Mehdi Nazari; Mohammad Sayyari
Abstract
The present investigations focused on the role of calcium ascorbate (CaAsc) on tomato seedlings under low-temperature stress. Study was conducted by spraying aqueous solution of CaAsc at 0, 50, and 100 mM, on tomato seedlings with 5-7 true leaves in order to counteract the adverse impacts of chilling ...
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The present investigations focused on the role of calcium ascorbate (CaAsc) on tomato seedlings under low-temperature stress. Study was conducted by spraying aqueous solution of CaAsc at 0, 50, and 100 mM, on tomato seedlings with 5-7 true leaves in order to counteract the adverse impacts of chilling stress. One week after foliar application of CaAsc, all seedlings were exposed to a chilling temperature of 3±0.5 °C for six days (six hours per day) in a growth chamber. Loss of membrane integrity due to chilling stress led to oxidation of phenolic compounds by activation of peroxides (POD) and polyphenol oxidase (PPO) enzymes. Higher phenylalanine ammonia-lyase (PAL) activity, which is responsible for phenolic compounds accumulation, due to chilling temperature, has been considered as defense mechanism of chilling stress. The results revealed that application of 50 mM CaAsc ameliorated chilling injury of tomato seedling, which was associated with lower electrolyte leakage (16.2 %) and malondialdehyde (1.54 nmol g-1 FW) accumulation. Also, CaAsc-treated seedlings with 50 and 100 mM of CaAsc exhibited higher total phenols accumulation (36.2 and 28.4 mg pyrogallol g-1 FW, Respectively) which results from higher PAL enzyme activity concurrent with lower POD and PPO enzymes activity. Enhancing chilling tolerance in tomato seedling treated with 50 mM CaAsc by triggering phenols metabolism was associated with better seedling growth rate.
Hassan Sarikhani; Mohammad-Sadegh Safariyan-Nejad
Abstract
One of the most important problems of strawberry cultivation in temperate regions is winter cold injuries. Current study investigated impacts of foliar application of glycine betaine (GB) at 0, 0.5, 1, 2 and 4 mM concentrations on the cold hardiness of strawberry. The plants were divided into two groups: ...
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One of the most important problems of strawberry cultivation in temperate regions is winter cold injuries. Current study investigated impacts of foliar application of glycine betaine (GB) at 0, 0.5, 1, 2 and 4 mM concentrations on the cold hardiness of strawberry. The plants were divided into two groups: one group for evaluation of cold hardiness at temperatures of -6, -9, -12, -15 and -18 °C; and the other for study of some biochemical characteristics. Results showed that GB treatment increased soluble carbohydrate and proline concentrations in both leaf and crown tissues, total protein concentration in leaf, and relative water content in leaf as compared to those in control. Based on LT50 calculated from electrolyte leakage and tetrazolium staining test, the GB application increased cold hardiness in strawberry plant based on its concentration. The highest cold hardiness was found in the 2 mM GB concentration based on electrolyte leakage and tetrazolium staining tests at -13.3 and -15.3 °C. Meanwhile, the lowest values of cold hardiness were observed in the control treatments based on electrolyte leakage and tetrazolium staining tests at -10.2 and -11.0 °C. Significant correlations were found between soluble carbohydrate and proline concentrations in leaf and crown, and total protein concentration with LT50 calculated from electrolyte leakage and tetrazolium staining test. We conclude that application of 2 mM GBhas the capacity to increase the freezing tolerance of strawberry and could be used as a prophylactic tool to reduce winter cold injury.
Maryam Bagheri; Mahmood Esna-Ashari; Ahmad Ershadi
Abstract
The objective of this study was to evaluate the storage life and quality of persimmon (Diospyros kaki Thunb.) fruit cv. ‘Karaj’ stored at 0°C for 4 months after postharvest calcium chloride treatment. Fruit weight loss, fruit firmness, total soluble solids, titratable acidity, total phenolic ...
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The objective of this study was to evaluate the storage life and quality of persimmon (Diospyros kaki Thunb.) fruit cv. ‘Karaj’ stored at 0°C for 4 months after postharvest calcium chloride treatment. Fruit weight loss, fruit firmness, total soluble solids, titratable acidity, total phenolic content, soluble tannin content, chilling injury, antioxidant activity, electrolyte leakage, and malondialdehyde content were measured in 0, 15, 30, 45, 60, 75, 90, 105, and 120 days after storage. Peroxidase and catalase enzyme activities were also determined at the end of the storage. Fruits were dipped in the solutions containing 0.5, 1, and 2% (w/v) CaCl2 as well as distilled water only as the control. Results showed that the fruit weight loss and chilling injury significantly decreased by CaCl2 treatments compared with the control. CaCl2 treatments also increased fruit firmness and catalase and antioxidant activities, whereas they reduced MDA content, EL, and peroxidase activity during 4 months of cold storage. The results indicated that CaCl2 application influenced TPC and soluble tannin compared with the control but had no significant effect on TA. The best result was obtained from the 2% CaCl2 treatment in almost all the studied parameters. In general, postharvest CaCl2 treatment of persimmon could decrease chilling symptoms during the cold storage.
Ali Akbar Ghasemi Soluklui; Ahmad Ershadi; Zia eldin Tabatabaee; Esmaeil Fallahi
Abstract
Freezing injury is an important limiting factor in the production of pomegranate in Iran.The aim of the present study was to evaluate the effect of paclobutrazol (PBZ) on cold hardiness of pomegranate (Punica granatum L.) cv. ‘Malas Saveh’. Different concentrations of PBZ including 0 (control), ...
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Freezing injury is an important limiting factor in the production of pomegranate in Iran.The aim of the present study was to evaluate the effect of paclobutrazol (PBZ) on cold hardiness of pomegranate (Punica granatum L.) cv. ‘Malas Saveh’. Different concentrations of PBZ including 0 (control), 31, 62, 125 or 250 mg L–1 were sprayed on one-year-old plants in August and the electrolyte leakage of their stems was measured at three acclimation stages (November, January, and March). PBZ treatments, especially at 125 and 250 mg L–1 concentrations increased cold hardiness, and corresponding soluble carbohydrates and proline contents. The highest variation in freezing tolerance was observed between control and PBZ-treated plants in January, and the lowest found in November. Irrespective of PBZ treatment, correlations between cold hardiness and soluble carbohydrate concentrations were stronger, compared to proline. Soluble carbohydrates were higher in January, associated with deep dormancy, whereas the maximum proline content was detected in March, at deacclimation stage. Results suggest that PBZ application can reduce low temperature-induced dysfunction of cell membrane through increasing soluble carbohydrates and proline contents.
