navel orange young trees do not suffer much damage up to -5° C, but as the temperature decreases, the damage caused by frost increases in the form of leaf abscission and Shoot dying back of branches. Carnauba wax has a positive role in this experiment by preventing leaf abscission at -8 ° C, but glycol potash has a negative role by increasing leaf abscission and Shoot dying back. Increasing leaf potassium levels through potash glycol not only did not increase cold resistance but also increased susceptibility to frost. Potassium must be supplied from other sources. The results of this experiment showed that the use of carnauba wax up to 48 hours before the possible cold, which is announced through meteorology, with a concentration of 4%, can keep it alive up to -8 ° C, which normally destroys the plant, but with passing through this temperature, for example at -11 degrees Celsius, is not able to maintain the plant.
Research Article
Maryam Heidarzade; Gholamreza Zarei; Abolfazl Morowati
Abstract
Introduction: Lemon verbena (Lippia citriodora H. B. k.) is a valuable medicinal plant because of the essential oils, such as neral and garanial, which are used in the pharmaceutical, food, cosmetic and sanitary industries. In different industries, using essential oil of medicinal plants depends on the ...
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Introduction: Lemon verbena (Lippia citriodora H. B. k.) is a valuable medicinal plant because of the essential oils, such as neral and garanial, which are used in the pharmaceutical, food, cosmetic and sanitary industries. In different industries, using essential oil of medicinal plants depends on the chemical composition, which is influenced by environmental factors, harvest time and farming methods.
Materials and Methods: This experiment was conducted to investigate the effect of different levels of urea fertilizer and several iron fertilizers on yield and quality of lemon verbena at Fathabad garden of Kerman in 2017. The plants were planted based on factorial experiment in format of a randomized complete block design with three replications. Different levels of urea fertilizer (0, 100, 150 and 200 kg ha-1) and different sources of iron fertilizers included non-use, iron sulfate, nano iron chelate and ortho-chelate iron, were considered in four levels. The measured traits included plant height, fresh and dry weight of leaf per plant, number of branch, chlorophyll content and essential oil quantity and quality. Essential oil extraction was carried out using water distillation method using Clevenger's apparatus and identification of essential oil compounds was performed by gas chromatography–mass spectrometry (GC/MAS). The data were subjected to variance analysis using SAS software and means comparison were done with LSD at 5% level.
Results and Discussion: The results showed that different levels of urea and various iron sources had significant effect on all traits. Treatment with 150 kg ha-1 urea had the highest effect on measured traits compared to control. Among the types of iron sources, ortho-chelate iron had highest effect on quantity and quality compared to other iron sources and control. Generally, 150 kg ha-1 urea in combination with ortho-chelate iron produced the highest quantitative and qualitative yield. The same trend was observed in chlorophyll (35 mg/ml) and oil content (1.3%). In this study, a significant positive correlation was observed between chlorophyll content of leaves with vegetative traits and essential oil, which confirmed the positive effect of chlorophyll content on measured traits. Evaluation of quality of the leaves, 20 chemical compositions were detected in essential oils that were more than 85 percent of the total components. The neral and geranial were the predominant compounds in essential oils and the lowest levels of these compounds were observed in control (33.8%) and the highest levels were observed in the combination of 150 kg ha-1 urea with nano iron chelate (44.9%). The essential oils are terpenoid compositions that their constructive units need to NADPH and ATP, thus the presence of nitrogen is essential for the formation of these compounds. Moreover, iron acts as a cofactor for NADPH and ATP activity in nitrogen metabolism. Therefore, the increase in nitrogen and iron absorption by the plant has increased the content of essential oil. Due to the fact that geranial and neral are the most important compounds used in the essential oil of lemon verbena in various industries, especially pharmaceutical industry. The results of this experiment can be used to increase the quantity and quality of lemon verbena.
Conclusion: The current study demonstrated that different levels of urea and various iron sources had a significant effects on all traits. Generally, 150 kg ha-1 urea in combination with ortho-chelate iron produced the highest quantitative and qualitative yield. A significant positive correlation was observed between chlorophyll content of leaves with vegetative traits and essential oil. Twenty chemical compositions were detected in essential oils that the neral and geranial were the most predominant compounds.
Research Article
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.
Research Article
Alireza Ladan Moghadam
Abstract
Introduction: One of the main factors in increasing the quantity and quality of crops is increasing soil organic matter. Biochar is a form of material burned in special conditions and added to soil as organic material, which increases soil organic matter and reduces environmental hazards. The increase ...
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Introduction: One of the main factors in increasing the quantity and quality of crops is increasing soil organic matter. Biochar is a form of material burned in special conditions and added to soil as organic material, which increases soil organic matter and reduces environmental hazards. The increase in organic matter improves the physical, and chemical properties of the soil, and ultimately increases the absorption of the elements by the plant. Biochar is one of the methods for increasing organic matter in the soil, which is produced by burning in low oxygen conditions. There are many studies that show that the use of coke can be beneficial for plant growth. Fragaria ananasa is an important plant in nutrition of human that cultivated extensive area of the world. The purpose of this study was to investigate the effect of two types of biochar produced from wheat and rice straws on some of the characteristics of strawberry cv. Kurdestan.
Materials and Methods: This research was conducted as a factorial based on a randomized complete block design with three replications. Each block contained 15 pots and 45 plants were planted in each pot. The treatments included 1.5 and 3% of the two types of straw, wheat and rice residues, along with three levels of chemical fertilizer containing zero, 50 and 70 % of the plant requirements. In order to prepare the biochar, wheat and rice straw separately put in a special container made for this purpose and were placed in an electric furnace at 550 °C for 2-2.5 hours. In this research, yield, fresh weight of the plant, number of fruits were measured by conventional methods. The amount of nitrogen, phosphorus, potassium and iron elements in two parts of the fruit and shoot were measured by Kjeldahl method, spectrophotometry, flame photometric sulfuric acid digestion and atomic absorption spectrometry, respectively.
Results: The results showed that the highest fruit yield was obtained in 70 % of fertilizer application and 3% of wheat straw (83.3 g per plant). Reason of increasing yield was to provide elements and improved conditions of soil. The results showed that the increase in the amount of chemical fertilizer and biochar significantly increased the plant yield. The greatest effect of biochar was observed when the chemical fertilizer has been sufficiently provided. The results showed that in the treatment of 70% of fertilizer requirement, using wheat and rice straws, nitrogen content increased to 0.7 and 0.5 g/100g of dry matter, respectively. The results have shown that the use of biochar has led to an increase in the fresh weight of the aboveground of the strawberry plant. The amount of phosphorus was 0.31 g/100g of fruit in the absence of chemical fertilizer and biochar. By increasing the requirement to 70% of chemical fertilizers plus 3% of rice straw the amount of phosphorus in the fruit reached to 0.37 g/100g . Results showed that the highest amount of iron in the fruit is found in 70% of fertilizer and 3% of biochar, equal to 13.5 mg/100g in the fruit. Also, the highest amount of iron in the aboveground obtained at the same treatment with 14.8 mg/ 100g.
Discussion: The burning of plant remains naturally induced a lot of damages on the farm, causing soil degradation and reduces plant yield. The results of this study and other researchers show that the use of biochar is an appropriate method for converting plant debris into useful material. The increase in the amount of biochar will improve the absorption of the elements needed by the plant. As a result, providing the nutrients needed for the plant will perform better. In general, the results showed that use of both types of biochar has a very beneficial effect on strawberry plants, and the biochar derived from wheat straw have better effect than rice straw on the plant quality and quantity properties. The fruits have been improved by using biochar and chemical fertilizer. This indicates the basic role of the chemical fertilizers that cannot be completely eliminated and should only reduce their consumption.
Research Article
Seyyed Mehdi Hosseinifarahi; Ghazanfar Mohamadineia
Abstract
Introduction: Bell pepper (Capsicum annuum) belongs to solanaceae family, which is cultivated and consumed in the world due to its high economic value. Bell peppers also have valuable nutritional and medicinal compounds, including natural colors, antioxidants and vitamins A, B and E. Salinity stress ...
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Introduction: Bell pepper (Capsicum annuum) belongs to solanaceae family, which is cultivated and consumed in the world due to its high economic value. Bell peppers also have valuable nutritional and medicinal compounds, including natural colors, antioxidants and vitamins A, B and E. Salinity stress is one of the most important environmental factors limiting growth, which has very adverse effects on plant growth and yield. Salinity stress reduced the yield of agricultural products due to the effect on the competitive absorption and transfer of nutrients in the plant. Nowadays, the increased tolerance of plants to environmental stresses from different pathways involve breeding programs and the use of plant growth regulators and organic substances. In comparison to breeding methods that are often long-term and cost-intensive, it is easy and inexpensive to use plant growth regulators such as Salicylic Acid (SA) and humic acid (HA).
Material and Methods: To investigate the effect of Salicylic Acid (SA) and Humic Acid (HA) on the improvement of tolerance to salinity and absorption of mineral elements under salinity stress in greenhouse culture, a factorial experiment based on Randomized Complete Block Design (RCBD) was conducted in Yasooj. The first factor was SA in three levels (0, 1, and 2 mM), the second factors HA in two levels (0 and 5 g l-1), and the third factors salinity in three levels (0, 50, and 100 mM). The bell pepper seedlings cv. California were obtained from a commercial producer and planted in 4-liter plastic pots containing perlite and cocopeat (1:1) in 2015. Plants were grown in a hydroponic greenhouse with day/night temperature (24.3 and 15.4 oC) and 60 to 80% RH in the village of Nahrgah in Yasouj. After the plants were established (having about 4–5 leaves), sodium chloride salt was used in the concentrations of 0, 50, and 100 mmol in the nutrient solution for salinity stress. To prevent a sudden shock, the first one week all the pots were irrigated with a 10 mM-food solution and in the second week with a 25 mM salt solution. After that, the plants irrigated 50 and finally 100 mg of sodium chloride. Traits such as plant height, number of leaves, number of flowers, number of fruits, and average fruit weight, and yield, fresh and dry weight of leaf were measured. The content of K, Ca, Fe and Na elements in the leaves and roots of treated and untreated plants were measured by an atomic absorption device equipped with a graphite furnace system. Data analysis (ANOVA) was performed using MSTAT-C statistical software. The means were compared with the Tukey test (P≤ 0.05) and the graphs were plotted with Excel.
Results and Discussion: Results showed that the salinity has negative effects on growth factors. The application of HA and SA reduced the negative effects of salinity and increased growth parameters. The application of HA and Salicylic acid increased the number of pepper fruits under salt stress conditions. The highest number of fruits was obtained in the plants treated with 5 g l-1 HA and 2 mM salicylic acid compared to the other treatments. The results of this experiment showed that the application of HA and Salicylic acid had a significant effect on the content of mineral elements in the leaves and roots of sweet peppers under salt stress. The highest amount of Fe was observed in the leaves of pepper plants treated with 100 mM and the lowest in untreated plants. The highest amount of leaf calcium was obtained in peppers treated with SA 2 mM and HA 5 g l-1 in comparison to other treatments. Application of SA 1 and 2 mM increased the concentration of calcium of the leaves and roots of the pepper plant. The highest root potassium were obtained in plants treated with 5 g l-1 HA and 1mM SA at salinity level of 100 mM in comparison to the other treatments.
Conclusion: Salinity is an environmental factor limiting the production of crops in plants. According to the results of present study, it can be concluded that salinity reduced the growth parameters of the bell pepper plant. The use of SA and HA increased bell pepper tolerance to salinity and improved the vegetative and reproductive characteristics and absorption of mineral elements. Therefore, the application of HA 5 g l-1 and 2 mM SA is suggested to reduce the negative effects of salinity stress on bell pepper.
Research Article
Azadeh Saffar Yazdi; Ali Ganjeali; Reza Farhoosh; Monireh Cheniany
Abstract
Introduction: Purslane (P. oleracea) is considered as valuable plant due to its high antioxidant compounds and important fatty acids such as omega-3 and 6. Phenolic and flavonoid compounds are one of the most important constituents in the purslane. Phenolics are a large group of natural plant compounds ...
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Introduction: Purslane (P. oleracea) is considered as valuable plant due to its high antioxidant compounds and important fatty acids such as omega-3 and 6. Phenolic and flavonoid compounds are one of the most important constituents in the purslane. Phenolics are a large group of natural plant compounds with antioxidant and Anti-inflammatory properties. Flavonoids, as a subset of phenolic compounds, have a wide range of effects on plants, including antioxidant activity and improve resistance to environmental stresses. Callus culture is one of the important strategies for the production secondary metabolites, which are difficult to produce chemically. Plant growth regulators including auxins and cytokinins play a crucial role in the stages of plant growth. Various combinations of these two hormones are used to make the desired changes in the cultures. Studies suggest that the accumulation of secondary metabolites can be increased by the application of different elicitors in medium. Researchers reported an increase in the content of secondary metabolites such as phenol and flavonoid compounds in calli treated with elicitors such as yeast extract. The purpose of this study was to determine the best explant, medium and hormonal treatment for calli induction of purslane. The effect of different levels of yeast extract on total phenol and flavonoid content and antioxidant capacity of purslane calluses was also investigated.
Materials and Methods: Seeds of purslane plant were cultivated in a solid 1/2MS medium for the preparation of sterile seedlings. The explants from sterile seedlings including to leaves, 1 cm stem specimens and terminal buds, were placed on MS and 1/2MS medium containing 0, 0.1, 0.3, and 0.5 mg L-1 BAP and NAA. After five months, calluses were evaluated for callogenesis and some morphological traits such as color, texture, and size, fresh and dry weight. This experiment was conducted based on completely randomized design with three replications. In the second experiment, the calluses obtained from the previous stage were transferred to MS medium with selected hormone treatment of the first experiment (0.5 mg L-1 NAA and BAP) and different levels of yeast extract (0, 125, 250, and 500 mg L-1). Total phenol and flavonoid contents of the calluses were determined by Folin-Ciocalteau and aluminum chloride methods, respectively. Furthermore, Ferric reducing antioxidant power (FRAP) and 1,1-diphenyl-2-picrylhydrazyl (DPPH) assays were used to determine the antioxidant activities.
Results and Discussion: The results showed that 1/2MS medium was suitable for sterile seedling production from purslane seeds. Based on the present study, only stem explants in a medium containing BAP and NAA, produced durable calluses. The color of the resulting calluses were green and had a constant and firm texture. The highest callus percentage (90.46%), the size (21.6 mm), and fresh (1826.5 mg) and dry weight (75.33 mg) of calluses belong to MS medium containing 0.5 mg L-1 BAP and NAA. Results of the second experiment showed positive and significant effects of yeast extract on the total phenol, flavonoid contents and antioxidant activities. The highest content of total phenol (664.12 mg GAE 100g-1 DW), flavonoid (42.25 mg QE 100g-1 DW) and FRAP data (787 µmol Fe g-1 DW) were obtained from the calli treated with 500 mg l-1 yeast extract. The maximum DPPH IC50 (2.45 mg ml-1) was also observed in control. The formation of callus associated with plant species, hormonal composition, the stage of development, and the type of explants. Auxin and cytokinin as plant growth regulators are key factors for controlling cell division in tissue culture. In most studies, callus formation in purslane plant were induced in medium containing auxin and cytokinin. The presence of green calluses derived from purslane explants can be due to the formation of chloroplastids in the cells of the callus tissue that rapidly produce chloroplasts under light conditions. In the second experiment, increased phenolic and flavonoid compounds with yeast extract treatment probably resulted in increased antioxidant activity.
Conclusion: In the present study, 1/2MS medium is suitable for the production of sterile seedlings from purslane seeds. MS medium containing 0.5 mg l-1 BAP and NAA is the best treatment for calli induction from stem specimens. The concentration of 500 mg L-1 of yeast extract is introduced as the most effective concentration for increasing the phenolic and flavonoid content and antioxidant activity in the purslane calluses.
Research Article
Atefeh Beigi Harchegani; Shahram Kiani; Alireza Hosseinpur
Abstract
Introduction: Ammonium (NH4+) and nitrate (NO3-) ions are the two main forms of nitrogen (N) for plants. But, they influence differently on growth and chemical composition of plants. The effect of N form on plant growth depends on plant species, development stage of plant, pH, and temperature, ratio ...
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Introduction: Ammonium (NH4+) and nitrate (NO3-) ions are the two main forms of nitrogen (N) for plants. But, they influence differently on growth and chemical composition of plants. The effect of N form on plant growth depends on plant species, development stage of plant, pH, and temperature, ratio of NH4+ /NO3- and nitrogen level of nutrient solution. Lettuce is one of the leafy vegetables that has been cultivated in soilless culture in many greenhouses in the world. This plant can respond well to NH4+ nutrition, but the information about optimum NH4+/NO3- ratio in the nutrient solution and respond of lettuce cultivars to partial replacement of NO3- by NH4+ is scarce. Application of nitrification inhibitors such as 3, 4-dimethylpyrazole phosphate (DMPP) with ammonium fertilizers lead to high N-use efficiency as well as reducing denitrification and leaching losses. Nitrification inhibitors are compounds that delay the biological oxidation of ammonium to nitrite by depressing the activity of Nitrosomonas bacteria. This study was conducted to elucidate the effect of nitrogen form (N-NO3− and N-NH4+) and the use of a nitrification inhibitor (DMPP) on chemical composition and yield of lettuce (Lactuca sativa L.) cultivars in research greenhouse of Shahrekord University.
Materials and Methods: A factorial experiment using completely randomized design was carried out with two factors of NH4+/NO3- ratio (0:100, 15:85 with and without DMPP, 30:70 with and without DMPP) and lettuce cultivars (Teresa and California) with three replications under hydroponic conditions. Lettuce plants were grown in 1.7 L plastic pots (one plant per pot) and the substrate used was mixture of cocopeat + perlite with ratio of 2:1 (v/v). Different nutrient solutions were applied by hand two or three times per week to obtain a leaching fraction of 5 to 20%. After seven weeks plants were harvested, fresh weight of shoots and roots were determined and plants were dried in an oven at 60 °C. Then, dry weight of shoots and roots were measured and plants were ground for nutrient analysis including of P, K, Ca, Mg, Fe, Mn, Zn and Cu.
Results and Discussion: The results showed that application of nutrient solution with NH4+/NO3- ratio of 30:70 in California cultivar and 15:85 in Teresa cultivar led to significant increase shoot P concentration compared with the 0:100 of NH4+/NO3- ratio (40 and 13%, respectively). This was due to synergistic effect of NH4+ on the uptake of P by roots. In both Teresa and California cultivars, replacing 30% NO3- in the nutrient solution with NH4+ resulted to significant decrease shoot K concentration (27.3 and 14.8% in Teresa and California cultivars, respectively) as well as shoot Ca concentration (42.0 and 31.1% in Teresa and California cultivars, respectively) compared with the 0:100 of NH4+/NO3- ratio. This decrease is related to antagonistic effects of NH4+ on the uptake of K and Mg by roots. In Teresa cultivar, increasing the NH4+/NO3- ratio to 15:85 led to the meaningful increase of shoot Fe (97%), Mn (68%) and Zn (54%) concentration in comparison with 0:100 of NH4+/NO3- ratio. But, in California cultivar shoot Mn concentration increased (65%) with 30% replacement of NO3- by NH4+. This means that changing NH4+/NO3- ratio in the nutrient solution is an excellent approach to control the relative uptake of cations and anions by the plant. The greatest quantity of shoot fresh weight in Teresa (334 g pot-1) and California (435 g pot-1) cultivars were obtained from 0:100 and 15:85 of NH4+/NO3- ratios, respectively. The current study indicates that the lettuce cultivars respond differently to the form of N supply. There is a genotypic variability in the ability of plants to supply carbon skeletons for NH4+ assimilation in the roots. Thus, California cultivar is a genotype sensitive to enhanced ammonium nutrition and Teresa cultivar is a genotype insensitive to enhanced ammonium nutrition. Increasing the NH4+/NO3- ratio to 30:70 led to the meaningful decrease (42%) of root fresh weight in comparison with nutrient solution without NH4+. Application of nitrification inhibitor DMPP with the NH4+/NO3- ratios of 15:85 and 30:70 had not significant effect on the shoot fresh and dry weight as well as the concentration of P, K and Cu in the shoot of both lettuce cultivars in comparison to these ratios without DMPP.
Conclusion: The results suggest that the NH4+/NO3- ratios of 0:100 and 15:85 can be recommended for production of Teresa and California lettuce cultivars under the conditions of the present study, respectively.
Research Article
Hossein Nastari Nasrabadi; Seyyed Farhad Saberali
Abstract
Introduction: Melon (Cucumis melo L.) is one of the most important vegetables in Cucurbitaceae family and one of the most important economic crops in the Torbat-e Jam. Growth and yield of agricultural crops are affected by biotic and abiotic environmental stresses. Salinity stress can be one of the most ...
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Introduction: Melon (Cucumis melo L.) is one of the most important vegetables in Cucurbitaceae family and one of the most important economic crops in the Torbat-e Jam. Growth and yield of agricultural crops are affected by biotic and abiotic environmental stresses. Salinity stress can be one of the most important environmental factors limiting the yield of plants, especially in arid and semi-arid regions. It has been reported that by application of bio-fertilizers, root and shoot dry weight and nitrogen concentration in alfalfa increased under salt stress. Sarabi et al (44) in a study of different genotypes of melons under salinity stress reported that salinity stress increases soluble sugars and proline content and decreases photosynthetic pigments. Growth-promoting bacteria can help plants under stress conditions by stabilizing atmospheric nitrogen, increasing the accessibility of nutrients, and interfering by the production of plant hormones such as auxin, cytokinin, and gibberellins. Soliman et al. (49) also reported that growth-promoting bacteria increase the absorption of elements, especially nitrogen, in Acacia saligana. Basilio et al. (7) showed that growth-promoting bacteria increase plant height and yield of wheat. The use of salicylic acid to create plant reactions to environmental stresses has been suggested. Raghami et al (39) reported that salicylic acid improves vegetative indexes and photosynthetic pigments in eggplant under salt stress. It has been reported that salicylic acid treatment increased K in wheat under salt stress. Due to the expansion of saline soils as well as the reduction of fresh water resources, the purpose of this experiment is to better establish melon seedlings under adverse environmental conditions and to maintain and develop this valuable crop.
Materials and Methods: In order to study the effect of biological fertilizers and salicylic acid on physiological parameters and growth of Khatooni melon under salinity stress conditions, a factorial experiment was conducted based on completely randomized design with three replications in Torbat-e-Jam University. Salicylic acid treatment was selected at two levels, without (SA0) and one mM (SA1) salicylic acid. Bacteria treatments were including Azotobacter (B1), Azospirilium (B2), Azotobacter and Azospirilum (B3) and without inoculation (B0) and salinity treatments were prepared in five concentrations: control (S0), 50 (S1), 100 (S2), 150 (S3) and 200 (S4) mM of sodium chloride.
Results and Discussion: Interaction effects of salinity, salicylic acid and bacteria showed, proline content was increased by salinity stress. The highest of proline content was obtained by combination of 200 mM salinity, one mM of salicylic acid and Azetobacter + Azospirilum (S4 SA1 B3) and the minimum of it was recorded in contorol (S0 SA0 B0). Under salinity conditions, the accumulation of compatible solutions such as proline, glycine, betaine and other organic solutions in the plant occurs, which play an important role in protecting the plant against the harmful effects of stress. On the other hand, the increase in proline content by growth-promoting bacteria may be due to an increase in the absorption of nutrients, especially nitrogen, because proline has a nitrogenous structure.
Without salinity stress no significant difference observed between salicylic acid treatments on soluble sugars, but soluble sugars content were significantly increased by increasing salinity stress. The maximum and minimum of soluble sugars content were recorded in combination 200 mM salinity and one mM of salicylic acid (S4 SA1) and control (S0 SA0) respectively. Plants try to overcome salinity stress by producing organic compounds that are osmotically active such as soluble sugars.
It has been reported that the use of salicylic acid in eggplant and barley under salinity stress has increased the production of soluble sugars, which is consistent with the results of this study. In general, accumulation of proline and soluble sugars content might be due to increased synthesis and decreased degradation under stress conditions. According to the results, photosynthetic pigments and relative water content percentage (RWC %) were decreased under salinity stress. Simple effects of salicylic acid (SA1) and bacteria treatments especially combination of bacteria (B3) significantly improved Chlorophyll a, b, carotenoids and RWC. Sarabi et al. (43) reported that chlorophyll content, carotenoids and RWC were decreased in melon under salinity stress. Kheirizadeh Arough et al (29) reported that application of bio-fertilizers and nano zinc oxid increased content of chlorophyll a, chlorophyll b and carotenoids in Triticale under salinity conditions.
Conclusion: Based on the obtained results in this study, we can use Azotobacter and Azospirillum together for seed inoculation and spraying with salicylic acid for obtaining better growth and yield under salt stress.
Research Article
Masud Ghasemi; Hossein Arouiee; Pejman Azadi; Atoosa Ali Ahmadi
Abstract
Introduction: Greater celandine (Chelidonium sp) is one of the plants that its propagation through seed occurs slowly. In addition, Chelidonium majus L. has limited habitats in Iran. For this reason, micropropagation can be considered as an effective method for its rapid and massive propagation and conservation, ...
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Introduction: Greater celandine (Chelidonium sp) is one of the plants that its propagation through seed occurs slowly. In addition, Chelidonium majus L. has limited habitats in Iran. For this reason, micropropagation can be considered as an effective method for its rapid and massive propagation and conservation, which can lead to the production of highly uniform plants. Chelidonium majus L. also contains a large amount of secondary metabolites of Isoquinoline alkaloids, including Chelidonine, Sanguinarine, Captesin, Berberrine and Chloritrine, and phenolic compounds. Therefore, the aim of this study was to investigate micropropagation of Chelidonium majus L. and compare the total phenol content in leaf, stem and root in obtained plantlets.
Materials and Methods: To begin the experiment, seeds of Chelidonium majus L. were first washed with distilled water containing a few drops of tween20. Then they were washed with 70% alcohol for 1 min and were finally washed with double-distilled water. Next, they were disinfected with 1% sodium hypochlorite for 5 min, and again were rinsed with distilled water for 3 times of 5, 15, and 180 min under laminar air flow hood. The effects of TDZ at concentrations 0, 0.25, 0.5, 0.75 and 1 mg/L, BAP at concentrations 0, 0.5, 1, 1.5, 2 mg/L considered. Then, the effect of best treatment in combination with NAA and IBA at 0.25, 0.5, 0.75 and 1 mg/L on growth parameters (number of shoot, shoot length and shoot formation capacity index), were studied. The effect of IBA, NAA and IAA at 0, 0.5, 1, 1.5 and 2 mg/L on rooting parameters (number of root and root length) in MS medium supplemented with 3 g/L activated charcoal in in vitro conditions were evaluated. Then different ratios of cocopeat, perlite and peat moss were used for acclimatization of the obtaining plants. Folin method was used to measure total phenol content. The experiment was conducted as factorial in a completely randomized design with four replications.
Results: The results of analysis of variance for proliferation and rooting traits showed that there were significant differences among the treatments at 1% probability level. The results of means comparison showed that the highest numbers of shoots and shoot formation capacity index were obtained from the treatment of 0.5 mg/L TDZ with the average of 8.12, which did not show a significant difference from the concentration of 0.25 mg/L TDZ, and the lowest shoot number was related to the control treatment. Increasing the amount of TDZ hormone led to the reduction in shoot number, so that at concentration of 1 mg/L TDZ, the average shoot number per explant was four. Combination of 0.5 mg/L TDZ with IBA and NAA had lower effect on Chelidonium majus L. proliferation. Moreover, the greatest shoot length was observed in the treatment of 2 mg/L BAP. Comparison of means values showed no significant difference between the treatments of 2 and 1.5 mg/L BAP at 1% probability level. In this study, MS medium containing 1.5 mg/L IBA was the most appropriate treatment for root formation. The effect of NAA hormone on root number of Chelidonium majus L. showed that the highest number of root was obtained from the treatment of 2 mg/L NAA. Besides, the effect of IAA on root number of Chelidonium majus L. showed that the highest number of root was observed in the treatment of 1 mg/L IAA, and the lowest number of root was related to the control treatment .The results of means comparison for the percentage of acclimatized plants showed that the ratio of 0:2:1 had a significant difference from the rest of the culture media and 85% of the plants were acclimatized, while the ratio of 1:2:1 showed the lowest percentage of acclimatization (20%). Furthermore, the results showed that the culture media had significant effect on acclimatization stage at 1% probability level. The results of the analysis of variance for total phenol content in leaf, stem and root tissues showed that there were significant differences among these three tissues. The results showed that the amount of total phenol in leaf was higher than in the stem, and the amount of phenol in root was insignificant.
Conclusion: Based on the results of this study, micropropagation can be used as a method for commercial production of this species under in vitro conditions.
Research Article
Mohammad Reza Naroui Rad; Behnam Bakhshi; Jahangir Kohpalekani Abbasi; Ahmad Ghasemi; Mansour Fazeli Rostampour
Abstract
Introduction: In Iran, there are various melon populations due to properties of cross pollination, which are mostly cultivated in the desert, so it is important to identify populations and study their response to low irrigation conditions and their selection. Sistan is one of the most important melon ...
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Introduction: In Iran, there are various melon populations due to properties of cross pollination, which are mostly cultivated in the desert, so it is important to identify populations and study their response to low irrigation conditions and their selection. Sistan is one of the most important melon production areas in the country. Every year, in the optimal water conditions of the region, cultivation area reaches nearly to 6,000 hectares, but the area under cultivation is affected by fluctuations in the Hirmand River. Its famous melons in the region include Sefidak, Firoozi and Helmendi, which are very popular among farmers in terms of taste. The amount of rainfall in this region is very small and the agriculture of the region is affected by the fluctuations of Hirmand River and these fluctuations cause damage to agricultural producers, but recognizing the best and most suitable genotypes can help a lot to melon production. Variation and selection are the important elements of the breeding program and the selection by the breeder requires a good variation in the population. In Iran, the largest producer of melons is province of Khorasan Razavi, with 48.7 percent of the production in country, and province of Sistan and Baluchistan with the 5.62 percent is in the fifth rank. Therefore, in this regard, it is necessary to consider the desirable populations and cultivars in terms of production and yield. The quality of soil and the limitation of water resources, especially in recent decades, have intensified the world's agriculture. In the most parts of Iran, especially in Sistan, due to recent drought, identification of resources and cultivars with the potential of optimal production is important. Therefore, the present study was conducted to evaluate the populations of melons and their response to different irrigation regimes.
Materials and Methods: In this study, the populations of the gene bank (34 population), mostly from the central and eastern regions of the Iran, along with two local sefidak and suski, which were relatively tolerant and sensitive, respectively to drought stress were cultivated in a simple square lattice design with 2 replications for comparison under normal and drought stress conditions. Under water deficit conditions, irrigation was carried out at water depletion of 75% and for normal irrigation with 50% water depletion from the field capacity. Soil moisture monitoring was carried out using a TDR device. Some morphological and physiological traits such as yield, number of fruits per plant, average fruit weight, fruit length and width, plant length, hole diameter, chlorophyll content, canopy temperature, relative water content were measured
Results and Discussion: Based on the results of combined analysis of variance, there was a significant difference between the populations for all traits except for the number of fruits per plant. The effect of the environment was significant only for the traits of soluble solids, single plant yield, canopy temperature and days to maturity also the interaction of the population with the environment was significant only for plant length, canopy temperature and root length, which indicated a different population reaction in relation to these traits under two conditions of normal and moisture stress. The results of the mean comparison of the traits showed that in normal conditions, the highest number of fruits belonged to numbers 1, 2, 6, 7 and 8, which had no significant difference with the check number 36. The results of analysis of factor in moisture stress condition showed that the first four factors justify nearly 70% of the variation among the traits. Therefore, the positive values of the first factor can be effective for selection of genotypes with a high yield and high fruit weight. However, the second factor with negative values of canopy temperature and positive values of leaf relative water content is effective in determining the high tolerance genotypes to moisture stress conditions.
Conclusion: Under normal and stress conditions, population number 23 had acceptable yields. The traits of fruit weight and size, flesh diameter and fruit length and width are among the traits that should be considered by the breeders according to their relationship with the yield. Genotypes with high root length had high tolerance to water deficit condition. In general, under stress conditions, more soluble solids were observed in the populations.
Research Article
Fardin Ghanbari; Mohammad Sayyari
Abstract
Introduction: Due to its low level of calorie and being as an excellent source of C and A vitamins as well as containing lycopene as a powerful antioxidant, Tomato (solanum lycopersicum, 2n=2 x=24), is extensively consumed in the world. According to the statistics presented in 2013, following China, ...
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Introduction: Due to its low level of calorie and being as an excellent source of C and A vitamins as well as containing lycopene as a powerful antioxidant, Tomato (solanum lycopersicum, 2n=2 x=24), is extensively consumed in the world. According to the statistics presented in 2013, following China, United States, Turkey and Egypt, Iran ranked sixth in tomato production (6174182 kg per year) world tomato production. Similar to other tropical crops, tomato is sensitive to chilling stress. The chilling stress is considered as one of the environmental factors influencing growth and development of many plants including tomato. Applying different environmental conditions and cultivation techniques within transplant production can mitigate the chilling stress of seedlings. The seedling hardening is one of the simple technique being employed to physiological characters of plant, so as to induce subsequent stress resistance. This phenomenon is so-called cross tolerance and it means that exposing plants to stressful conditions can induce plant tolerance to upcoming stresses. Therefore, the objective of our study was to investigate the effect of drought hardening and chilling stress on tomato plant growth and productivity in field condition.
Materials and Methods: This experiment was conducted in greenhouse and research laboratories of agricultural college of Bu Ali Sina University. First of all, the seeds of tomato cv. C.H Falat, were sown in pots filled with perlite and vermiculite (ratio 2:1) and then maintained under natural light and at 25±2°C / 18±2°C (day/night). At four-leaf full development stage, seedlings were subjected to seven-day drought stress simulated with polyethylene glycol 6000 (PEG) at three levels: control (0% PEG), moderate drought stress (10 % PEG equaling to 0.18 Mpa osmotic potential) and severe drought stress (20% PEG equaling to 0.57 Mpa osmotic potential). After employing different levels of drought stress and consequently placing them in recovery for 48 h, they were exposed to chilling stress and non-chilling stress condition. For imposing chilling stress, the seedlings were transferred into growth chamber under 3°C for 6 days and 6 h per day. After receiving chilling stress treatments, the produced seedlings, were planted in the field.
Results and Discussion: In the present study, drought pretreatment reduced the effects of cold stress on fruit yield and quality. Results revealed that, the growth and yield of tomato plants were significantly increased by drought stress pretreatment in field condition. Herein, Seedlings without receiving drought pretreatment slowly grew and gained lower yield than those receiving drought. Some traits such as higher fruit size and shelf life and low number of decayed end blossom fruits were gained by drought application. The highest growth and yield rates were obtained through 10% PEG. These results indicate that drought stress at seedling stage increases the yield of tomato without harmful effects on fruit quality. The results showed that in 0% PEG treatment (control), chilling stress increased the number of days for flowering and fruiting, which indicates the growth retardation in this plant under cold stress condition. Drought pre-treatment using PEG increased the thickness of the pericarp and its post-harvest life, which may indicate the maintenance of the effects of initial stress in all stages of vegetative and reproductive growth. It has been reported that cold stress directly affects the growth potential of plants that interfere with the proper production of plants by disrupting metabolic reactions and indirectly by preventing the absorption of water by plants and oxidative stress (Hussain et al., 2018). In the present study, pre-treatment of drought reduced the destructive effects of chilling stress on fruit size. These results show that pre-treatment of drought (especially 10% PEG) had a significant effect on increasing fruit size and preventing its fruit yield reduction due to cold treatment. Similarly, Paradosi et al. (1987) reported that water stress in tomato plants increased its tolerance to cold and maintained the growth of tomato plants and its yield in cold greenhouse conditions. So far, there have been no reports of interactions between environmental stresses on fruit size, but the effects of drought stress on tomato fruit have been studied.
Conclusion: In general, the results of this experiment showed that the effects of drought pre-treatment on seedling remain in the next stages of tomato growth and can have beneficial effects on growth and yield of tomato in field conditions.
Research Article
Mansour Fazeli Rostampour
Abstract
Introduction: Yaghooti grape (Vitis vinifera L.) is an important variety in Iran and also it is the most important horticultural product of Sistan region. This variety is of interest for economical aspect. Because continuous drought in Sistan region has been a serious threat to the grape production, ...
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Introduction: Yaghooti grape (Vitis vinifera L.) is an important variety in Iran and also it is the most important horticultural product of Sistan region. This variety is of interest for economical aspect. Because continuous drought in Sistan region has been a serious threat to the grape production, local farmers have to manage the problem by reducing the volume and irrigation intervals. The canopy plays a key role in radiation energy capture via photosynthesis apparatus, water use as regulated by transpiration, and microclimate of ripening grapes and also grape yield, quality, vigor, and the prevention of grape diseases. Since vines has high vegetative growth makes them compete with the reproductive growth, therefore vines be pruned every year.
Materials and Methods: In order to evaluate the effects of irrigation regime and green pruning on some physiological traits and fruit yield of Yaghooti grape, the present research was conducted in the research and extensional garden of Zahak city during 2017-2018. An experiment was carried out in the form of a split plot based on randomized complete block design with three replications. Three irrigation regimes of 100, 75 and 50 percent of the grape water requirement based on the potential evapotranspiration of grape and green pruning with three levels including the control plot or the local practice of not green pruning (P1), pruning the green branches starting from the sixth leaf above the last grape bunch (P2) and pruning the green branches starting from the sixth leaf above the last grape bunch along with green pruning of the green branches without fruit and pruning the unproductive brunches (P3) were allocated to main and sub-plots, respectively. ‘Yaghooti vines were 8 years old and trained as a traditional system. The vines were spaced 3 × 3 m. Water requirement of grape was determined according to the FAO method using data from a Class A evaporation pan. The analysis of variance for each variable was performed with the PROC GLM procedure in SAS 9.4. Multiple linear regression was used to determine the relationships of leaf relative water content, proline, soluble sugars, relative membrane permeability, chlorophyll index, and leaf area to fruit yield.
Results and Discussion: By reducing water consumption from 100 to 75% of grape water requirement, leaf relative water content, fruit juice acidity, chlorophyll index, leaf area and fruit yield decreased 10.1, 6.5, 8.6, 11 and 18.8%, respectively and also proline, soluble sugars and relative membrane permeability increased 67.3, 8.75 and 44.84%, respectively. The P3 treatment compared to control induced an increase in relative leaf water content, chlorophyll index, and fruit yield by 14.7, 12.2 and 25%, respectively as well as a reduction in proline, soluble sugars, relative membrane permeability, fruit juice acidity and leaf area index by 18.34%, 12.1%, 6.8%, 8.3% and 21.3%, respectively. Also the results indicated that providing the 100% of the water requirement combined with pruning the green branches starting from the sixth leaf above the last grape bunch in combination with green pruning of the green branches without fruit and pruning the unproductive brunches (P3) caused the highest grape fruit yield (7797 kg ha-1). Also the interaction effect of meeting 75% of the water requirement and the green pruning had the same result as that of meeting 100%of water requirement under no green pruning conditions. In other words, the green pruning could result in saving 25% of water used by the grape cv. Yaghooti without reducing fruit yield. The multiple linear regression analysis indicated that proline and leaf area were the most important traits impacting fruit yield in Yaghooti cultivar.
Conclusion: Reducing the water potential of vine causes different responses. The most important are a decrease in number cells of fruit, vegetative growth, leaf area, relative leaf water content, chlorophyll content, fruit yield, and increase in the compatible osmolytes. The growing shoots are a strong sink for the consumption of photosynthetic materials. The above mentioned effect causes an increase in the branch overgrowth and its overshadowing. All this factors compete with vine fruit production. So, green pruning and removal of apical dominance eliminates a strong place of nutrient absorption. In other words, green pruning results in a greater accumulation being used by flowers and fruits, causing sufficient light penetration into the crown and reducing evapotranspiration, leading to an increased water consumption and fruit yield.
