Mohammad Soleimani; Mostafa Mobli; Ali Akbar Ramin; Bahram Baninasab; Leila Aslani
Abstract
Introduction: Cold stress is one of the limiting factors for plant growth and yield production in most parts of the world. Cold stress damages cells through changes in the activity of macromolecules, decreasing osmotic potential, and significant changes in other parts of the cell. Cold stress in young ...
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Introduction: Cold stress is one of the limiting factors for plant growth and yield production in most parts of the world. Cold stress damages cells through changes in the activity of macromolecules, decreasing osmotic potential, and significant changes in other parts of the cell. Cold stress in young seedlings generally reduces leaf development, induces wilting and chlorosis and in more severe cases, browning and necrosis become visible. Cucumber is a sensitive plant to low temperature and its cultivation, except the southern and central parts of Iran, occurs in areas where there is a possibility of cold stress in the early part of the growing season due to the low temperature. The different ways for controlling cold stress had been used; one of them is using plant growth regulators such as spermidine. Spermidine is one of the polyamines that has been used in recent years to control cold stress. The effect of cold treatment on the amount of indigenous leaf polyamines has been reported differently between cold-resistant and sensitive cucumber cultivars. During the cold stress, the amount of indigenous spermidine in leaves of cold-resistant cucumber cultivars and sensitive cultivars increased significantly and remained unchanged, respectively. The increase in the content of putrescent, spermidine and spermine in cold resistant cultivars during cold stress was probably due to the increased activity of ornithine decarboxylase (ODC). The amount of polyamines in chickpea plants that were exposured to low temperatures (12-15°C and 4-6°C are related to mean maximum and minimum temperature of the farm, respectively) increased six to nine times. Adding spermidine to the cucumber growing medium before applying cold treatment increased spermidine amount in all organs and increased cold tolerance.
Materials and Methods: To study the effect of spermidine on cold tolerance of cucumber, seedling of ‘Rashid’ cultivar, an experiment was conducted based on completely randomized design with four replications and four treatments consist of different concentrations of spermidine (0, 0.1, 0.5 and 1 mM) in incubator of College of Agriculture, Isfahan University of Technology. So seeds were exposed to 20°C for 7 days in a humid condition and then were treated with 0, 0.1, 0.5 or 1 mM spermidine, the remaining 8 days they were kept at 6 or 9°C. The treatments performed in dark conditions until the second day of germination and received 8 hours of light daily from the third day until the end of the experiment. At the end of each experiment, shoot and root length were measured by use of the ruler, shoot and root fresh and dry weight were measured by use of digital scale, shoot and root ion leakage were measured based on Lates method (3) and shoot and root proline concentration were measured based on Bites et al., (2) method. To compare the effects of temperature and its interactions with spermidine, data of two experiments analyzed as split plot experiment (Different temperatures and spermidine concentrations were as main and subplots, respectively).
Results and Discussion: The findings of this study showed that application of the highest concentration of spermidine (1 mM) in 9°C had the inverse effect on cold tolerance, so it decreased the fresh and dry weight of root. In 6°C, 0.5 mM spermidine was more effective than other concentrations, and it increased root fresh weight, shoot proline concentration and decreased root ion leakage. It has been shown that the non-saturated lipid profile of membranes of cold-resistant plants in comparison of non-resistant plants is significantly increased, and this increase is associated with a decrease in cell ion leakage. Proline works as a nitrogen source and soluble substance that helps the plant to combat again stress conditions. The split-plot analysis of data showed that 0.5 and 0.1 mM spermidine treatments increased root length, root fresh and dry weight significantly. The study of spermidine concentrations ×temperatures showed that the increasing effect of 0.5 mM spermidine on root length, root fresh and dry weight was only visible in 6°C.
Azam Amiri; Bahram Baninasab
Abstract
Introduction: Salinity is a common abiotic stress that seriously affects crop production in some parts of the world, particularly in arid and semi-arid regions. The deleterious effects of salinity on plant growth are associated with low osmotic potential of soil solution (water stress), nutritional imbalance, ...
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Introduction: Salinity is a common abiotic stress that seriously affects crop production in some parts of the world, particularly in arid and semi-arid regions. The deleterious effects of salinity on plant growth are associated with low osmotic potential of soil solution (water stress), nutritional imbalance, specific ion effect (salt stress), or a combination of these factors. Paclobutrazol (PBZ), a member of the triazole plant growth inhibitor group, is a broad-spectrum gibberellin biosynthesis inhibitor. Triazoles have both fungal toxicity and plant growth regulatory effects. They also increase tolerance of various plant species to biotic and abiotic stresses, including fungal pathogens, drought, air pollutants, and low- and high-temperature stress. According to our knowledge, there are no reports on the effects of exogenous PBZ enhancing vegetative peach- almond hybrid (GF 677) rootstock tolerance to salt stress. Therefore, the objective of this work was the possibility test of this idea that PBZ application would protect GF 677 rootstock from damaging effects of salinity.
Materials and Methods: One-year-old rooted cuttings of GF 677 were grown in in plastic pots in the research greenhouse of Agricultural College, Isfahan University of Technology of Iran. The minimum and maximum temperatures during the experiment period were 19 and 32˚C, respectively. After cutting establishment (3 months), the plants were sprayed twice (with a 7 days interval) with 0 (control), 20 and 40 mg l-1 PBZ to the point of run-off. One week after the second foliar application of PBZ, each plants was subjected to one of several salt stress treatments. The salt treatments (0, 25 and 50 mM NaCl) were applied to the pots intervals in 0.5 l of irrigation water. To avoid osmotic shock, the NaCl concentration was increased gradually. The layout was a 3×3 factorial experiment in a completely randomized design, with four replications. The experimental measurements were carried out 60 days after beginning the salt treatments.
Results and Discussion: The results showed that salt stress and application of PBZ significantly affected injury rating valve (IRV). The Injury rating value of plants was found to increase significantly as the salt concentration was raised. After exposure to salt stress those plants that did not receive PBZ exhibited higher symptoms of salt injury. There was a significant interaction between salinity and PBZ application. The lowest IRV in all NaCl concentrations observed when 20 mg l-1 PBZ was applied. Salinity caused significant decrease leaf parameters so that the lowest means of leaf number (12.5) and leaf fresh weight (6.52 g) were recorded at 50 mM NaCl treatment, showing a 55.80% and 41.78% decrease compared with the control, respectively. The application of PBZ significantly increased leaf number, with the largest increase when 40 mg l-1 PBZ was applied. The interaction between salinity and the application of PBZ showed that at 25 mM NaCl maximum valve of leaf number was observed in plants after spraying with 40 mg l-1 PBZ. Relative leaf chlorophyll (RLC) was not affected by salt stress. Application of PBZ significantly increased relative RLC value compared with the control, with the largest increase in RLC measured when 20 mg l-1 PBZ was applied. The interaction between salinity and the application of PBZ showed that at 50 mM NaCl maximum valve of RLC was observed in plants after spraying with 20 mg l-1 PBZ. The proline content of leaves was significantly influenced by the salt stress and PBZ application, but not their interaction. Salinity stress, increased proline content in the leaves of salt-treated plants. At 50 mM NaCl, proline content was maximum compared to those of the controls and other salt levels. PBZ treatment increased proline content in leaves. The highest proline content was obtained from leaves of the plants treated with 40 mg l-1 PBZ (55.62μmol g-1 FW), which was 39.18 % more than the control. Salt stress significantly reduced the relative water content (RWC) with maximum reduction observed in plants grown by 50 mM NaCl. Application of PBZ significantly increased RWC compared with the control, with the largest increasing in RWC at 20 mg l-1 PBZ application. Leaf electrolyte leakage was affected by both salt stress and PBZ application. Salt stress significantly increased leaf electrolyte leakage, with a maximum increase observed in plants grown by 50 mM NaCl. The application of PBZ significantly decreased electrolyte leakage in leaf discs, with the largest decreaseing in leaf electrolyte leakage measured at 20 mg l-1 PBZ application..There was a significant interaction between salinity × PBZ concentrations. However, the greatest decreasing in leaf electrolyte leakage occurred at 40 mg l-1 PBZ in non-saline condition. In this study, the correlation between vegetation and physiological parameters of GF677 plants subjected to salt stress was analyzed. These correlations suggested that salt injury symptoms was negatively correlated with number and fresh weight of a leaf, RWC, RLC, but positively correlated with proline content and leaf electrolyte leakage.
Conclusions: in overall, this investigation revealed that salt stress had an inhibitory effect on the vegetative growth of GF 677 plants. The responses of GF 677 plants to the PBZ treatments suggest that the application of PBZ could partially increase the survival capacity of GF 677 plants and protect the plants against injuries such salt stress.
Farzaneh Olyaei; Bahram Baninasab; Cyrus Ghobadi
Abstract
Introduction: Salinity is a common abiotic stress that seriously affects crop production around the world, particularly in arid and semi-arid regions.The deleterious effects of salinity on plant growth are associated with low osmotic potential of soil solution (water stress), nutritional imbalance, specific ...
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Introduction: Salinity is a common abiotic stress that seriously affects crop production around the world, particularly in arid and semi-arid regions.The deleterious effects of salinity on plant growth are associated with low osmotic potential of soil solution (water stress), nutritional imbalance, specific ion effect (salt stress), or a combination of these factors. Olive is one of the most important fruit crops in Iran and the world. Despite olive has been classified as moderately salt tolerant plant, poor quality of irrigation water in association with salt build-up soils has reduced the yields, especially in arid and semi-arid regions of Iran. The tolerance of the olive to salt is to a great extent depends on the cultivar. Selecting salinity-resistant cultivars is one of the most important strategies used for mitigating salinity effects on olive. Therefore, this study was performed to assess the salt tolerance of four olive cultivars under greenhouse condition.
Materials and Methods: For this purpose, one-year-old rooted cuttings of Iranian olive cultivars (‘Dakal’, ‘Shiraz’, ‘Zard’) and non-Iranian cultivar ‘Amigdal’ were grown in the research greenhouse of Agricultural College, Isfahan University of Technology of Iran. Plants were grown in plastic pots. The pots were 180 mm in diameter and 20 mm in depth with volume of 7 L. The minimum and maximum temperatures during the experiment period were 19 and 35˚C, respectively. After sticking the cuttings, the pots with uniform plants were subjected to the treatment with 0 (control), 100, 150 or 200 mMNaCl. The electrical conductivities of these solutions were 0.003, 10.52, 15.43 and 19.55 dS m-1, respectively. To avoid osmotic shock, the NaCl concentration was gradually increased. The layout was a 4×4 factorial experiment based oncompletely randomized design, with four replications. The experimental measurements were carried out three months after beginning the salt treatments.
Results and Discussion:The results showed that salt stress and cultivar hadsignificant effects on all of vegetative and physiological parameters. Injury rating valueof plants wasfound to increase significantly as the salt concentration was raised. Among the cultivars, the highest injury rating value (2.75) belonged to Amigdal cultivar, while the lowest means (2.00) was related to Dakal cultivar. By increasing the salinity level, stem heightincreasing ratesignificantly decreased. The lowest means (18.17%) belonged to 200 mMNaCl treatment, showing 81.83% decrease compared with control. Among the cultivars, Zard showed the highest means of increase in stem height (71.75%). Leaf area influenced significantly by salinity, sothat the lowest means of leaf area (35.05%) was recorded for200 mMNaCl treatment, showing a 69.91% decrease compared with the control. The highest leaf area belonged to Shiraz cultivar, which had a significant difference with Zard and Amigdal cultivars. Compared with the control, salinity caused 50.83% and 54.36% decreases in shoot fresh and dry weight in 200 mMNaCl, respectively. The highest shoot fresh and dry weightswere recorded forZard cultivar. The lowest shoot fresh and dry weights were observed forAmigdal cultivar.Increment of salinity concentration significantly declined root fresh and dry weight. Among the cultivars, the highest means of root fresh weightbelonged to Amigdal cultivar, whereas the lowest was related to Shiraz cultivar. The highest and lowest root dry weightswere observed forDakal and Amigdal cultivars, respectively.Salinity significantly decreased relative water content.The lowest leaf relative water content (66.04%) was recorded in 200 mMNaCl treatment, showing a 23.43% decrease compared with the control.Zard cultivar showed the highestleafrelative water content. Salinity stress decreased chlorophyll fluorescence in leaves of salt-treated olive plants. At 200 mMNaCl, leaf chlorophyll fluorescence was minimal as compared to control and other salt levels. The highest leaf chlorophyll fluorescence ratio (0.74) was recorded forZard cultivar. However, Amigdal cultivar showed the lowest means for this index (0.60).Salinity significantly decreasedleaf chlorophyll content.The lowest leaf chlorophyll content (69.39%) was recorded in 200 mMNaCl, showing a 66.80% decrease compared with the control.Among the cultivars, Zard showed the highest leaf chlorophyll content (170.33). In the present study, the increase in proline content in the NaCl-treated plants was noted, with the highest level being attained with 200 mMNaCl. The highest proline content (1.03 µmol.g-1 F.W.)was observed in Zard cultivar. Salinity stress increased malondialdehyde content in the leaves of salt-treated plants. The highest malondialdehyde content was obtained from leaves of plants treated with 200 mMNaCl. The highest malondialdehyde content was recorded in Amigdal cultivar.Shirazl cultivar showed the lowest malondialdehyde content. In this study, the correlation betweenvegetative and physiological parameters of olive plants subjected to salt stress was analysed. These correlations suggested that salt injury symptoms was negatively correlated with relative water content, leaf chlorophyll fluorescence and leaf chlorophyll content, but positively correlated with proline content and malondialdehyde content.
Conclusion: In overall, this investigation revealed that salt stress had aninhibitory effect on the vegetative growth of olive plants.The responses of olive cultivars to salt stress suggested that Zard and Shiraz cultivars were more tolerant and ‘Amygdal’ was the most sensitive to changes in the salt levels.
Maryam Hojjati; Nematollah Etemadi; Bahram Baninasab
Abstract
Abstract
Growth retardants are new chemical organic compounds that increase period of flowering, leave chlorophyll, lateral shoot number, flower number and decrease vegetative growth. They also increase dry, cold and heat tolerance. Paclobutrazol and Cycocel are examples of these compounds. This ...
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Abstract
Growth retardants are new chemical organic compounds that increase period of flowering, leave chlorophyll, lateral shoot number, flower number and decrease vegetative growth. They also increase dry, cold and heat tolerance. Paclobutrazol and Cycocel are examples of these compounds. This study was conducted to evaluate the effect of Paclobutrazol and Cycocel on some quantitative and qualitative traits of Rudbeckia. Plants transplanted at Horticulture Department Farm, College of Agriculture, Isfahan University of Technology. The experiment was conducted based on randomized completed block design with 3 replications. Traits were studied included height, leaf and flower number, lateral shoot number, flower diameter, lateral shoot length, leave chlorophyll, the period of flowering , root fresh and dry weight, leaf area, root number, diameter and length, root and shoot carbohydrate. Results showed that Paclobutrazol 30 ppm reduced leaf number. Cycocel 2000 ppm produced the most leave chlorophyll, the period of the flowering and root diameter. Paclobutrazol 5 ppm and Cycocel 500 ppm reduced flower number. All treatments except Cycocel 500 ppm significantly reduced leaf area. There were no significant difference between treatments related to height, lateral shoot number, lateral shoot length, flower diameter, root fresh and dry weight and root and shoot carbohydrate.
Keywords: Rudbeckia, Paclobutrazol, Cycocel, Vegetative growth, Flowering
Negar Simkeshzadeh; Mostafa Mobli; Nematollah Etemadi; Bahram Baninasab
Abstract
Abstract
Planting of olive (Olea europaea L.) tree due to salt and drought tolerance and ever green habit increasingly is considered in urban landscape in recent years. The low resistance to cold has been a major problem in using this tree in temperate and cold zones. So, determination of frost resistance ...
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Abstract
Planting of olive (Olea europaea L.) tree due to salt and drought tolerance and ever green habit increasingly is considered in urban landscape in recent years. The low resistance to cold has been a major problem in using this tree in temperate and cold zones. So, determination of frost resistance cultivars is one of the important measures for use of this tree in urban landscape. To evaluate frost resistance of 15 olive cultivars and to compare the visual assessment and chlorophyll fluorescence methods, a factorial experiment was carried out using 7- year- old olive trees which were planted in randomized complete block design with 3 replications. In visual method, frost damage of winters 2007 and 2008 to plants (percentage of drying by scoring and percentage of leaf abscission) were measured. Results of this experiment showed that ‘Amphisis’ followed by 'Gorgan' and 'Shengeh' were tolerant and ‘Kroneiki’ and ‘Rashid’ were sensitive cultivars to low temperatures. In method of chlorophyll fluorescence, in July 2008 leave samples of each cultivar was gradually incubated in 0, -5, -10, -15 and -20 ° C for one hour at least. Then Fv/Fm value of each sample was measured with fluorescence spectrometer. Results indicated that 0 and -5 ° C had no damage on samples and all cultivars tolerated these temperatures (Fv/Fm> 0.83). When temperature reduced to -10 and -15 ° C the stress on plants increased and ‘Rashid’ showed the lowest Fv/Fm (0.243 and 0.001 respectively) and was the most frost sensitive. Decreasing temperature to -20 °C had no further significant effect on reduction of Fv/Fm index and showed no difference between cultivars. Based on this method, ‘Shengeh’, ‘Gorgan’ and ‘Amphisis’ were tolerant cultivars and ‘Rashid’, ‘Spain’, ‘Manzanilla’ and ‘Kroneiki’ were sensitive cultivars to low temperatures which confirmed the results of visual assessment.
Keywords: Chlorophyll fluorescence, Frost resistance, Olive, Visual assessment
Fatemeh Shakeri; Bahram Baninasab; Sirus Ghobadi; Mostafa Mobli
Abstract
Abstract
To investigate the effects of paclobutrazol (PBZ) on vegetative and reproductive growth of Strawberry cv. Selva a factorial experiment in a completely randomized design with three replications was carried out in greenhouse of Agriculture College, Isfahan University of Technology. PBZ was applied ...
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Abstract
To investigate the effects of paclobutrazol (PBZ) on vegetative and reproductive growth of Strawberry cv. Selva a factorial experiment in a completely randomized design with three replications was carried out in greenhouse of Agriculture College, Isfahan University of Technology. PBZ was applied in two methods, drench and foliar spray, at 0, 0.5, 1, 1.5 and 2 mg active ingredient per plant. The results indicated that applications of PBZ as foliar spray was more effective than soil drench on vegetative and reproductive growth. With increasing the amount of PBZ leaf area, shoot fresh weight, whole plant fresh weight and petiole length of treated strawberries were decreased, however fresh weight, number and diameter of roots were not affected by PBZ. Also PBZ had no significant effect on fruit firmness, total soluble solids and vitamin C. The interaction of PBZ and its method of application on characteristics including leaf area, petiole length and diameter, total fresh weight, shoot fresh weight, leaf chlorophyll content, yield, fruit diameter and harvest index were significant. Foliar application of PBZ at the rate of 2 mg active ingredient per plant lead to maximum value of petiole diameter, leaf chlorophyll content and harvest index. Yield (fruit/plant) was also increased (27.16%) when the plants received 1 mg active ingredient per plant PBZ through soil drench method.
Key words: Paclobutrazol, Strawberry, Soil application, Foliar application
