Journal of Plant Process and Function

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Plants activate antioxidant defense mechanisms under stress, which help maintaining the structural integrity of cell components and possibly reduces oxidative damage.  Low temperature stress leads to the production of reactive oxygen species and oxidative damage to plants. In this study, the effect of putrescine and proline on reducing the production of reactive oxygen species and increasing the activity of antioxidant enzymes in the peel of three Citrus species have been investigated. Traits related to cold resistance of Citrus species including production of reactive oxygen species and antioxidant enzymes such as superoxide dismutase, guaiacol peroxidase, Catalase, ascorbate peroxidase and lipoxidase were analyzed. The results showed that with decreasing temperature, the production of reactive oxygen species and activity of antioxidants increased in three Citrus species. In both C. reticulata and C. sinensis species, the activity of enzymes of antioxidant are higher than that of C. paradisi. However, the production of reactive oxygen species in C. paradisi is higher than the other two species. Treatment of fruits with proline and putrescine leads to a decrease in the production of reactive oxygen species. The highest amount of glutathione peroxidase and ascorbate peroxidase was observed at -3°C temperature and in fruits treated with proline 20 Mm. With increasing of proline and putrescine level, the activity of CAT and LOX increaseed too. Exogenous application of proline and putrescine increased the levels of endogenous proline in Citrus species. The levels of endogenous proline under both low temperature and exogenous proline and putrescine were higher in C. reticulata compared with two other species. In general, the treatment of putrescine and proline has led to the improvement of defense activities in stressed plants and has significantly increased in the C. reticulata species compared to the other two species.

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Peach (Prunus persica) is one of the most important Iranian horticulture fruit. But the short of storage life and post-harvest losses are the Basie problems of fruit. This experiment was carried out to determine the effect of Folic acid on increasing shelf life of “Alberta” Peach in experimental university shahid Bahonar Kerman on design a randomized complete with three replication. Fruits of Peach treatment with Folic acid 0, 20 and 40 mMol for 5 Min and then stored at 1^oC, 85-90% relative humidity for 21 days. Percentage of injured fruits, ion leakage, lipid peroxidation, hydrogen peroxide, organic acid, peroxidase and catalase activity and total soluble solids (TSS), were evaluated. The results showed that the effective compared to control and reduced percentage of injured fruits, ion leakage, lipid peroxidation, hydrogen peroxide. Generally, the results showed that the application of Folic acid 40 mMol were the most effective treatment.

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Low temperature stress is lead to accumulation of proteins, osmolytes and antioxidants that is involved in tolerance to stress conditions. This study was done to evaluate dehydrin, gamma-aminobutyric acid (GABA), endogenous proline and activities of antioxidant in Citrus reticulate under low temperature stress (1°C, -1°C and -3°C). The results of western blot showed proteins with the molecular weight of 30.19, 36.3 and 62.25 kDa were induced in C. reticulata under different temperatures. Also, level of endogenous proline, GABA and activities of antioxidant enzymes (SOD and APX) with decreasing of temperature were increased. Generally, in fruits under the temperature of -3°C, levels of antioxidants and protein accumulation increased.

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This research was conducted in order to investigate the effect of hydrogen peroxide and brassinosteroid hormone on growth after harvesting Kino mandarin based on a completely randomized design with 5 treatments and 3 replications on Kino mandarin fruit harvested from Jiroft Commercial Gardens located in Jiroft Agriculture and Industry. Test treatments were by immersion method (for 5 minutes) and included oxygenated water with concentrations of 10 and 15 µM; brassinosteroid with concentrations of 0.5 and 1 mg/l; and distilled water treatment (control). Then the fruits were transferred to the cold room and kept at 4 degrees Celsius for 30 days and every 10 days the amount of damaged fruits, acidity and titratable acid, amount of soluble solids, lipid peroxidation, amount of peroxide hydrogen, peroxidase enzyme activity and catalase enzyme activity were investigated. The results showed that the effect of both treatments on improving the post-harvest life and quality characteristics of tangerine fruits was significant compared to the control. Thus, the use of brassinosteroid and hydrogen peroxide caused a decrease in the percentage of damaged fruits, lipid peroxidation, the amount of hydrogen peroxide, and increased activity of peroxidase enzyme and catalase enzyme activity during storage, and brassinosteroid hormone with a concentration of 1 mg/l and then hydrogen peroxide (15 µM) compared to other treatments had the greatest effect during storage on improving the life after harvesting of Kino mandarin fruit.

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One of the basic ways to increase the storage life of fruits is to use treatments that can increase their quality and marketability. In this research, compounds such as proline and GABA have been used due to their antioxidant properties in order to protect cell membranes, maintain quality and increase shelf life during the post-harvest period in sweet lemon fruits. The treatments included concentrations of GABA 100 and 200 mM/l, proline 250 and 500 mM/l, and distilled water (control). Then the desired fruits were treated in the desired solutions for 5 minutes by the immersion method. After the fruits were completely dried, they were placed in packs of 5 and transferred to the cold room, where they were kept at a temperature of 12 degrees Celsius for 4 months. Once every 30 days, a number of fruits were taken out of the cold room, and similar traits were observed. The percentage of fruit damage, organic acids, amount of dissolved solids, activity of peroxidase and catalase enzymes, hydrogen peroxide, lipid peroxidation and leakage were investigated. The results showed that the amount of damage, ion leakage, hydrogen peroxide and lipid peroxidation in the fruits treated with GABA 200 mM/l and proline 250 mM/l decreased compared to the control. The treatment of sweet lemon fruits with GABA 200 mM/l and proline 250 mM/l has led to an increase in the amount of soluble solids and organic acids, as well as the activity of peroxidase and catalase enzymes. Therefore, the use of GABA and proelin can be recommended to increase the storage life of fruit at the commercial level.

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In this study, one product derived from sodium nitroprusside (SNP) was used as a nitric oxide (NO) donor and evaluated as a stimulant bud break agent of Ahmad-Aghaei pistachio. Trees were treated by SNP 0, 0.30, 0.60, 0.90 and 1.20 mM in two stages (4 and 8 weeks before normal budbreak (February 1 and January 1, respectively)) with a factorial experiment in a randomized complete block design with four replications. Results showed that SNP treatment hastened the bud break date and increased the yield. SNP decreased the misshapen nuts and empty and non-splitting shells compared with the control treatment. In both ON and OFF years, the effect of SNP was greatly dependent on both times of application and concentrations used. Results showed that exogenous application of this compound, especially during the second application, increased splitting shell nut, number of nuts per cluster, number of nuts per ounce, leaf area, shoot length, and shoot diameterin both ON and OFF years. No limitations were encountered. The results of this study might apply to pistachio and temperate fruit-growing regions with a mild winter. Because in mild winter, pistachio trees' chilling requirements are not resolved, and this substance helps with this deficiency.