Pomology
Shima Sorori; Ahmad Asgharzade; Ali Marjani; Malihe Samadi
Abstract
Introduction Drought is one of the most important environmental stresses. It limits crop production in the world and has adverse impacts on growth of plants and their metabolic processes. By changing some of the metabolic processes, drought stress changes the behaviour of plants and, eventually, ...
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Introduction Drought is one of the most important environmental stresses. It limits crop production in the world and has adverse impacts on growth of plants and their metabolic processes. By changing some of the metabolic processes, drought stress changes the behaviour of plants and, eventually, makes them resistant to some stresses. Given the water crisis in Iran, and since most of the available water is used in the agriculture sector, there is a need to change the current cropping pattern. The substitution of low-water-use for high-water-use plants could be an important water management strategy. Every physiological and biochemical factor involved in water conservation in plants is an effective factor in introducing tolerant varieties.Materials and MethodsThe required chemicals ( 80% acetone, 95% ethanol, ninhydrin, glacial acetic acid, benzene, proline, pure glucose, anthrone, sulfuric acid, potassium phosphate, polyvinylpyrrolidone [PVP], EDTA, hydrogen peroxide and guaiacol) were purchased from the Merck Company. This study was carried out in the spring and summer of 2019 in the Research Greenhouse of Islamic Azad University of Bojnourd. The rooted cuttings of 18 dominant grape varieties in the region (Kolahdari, KajAngoor, Fakhri, sefid Beryan, Divaneh, Sahebi, La’l, Siyah, Shiregi, Garmeh, Khalili, SanjariKajAngoor, Keshmeshi, Ghareghat, Maskeh, Asgari, Flame Seedless and White Seedless) were planted in plastic pots with a diameter of 35 cm and a height of 40 cm. The soil was a mixture of blown sand, leaf litter, and garden soil in the 1:1:1 ratio. Before the experiment, all pots were irrigated to reach field capacity.The factorial experiment was conducted using completely randomized design with three replications. The first factor was irrigation cessation (15-day drought stress) and control (irrigation to field capacity level). The second factor was variety (18 varieties).To apply the stress condition, irrigation cessation continued until leaf wilting signs were appeared. Based on previous experience, the duration of tolerance to drought stress was approximately 2 weeks. During the experiment, the minimum and maximum greenhouse temperatures were, respectively, 18.5 °C and 34 °C and natural light was used.Results and Discussion The results of analysis variance showed that drought stress significantly increased the amount of electrolyte leakage (6.29), and activities of peroxidase (0.056 katal per ml) and catalase (0.92 katal per ml). It also decreased leaf relative water content (61.95%), relative chlorophyll content (16.85) and contents of chlorophyll a (3.45 mg/g), chlorophyll b (1.12 mg/g) and carotenoids (2.84 mg/g).Grape varieties respond differently to drought stress and, in general, water scarcity reduces their leaf RWC and chlorophyll contents. According to Schutz and Fangmier (2001), a decrease in chlorophyll content under stress conditions is because of an increase in the production of oxygen radicals in the cell. These free radicals can cause peroxidation and decomposition of the pigments. The intensity and greenness of the leaves reduce with decreasing the chlorophyll concentration and accelerating the process of aging.Reduced greenness of the leaves under long-term stress conditions may be partially due to reduced nitrogen flow into the tissues and changing activities of such enzymes as nitrate reductase. Since nitrogen is a constituent of a chlorophyll molecule, its deficiency in plants may slow down the formation of chlorophyll. Lawlor and Cornic (2002) showed the effectiveness of carotenoid, as an auxiliary pigment, in protecting thylakoid membranes and preventing chlorophyll photo-oxidation. Drought stress increases the activity of the peroxidase and catalase enzymes in both drought-sensitive and -resistant varieties; however, the activity of antioxidative enzymes is significantly higher in the stress-resistant varieties.The studied cultivars were divided into the three groups include of tolerant (White Seedless, Garmeh, Maskeh, Flame Seedless, Fakhri, Khalili and Divaneh), semi-susceptible (Kolahdari, Sefid Beryan, Sahebi, Laal, Shiregi, Kaj Angoor Sanjari and Asgari) and sensitive (Siah, Ghare-Ghat, Kaj Angoor Sanjari and Keshmeshi) cultivars to drought stress. Among the studied cultivars, White Seedless had the highest levels of relative leaf water (77.81%), relative chlorophyll content (28.62), carotenoids (4.81 mg/g) and the lowest amount of electrolyte leakage (31.5) and Garmeh the highest chlorophyll a (6.64 mg/g) and chlorophyll b (2.12 mg/g) contents and peroxidase (0.0618 katal per ml) and catalase activities (0.959 katal per ml).Conclusion The grape plant adaptation to drought stress is the result of changes in many morphological, physiological, and biochemical mechanisms, which cause changes in the rate of electrolyte leakage, leaf RWC, proline content, soluble solids, speed of photosynthesis, enzymatic activities, etc. The results showed that the white seedless variety had the highest leaf RWC, relative chlorophyll content, carotenoid content, and the lowest electrolyte leakage. Besides, Garmeh variety with the highest chlorophyll a and b, peroxidase, and catalase contents is amongst the most resistant varieties.
Asma Abbasi Kashani; Ali Ebadi; Mohammadreza Fattahi; Majid Shokrpour
Abstract
Introduction: Grape (V. vinifera L.) is one of the most important crops in the world and Iran, and play a major role in the export income. According to World Food Organization statistics, the area under global cultivation has been seven million hectares and Iran ranks seventh in the world with 316,000 ...
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Introduction: Grape (V. vinifera L.) is one of the most important crops in the world and Iran, and play a major role in the export income. According to World Food Organization statistics, the area under global cultivation has been seven million hectares and Iran ranks seventh in the world with 316,000 hectares. Grape production is about 77.5 million tons and Iran is ninth in the world with production of about 2.5 million tons. Fars province is in the first place with 75,000 hectares of fertile vineyards. Qazvin, Khorasan Razavi, West Azarbaijan, Hamadan and East Azarbaijan provinces are also ranked next. Cold stress is one of the constraints on the cultivation of grapes, so prevention of frost damage is one of the important points in the world's grape areas. This damage could be due to early autumn cold and late spring in the temperate region, such as winter frost of 2007, early autumn frost of 2015 and late spring frost of 2014 and 2017. Protecting plants against the harmful effects of low temperatures in agriculture is considerable. One way to prevent frost damages is using plant growth regulators such as salicylic acid. It seems that salicylic acid plays a role in the resistance to the cold stress, and it probably contributes to the activity of antioxidant enzymes and hydrogen peroxide metabolism, so it reduces cold stress damages and increases the plant tolerance to frost. The role of salicylic acid against cold stress have been reported in various plants such as lemon, pistachio, peach, pomegranate, apricot and walnut. Studies have shown that application of salicylic acid on grape seedlings increased the resistance to thermal stresses by reducing ion leakage and decreased the peroxidation of the cell membranes. Also, SA increased the proline and soluble carbohydrates in Plukenetia volubilis seedlings. In the present study, the effects of salicylic acid was investigated on the reaction of potted seedlings of some grape varieties under the spring frost. Then shoot burn percentage, recovery, ion leakage and peroxidation of membrane lipids of seedlings were investigated after cold application. Therefore, the changes in the amount of some osmotic regulators such as proline, soluble carbohydrates, and antioxidants such as phenolic compounds were evaluated by salicylic acid and cold treatments. Materials and Methods: This research was carried out in greenhouse of Department of Horticulture Engineering of College of Agriculture and Natural Resources, University of Tehran, Karaj, Iran, in spring 2017 on two-year potted seedlings. It was carried out in a completely randomized design with three replications to evaluate the effects of salicylic acid on reducing the damage of spring frost in some grape varieties such as Bidaneh Sefid, Perlette and Riparia species. Salicylic acid was sprayed at 0, 0.5 and 1 mM in E-L=11 on two year-old potted. After 24 hours, cold treatment was applied at 0 and -2 °C and normal temperature (as control) for 8 h. Control was in the greenhouse with natural temperature. Potted plants were transferred to the greenhouse and after 72 hours, the burn percentage was calculated. Also, recovery of the seedling was determined 20 days after the cold. Other parameters were measured such as ion leakage, malondialdehyde, soluble carbohydrates, proline and phenolic compounds. Statistical analysis and mean comparison of the results was done by SPSS and LSD test. Results and Discussion: According to the results, salicylic acid and cold treatments had significant effects on some characteristics of Vinifera species such as Bidaneh Sefid, Perlette and Riparia species. The results showed that with increasing the cold stress to -2 °C, the burned shoot percentage was increased and the grown buds percentage was decreased compared to control, and electrolytic leakage and malondialdehyde were increased at same temperature. Salicylic acid 1 mM reduced the damage to shoots and increased the recovery of seedlings. The lowest amount of electrolytic leakage and malondialdehyde were observed in 1 mM salicylic acid treated seedlings compared to non-treated. According to the results, application 1mM salicylic acid increased osmotic regulators and antioxidants such as proline, solution carbohydrates and phenolic compounds. There was a significant difference between Vinifera and Riparya species at -2 °C in some parameters such as burned shoot, recovery, ion leakage and malondialdehyde. Also, there were significant differences between Bidaneh Sefid, Perlette and Riparia species at -2 °C and 1 mM in proline, solution carbohydrates and phenolic compounds. It has been reported that salicylic acid plays a role of osmotic regulation for the cell and it can reduce the damage of frost by stimulating the hydrolysis of insoluble carbohydrates or proteins and enhancing compounds such as soluble carbohydrates, so it led to reduce the freezing point of the tissue. Increasing in soluble carbohydrates have been reported in grapes and lemon by salicylic acid spraying. Conclusions: Spring frost has damaging effects on grapevine and can lead to a lot of economic damage to gardeners. Therefore, it can be prevented by some plant regulators such as salicylic acid. The results of the present study showed that the damage caused by cold treatment in control seedlings was more than the plants that were treated with salicylic acid and concentration of 1 mM salicylic acid at 2°C had a positive effect on reduction of morphological damage severity as well as reduction peroxidation of the cell membrane. Cold tolerance of seedlings may be due to the role of salicylic acid in increasing antioxidant substances such as phenolic compounds, as well as in increasing osmotic regulators such as proline and soluble carbohydrates, thereby increasing cell sap concentration and tissue freezing point. This reduced the negative effects of low temperature and reduced cell membrane damage and electrolyte leakage and improved the recovery ability of two-year-old potted seedlings of Bidaneh Sefid, Perlette and Riparia species. So, it can be concluded that among different tested species, Riparia had the lowest percentage of shoot burn and highest recovery ability than the cultivars of Vinifera. Among the genotypes of Vinifera species, Bidaneh Sefid was the most proline and soluble carbohydrate compared to Perlette, indicating a higher adaptation to cold conditions.
