جستجوی مقالات مرتبط با کلیدواژه « پراکسیداز » در نشریات گروه « باغبانی »

 Medicinal plants have reservoirs rich in the active ingredients of many medicines. Medicinal plants have rich reservoirs of essential active ingredients of many drugs. Considering the importance of medicinal plants, especially in the pharmaceutical industry and their scarcity in nature, it is very important to study the various agricultural aspects of these plants, considering the increasing spread of saline soils, to find a solution. It seems necessary to prevent living and non-living environmental stresses or at least reduce them. One of these methods is the use of symbiotic relationships between mycorrhizal fungi and host plants, which reduces the stress caused by salinity. Due to the increasing expansion of saline soils, it seems necessary to find solutions that can prevent or at least reduce the living and non-living environmental stresses. There are different ways to overcome these tensions in different situations. Water salinization is one of the most important environmental limiting factors for crop production, especially in arid and semi-arid regions of the world, since Iran is located in the arid region of the world, given that salinity is one of the environmental factors. Are that have a strong effect on the growth and activity of lemongrass; There are also vast resources of saline and semi-saline groundwater, although not currently used and likely to be used in the future. Solutions to address abiotic stresses include the use of biofertilizers. One of these methods is to use the symbiosis of fungi with host plants, which leads to a reduction in salinity stress. The aim of this study was to investigate the effect of Arbuscular mycorrhizal fungi. On vegetative and biochemical traits of lemongrass under salinity stress. Salinity is one of the most important factors limiting the growth and production of crops. Fungi as a biological fertilizer can be useful in meeting the nutritional needs of plants and reducing the effects of environmental stresses on plants.
 
 The experiment was a factorial experiment in a completely randomized design with two factors of four salinity levels (0, 5, 10 and 15 ds.m-1 NaCl) and fungi (no inoculation and fungal inoculation). For inoculation of Arbuscular mycorrhizal fungi with mixed potting soil was applied to the lemongrass. Plant height, root length, fresh and dry weight of leaves, relative water content, catalase, peroxidase and polyphenol oxidase were measured.
 
 The results indicate that all studied traits were significantly affected by the interaction of mycorrhiza and salinity stress. The application of mycorrhizal fungi in the presence of salinity stress due to the absorption of nutrients and water led to improved growth of lemongrass. The results showed that under salinity stress of 150 mM plant height, root length, fresh and dry weight of leaves, relative water content, catalase, peroxidase and polyphenol oxidase enzymes in lemongrass inoculated with arbuscular fungus at 23.05, 32.69, 25.31, 48.14, 31.83, 30.33, 52.72 and 33.41% respectively, increased compared to the control (no inoculation). In general, based on the results of this study, it can be concluded that the use of mycorrhizal fungi can increase the salinity tolerance of lemongrass and cultivate it in saline soil.
 
In summary, the results of the present study showed that inoculation of the fungi can protect the lemongrass plant against salinity stress. In addition, the effect of mycorrhizal fungi on lemongrass under salinity stress has been investigated for the first time. According to the results obtained in this study, salinity reduced morphological parameters and lemongrass as a reaction to salinity to maintain its status to increase the amount of enzyme activity through the mechanism of osmotic regulation to stress conditions. Compromise and to some extent deal with salinity. In the study, it was observed that inoculation with Arbuscular had a positive effect on all measured traits. The application of mycorrhizal fungi in the presence of salinity stress due to the absorption of nutrients and water led to improved growth of lemongrass. By examining all the measured traits, it can be concluded that by using mycorrhizal fungi, the salinity resistance of lemongrass can be increased and cultivated in saline soil. Arbuscular species seems to be more suitable for improving the growth of lemongrass in all conditions.

This trial was conducted in order to evaluating nine apple rootstocks including MM106, M26, Ottawa3, Suporter4, M9, M7, P22 , MM111 and local rootstock "Gamialmasi" in different levels boron (0, 15, 30, 45 and 60 mg/kg soil). Results indicated that height rootstock, LAI, wet and dry weight leaf, chlorophyll index, WRC and vegetative growth rate reduced in comparison control as increased boron soil in all rootstocks. Vegetative growth ceased in all rootstocks, exception M26 and P22. Also, ion leakage and MDH increased as raised boron level in soil. Ascorbate peroxidase and super oxide dismutase leaf activity increased at first and then decreased with increasing boron levels in soil. Based on leaf analysis, leaf boron concentration in M26 and P22 was less than other rootstocks. Vegetative, physiological and biochemical assessments showed that M26 and P22 were more tolerate in relation other rootstocks.

In the present study, first, an in vitro experiment was conducted to study the effects of Thymus vulgaris L., Foeniculum vulgare Mill., Rosmarinus officinalis L., and Mentha piperita L. water extracts on reducing the growth of Fusarium rot disease factor of cucumber (Fusarium oxysporum f. sp. radicis-cucumerinum (forc)) by the saturated paper disk method. According to the results, the water extracts of Th. vulgaris, F. vulgare, R. officinalis, and M. piperita at a concentration of 250 ppm with the inhibitory zone diameter of 24.66, 17.33, 11.66, and 10.33 mm, respectively, showed the highest antifungal activity compared to the control (the inhibitory zone diameter of 3.66 mm). Then, it followed by a greenhouse experiment to investigate the effects of Th. vulgaris and F. vulgare water extracts on the cucumber cv. Nagene treated with F. oxysporum. The water extract of Th. vulgaris at a concentration of 200 ppm with the disease index of 31% showed the greatest reduction in the disease symptoms compared to the infected control and the F. vulgare treatment with the disease indices of 82.66 and 42%, respectively. Study on the activity of polyphenol oxidase, β-1, 3-glucanase, and peroxidase enzymes under the greenhouse conditions showed that the activity of all three enzymes had an increasing trend. So that the activity of enzymes in the combined treatment of Th. vulgaris water extract (200 ppm) and pathogen increased respectively from 1.12, 1.11, and 0.27 ΔOD/min/mg protein on the first day after the inoculation to 5.25, 4.81, and 2.88 ΔOD/min/mg protein on the 12th day, and it had a significant difference with the control. Considering the results of this research, it was found that the water extract of Th. vulgaris, in addition to the direct fungicidal effect, could increase the activity of defense enzymes in the cucumber plants resulted in the host plant resistance induction against the pathogen.

Black cumin (Nigella sativa L.) seeds are used in the traditional medicine in many countries to prevent and treat many disorders and diseases including cough, asthma, nasal congestion, headache, toothache, intestinal worms, menstrual disorders, gastrointestinal diseases, and impotence. To study the effects of humic acid and iron nanochelate on the content of osmotic protective osmolites including glucose, fructose, sucrose, proline, superoxide dismutase, catalase, and peroxidase of medicinal plant black cumin under the drought stress conditions, an experiment was conducted as a split factorial based on the randomized complete block design with three treatments in three replications at the Agricultural and Natural Resources Research Station of Eqlid city during two crop years of 2018 and 2019. The main plot consisted of three levels of irrigation (50, 75, and 100% of available water) and sub-plots included humic acid (0, 250, and 500 mg l-1) and iron nanochelate (0, 1, and 2 g l-1). The results showed that the effects of irrigation, humic acid, and iron chelate treatments on the catalase, superoxide dismutase, glucose, and peroxidase content, irrigation treatments on the proline content, and irrigation and humic acid treatments on the sucrose and fructose content were significant. The content of all protective osmolites increased in the 50% drought stress treatment. The highest content of glucose, fructose, and sucrose was obtained in the 50% drought stress, 500 mg l-1 humic acid, and 2 g l-1 iron nanochelate treatment. Overall, based on the results of this experiment, the application of humic acid fertilizer (500 mg l-1) and iron nanochelate (2 g l-1) could be recommended to reduce the effects of drought stress on black cumin.

Salinity stress is one of the most important factors in reducing the crop yield in the world. The application of humic acid along with selenium can improve the plant yield under salinity stress conditions by increasing the antioxidant capacity. To evaluate the effects of humic acid and selenium application under salinity stress conditions in Calendula officinalis L., a factorial greenhouse experiment was conducted in a completely randomized design with three replications in Islamshahr city in 2018. The experimental treatments included sodium chloride (0, 50, and 100 mg l-1), humic acid (0, 100, and 200 mg l-1), and selenium (0, 5, and 10 mg l-1) and their combined effects. The results showed that increasing the salinity significantly reduced the fresh and dry weight of shoots and roots and number of flowers per plant. The foliar application of 200 mg l-1 humic acid and 10 mg l-1 selenium improved carotenoids content of the petals and total chlorophyll of the leaves at all salinity levels. Also, with increasing the sodium chloride level up to 100 mg l-1, the amount of proline increased significantly. Meanwhile, the interaction treatments of humic acid and selenium had significant effects (P≤0.0.1) on improving the activity of superoxide dismutase and peroxidase enzymes at different salinity levels. The highest amount of essential oil (1.37%) was obtained in the interaction treatment of 200 mg l-1 humic acid and 10 mg l-1 selenium under salinity stress of 50 mg l-1 sodium chloride. In general, the results of this study showed that the foliar application of 200 mg l-1 humic acid and 10 mg l-1 selenium could be effective in reducing the negative effects of salinity stress on  C. officinalis.

In order to evaluate the effect of γ-aminobutyric acid and spermine on some morphological and physiological traits of Damask rose plant, a completely randomized design was carried out in spring and summer 2017 and in Zanjan University in three replications. Experimental treatments consisted of three levels of gamma aminobutyric acid (1, 5, 10 mM) and three levels of spermine (0.5, 1, 1.5 mM). The evaluated traits included morphological traits (plant height, number of flowers, number of flowering branches, plant shadow diameter, average number of flowers per branch and petal dry weight) and physiological traits (total chlorophyll, chlorophyll a, chlorophyll b, carotenoids, leaf flavonoids, petal flavonoids and peroxidase enzyme activity). The results showed that there was a significant difference in all the traits, except plant height, plant shadow diameter and number of flowering branches, compared to the control. Based on the results the concentration of 5 mM gamma aminobutyric acid and 1 mM spermine improved the morphophysiological traits in reproductive stage.

Drought is one of the most important factors limiting plant growth worldwide and the most common environmental stress. In response to environmental stresses, abscisic acid (ABA) plays an important role in initiating and coordinating many physiological and biochemical processes in reducing oxidative stress. To study the effects of abscisic acid on some antioxidant enzymes and proline of Lavendula angustifolia cv. Organic Munestead under deficit irrigation stress, a pot experiment was conducted as factorial based on randomized complete block design with three replications. The treatments were four levels of irrigation regimes (30-40, 50-60, 70-80 and 90-100 percent field capacity (FC)) and ABA including three levels (0, 15 and 30 mM/L). Traits evaluated in flowering stage. The highest level of drought resulted an increasing 91% in proline and decreasing 29.88% in carotenoid compared to control. Abscisic acid had a significant effect on all traits, except of carotenoid content. Abscisic acid 30 mM/L spray and irrigation regimes 30-40 percent FC induced the highest content of CAT, POD and SOD, while the maximum of antioxidant activity (70.54 mg/g DW) has resulted in ABA 15 Mm/L application and irrigation regimes 50-60 percent FC and the maximum of proline (2.51 mg/g DW) has resulted in ABA 15 mM/L application and irrigation regimes 30-40 percent FC. The highest fresh and dry weight of shoot and root were obtained from non-application of ABS in irrigation of 90-100% FC. It is determined abscisic acid application in deficit irrigation stress conditions increased the activity of antioxidant enzymes of lavender to counteract the negative effects of deficit irrigation stress.

In order to accelerate the flowering time in four late flowering chrysanthemum cultivars, the effect of different concentrations of gibberellic acid and day length on flowering time and some quantitative and qualitative characteristics, an experiment was conducted as a factorial split plot in a completely randomized design with three treatments and four replications. Cultivars included Ariamanesh, Roxana, Dina and Oran. Gibberellic acid treatment at four levels (0, 75, 150 and 300 mg/ l) and foliar application time at two levels (30 and 45 days after transplanting) were applied. Daytime treatments at three levels included 16 hours of light - 8 hours of darkness (control), 12 hours of light - 12 hours of darkness and 8 hours of light - 16 hours of darkness. In this experiment, the main and sub plots were day length and gibberellic acid, respectively. The studied traits included flowering stem length, flower number, flower diameter, dry weight of flowers and leaves, content of photosynthetic pigments, peroxidase and number of days to flowering. The results showed that the highest flower number, diameter and dry weight of flowers were obtained in the treatment of 300 mg/l gibberellic acid and 16 hours of darkness. Flowering time was accelerated by 300 mg/l gibberellic acid and 16 hours in the dark compared to the control for about 21 days. Dina cultivar was also recognized as the best cultivar in response to different levels of gibberellic acid and reduction in day length, so that the number of days to flowering in this cultivar compared to other cultivars showed a significant decrease.

Heavy metal contamination has become a serious environmental problem. The effects of 0, 30 and 60 mgL-1 Cu in the irrigation water and, 0, 2 and 4 mgL-1 sea algal extract (Ascophyllum nodosum) foliar applications on the growth and some physiological characteristics of Lepidium sativum were studied. The experiment was factorial based on RCBD. Malondialdehyde content was affected by 60 mgL-1 Cu treatment. Plant dry weight, total phenolic content and proline, Cu2+, K+, Mg2+, Fe2+ contents as well as catalase and peroxidase activity were influenced by the interaction effects of Cu treatment and foliar application of A. nodosum. For proline content, Cu control × 2 and 4 mgL-1 foliar application of algal extract was the treatment of choice. The lowest amount of total phenolics content was recorded with control plants. Peroxidase and Cu2+ content hold the top quantities at Cu of 60 mgL-1 × non foliar applications. Plant dry weight had the highest data for Cu control × 2 mgL-1 foliar application and Cu of 30 mgL-1 × 2 mgL-1 algal foliar application. The data clearly shows that algal extract; due to the abundance of some nutritional elements reduces the toxic effects of Cu metals on plants.

Melon, like other members of cucurbitaceae family, is sensitive to cold stress. Applying different cultivation techniques in the nursery can provide some degree of tolerance to environmental stresses in the plants. In the other words, applying stress conditions on plants may cause them to withstand subsequent stresses, this is so called a cross-adaptation or cross-tolerance. For example, Whitaker (1994) showed that cold stress damage can be mitigated by temperature pretreatment. This technique was then used to improve stress tolerance in different plants. In this regard, heat treatment has been used to increase the chilling tolerance in fruits and vegetables. Therefore, in this study, the possibility of increasing cold stress tolerance in melon seedlings using heat shock was investigated.

The experiment was conducted in a completely randomized design (CRD) with three replications and five treatments (including control and spraying with water at temperatures of 20, 45, 50 and 55 °C for 90 seconds) in Faculty of Agriculture of Ilam University in 2019. Heat treatments where used as foliar spray by heated water. After applying different levels of heat treatment and recovery at 24 hours, seedlings were exposed to chilling stress at 3 °C for 6 h in 6 consecutive days. All seedlings were transferred to greenhouse and after 72 hours, the related traits were measured.

Results showed that pre-treated seedlings had higher growth rate than control seedlings at the end of chilling period. Heat shock pretreatment significantly increased the content of chlorophyll, proline and hydrogen peroxide and reduced the amount of malondialdehyde compared to the control. The lowest amount of malondialdehyde (1.14 nmol g-1 fresh weight) was observed in the 50 °C treatment, which was 50% lower than the control. Similar to other environmental stresses, low temperature usually leads ROS production and oxidative stress. Malondialdehyde content is an index to measure membrane lipid peroxidation and its measurement is a criterion of damage to plants in stress conditions. Reduction of malondialdehyde has been reported to increase cell membrane stability and increase stress tolerance in plants. In the present study, heat shock reduced the accumulation of malondialdehyde compared to the control, indicating a decrease in cold effects on the plant. Mei and Song (2010) investigated the effect of heat pretreatment on increasing high temperature tolerance in barley, and reported that using this method by stimulating the synthesis of antioxidant enzymes prevented the increase of malondialdehyde in the plant under heat stress. Therefore, maintaining the membrane structure and decreasing the accumulation of malondialdehyde in melon seedlings under cold conditions indicates an improvement of plant defense responses induced by heat shock. Environmental stresses including cold stress by producing hydrogen peroxide and other free radicals lead to oxidative stress and damage plant cells. Hydrogen peroxide is converted to water by ascorbate peroxidase, peroxide redoxin, glutathione peroxidase and guaiacol peroxidase groups. Therefore, increasing the activity of antioxidant enzymes in plants is one of the most important mechanisms of the plant to cope with stress conditions. In the present study, heat shock pretreatment significantly increased peroxidase (POD) and poly phenol oxidase (PPO) activity and increased the amount of proline and hydrogen peroxide. In this regard, it has been reported that hydrogen peroxide has a dual role in plants and its increase in stress conditions by regulating the production of antioxidant enzymes helps plants to enhance their tolerance to the stress conditions. Our results is in consistent with Ao et al. (2013) report that stated hardening pretreatment of Jatropha curcas seedlings caused to increase the antioxidant enzymes activity, plant glutathione and ascorbate content. The increases in antioxidant enzymes activity by heat shock might be a positive mechanism, which facilitate the scavenging of ROS and induce plant growth and development under chilling stress. These results indicate that antioxidant defense system has a specific role in enhancing plant tolerance to stress conditions and hydrogen peroxide play an important signaling role in plant adaptive responses.

In general, the results showed that heat shock (especially at 50 and 55 oC) caused positive physiological changes in melon seedlings and could increase their tolerance to cold stress conditions.

Cut roses are one of the most important flowers in the ornamental plant industry that are widely cultivated all over the world. Longevity and postharvest quality is the most important characteristic in evaluating the quality of cut flowers which is influenced by various pre and post-harvest factors. Light, as one of the environmental cues in the postharvest condition of cut flowers, can play an important role in its qualitative characteristics. To the best of our knowledge, no detailed study has been reported so far in this case. This study aimed to investigate the intensity of light required for preserving the quality of cut flowers during the postharvest handling. This experiment was carried out as factorial in a completely randomized design with three replications in a postharvest room. The area was divided into three sections by optical shutters and the light intensity levels were applied in each section. Treatments were designed at three levels of light intensity of 15, 25 and 50 µmol m-2 s-1 emitting by LED lighting bulbs. The studied traits were vase life, activity of catalase and peroxidase enzymes, proline, relative fresh weight, anthocyanin, carotenoid and chlorophyll content. Results showed that the highest activity of catalase and peroxidase enzymes were at light intensity of 15 and 50 µmol m-2 s-1, respectively, and their activity decreased significantly during the vase life. The proline content increased with time and the highest level was observed in all three treatments on day 9 after harvest. The highest relative fresh weight was observed at light intensity of 15 µmol m-2 s-1 and in the vase life on the third day after harvest. The lowest relative fresh weight was also in the light intensity of 25 µmol m-2 s-1. In spite of these observations, however, there was no significant difference between the vase life, carotenoids, chlorophyll and anthocyanins of cut flowers at light intensities of 15, 25, and 50 µmol m-2 s-1. According to the results of this study, in order to improve the qualitative and quantitative characteristics of cut flowers during the post-harvest period, the light intensity of 15 µmol m-2 s-1 is recommended for flower shops industry.

In this study, the effects of deficit irrigation along with a foliar application of silicon on growth, yield, and quality of tomato (Lycopersicon esculentum L. cv BHN) were evaluated. This experiment was conducted as a factorial arrangement in a completely randomized design with three replications. Tomato plants were planted in pots containing coco-peat and perlite (80:20 v/v). The plants were treated with different irrigation levels (60, 80, and 100% full irrigation) and different levels of silicon (0, 100, and 200 mg L-1). Results showed that with an increase in irrigation levels vegetative growth and fruit quality was improved. The highest plant height and fruit number were found in 100% water requirement. Application of 200 mg L-1 silicon significantly increased fruit number and yield in 60% deficit irrigation. Deficit irrigation significantly increased catalase and peroxidase enzyme activity. The application of 100 mg L-1 silicon could increase TSS in 80% deficit irrigation. Overall, it seems that foliar application of silicon (200 mg L-1) could alleviate the negative effects of drought stress in tomato and improved growth, yield, and fruit quality under drought stress conditions.

Gerbera flower belongs to the Composite family and is one of the five top cut flowers in the world in terms of production and consumption, which has a great economic value in the international flowering industry. This study was designed to evaluate whether calcium pre-harvest foliar application in hydroponic culture, provided through 0, 0.5, 1 and 1.5% of CaCl2 and CaNO3, could extend quality of gerbera cut flower. The layout was factorial experiment in completely randomized design (CRD) with four replication.  Afterwards, for evaluation of associated traits with vase life, the produced flowers were kept in a vase solution containing 200 mg/L hydroxyquinoline sulfate with temperature conditions of 20 °C. The results showed that vase life of flowers extended 6.1 and 5 days by application 1% CaCl2 for Intens and Rosalin respectively. All treatments were effective in the increasing relative fresh weight of flower due to increase water uptake. The results also revealed that the calcium pretreatment delayed flowers senescence and maintained leaf protein and petal anthocyanin content. Application of calcium resulted in a decrease in electrolyte leakage and malondialdehyde content in the cut flowers of both cultivars, providing evidence for delay of senescence in calcium-treated cut flowers. Also, results showed that calcium application significantly increased Peroxidase (POD) and phenylalanine ammonia-lyase (PAL) of both cultivars.  The maximum and the minimum PAL and POD activities were observed in resistant and sensitive cultivars, respectively. Taken together, pre-harvest application of calcium (especially 1% CaCl2) might be promising approaches to improve postharvest performance of gerbera cut flowers.

 The ability to tolerate cold will not be possible without stopping or inducing sleep, which is one of the important steps in the life cycle of plants in temperate regions. This period is one of the important factors in preventing cold damages in winter and spring in temperate regions. Various studies in controlled conditions on plants have shown that in plants, when entering and leaving this period, various changes occur in materials such as proteins, enzymes and hormones. In order to control the harmful effects of active oxygen species, plants have defense mechanisms. Catalase, peroxidase and superoxide dismutase enzymes are a defensive team whose common goal is to defend against the destructive effects of active oxygen species. This study was carried out to determine the chill requirement and its relationship with the changes in the activity of antioxidants enzymes and proline.

 The experiment was conducted at agricultural Research Station of Khalat-Pooshan and the Laboratory of Flower Biology and Physiology of Fruit Growth in the Department of Horticulture, Faculty of Agriculture, Tabriz University in 2015-2016. Flower buds needed for testing were selected from ‘Siah Shabestar’, Zard Mashhad, Zoodras cultivars and a local genotype of sour cherry. Once a month, enough buds were harvested and until the experiments began, they were kept inside the freezer inside an aluminum foil at -80 ° C. In order to estimate the chill requirement, four replicates (4 geographic directions) from each cultivar and from each replication four branches with the same length and diameter were removed. The amount of chilling accumulation and chilling requirement in each month was calculated according to Utah model. In order to estimate fresh weight, four replicates in each cultivar were selected and in each replication five buds were selected from different parts of the branch. The statistical design used in the determination of the chill requirement was a randomized complete block design. Enzymatic and proline data were analyzed in a completely randomized design as factorial

 Chill requirement: Based on the Utah model, the chill requirement of sweet and sour cherry cultivars contains Zard Mashhad, Zoodras and Siah Shabestar were calculated 752, 780, 867 and 961 CU, respectively. There was a significant difference in the activity of superoxide dismutase enzymes between cultivars and different sampling times at 1% probability level. Siah Shabestar cultivars with the highest chill requirement had the lowest SOD enzymatic activity and Zard Mashhad and Zoodras were intermediate cultivars in terms of enzymatic activity. Sour cherries, which had the least chill requirement, showed the highest levels of SOD enzyme activity. This is consistent with the results of some researchers regarding apricot stated that the low chill apricot cultivars had the highest SOD enzymatic activity. The sour cherry had the highest amount of POX enzymatic activity with the least amount of chill requirement, and also Siah Shabestar has the least chill requirement. Like the two previous enzymes, the activity of catalase was highest in sour cherries and the lowest was observed in Siah Shabestar. In terms of the presence of free proline, there was no significant difference between the Zard Mashhad cultivars and Zoodras, while there was a significant difference between these two cultivars and Sour Cherry and Siah Shabestar. Zoodras cultivar has the highest and our cherry has the lowest amount of free proline. Between different cultivars, in terms of fresh weight of buds, there is a significant difference at 1% probability level before and after placement in the growth chamber. The increase in fresh weight of sour cherry and Zard Mashhad, Zoodras and Siah Shabestar cultivars were 25, 27, 31.5 and 33%, respectively. The highest fresh weight before and after placement in growth chamber was observed in Siah Shabestar and sour cherry was the lowest. In all the cultivars, the activity of all three enzymes were initially at maximum (369 CU), then, with the cooling of the air and the initiation of deep dormancy, the activity of these enzymes were greatly reduced (820 CU) and then again increased in the activity of this enzyme (963 CU), which is similar to other studies.

Conclusions :

The results of this study showed that the antioxidant metabolism in plants is influenced by seasonal cycle changes and enzymatic activity changes depending on temperature, so that sour cherry with the least chill requirement has the most activity of the enzyme catalase, peroxidase and superoxide dismutase and Siah Shabestar, which have the most chill requirement, have the least enzymatic activity. Accordingly, the enzymatic antioxidant system activity of the flower buds was relatively high at the beginning of the dormancy period, but decreased during the end of dormancy. Also, the amount of free proline at the end of dormancy and the stage of dormancy breaking was highest and the lowest was in the deep dormancy period.

In order to study responses of potato plantlets under in vitro conditions to osmotic and temperature stresses, a factorial experiment was conducted in a completely randomized blocks design with three replications. The first factor was osmotic stress caused by polyethylene glycol 6000 in four levels including control, 0.5, 0.1 and -1.5 MPa which were equal to 0, 200, 300 and 370 grl-1 PEG. The second factor was temperature at three levels of 15, 25 and 35 °C applied on plantlets of three Promising clones (143, 301 and 306) and two commercial cultivars (Picasso and Marfona) in MS medium. Physiological and biochemical traits including relative water content (RWC), electrolyte leakage (EL), proline, catalase (CAT), peroxidase (POX) and ascorbate peroxidase (APX) as well as protein content were measured. Results of variance analysis showed that the simple effects of three factors as well as the interaction were significant at 1≤0.01 on the mentioned traits, but the protein content was not significant. Comparing the mean of treatments showed that by increasing the temperature and concentrations of PEG, RWC was reduced, while EL, proline content, CAT, POX and APX enzymes activity were increased. Also, results indicated that Marfona was more tolerant to stress conditions than other varieties and clones, which seems is due to preventing the effects of stress by increasing the accumulation of proline and the activity of antioxidant enzymes. Clone 306 was more susceptible than other varieties and clones and showed more vulnerability to stress and its plantlets were killed by increasing stress levels. The combination of osmotic and temperature stresses were not tolerated by potato’s plantlets under in vitro conditions, because osmotic stress of -0.5 MPa and higher in combined with 35°C caused the plantlets to dry.

The reduction in the internal energy after harvesting of rose cut flowers accelerates the senescence process and prevents the full opening of the bud. In this experiment's effects of energy, suppliers included sucrose (1%, 2% and 3%), mannitol (100, 200 and 300 mM) and ATP (0.1, 0.3, 0.5 and 0.7 mM) on the vase life of Rosa hybrida cv. Samurai investigated, The results of continuous treatment with sources of energy supply showed that ATP treatment of 0.7 mM had the highest effect on the vase life of cut flowers (14.2 days), which showed 5.8 days increase in vase life compared with control treatment (8.2 days). ATP at 0.3, 0.5 mM concentrations increased the vase life of cut flowers to 11 and 12 days, respectively. Also, the vase life in sucrose 3% was 11.4 days. In the above treatments, solution uptake, relative fresh weight, and relative flower diameter were higher than other treatments. Besides, the activity of peroxidase enzyme and ion leakage of petal during the postharvest period was lower in treated cut flowers with concentrations of 0.7 and 0.5 mM ATP. Results showed that the use of different concentrations of mannitol did not increase the vase life of rose and had a negative effect on the quality of flowers so that the vase life of cut flowers was 1.8 days lower than the control treatment. Our results showed that the supply of energy for cut flowers by ATP treatments can be an effective way to maintain the longevity of rose cut flowers. Therefore, it is recommended to use of ATP (0.7 and 0.5 mM) in vase solution to maintain the postharvest quality of Rose cut flowers.

In order to investigate the effect of drought on some of the olive cultivars, a pot experiment was conducted in a completely randomized design in Gilan-Gharb city of Kermanshah Province in pot condition during 2015. The treatments consisted of three irrigation levels of 100 (control), 75 and 50% field capacity, and three olive cultivars (Zard, Amigdalolia and Konservolia). The results showed that vegetative growth such as plant height, Leaf number, leaf area and root length were significantly affected by water stress depending on the cultivar. Peroxidase and catalase enzymes activity were significantly different between cultivars under water stress. The highest levels of peroxidase and catalase activity were observed in Konservolia cultivar and 50% irrigation treatments. The amount of phenol increased under water stress. Zard, Amigdalolia and Konservolia had the highest levels of phenol under stress treatments in compare to the control plants, respectively. The amount of malondialdehyde in different treatments was significantly affected by drought stress. The highest amount of malondialdehyde was observed in irrigation treatments of 50% in Zard cultivar with about 57% compared to control plants. Generally, according to the response of cultivars, they differed in drought stress, and each showed a specific response. Vegetative growth under conditions of drought stress was higher in Zard, Konservolia and Amigdalolia cultivars, respectively. Zard variety was superior in terms of phenol content and peroxidase and catalase activity, while Konservolia had the highest sugar content.