Pomology
Sayeede Khodaei; Ebrahim Ganji Moghaddam; Mahbube Zamanipour
Abstract
IntroductionSince Iran is one of the arid and semi-arid regions of the world and due to the great importance of water in agriculture, it is very important to conduct research to improve drought stress in order to produce more quality products. In this regard, this study was conducted to investigate the ...
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IntroductionSince Iran is one of the arid and semi-arid regions of the world and due to the great importance of water in agriculture, it is very important to conduct research to improve drought stress in order to produce more quality products. In this regard, this study was conducted to investigate the effect of mycorrhiza species on some morphological and physiological characteristics of peach seedlings under drought stress. Arbuscular mycorrhizal fungi coexist with the roots of various plants and have a broad effect on their growth. These fungus are effective in the initial establishment of the plant under drought conditions. Arbuscular mycorrhizal fungi increases plant resistance to dehydration by increasing growth and uptake of nutrients, especially phosphorus. Matherials and MethodsIn order to investigate the effect of three species of Arbuscular mycorrhizal fungi on some vegetative characteristics and phosphorus absorption of peach seedlings under drought stress conditions, a factorial experiment was conducted based on a randomized complete block design with four replications. The experimental factors included: drought stress at four levels (100, 80, 60 and 40 percent of field capacity) and the second factor application of mycorrhizal fungus at four levels: application of three species of mycorrhiza fungi and three species of fungi, each in three concentration (75, 100, 125 g in a pot) with chemical fertilizer (100 g triple super phosphate for each pot) and fertilizer (without mycorrhiza) and control (without fertilizer and mycorrhiza). The measurements were comprised root traits, stem diameter, vegetative growth of branches, leaf area index, vegetation index, relative leaf water content, chlorophyll fluorescence, leaf electrolyte leakage, leaf phosphorus and colonization root percent. Results and DiscussionResult showed that application of mycorrhizal fungi seems to be effective in reducing the effects of dehydration stress. The use of these fungi had a positive effect on reducing leaf electrolyte leakage under severe dehydration. According to the results obtained in this experiment, the highest efficiency in drought stress conditions was observed in G. mosseae and G. intraradices. Under drought stress conditions, the lowest values of root volume, greenness index, chlorophyll fluorescence, leaf electrolyte leakage, root colonization and leaf phosphorus content were observed. With increasing of drought stress, all of the mentioned traits reduced and mycorrhiza fungi had a positive significant effect on all studied traits. In this study, it was found that with increasing stress intensity, the traits were negatively affected and led to irreparable damage to the product. Therefore, it is expected that by preventing or minimizing the effects of stress, an effective step was taken to increase performance. The significant decrease in root colonization with increasing stress is probably due to the decrease in the growth of hyphae. The most important step after spore germination is the growth of hyphae resulting from germination, which plays an essential role in root colonization. Apparently, hyphae growth is more affected by osmotic potential than spore growth. The results obtained from this research showed that the roots of peach seedlings have significant symbiosis potential with arbuscular mycorrhizal fungi (Peymaneh & Zarei, 2013). According to Miyashita et al. (2005) Leaf photosynthesis activity can be used as a useful tool for classification of drought tolerant plants. Sajjadinia et al. (2010) regarding the relative water content and photosynthesis of several pistachio cultivars reported high correlation and high diversity in different stages and cultivars and stated that the decrease in relative water content strongly reduces transpiration, stomatal conductance and photosynthesis, which our results are consistent. With the escalation of tension, the greenness index also decreased; So that in the conditions of severe stress (40% of crop capacity), the amount of greenness index reached the lowest value. In the conditions of severe stress due to interruption of continuous irrigation, the plants entered from the stage of mild stress to the stage of severe dry stress, which seems that under these conditions, the decrease in the concentration of chlorophyll, in addition to the decrease in the amount of synthesis, is caused by the decomposition of chlorophyll due to the increase in the amount chlorophyllase, peroxidase and phenolic compounds. According to Schutz and Fangmier (2001), the decrease in the amount of chlorophyll in stress conditions is related to the increase in the production of oxygen radicals in the cell. These free radicals cause peroxidation and as a result the decomposition of this pigment. The greenness index is considered one of the most important growth parameters, which is reduced by drought stress conditions, and the results indicate that the treatment of mycorrhizal fungi in all three types of inoculated mushrooms has improved the greenness index and the adverse effects It has removed the drought stress to a great extent (Figure 6), which can be attributed to the improvement of water and food absorption by mycorrhizal roots (Larsson et al., 2008). Conclusion In general, this study showed that the best treatment related to the mycorrizha fungi was mosseae, which had the most effect on reducing the negative effects of stress
Growing vegetables
S. Khosravi; M. Haghighi
Abstract
Introduction: Brassinosteroids promote plant growth by enhancing some metabolic activities such as photosynthesis, nucleic acid biosynthesis, proteins and carbohydrates. Mechanisms of resistance and tolerance in plants have been developed to tolerate water deficit stress. One way to deal with drought ...
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Introduction: Brassinosteroids promote plant growth by enhancing some metabolic activities such as photosynthesis, nucleic acid biosynthesis, proteins and carbohydrates. Mechanisms of resistance and tolerance in plants have been developed to tolerate water deficit stress. One way to deal with drought is to use plant growth regulators. Brassinosteroids were first extracted from the pollen of turnip (Brassica napus) and were considered as the sixth group of plant growth regulators. These compounds stimulate growth and cell division and affect electrical properties, membrane permeability, stability and activity of membrane enzymes. Nowadays, brassinosteroids have been extracted from various plants and their structure and function have been identified.Materials and Methods: This experiment was conducted in a factorial experiment based on a completely randomized design on Capsicum annuum L. Castello cultivar under the average daily temperature of 25 °C and 18 °C at 75% relative humidity in greenhouses. Research conducted by the College of Agriculture, Isfahan University of Technology, with four drought treatments using polyethylene glycol 6000 solutions at four levels of 0, -6, -7, and -8 bar. Brassinosteroids were sprayed in two 1 μM control levels. Pepper seeds planted in transplanting trays containing 1 to 2 volumes perlite and vermiculite substrate. When the actual leaf of seedlings appeared, the root thoroughly rinsed with distilled water and then were transferred to black plastic containers with a diameter of 16 and height 13cm and 1L volume containing Johnson's nutrient solution including four dry treatments using 6000 polyethylene glycol solution and aerated in control for 15 minutes every 5 minutes. At the end of the experiment, vegetative factors such as fresh and dry weight of different parts of the plant, plant length, and volume, and physiological factors such as proline and abscisic acid content and chlorophyll fluorescence changes were measured.Results: The results of the analysis of variance table showed that brassinosteroid had no significant effect on most vegetative traits except root volume and weight and all physiological traits except chlorophyll fluorescence and the mentioned traits increased with the application of 1 mM brassinosteroid. However, the main effects of drought except for amino acid and the interaction of drought and brassinosteroids were significant on all traits. The results of the main drought effects showed that the root fresh weight at -8 bar and dry weight at -7 bar significantly decreased, whereas fresh and dry weight of the shoots at lower than -6 bar. The onset of decline showed that the root length and volume appeared to decrease with the onset of stress by -6 bar and the plant length also reduced with the first stress level. Drought stress at -6 bar level decreased chlorophyll fluorescence, chlorophyll index and Abscisic acid while at -7 bar decreased protein and increased proline. The results also showed that the amount of sulfuric, essential and unnecessary amino acids were significantly reduced by drought stress and brassinosteroid had no effect. Total amino acid content decreased with drought stress but there was no significant difference with control. With increasing drought stress, the fresh and dry weights of shoots decreased and the intensity of shoots decreased. The intensity of shoot growth decreased with the use of brassinosteroids at moderate stress but the mentioned trait showed the same adverse effects at all levels of stress. Brasinosteroid application decreased stress indices such as proline (7%) and abscisic acid (50%) and this decrease was more pronounced in proline, especially in more severe treatments. Amino acid and protein levels decreased with drought stress, and the use of brassinosteroids could not be effectively affected by this reduction, especially for the compounds and the amount of amino acids.The results of biplot analysis showed that the vegetative and protein traits had better mean in stress condition in the presence and absence of stress and in higher stress severity and application of brassinosteroid affected root fresh weight and abscisic acid content more than the other traits. While in mild stress it seemed to be more effectively on the steroid and most of the vegetative and physiological traits than the control.Conclusion: It seems that the application of brassinosteroids on pepper seedling in drought stress at a concentration of 1 μM is effective in maintaining vegetative properties and reducing negative effects of stress and reducing stress indices.
S.M.B. Razavi nia; N. Pourghasemian; F. Najafi
Abstract
Introduction: Pollution of the biosphere with toxic levels of metals has accelerated dramatically since the beginning of the industrial revolution. Soil pollution by heavy metals including cadmium (Cd) and lead (Pb) is a global problem, which can cause agricultural lands to become hazardous for wildlife ...
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Introduction: Pollution of the biosphere with toxic levels of metals has accelerated dramatically since the beginning of the industrial revolution. Soil pollution by heavy metals including cadmium (Cd) and lead (Pb) is a global problem, which can cause agricultural lands to become hazardous for wildlife and human populations. Accumulated Cd and Pb in their roots and shoots may also be negatively affect their photosynthesis, growth, and reproduction. Cd and Pb uptake and their effects on plants may be influenced by a variety of factors, e.g. the plant species, cultivar, soil characteristics and etc. Heavy metals such as Cd and Pb may cause the formation of reactive oxygen species (ROS), damage plant tissue membranes, and inhibit photosynthesis, carbon dioxide assimilation, and growth. Photosynthesis is the fundamental process of energy metabolism and therefore, closely related to the plants growth and productivity. However, it is a sensitive process and an important target of environmental stresses. Plants counteract the harmful effects of heavy metals by a variety of protective mechanisms including immobilization, exclusion, chelation, compartmentalization, osmotic regulation and elevating antioxidant system.
Lemon balm (Melissa officinalis L.) is a widely grown aromatic and medicinal plant of the Labiatae family. The plant has various therapeutic properties and is also used to flavor different food products due to its particular taste. Little scientific data exist on the response of this medicinal plant to Cd and Pb stress. Therefore, the objective of this work was to investigate the biological and physiological responses of lemon balm (Melissa officinalis L.) under cadmium and lead stress conditions.
Materials and Methods: A factorial randomized complete block design experiment with four replications was used to study the effect of Cd in four concentrations (0, 6, 12 and 24 mg.kg-1 soil) as well as Pb in four concentrations (0, 150 300 and 450 mg. Kg-1 soil). Before harvesting, chlorophyll fluorescence, photosynthetic and transpiration rates were measured with fluorescence meter and photosynthetic meter, respectively. Thereafter, plants were harvested and the roots were washed in distilled water. Then, half of the plants were separated into roots and shoots, which were dried at 105 °C for 24 h to determine the dry weight, Cd and Pb concentrations, Cd transfer factor and essential oil content. The other half of the plants were separated into roots and shoots, kept in liquid nitrogen, and then stored in freezer for one week to determine proline and shoot MDA concentrations. Data were subjected to two-way analysis of variance (ANOVA) and the difference between means was compared using LSD test. A significance level of 95% was applied by SAS 9.2.
Results and Discussion: According to the results, root and shoot dry weight, protein content, photosynthetic rate, transpiration rate and chlorophyll fluorescence were decreased by increasing Cd and Pb concentrations. However, Cd concentration decreased these traits more than Pb. The shoot MDA concentration, essential oil and proline content were enhanced by increasing Cd and Pbconcentrations. The combination of two pollutants (Cd and Pb) together reduces the negative impact of each element alone. Shoot and root Cd and Pb concentrations were increased by increasing Cd and Pbconcentrations. The interaction effect of Cd×Pbapplication showed that increasing Cd concentration decreased root and shoot Pb concentrations and increasing Pb concentration decreased root and shoot Cd concentrations. Cd and Pb were not detected in essential oil. Moreover, the Cd transfer factor was increased with increasing Pb concentration under high Cd concentration levels (12 and 24 mg.kg-1).
Conclusion: This study demonstrated that Cd toxicity is more than Pb toxicity due to its high mobility. There was an antagonistic relationship between Cd and Pb. Furthermore, due to the absence of Cd and Pb in the essential oil, lemon balm may be a suitable plant for areas contaminated with heavy metals especial Cd and Pb.
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.
M. Mahmoodnia; Mohammad farsi; S.H. Marashi; P. Ebadi
Abstract
Investigation of the cultivated tomato plant as a plant ideal system along with the drought resistant wild species can be useful to a better understanding of the mechanisms of drought resistance and improvement of tomato plants. To investigate the effect of drought stress on leaf Relative Water Content ...
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Investigation of the cultivated tomato plant as a plant ideal system along with the drought resistant wild species can be useful to a better understanding of the mechanisms of drought resistance and improvement of tomato plants. To investigate the effect of drought stress on leaf Relative Water Content (RWC), electrolyte leakage and photosynthetic parameters in four species of tomato (a cultivated species and three wild species) at two levels of irrigation (field capacity and 40% field capacity) and four time periods (before stress, 10 days after stress, 20 days after stress and recovery) a factorial experiment based on Completely Randomized Design (CRD) was used. Among the tested species, cultivated species showed the highest decrease in RWC. Electrolyte leakage was significantly increased in stress conditions. The rate of photosynthesis and chlorophyll fluorescence yield in the two drought resistant wild species increased in stress conditions unlike of cultivated species, probably because of more adaptation of these species with low water conditions. The results showed that each of these species according to their own mechanism for dealing with drought stress, in one or more properties are superior to other species. it is therefore suggested that the different species for future studies (molecular) with different characteristics to be used.
