جستجوی مقالات مرتبط با کلیدواژه "سرمازدگی" در نشریات گروه "باغبانی"

In cold-sensitive products, low temperatures lead to chilling injuries. Under chilling stress conditions, the production of reactive oxygen species increases and causes oxidative stress. Plants have developed an efficient antioxidant defense system to prevent the accumulation and elimination of reactive oxygen species. With the aim of investigating the antioxidant activity of melons under low temperature conditions, seven melon genotypes including 4 parents (Abadan, Khatouni, Dudaim and Japan) and 3 hybrids (Khatouni×Abadan, Dudaim×Khatoni and Japan× Khatouni) were cultivated in the Horticultural Science Research Center, University of Tehran, Karaj, in the years 2018 and 2019. After harvesting, the fruits were kept at three temperatures (1, 4 and 13° C) for thirty days. The results of the research showed that the firmness of the tissue and the total soluble solids were higher in the samples of Japan and Japan×Khatouni genotypes compared to other melons. Also, Japan and Japan×Khatouni genotypes showed the lowest chilling index (10% and 8% respectively) after thirty days. The lowest firmness and soluble solids and  the highest malondialdehyde content  was found in Dudaim×Khatouni genotype  and the highest chilling index (45%) was seen in Khatouni × Abadan genotype. The amount of activity of antioxidant enzymes (catalase, peroxidase and superoxide dismutase) was higher in melons that had a lower chilling index. The highest activity of antioxidant enzymes was seen in Japan and Japan×Khatouni genotypes.  It seems that the elevated levels of catalase, peroxidase, and superoxide dismutase enzymes contribute to improving cold resistance in these samples of melon. Japan and Japan×Khatouni are recommended as genotypes with high durability and shelf life (up to 30 days) at low temperatures conditions.

A study was carried out to investigate the effect of combined treatment of carboxymethyl cellulose (CMC) with different concentrations of Inian clove essential oil (M) on the storage life of Ahmad Aghaei pistachio cultivar. This research was carried out as a factorial experiment based on completely randomized design. Treatments in two levels, one concentration of edible coating: control (distilled water), 0.5% CMC along with three different concentrations of M oil including; 400, 800 and 1200 mgL-1 and the second factor of the storage period was investigated at two levels (25 and 50 days). The results showed that during storage period, hull and kernel moisture, aroma and taste decreased in all treatments, but the amount of ion leakage, peroxidas activity, browning, decay and chilling injury were increased. The application of CMC along with 400 and 1200 mgL-1 of M recorded the best taste compared to the control sample. The lowest of ion leakage was related to the combined treatment of CMC with 1200 mg, which was not significantly different from the combined treatment of CMC with 800 mgL-1. Pistachios treated with distilled water showed a higher level of decay (22%), chilling injury (22%) and peroxidase enzyme activity (48%), compared to the combined treatments.

Sweet cherry is very popular due to its early maturity, high transportability, attractive appearance and good taste of the fruit. The high content of sugars, ascorbic acid, vitamins, carbohydrates and organic acids in the fruit increases the interest in this product both in industrial gardening and home gardening. The damage caused by cold in the critical stages of plant growth is one of the important factors in reducing the yield of plants all over the world. Salicylic acid is one of the phenolic compounds that is produced by the roots, and by reducing the activities of reactive oxygen species, it increases the resistance of plants to various environmental stresses (Mahmoudi et al., 2019). Salicylic acid not only plays an important role in determining the quality, color and taste of grape fruit (Hajivand & Rahmati, 2018), but also in the plant's response to environmental stresses such as drought (Miura & Tad, 2014), cold (Kosova et al., 2014) salinity (Noreen et al., 2014) and heavy metal stress (Mahmoudi et al., 2019) are effective. Commercial compounds such as plant growth regulators, including antiperspirant and antifreeze substances, are also used to increase cold resistance or delay the breaking of bud stagnation in horticultural crops (Mahmoudzade et al., 2012). Another way to reduce spring cold damage is to use Natural Plant Antifreeze. These materials either act as a mechanical barrier to prevent the formation of ice crystals on sensitive plant tissues or activate cold resistance systems in the plant (Hajivand & Rahmati, 2018).

In order to investigate the effect of the application of growth regulators, on the cold resistance of the cherry tree variety "Siah Daneh Mashhad", a factorial experiment was conducted in the form of a randomized complete block design with 3 factors of growth regulators each at 3 levels. (salicylic acid: zero, 1.5 and 3 mM), (natural antifreeze Thiofer: zero, 2.5 and 5 per 1000) and (soybean oil: zero, 2.5 and 5 per 1000)} and in 4 repetitions It was performed in a commercial garden located in Serain city in 2018 and 2019.

The results of the variance analysis revealed that the three-way interactions of the experimental factors significantly influenced the percentage of healthy pistils and the duration of flowering cessation at the 1% probability level. The highest percentage of healthy pistils, reaching 69.25%, was observed in the treatment involving foliar spray application of salicylic acid (1.5 mM) combined with soybean oil (5/1000) and foliar spraying of Thiofer natural antifreeze (5/1000). Furthermore, the combined effect of salicylic acid and natural antifreeze was found to be the most effective in delaying the onset of flower opening. The highest amount of ion leakage percentage was observed in the control treatment and the lowest amount was observed in the 3 mM salicylic acid foliar treatment along with soybean oil (5 per 1000) Thiofer. According to the data variance analysis table (Table 1), the ion leakage index was affected by the simple effect of salicylic acid, soybean oil and antifreeze and the interaction effect of salicylic acid oil × salt, salicylic acid × soybean oil, and soybean oil × antifreeze. The activity of malondialdehyde was affected by the simple effect of salicylic acid and soybean oil and the interaction effect of salicylic acid × year and year × soybean oil (Table 1). The total phenolic content was also affected by the simple effect of salicylic acid and soybean oil (Table 1). According to Figure 11, increasing the concentration of salicylic acid increased the content of total phenol, so that the highest content of total phenol (53.22%) was obtained in the treatment of 3 mM salicylic acid, while there was no significant difference in the treatment of 1.5 mM salicylic acid. . To adapt to the cold, phenolic compounds accumulate in plants, which are related to the antioxidant capacity of the plant (Mozafari &Yazdan Panah, 2018). A decrease in temperature increases the accumulation of phenolic compounds in the plant and can act as a mechanism to adapt and overcome the oxidative stress caused by low temperature (Balasundram et al., 2007). Balasundram and colleagues (Balasundram et al., 2007) noted that grape plants exhibit an accumulation of phenolic compounds and proteins while maintaining membrane stability at low temperatures. This accumulation leads to reduced production of malondialdehyde, enhancing the plant's adaptability and tolerance to cold temperatures, thereby reducing the risk of freezing. Similar observations of increased phenolic compound levels during cold adaptation have been reported in pistachios (Palonen, 1999) and apples (Huang & Wang, 1982). Chen and Tian (Chan & Tian, 2006) reported an increase in phenolic compound accumulation following enhanced activity of phenylalanine ammonia-lyase enzymes in grapes treated with salicylic acid. From their findings, they concluded that salicylic acid plays a pivotal role in the biosynthesis of phenolic compounds and the activation of plant defense genes.

According to the observations of this research, it can be concluded that the use of salicylic acid along with soybean oil and natural antifreeze of Thiofer is a suitable solution in order to delay the opening time of flowers and also to increase the indicators of cherry cold resistance against The tension is cold.

Identification of superior genotypes within the rich fruit trees germplasm in Iran is an important task. Eighty suitable genotypes were selected within the 600 genotypes that were grown in the Barzok, Kashan region, then 11 genotypes were considered as the superior genotypes. Besides recording the flowering periods of the 80 suitable genotypes, evaluation of the 11 superior genotypes was recorded during the 2017 and 2018 growing seasons. A 21 days difference at the beginning of flowering was recorded during two years of study. The high variability within the studied genotypes was observed in flower density. The genotype KB1045 with 158 flowers and genotype KB12939 with 60 flowers in 100 cm of shoot showed the biggest and lowest flower density, respectively. The highest fruit set record on 15 days after controlled self-pollination was recorded on genotype KB1045 (53.83 % fruit set) and the lowest was belong to genotype KB4541 (with 0 % fruit set). The microscopic examinations showed well germination of transferred pollens on the self-pollinated stigma. The microscopic fluorescence examination of pollen tube growth in the style at 48, 72, 96, and 120 h after self-pollination showed that very rare pollen tubes reached the ovary, so confirmed the incompatibility of the studied genotypes. Because the studied genotypes were superior in terms of many morphological traits, the obtained results can facilitate further apricot breeding programs on these genotypes.

Chilling injury (CI) is one of the main factors involved in reducing pomegranate quality during cold storage. In the present study, the interaction between 1-MCP and three different coatings (cellophane, confectionery waxy paper and 1%, 2% sodium alginate) on maintenance of postharvest quality of pomegranate fruits were investigated during 120 days of cold storage .The results showed that uncoated fruits had higher weight loss and total soluble solids (TSS) than coated fruits during storage. The results also showed that untreated (control) fruits showed higher weight loss, decay and total soluble solids (TSS) than 1-MCP treated fruits during cold storage. Cellophane had a significant effect on delaying ion leakage and preventing weight loss of pomegranate fruit.The 1-MCP+cellophane and 1-MCP+confectionery wax paper could reduce chilling injury by delaying the reduction of bioactive compounds such as total phenolics and antioxidant activity. The lowest decay severity was also observed in fruits treated with 1-MCP. In general, it can be concluded that postharvest application of 1-MCP+cellophane was the most effective treatment to induce chilling tolerance and extend the storage life of pomegranate.

Cornelian cherry fruit is an important source of vitamins and antioxidant compounds, and the prevention of the reduction of fruit nutritional value, appearance quality and firmness during the post-harvest period is one of the important issue in this fruit. The effect of phenylalanine postharvest treatment (0, 2, 4, 6 mmol), and different storage times (7, 14 and 21 days) on maintaining the physicochemical properties of cornelian cherry fruit during storage as a factorial experiment based on completely randomized design with three replications was investigated in current research. Immediately after treatment, the fruits were placed in a cold storage at 2±1 °C and relative humidity of 85±5%. Based on the results, the maximum content of anthocyanin (2.6 mg CYN-3-GLU/100g FW), flavonoids (13.16 mg QE/100g FW), total phenol (371.8 mg GAE/100g FW), soluble solids (17.66 %) in the third week and maximum content of ascorbic acid (26.89 mg/100g FW) were accompanied by 2 mmol phenylalanine. The lowest amount of H2O2 (0.36 µmol/100g FW) and the percentage of frostbite, and also the highest amount of proline (0.36 mg/g FW) were observed with 6 mmol phenylalanine treatment in the third week. The results showed in order to achieve the important goal of storage cornelian cherry in the cold storage, which maintains the desired physical and chemical characteristics of this fruit and has a longer shelf than storage at normal temperature, 2 mmol phenylalanine can be the most appropriate treatment.

Eggplant (Solanum melongena L.) is an important non-climacteric fruit grown in tropical and subtropical regions. The total production in Iran and world for eggplants in 2018 were estimated 54077210 and 666838 tons, respectively, and Iran ranked fifth in the production of this product. The health-promoting attributes of eggplant are derived from the phytochemicals with good source of antioxidants (anthocyanin and phenolic acids), dietary fiber and vitamins. Fruit deterioration during long term storage is associated with appearance quality reduction, calyx discoloration, softening and pulp browning caused by the oxidation of phenolic compounds. Hydrogen Sulfide (H2S) is a flammable and colorless gas, that similar to carbon monoxide and nitric oxide, is known as third leading signaling molecule. It has been reported that H2S play an imperative role in the postharvest physiology and chilling injury of various fruits and vegetables. In recent years, exogenous phenylalanine (PA) application has been employed as a beneficial procedure for enhancing quality in fruits and vegetables by promoting higher phenols and flavonoids accumulation arising from higher PAL enzyme activity and proline accumulation exhibiting higher ROS scavenging capacity. Thus, the aim of this study was to investigate the postharvest application of H2S and PA on quality and postharvest storage of eggplant fruit during storage at 7 °C for 21 days. Eggplant fruits (Solanum melongena cv. Hadrian) were harvested at commercially maturity stage in Jun 2019 from a greenhouse in Hashtgerd city, Iran. Fruit selected for uniform size, shape, and color, and immediately transported to the laboratory. They were divided into seven parts for the following treatments: control (0), hydrogen Sulfide (H2S) at 0.1, 0.2 or 0.3 mM and phenylalanine (PA) at 2.5, 5 or 7.5 mM. Each treatment was done in three replicates, consists of 24 fruits from each replicate, and then randomly divided into four groups include six fruits. One group was analyzed 24 hrs. after harvesting and another groups stored at 7 ± 1 °C and 85% RH for 21 days. At 7-day intervals, one group was taken at random and transferred for one day at 20 °C (shelf-life), and subjected to physicochemical analysis. For H2S fumigation, fruit was placed at the bottom of a sealed 15 L container with different aqueous sodium hydrosulfide (NaHS) solution concentrations for 10 min, and for PA treatments, the fruits were immersed in 10 L of fresh phenylalanine solution for 10 min and in distilled water as a control. The fruits were allowed to completely dry at room temperature before storage. The results showed that fruits treated by PA and H2S exhibited higher fruit firmness, chlorophyll, anthocyanin, total soluble solids (TSS), vitamin C, pH and titratable acidity (TA) accompanied by lower weight loss and chilling indices during storage at 7 ºC for 21 days. In control eggplant fruits, fruit firmness (24.2%), chlorophyll (45.8%), vitamin C (34.1 %), anthocyanin content (66.2 %) and TA (44.8) decreased, and weight loss (7.5 %), TSS (8.2%) and chilling indices (4.5 %) increased during 21 storage time. The maximum fruit firmness (1.37 and 1.34 kg cm-2), anthocyanin content (5.02 and 4.2 mg L-1) and TA (18.67 and 1.37 %), and the lowest weight loss (3.67 and 3.7 %) and chilling index (1.6 and 1.3 %) was found in fruits treated with H2S at 3 mM and PA at 7.5 mM during storage at 7 °C for 21 days, respectively. It has been reported that texture correlates with firmness and higher firmness is a characteristic indicator of good texture during postharvest storage of fresh products. Soluble solid contents, titratable acidity (TA) and sugars have been known as important attributes contributing in overall sensory quality of fruits and vegetables. Development of the chilling injury disorder significantly reduces quality of fruits and vegetables due to diminished consumer’s acceptance. So, start of chilling injury symptoms eventually becomes economically critical postharvest constraint that defines the storage life potential of the products. Decline chilling injury in responses to H2S and PA treatments may resulted from higher ROS scavenging enzymes SOD, CAT, APX and POD activity and proline, phenols and flavonoids accumulation giving rise to conferring chilling tolerance. According to results, PA at 7.5 mM and H2S at 3 mM had the highest positive effect on maintain firmness and fruit quality and reducing weight loss and chilling, therefor postharvest treatment of PA and H2S can be proposed to improve fruit quality and postharvest life during storage period.

In recent years, γ-aminobutyric acid (GABA), a non-proteinogenic four-carbon signaling amino acid, has been employed as a safe strategy for attenuating chilling injury and fungal decay, delaying senescence and keeping sensory and nutritional quality of fruits and vegetables during postharvest life. In addition to applying GABA as exogenous safe procedure, heightening cellular GABA shunt pathway activity also is pivotal for attenuating chilling injury and fungal decay, delaying senescence and keeping sensory and nutritional quality of fruits and vegetables during postharvest life. Low temperature storage is widely employed for prolonging postharvest life of fruits and vegetables accompanying by keeping sensory and nutritional quality. Tomato is one of the most important horticultural crops, which exhibits higher benefits for human health but being endemic to subtropical climates, they are very vulnerable to chilling injury. Cold storage application is normally employed as a regular low-cost real postharvest technology. Owing to its great socio-economic significance, great efforts have been done by researchers to attenuating chilling injury in tomato fruits during low temperature storage employing safe strategies such as melatonin, brassinosteroids, salicylic acid, nitric oxide, and gibberellic acid. Attenuating chilling injury in tomato fruits by postharvest treatments may attribute to keeping safe membrane integrity representing by lower electrolyte leakage and malondialdehyde (MDA) accumulation occurring by eliciting endogenous polyamines, proline and nitric oxide accumulation by activating CBF1 signaling pathway, hampering phospholipase D (PLD) and lipoxygenase (LOX) enzymes activity, activating reactive oxygen species (ROS) scavenging enzymes activity resulting in higher ascorbic acid and glutathione accumulation, maintaining endogenous GA3 homeostasis occurring by higher CBF1 signaling pathway concurrent with higher endogenous salicylic acid accumulation, which not only are pivotal for conferring chilling tolerance in tomato fruits but also are crucial for preserving sensory and nutritional quality.

Tomato fruits (Solanum lycopersicum cv. Izmir) were picked at the mature green stage in Zanjan Province, Iran, and transported to the fruit analysis laboratory at Zanjan University. In the laboratory, the fruit was screened for uniform size, maturity, and absence of mechanical damage. Fruits (1440) were divided into four groups, each consisting of 360 fruits. The experiment was done in triplicate in which each replicate consisted of 120 fruits. The exogenous GABA applying was done by immersing of fruits in GABA at 0, 0.1, 1, and 5 mM for 15 min at 20 ˚C. Then, fruits were air dried at room temperature and stored at 4 ± 0.5 ºC (85–90 % RH) for 28 days. After assessment of chilling injury every 7 days during storage at 4 ˚C followed by shelf life at 25 ºC for 3 days, biochemical analyses were performed.

In recent experiment, we showed that the exogenous GABA applying, especially at 5 mM, is beneficial for attenuating chilling injury in tomato fruits during storage at 4 ºC for 28 days which was associated with higher membrane integrity representing by lower electrolyte leakage and malondialdehyde (MDA) accumulation. Keeping safe membrane integrity in tomato fruits in response to exogenous GABA applying may ascribe to triggering reactive oxygen species (ROS) scavenging catalase (CAT), superoxide dismutase (SOD) and ascorbate peroxidase (APX) enzymes activity giving rise to higher endogenous ascorbic acid accumulation concomitant with promoting phenylpropanoid pathway activity representing by higher phenylalanine ammonia lyase (PAL) enzyme activity giving rise to higher phenols and flavonoids accumulation and superior DPPH scavenging capacity.

Therefore, exogenous application of GABA not only is proficient for attenuating chilling injury but also is beneficial for preserving nutritional quality of tomato fruits during storage at 4 ºC for 28 days.

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.

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.

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.

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.

In this study, the effect of amino acids and Pepton were investigated on some qualitative features and shelf life of pomegranate fruit. This experiment was conducted in two years using randomized complete block design with three treatments, Control, Amino acids, Pepton(soy protein hydrolyzed), in three replications on Malas-e- Save cultivar. Amino acids and Pepton were used at a concentration of two per thousand, at three times in pomegranate fruit developmental stages (from June 1, after fruit set of first flowers, at intervals of one month), quantitative and qualitative factors of fruit were evaluated after harvest and storage time for three months at 5±1 °C and 85% humidity. Results showed amino acid and Pepton did not have a significant effect on weight, fruit length and diameter, pH, fruit juice and flavor index. The lowest percentage of white arils was detected in fruit with amino acid treatment, followed by Pepton treatment compared to control. Total antioxidant activity significantly increased as a result of Pepton application compared with other treatments. Results showed, after storage duration, according to sensory evaluation, fruits treated with amino acid were more marketable in terms of quality of the skin (color and freshness), color and taste of arils, compared to others and the lowest chilling injury was observed in the fruits under this treatment. Results showed Peptone could not achieve our expectation as a source of amino acids, to enhance the quality and shelf life of thepomegranate fruit.

Lime fruits has including economic and nutritional value but the fresh consumption of this fruit compare to processing methods is less, because of its low storage capacity. This research has been designed for study the effects of different concentrations of salicylic acid (0, 1, 2 and 3 mM) on quantitative and qualitative characteristics of lime fruit in storage period (0, 20, 40 and 60 days). This research based factorial on completely randomized design with four replications (10 fruit per replication). Each treatment was immersed in salicylic acid for 5 minutes and after drying, were packed in disposable containers and transferred in storage at temperature of 4±1 ° C with relative humidity 85 ± 5 ° C. The results showed during storage, fruit acidity and aroma were decreased and fruit bitterness was increased. 60 days after storage, salicylic acid 3 and 2 mM, compare to the control recorded the highest fruit acidity (60%). At the end of storage salicylic acid 1 mM compare to the control had the lowest fruit bitterness (20%), flavedo browning and malondialdehyde. After 60-day storage, the lowest chilling percentage and decay and highest acidity and phenolic compound (66%) related to salicylic acid 3 mM compare to control. Salicylic acid had protected fruit acidity and antioxidant activity and prevented decay, chilling injury, browning and malondialdehyde. It seems that the use of salicylic acid 2 and 1 mM can maintain some qualitative and quantitative properties of lime fruit during 60 days of storage at 4 ± 1 °C.

Nowadays, horticultural products especially in our country are damaged by the climate change events (rising temperatures, water shortage associated by drought and extreme temperature fluctuations). The greatest economic damage to horticultural crops are caused by winter chilling and / or spring frosts, in which has been increased by seventimes during the last 10 years. Indeed, just during 9 months of 2016-2017 year, the chilling/frost damages were reached to 140 million euro of the total damage value of 240 million euro to agriculture (about 60%). According to the Agricultural Insurance Fund, maximum amount of compensation to farmers of the country was paid to apples, walnuts, grapes, almonds, pomegranates, oranges and pistachios orchardists, respectively. Grape (Vitisvinifera), a member of the Vitaceae family, is the most important horticultural crop in Takestan region, ranking top in producing raisins in Iran. Yearly, horticultural practices in order to reduce the severity of chilling damages to crops cost a lot under orchard conditions. Some of these practices are included burying vines under soil, winter ice-watering, flood irrigation, and turning the heaters on. Nowadays, cheap and fast alternative methods such as anti-freezes spraying havebeen considered to reduce the freeze injuries under orchards. These compounds as mechanical barriers either prevent the ice crystals formation on the sensitive plant tissues or activate the freezing tolerance mechanisms in the plants. Salicylic acid (SA), a type of phenolic acid, is one of the most secondary metabolites in the grape. SA not only plays an important role on the determination of the quality, color and taste of fruit, but also influences on the plant responses into environmental stresses such as drought, chilling, salinity and heavy metals. Natural osmolites such as soluble sugars, amino-acids and ammonium compounds are accumulated inside the plants under natural conditions. Commercial anti-freeze/anti-transpiration compounds on the basis of the mentioned natural osmolites are used to increase the freezing tolerance or postponing the bud break of horticultural crops. For example, Bio-bloom, Tiofer®, Cropaid® and Fosnutren® were used as anti-freeze compounds under almond, cherry, pistachio and apple orchards in Iran. The efficiency of this method to reduce the chilling injuries in vineyards is not well known. Therefore, to consider the effects of plant basis anti-freeze compounds on the freezing tolerance of red seedless grape under Takestan climate conditions, the current experimentation was conducted. In this regard, the important freezing tolerance determining osmolites as well as some of the qualitative and quantitative characters of vines in response to these compounds were evaluated.
In order to study the likely increase in grape spring freezing tolerance using the anti-freeze compounds under the orchard, an experiment was conducted as randomized completeblock design (RCBD) with anti-freeze compounds in Agriculture and Natural Resources Research Center of Qazvin during 2012-2013. Minimum monthly temperature during the autumn and winter months was -12.2 °C. The treatments including the spray of SA, Tiofer®, Cropaid®, Bio-Bloom® and water (control) were used on vines during fourphonological stages: before plant dormancy, during bud swelling, start of clustering and during the final clustering on the three red seedless vines per plot. Quantitative and qualitative characters such as cluster weight, yield and total soluble solids (TSS) were measured. Leaves osmolites contents such as proline (Bates et al.,1973) and glycin-betain (Grieve and Grattan.,1983) as well as the status of the freezing resistance index enzymes activities such as Glutathione peroxidase (GPX) (Updhyaya et al.,), Ascorbateperoxidase (APX) (Nakano and Asada,1981) and Catalase (CAT) (Aebi, 1984) were evaluated. All statistical analyses were made using SAS software. The comparison of mean values for the different treatments was made by ANOVA, followed by the Duncan’s test at the significant level of 0.05.
The results showed that the anti-freeze compounds resulted in an significant increase in the TSS, cluster weight and yield by 22%, 17% and 26%, respectively and the most effectswas observed in Bio-bloom. Our results regarding the effect of SA on the TSS was in accordance with other researchers (ShokrollahFaam, 2011; Sedighi et al., 2011; Champa et al., 2014;Marzouk and Kasm, 2011). However the effect of other anti-freeze compounds on the quantitative characteristics has not studied yet. Tiofer and Cropaid had no significant effect on the grape cluster weight. Proline content increased significantly using anti-freeze compounds compared to control during 2012-2013. But there was no significant difference between the different anti-freeze compounds for proline content. The most important content of betaine-glysine was observed in SA and Bio-bloom treatments. A decrease in air temperature during 2013 dormancy period resulted in higher amount of osmolytes contents (betaine glycine) and freezing resistance index enzymes activities compared to those of 2012. The most important contents of these enzymes activities were obtained in SA, Tiofer, Cropaid and Bio-Bloom treatments, respectively and the less important content was observed in control.
According to these results the commercial anti-freeze compounds could be useful not only for an increase in the grape spring freeze resistance but also for an improvement in the grape cluster weight, total soluble solids and yield. Osmolytes contents such as such as proline and betaine glycine and enzymes GPX, APX, CAT are significantly higher in anti-freeze treated plants compared to control. Since high levels of soluble solids, mentioned osmolytes and enzymes resulted in an increase in cold resistance in plant, the use of antifreeze as an easy and inexpensive way to increase the cold hardiness of grapes is recommended. These results were obtained with this antifreeze in 5 ppm concentration. Therefore more researches on the other varieties using different concentrations of anti-freeze compounds are recommended.

Most deciduous trees need low temperature to break flower bud dormancy. One of the most important abiotic stresses is low temperature which limits production of temperate fruits. Pear production has been considerably reduced in recent years. Important pear cultivars show different levels of resistance to cold. Cold compatibility followed by resistance increase is controlled genetically and contains several mechanisms which lead to production of different metabolites such as: polypeptides, amino acids and sugars. The object of this research was to evaluate the frost resistance of different ‘Dare Gazi’ genotypes and other pear cultivars in Mashhad climate condition.
This study was conducted to investigate the frost resistance of 23 ‘Dare Gazi’ pear genotypes and nine other cultivars include: ‘William’s’, ‘Bell de june’, ‘Spadona’, ‘Koshia’, ‘Domkaj’, ‘Torsh’, ‘Sebri’ and ‘Tabrizi’. Plant material contained vegetative and reproductive buds of one-year-old shoot samples which were collected from 25-year old trees on March 2014, four days after winter cold (-6.6 °C) in three directions of trees and sent to the laboratory. Frost damages of vegetative and reproductive buds were investigated based on visual observations (%), electrolyte leakage (EC) and proline content. EC was measured with a Metrohm 644 digital conductivity meter and proline content was measured based on Bates et al. (1973) method, using acid ninhydrin. The experiment was performed on completely randomized experimental design with three replications. Statistical analysis was carried out using MSTAT-C and Excel software. Mean values were compared using the least significance difference test (LSD) at 1% levels. Cluster analysis was conducted by SPSS 16 program.
Highest EC of reproductive buds was observed in ‘Dare Gazi’ 10, 19, ‘Tabrizi’ and ‘Torsh’ whereas ‘Dare Gazi’ 8, 18 and ‘Bell de June’ had the lowest EC. Based on visual observations, the least percentage of damaged reproductive buds was observed in ‘Dare Gazi’ 22 while ‘William’s’ suffered from frost at the highest damage level (96%). Göndör and Tóth (1998) studied 13 pear cultivars by microscopic observations of flower buds and found that ‘Packham's Triumph’ was relatively resistant under Hungarian ecological conditions. Honty et al. (2008) reported that Kaiser was the most sensitive pear cultivar to low temperatures during endodormancy and ecodormancy. Khorshidi et al. (2014) described that pear reproductive buds of ‘Ghodumi’ were the most tolerant. Considering the vegetative buds, ‘Dare Gazi’ 19 had the highest EC (74.47 %) which was not significantly different from ‘Dare Gazi’ 10, 20 and 3 whereas the lowest one was found in ‘William’s’(24.75%). The highest percentage of healthy vegetative buds was found in ‘Dare Gazi’ 1 (50%) which did not show a significant difference with ‘Dare Gazi’ 12, 5 and 7. ‘Tabrizi’ was the most sensitive and had most damaged vegetative buds (95.99%). Khorshidi et al. (2014) observed the least damaged vegetative buds in ‘Dare Gazi’ and the most damaged buds in ‘Boheme’ and ‘Ghodumi’. Palonen and Buszard (1997) mentioned that hardiness of woody tissue of apples did not seem related to flower bud hardiness. The highest proline content of reproductive buds was found in ‘Dare Gazi’ 20 (21.28 µmol g-1FW) and the lowest content observed in ‘Dare Gazi’ 2 (0.1 µmol g-1 FW). Young (1977) described that increase in proline was not correlated well with relative cold hardiness of citrus rootstocks. Data did not show any significant correlation between EC and proline content. Barka and Audran (1997) studied grape buds and shoots and reached a high negative correlation between proline content and frosttolerance. Yelonsky (1979) indicated that accumulation of proline was not correlated to cold hardiness. The results of present experiment were in agreement with Duncan and Jack (1987) findings which reported that increase in proline was not always correspondent to cold resistance. Based on the cluster analysis, the genotypes laid in two distinct groups. First group included ‘Dare Gazi’1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 12, 13, 14, 15, 17, 18, 19, 20, 23 and ‘Sebri’, ‘Domkaj’, ‘Bell de june’ and ‘Koshia’ and second group include ‘Dare Gazi’ 11,16, 21 and ‘William’s’, ‘Spadona’ and ‘Torsh’. Frost damage, EC and proline content were higher in the first group compared to second group.
Cosidering‘DareGazi’ genotypes, no correlation was found between proline content and frost damage rate. This shows that morphological differences among ‘Dare Gazi’ genotypes could be due to the existing of genetic variation of these genotypes or they are different clones of one cultivar.

Due to high quality, Iran pomegranate is quite competitive compared to other countries is unrivaled among agricultural products and has great economic importance. Using essential oil is a new idea to reduce postharvest losses and increase the horticultural crop storage life and control of fungal infection. In this context, a factorial experiment based on completely randomized design was conducted to study the postharvest spraying of thyme essential oil on storage life and qualitative characteristics of pomegranate fruit (cv. Tarom red skin)
Pomegranate fruit (cv. Tarom red skin) was prepared and transferred to University of Zanjan, Horticulture postharvest physiology lab. Treatments were included essential oil of thyme at four levels (0, 500, 1000, 1500 mg/l) and the cold time storage (6 °C and 85% of relative humidity) at three levels (one, two and three months (by four replications. In the first experiment, 180 normal pomegranate fruits were treated with thyme essential oil. In the second experiment, fruits were infected with spores of the fungus Aspergillus niger and then treated with essential oil. During experiment, total soluble solids (TSS), titratable acidity (TA), TSS/TA ratio, pH, anthocyanin, electrolyte leakage, chilling injury, weight loss and fungal decay were evaluated. Fruit juice TSS was determined with a hand-refractometer at room temperature. TA was determined by titration an aliquot (20 mL) of the juice with 0.1 N NaOH and the results were expressed as a percentage of citric acid. The maturity index (TSS/TA ratio) was evaluated as the TSS/TA ratio. Fruit juice pH was measured using a pH meter. Anthocyanin was performed to method Fuleki & Francis. Electrolyte leakage was measured according to McCollum & McDonald method. Weight loss was measured according to Ershadi method. Chilling injury was measured by Wang method. Decay was visually evaluated and expressed as percentage. An analysis of variance was used to analyze difference between treatments and the Duncan test was applied for mean separation at p

Fruit spoilage of pomegranate is one of the most important problems in postharvest stages and its exports. This decay is mainly due to the influence and spread of saprophytic or parasitic fungi into the pomegranate fruits. In this purpose effects of essential oil from medicinal plants include; caraway (Carum carvi) and peppermint (Mentha piperetta)، and packaging (whit or no polyethylene bags) were investigated on shelf life، quality، decay percentage، chilling index and biochemical traits. The pomegranate fruits were kept in 5±1ºC and 85-90 percent humidity. The results showed that the highest amount of chilling index and weight loss was in without polyethylene bag treatment by 3. 45 and 17. 03، respectively. On the other hand the most percent of fungal infection was observed in polyethylene alone treatment by 29. 41%. Whereas، essential oils (1000 ppm) of caraway and peppermint was able to control postharvest fungal infection caused by LDPE packaging، completely. The usage of caraway essential oil on pomegranate fruits increased phenolic compounds and antioxidant activity، significantly.

The effects of different concentrations of salicylic acid as compared with control and as well with distilled water treatment were assessed on induction of resistance to chilling injury and quality of sweet lemon during its storage. For the purpose, sweet lemon fruits were treated by immersion method for 5 minutes in salicylic acid (200,400 and 600 mg/lit) and then packed in polyethylene bags to be stored in cold storage (4±1oC) for two months. At the end of the storage period, fruits were transferred to 25 ° C environment for 5 days while the effects of treatments on chilling injury, total soluble solids, ion leakage percentage, vitamin C, weight loss and decay percentage being investigated. Based on the obtained results, salicylic acid decreased chilling injury, preserved quality appearance and prevented water loss of the fruits without any deleterious effect on internal quality. The highest chilling injury occured in control and the lowest in fruits treated with 400 mg /lit of salicylic acid at low temperature, even after keeping them later at high temperatures. In terms of weight loss and reduction of vitamin C and total acids, significant differences were observed between treated vs control fruits. Furthermore, no significant differences of total soluble solids (TSS) and pH were found between treated vs control fruits. In total, treatment with 400mg/lit of salicylic acid showed fruits with the best appearance and the most controlling effect on chilling injury.

Chilling injury of vegetative and generative buds, bark and wood during fall and winter seasons are mainly limiting factors for productivity of fruits. Selecting and expanding cultivars for more yield and quality without attention to the rate of their frost resistance are impossible. In this research, the rate of relative resistance of some peach and nectarine cultivars at a sudden downfall of temperature was analyzed in vivo weather conditions during the 2008 winter season in Mashhad. The meteorology station of the studied area (Golmakan station) registered -22°C for the minimum temperature of this year on 13th January, which was a little different from the weather of Mashhad. This test is performed as factorials in the form of a randomized complete block design with three replications. Relative ionic leakage is used on reproductive and vegetative buds, annual and biennial wood in peach cultivars (J.H.Hale, Elberta, Redhaven, Mashhad Sorkhosepfide and Mashhad Ghermez) and nectarine cultivars (Indipendens, Qiuota, Nectared 6 and Stargold). Between studied peach and nectarine cultivars, Mashhad Sorkhosephid and Mashhad Ghermez cultivars, which are cultivars native to Iran, were the most resistant reproductive buds that did not have a significant difference in comparison with other peach and nectarine cultivars with the exclusion of Indipendense cultivar. The most sensitive reproductive buds were nectarine Indipendense cultivar and the most resistant vegetative buds were Mashhad Sorkhosephid and Redhaven in peach cultivars and Nectared 6 and Qiuta cultivars in nectarine cultivars. The relative ionic leakage of annual wood in peach cultivars was more than nectarine cultivars. But the relative ionic leakage between peach cultivars was not significant and Nectared 6 cultivar did not have any difference compared to peach cultivars. The "Sorkhosephid" peach cultivar of Mashhad had more solution carbohydrates in generative buds and annual wood (93.33 and 136.50 mg/lit, respectively) than other studied cultivars. Results of sugar rate followed relative ionic leakage and visual observations and showed increasing sugar and decreasing ionic leakage in organ caused lower their susceptibility to cold.