Pomology
Esmaeil Khaleghi; Masumeh Zamani Dehbari; Norollah Moallemi
Abstract
IntroductionCitrus fruits are one of the most commercial fruit products in the world, whose growth and production are affected by abiotic stresses. Drought stress is one of the most important abiotic stresses that affects all the vital processes of the plant. One of the ways to moderate the negative ...
Read More
IntroductionCitrus fruits are one of the most commercial fruit products in the world, whose growth and production are affected by abiotic stresses. Drought stress is one of the most important abiotic stresses that affects all the vital processes of the plant. One of the ways to moderate the negative effects of drought stress is the use of polyamines. Polyamines are a group of biochemical compounds that are used as one of the most effective compounds to resist environmental stresses. Polyamines have a wide role in various plant growth processes, such that they play a significant role in modulating various types of biotic and abiotic stresses. Studies have shown that application of putrescine increases the fresh and dry weight of the shoot and root parts, leaf relative water content, photosynthetic pigments, leaf surface, and photosynthesis in plants under drought stress. Materials and MethodsThis study was conducted to investigate the effect of different levels of putrescine (0, 0.5, 1 and 2 mM) and different levels of irrigation (100, 75 and 50% of evotranspiration potential) on morpho-physical traits of lime seedlings as a factorial experiment based on randomized complete block design with 3 replications.Two-year-old lime seedlings were obtained from a commercial nursery located in Dezful city (approved by the Khuzestan Agricultural Jihad Organization). Then, they were located in 15-kilogram pots and kept for 2 months in the greenhouse to adapting to the environmental conditions. In order to apply the irrigation regime, 4 pots were considered as reference plants and the amount of irrigation water was determined by weighing these pots. First, the weight of reference pots was calculated in field capacity mode. Then, after 7 days, the pots were weighed again and the difference between the primary and secondary weights was considered as the amount of irrigation water of 100% plant evaporation and transpiration, and according to that, 75% irrigation and 50% evaporation and transpiration potential were applied. The first foliar spraying with putrescine was done at first of March in Field capacity (foliar spraying was done once every month for 4 months from March to June). At the end of the experiment, the fresh and dry weight of root and shoot, number of leaves, relative water content, leaf water potential, photosynthesis, transpiration, stomatal conductance, were measured. Statistical data analysis was done using MSTATC software and, Duncan's multi-range test was used to mean comparation at the 5% probability level. Results and DiscussionResults showed that the rate of photosynthesis, stomatal conductance, relative water content of leaves, fresh and dry weight of aerial part and root decreased by reducing the amount of irrigation from 100 to 75 and 50%, of ETcrop. The reduction of growth parameters under drought stress can be due to the closing of the stomata and the reduction of carbon dioxide emission into the leaves, which can lead to lower levels of chlorophyll and photosynthesis, induction of oxidative stress, and finally less growth in plants. It has also been stated that the decrease in growth caused by drought stress in the initial stages of the stress can be due to the decrease in cell growth and development due to the decrease in turgor pressure and the decrease in the intensity of photosynthesis due to the closing of stomata. Also, the results showed that foliar spraying with 2 mM putrescine increased photosynthesis, stomatal conductance, relative water content of leaves, wet and dry weight of aerial parts and roots at all irrigation levels. The researchers believed that the increase in growth parameters, relative water content and photosynthetic pigments with putrescine foliar spraying can be related to the antioxidant properties of putrescine and its osmolality role in dry conditions. Other researches have shown that putrescine may modulate certain ion channels and increase the permeability of the membrane to calcium and cause a decrease in the entry of potassium into the membrane, which causes a decrease in the exit of water from the cell. Also, putrescine may increase leaf water potential and leaf content through osmotic regulation of the plant by increasing proline. ConclusionIn general, the results showed that foliar spraying of putrescine, especially at 2 mM concentration has the greatest effect on increasing growth parameters, including fresh and dry weight of shoots and roots, leaf area, increasing the relative water content, leaf water potential and Gas exchanges and reducing the amount of ion leakage under drought stress conditions.
Medicinal Plants
Mehdi Moradi; Bahram Abedi; Hossein Arouiee; Sasan Aliniaeifard; Kamal Ghasemi Bezdi
Abstract
Background and objectives
Light is the main environmental factor for plant growth and development. Different attributes of light such as intensity, quality and duration affect plant growth and productivity. Light spectrum of growing environment is a determinant factor for plant growth ...
Read More
Background and objectives
Light is the main environmental factor for plant growth and development. Different attributes of light such as intensity, quality and duration affect plant growth and productivity. Light spectrum of growing environment is a determinant factor for plant growth and photosynthesis. The photosynthetic reactions are directly affected by various light parameters including its spectrum and intensity. Photosystem I and II (PSI and PSII) in the electron transport chain of photosynthetic apparatus are involved in converting solar energy to chemical compounds in plants. It has been found that the PSII is sensitive to light quality. Using The OJIP test, we can investigate the efficiency of various biological phases of the electron transport system. Light sources such as metal-halide, fluorescent, high-pressure sodium, neon lamps and light-emitting diode (LED) can be used for production of plants in closed environments instead of sunlight. Manipulation of the light spectrum of the lamps could trigger potential benefits by enhancing plant growth. Nowadays, by using the LED technology, it is possible to study the physiological effect of different light spectra for optimization of growth conditions and for increase the production of plants in controlled environments. This research was conducted to investigate photosynthetic apparatus, growth parameters, stomatal characteristics, transpiration rate and essential oil content of Salvia officinalis under different light spectra.
Materials and Methods
In this study, the effects of different light spectra were implemented and performed as a pot experiment using soilless media in the plant growth chamber based on a completely randomized design with 6 lighting spectra including White, Blue, Red and three combinations of R and B lights (R30:B70, R50:B50 and R70:B30) with three replications. The light intensity in all growth chambers was adjusted to photosynthetic photon flux density (PPFD) of 250 ±10 μmol m-2s-1 and light spectrum were monitored using a sekonic light meter (Sekonic C-7000, Japan). Growth condition was set at 14/10 h day/night cycles, 25/22oC day/night temperatures and 40% relative humidity. Three month following plant growth under different light spectra, the plants were evaluated for their growth parameters, stomatal characteristics (stomatal length, stomatal width, pore length or aperture) transpiration rate (E), relative water content (RWC), photosynthetic apparatus (evaluation of OJIP) and essential oil content. Data analysis of variance (ANOVA) was performed using IBM SAS software (Version 9.1) and the differences between means were assessed using Duncan’s multiple range tests at p≤ 0.05.
Results
The results showed that the stomata characteristics, photosynthetic performance, growth characteristics and essential oil content of Salvia officinalis were affected by different light spectra. Increasing the ratio of red light especially combined Red and Blue lights (R70:B30) led to the improvement of growth characteristics. Transient induction of chlorophyll fluorescence showed that the highest fluorescence intensities at all OJIP steps were detected in Red light. The lowest Fv/F0 and Fv/Fm were obtained in plants grown under Red light. Occurrence of leaf epinasty and decrease in Fv/Fm indicative of phenomenon of red light syndrome in the plants under Red treatment. Red light caused a reduction in performance index per absorbed light efficiency of (PIABS) and increase in quantum energy dissipation (ΦD0), light absorption (ABS/RC) and electron trapping (TR0/RC) per reaction center. The highest Fv/F0, Fv/Fm and PIABS were obtained under combination of Red and Rlue light. The highest ΦE0 was also detected in combination of Red and Blue light. The narrow and large stomatal apertures were detected under Red and Blue light, respectively. The highest transpiration rate was achieved in plants grown under Blue light LED. Increasing the ratio of Red light resulted in reduction in transpiration rate and improvement of leaf capacity to control water loss via reducing the opening of stomata. The highest amount of essential oil (1/75% v/w) was achieved in plants exposed to combination of Red:Blue light spectra (R70:B30).
Conclusion
light spectrum during plant growth can change plant metabolism, LED can be used in favor of producing good-quality food in controlled environment agriculture due to their ease of application, waveband manipulation and limited heat production. Our result showed that photosynthetic apparatus, growth parameters, stomatal characteristics, transpiration rate, relative water content and essential oil content of plants were considerably influenced by light spectra. Using OJIP test confirmed that plants grown under monochromatic Red and Blue lights were less efficient to successfully transfer the excitons and most of the absorbed energy by the photosystems was dissipated as heat. In conclusion, combined Red and Blue lights (especially R70:B30) caused favorable growth, photosynthetic functionality and maximum essential oil content of Salvia officinalis. Therefore, combination of R and B lights (R70:B30) should be considered for production of Salvia officinalis under artificial light systems during commercial controlled environment production of plants.
Ornamental plants
Davood Kazemi; Maryam Dehestani Ardakani
Abstract
Introduction Different aspects of light including intensity, quality (spectra), and duration (photoperiod) can influence plant growth and development. The growth and development of ornamental plants are also influenced by light intensity and quality. Energy saving in greenhouse production has received ...
Read More
Introduction Different aspects of light including intensity, quality (spectra), and duration (photoperiod) can influence plant growth and development. The growth and development of ornamental plants are also influenced by light intensity and quality. Energy saving in greenhouse production has received much attention lately. One reason for the interest in utilizing light quality to modulate plant growth and morphology is the recent development of light-emitting diodes (LEDs) as a lighting source in greenhouse production. Such small diodes can easily be placed close to the canopy and can be used to apply a narrow-band light spectrum to the plants. Specific requirements for light spectral distribution for specific processes like morphogenesis, photosynthesis, chlorophyll and anthocyanin synthesis have been determined in different species. The aim of the current study was to investigate the biophysical properties of chlorophyll fluorescence of Hypoestes phyllostachya plants in response to different light spectra.Materials and Methods Research experiments were conducted on Hypoestes phyllostachya in a completely randomized design with six treatments of different light quality and three replications. The seeds were planted in plugs and in a mixture of 70% peat moss and 30% perlite. Seedlings were grown in natural greenhouse (control) and LED (100% Blue, 15% Blue +85% Red, 30% Blue +70% Red, 15% Blue +65% Red + 20% White and 30% Blue +50% Red + 20% White). Since the main goal of the study was to compare the effect of LED light quality with sunlight in conventional greenhouse conditions. The LED treatments were applied from fourth month old seedlings until five weeks in a growth chamber with the light/dark regime of 15/9 hours, 23±5°C temperature, and 65±5% relative humidity. While, their pots in the greenhouse with 55±5 mol.m-2.d-1 DLI, 21±5°C average daily temperature and 65±5% relative humidity (Data logger 8808 temp. + RH) were regarded as the control treatment. After five weeks, the fluorescence chlorophyll was measured.Selected leaves were dark-adapted prior to the measurements and OJIP protocol was applied using a fluorometer (FluorPen FP 100-MAX, photon system instruments, Drasov, Czech Republic). The fluorescence measurement was performed using a saturating. FluorPen software was used to extract data from the original measurement. Data extracted were used to analyze the following data according to the equations of the JIP test: fluorescence intensities at 50 μs (F 50 μs, considered as the F0), 2 ms (J-step denoted as FJ), 60 ms (I-step, FI), and maximum fluorescence intensity (FM, FP). The JIP-test was used to quantify the amount of energy that flow via the PSII. Performance index was measured on the absorption basis (PIABS, a multi-parametric expression). Probability that a trapped exaction promote an electron in electron transport chain (ETC) beyond the primary acceptor Quinone (QA−), maximum quantum efficiency of PSII (FV/FM), specific energy fluxes per reaction center (RC) for energy absorption (ABS/RC), trapped energy flux (TR0/RC), electron transport flux (ET0/RC) and dissipated energy flux (DI0/RC) were calculated according. Finally, the data were statistically analyzed with SAS (9.4) software package, and the means were compared by LSD test at p < 0.05 level. Results and Discussion Fast Chl fluorescence induction curves (OJIP) was the main parameters used for the screening of different light treatments. OJIP test is shown to be a proxy to detect PSII bioenergetics and indicates changes in the status and function of PSII reaction centers, antenna, as well as in donor and acceptor sides of PSII. The maximum quantum yield of PSII (FV/FM) and relative maximal variable fluorescence (Fm/F0), significantly increased in 15% Blue +85% Red, 30% Blue +70% Red, 15% Blue +65% Red + 20% White. PIABS, one of the OIJP test parameters that provide valuable awareness about photosynthtic performance, considerably decreased under control and 30% Blue +50% Red + 20% White treatment. Unlike PIABS, ET0/RC did not show a significant difference under different treatments. The specific energy fluxes per RC for energy absorption (ABS/RC) significantly increased under control and 30% Blue +50% Red + 20% White treatment. TR0/RC increased in plants under control and 30% Blue +50% Red + 20% White treatment. Treated plants under 15% Blue +85% Red and 30% Blue +70% Red showed the lowest in dissipated energy flux (DI0/RC). During an ideal condition without any additional stress, the total PSII pool can be completely inactivate and retrieve without a detectable photoinhibition.Conclusion When plants exposed to 100% Blue and 30% Blue +50% Red + 20% White treatments as well as in control plants, FM/F0, FV/FM and PIABS significantly decreased. Also ABS/RC, TR0/RC and DI0/RC, significantly increased.
Medicinal Plants
Maryam Yaghobvand; Hassan Mumivand; Mohammad Reza Raji; Ashkan Banan
Abstract
IntroductionThe aeroponic system is a promising technique for the future of agriculture, growing plants in an air or mist environment without the use of soil or an aggregate medium. In aeroponic, plants are suspended in a closed or semi-closed environment by spraying the plant's dangling roots and lower ...
Read More
IntroductionThe aeroponic system is a promising technique for the future of agriculture, growing plants in an air or mist environment without the use of soil or an aggregate medium. In aeroponic, plants are suspended in a closed or semi-closed environment by spraying the plant's dangling roots and lower stem with an atomized or sprayed, nutrient-rich water solution (30). Increased aeration of nutrient solution delivers more oxygen to plant roots in aeroponic in compare to conventional hydroponic systems, stimulating growth and helping to prevent pathogen formation (1). Cultivation of medicinal plants under controlled conditions of aeroponic and hydroponic systems commercially provides a better result in terms of quality improvement, bioactivity and biomass production (5, 4).Mint (Mentha) is one of the most important genus of Lamiaceae family. Different species of the genus have high economic value, due to their active and aromatic substances and are used as raw materials in food, cosmetics, health, beverage and pharmaceutical industries. M. piperita, M. spicata and M. suaveolens are the most common and popular species of the genus for cultivation. M. aquatica is also a perennial plant of the genus that is cultivated in Europe, North and Northwest Africa and Southwest Asia (2). Aeroponic system is more cost effective than other systems. Because of the reduced volume of solution throughput, less water and fewer nutrients are needed in the system at any given time compared to other nutrient delivery systems. However, due to lack of research and sufficient technical information, the use of aeroponic system is not common among farmers and greenhouse owners. In addition, many tips are not yet scientifically known about the cultivation of different plant species in this system (4). Despite the benefits of aeroponics, no research has been previously conducted on the cultivation of different species of mint in this system. Therefore, the present study was conducted with the aim of investigation of growth, yield and morpho-physiological characteristics of five mint species in the aeroponic system.Methods and MethodsThis study was conducted in greenhouses of faculty of Agriculture and Natural Resources of Lorestan University in 2020. The experiment was performed as a split plot design. Mentha species (including M. aquatica, M. pulegium, M. spicata, M. suaveolens and M. piperita) were considered as the main plot and harvest time (first and second harvests) was used as sub-plot. In each experimental block, one row (with ten plants) of five mint species was planted. In the early stages of growth, plants were fed with half Hoagland nutrient solution and then with complete Hoagland solution. Finally, morphological and physiological traits and some biochemical characteristics of plants were measured. After harvesting the first batch of plants and in order to better evaluation of species in the aeroponics system, all studied traits were measured about two months after the first harvest. Analysis of variance was performed based on the experimental design using SAS software. The comparison of means was also done with the least significant difference (LSD) test at the level of 5%.Results and DiscussionThe results showed that M. spicata and M. suaveolens had the highest leaf to stem ratio. The highest stem dry weight and plant height were related to M. pulegium. While, the highest leaf area, leaf fresh and dry weight, stem fresh and dry weight, stolon fresh and dry weight, shoot fresh and dry weight, total plant dry weight and relative water content were related to M. aquatic, followed by M. piperita. In addition, M. piperita had shown the highest fresh root weight. The highest amount of carotenoid and chlorophyll, photosynthesis rate and CO2 under the stomata was obtained in M. piperita. In this experiment, most of the yield-attributes traits including leaf area, leaf fresh and dry weight, root fresh weight, shoot fresh weight and total plant dry weight, as well as relative water content and photosynthesis rate were higher in the second harvest than the first one.ConclusionAll studied species in this experiment were successfully growth in the aeroponic system. Due to high water use efficiency, no need for soil and high crop production, mint cultivation in the aeroponic system can be a healthy and profitable alternative to in soil cultivation approach. According to the results of the present study, M. aquatica has shown higher performance than other species in terms of the yield attributes traits (including leaf number, leaf area, fresh and dry weight of plant, fresh and dry weight of shoots and fresh and dry weight of leaves). Among the other species, the highest shoot dry weight and plant dry weight was obtained by M. piperita. Finally, the high potential of M. aquatica and M. piperita for cultivation in the aeroponic system can be concluded.
Fahimeh Dezhabad; Maryam Haghighi
Abstract
Introduction: Most plants, especially those that are native to hot areas, show signs of injury when exposed to low temperatures. Damages caused by cold stress occurs at the cell and organs level, which reflects it at the plant surface. Color change, chlorosis, general reduction of growth, cellular tissue ...
Read More
Introduction: Most plants, especially those that are native to hot areas, show signs of injury when exposed to low temperatures. Damages caused by cold stress occurs at the cell and organs level, which reflects it at the plant surface. Color change, chlorosis, general reduction of growth, cellular tissue destruction, non-absorption of nutrients, reduction of photosynthesis, non-transferring photosynthetic materials are from early effects of cold stress. Cellular responses to colds including loss of thoracic pressure, vacuolization, collapse of cytoplasmic membrane balance, cytoplasmic flow loss, and general organ dysfunction. The susceptibility of the plant to frost is different depending on the type of plant, variety, tissue morphology and other cellular characteristics, as well as the cold conditions of the period, time and cold intensity. In addition, it seems that organs of the plant have different degrees of cold tolerance. If the temperature of the aerial part is favorable, the low temperature of the root zone can be one of the factors limiting the root system and plant growth. The consumption of balanced boron content by neutralizing the negative effects of cold stress and mechanisms such as maintaining the structure of the membrane, improving and increasing root growth, increasing the synthesis of proteins needed for the plant, adjustment of stomatal movements and improved stomatal conductance, increased cell division, increased nitrogen metabolism and chlorophyll production, and its consequence was increased photosynthesis and dry matter production, increased activity of antioxidants, calcium / potassium ratio adjustment, optimizing the transfer of calcium in the plant, adjusting the amount of water and conducting it in the cell, increasing the moisture content and relative content of leaf water, transferring soluble materials and increasing water use efficiency creates a relative resistance to low temperature stress. Although the root temperature is very effective in plant growth, it has been less attractive. Therefore, the aim of this study was to investigate the effect of low temperature of root and shoot on the ability to restore plant growth and physiological activity in the presence and absence of boron.
Materials and Methods: In order to compare the impact of sudden low temperature stress of root and shoot on recovery of vegetative and physiological traits of tomato, a research was conducted in two separate experiments under controlled conditions in the greenhouse of Faculty of Agriculture, Isfahan University of Technology. Two experiments were factorial based on completely randomized design with 10 replications including two concentrations of boron (0, 0.5, 1 and 1.5 in ppm) and two temperature levels of shoot and root sections (10 degrees’ Celsius temperature, and 11 rootstock temperatures and 22 ° C optimum and control temperatures). Indicators included photosynthesis rate, respiration rate, stomatal carbon dioxide, stomatal conductance, chlorophyll fluorescence, chlorophyll index, water use efficiency, proline, antioxidant, phenol secretion from root and leaf extracts, leaf relative water content, soluble protein concentration, ion leakage, leaf water potential, root and shoot dry weights and starch content. Finally, the analysis of the results was done by statistical software statistic and comparing the meanings by LSD test at 5% level.
Result and discussion: The results showed that the highest amount of photosynthesis, root dry weight and dry weight of the aerial part were in the consumption of 0.5 ppm of boron during abrupt stresses of low temperature on the root after the recovery period. The highest amount of stem proline and electrolyte leakage were also obtained from 0.5-1.5 ppm of boron consumption during abrupt low temperature on the shoot part. According to the results, it was found that when stress has entered from the root zone to the aerial part of the plant, the plant was in the better conditions after the recovery period. It seems that when a cold stress occurred on the roots, the plant can produced more antioxidant substances, including phenol and proline, while counteracting the relative water content of the leaves were more effective with radical agents. Thus, in normal conditions, the roots of the plant operated at a lower temperature than the airspace. They also exhibited more adaptations to the lower air at the lower temperature than the air section and the plant is less damaged. At levels above the boron element due to the effect of boron toxicity and the production of excess free oxygen radicals, the plant probably suffered more severe damage than cold damage.
Conclusions: Sudden low temperatures stresses on the root and shoot had negative effects on the recovery of the vegetative and physiological traits of tomatoes. When lower temperatures were imposed on the shoot, the plant suffered much more damages. Consumption of 0.5 ppm of boron during cold stress by creating optimal conditions for growth also caused the relative neutralization.
Morteza Goldani; Maryam Kamali; Mohammad Ghiasabadi
Abstract
Introduction: Salinity tolerance in plants can increase the importance of it as a result of the decreasing availability of high-quality irrigation water. Saline irrigation water can have many negative effects on crops. When irrigation water has high salinity, the salt may precipitate on the leaves as ...
Read More
Introduction: Salinity tolerance in plants can increase the importance of it as a result of the decreasing availability of high-quality irrigation water. Saline irrigation water can have many negative effects on crops. When irrigation water has high salinity, the salt may precipitate on the leaves as the water evaporates. Thus it can result in foliar uptake and phytotoxicity. The irrigation water may also cause accumulation of salt in the substrate, which may lead to salt uptake by the plants. Salt injury occurs when too much NaCl accumulates in the substrate. When excessive concentrations of NaCl are present in the soil, water uptake may be inhibited and it causing a physiological drought stress. However, potassium is required by plants in amounts (in kg unit) of similar or greater than nitrogen (N). K Uptake by the plant is highly selective and closely coupled to metabolic activity. At all levels in plants, within individual cells, tissues and in long-distance transport via the xylem and phloem, K exists as a free ion in solution or electrostatically bound cation. Potassium takes part in many essential processes such as enzyme activation, protein synthesis, photosynthesis, phloem transport, osmoregulation, cation-anion balance, stomatal movement and light-driven nastic movements. Potassium Chloride (KCl) is used as a source of nutrients in agricultural development and also used as relieve salinity stress.
Materials and Methods: In order to study the mitigation effects of KCl on salinity (NaCl) in mustard plant (Parkland and Goldrush), an experiment was carried out at the Research Greenhouse, Faculty of Agriculture, Ferdowsi University of Mashhad, Iran. The experiment was managed as a factorial arrangement based on completely randomized design in three replications. Treatments were included NaCl (0, 30, 60 and 90 mM) and KCl (0 and 20 mM) and two cultivars.
Relative water content was calculated by the following formula using leaf disc obtained from a young leaf of each plant.
(DW+ FW/ DW+ TW)*100FW=fresh weight, DW=dry weight, and TW=turgid weight
Electrolytic leakage was calculated by the following formula:
EL=L1/L2 where L1 is electric conduction of leaf after putting in the deionized water in 25°C and L2 is the electric conduction of the autoclaved samples.
Leaf area was measured by Leaf area meter. Shoot and root dry weights were determined after drying the samples in 75°C for 48 h.
Chlorophyll concentration was calculated by the fallowing formula:
Chla (μg/ml) = 15.65A666 – 7.340 A653
Chlb (μg/mml) = 27.05A653 – 11.21 A666
Analysis of variance was calculated using MSTAT-C.1software and means were compared by LSD test at probability level of 5%.
Results and Discussion: The results showed that the treatments of NaCl, KCl and interactions with cultivars were significantly different on dry weight, leaf area, photosynthesis, stoma conductivity and chlorophyll rate. The maximum shoot dry weight (3.44 g/plant) and photosynthesis rate was obtained from T2 (20 mMKCl and without NaCl). The maximum membrane stability index was obtained in Goldrush cultivar and T2. The minimum of these traits were observed in zero mMKCl and 90 mMNaCl. High level of NaCl (60 and 90 Mm) and increasing application of KCl could not improve all traits. According to the result of the analysis of variance increasing density of sodium chloride in planting areas has a special effect on the size of leaves, weight of dried plant and each leaf and dried root. This effect shows a meaningful variation between the weight of dried leaves and its dried root and shoots. The salty areas have a lot of negative ions like Magnesium, Chlorine, sodium and sulfate. These materials are harmful by themselves or cause affective disorder in plants metabolism. Salinity treatments applied to significant influence (p≤0.01) on the characteristics of photosynthesis, stomatal conductance and number of stomata was read out by SPAD. For example, sodium and potassium competition and chlorine and nitrate competition impairs the absorption of nutrients. The result of this reaction is that the plant needs more energy for producing organic matter so it loses most of its energy to resist against salt. This situation causes a low activity of the root and the growing of shoot consequently reduces. Also, weight and length of plant would reduce too. For example, existing potassium in salty lands causes the reduction of sodium in the shoot of plants. This research was done in a pot with the same amount of salt. Potassium causes the reduction of toxicity effects of sodium. This research showed that the potassium can regulate osmotic pressure and permeability of plant cell membranes and also cause to increase plant tolerance to salinity.
Conclusion: In salty condition, increasing the amount of sodium causes the reduction of potassium, compared with sodium. As a matter of fact this kind of reaction causes the reduction of potassium compared with sodium. We know that potassium can cause a suitable osmotic pressure and reduce the destructive effect of oxidation. So, amount of potassium more than sodium in salty lands is known as the standard resistance. In general, increasing the salinity of sodium chloride can decrease morphological and physiological traits of mustard. The use of potassium chloride in T2 treatment showed the best result. However, Goldrush cultivar showed better results compared with Parkland cultivar in salt tolerance.
Taimoor Javadi
Abstract
Introduction: Drought is a major environmental stress that affects agricultural systems and induces several physiological, biochemical and molecular responses in plants. Drought inhibits the plant photosynthesis causing changes of chlorophyll contents, damage the photosynthetic apparatus and decreases ...
Read More
Introduction: Drought is a major environmental stress that affects agricultural systems and induces several physiological, biochemical and molecular responses in plants. Drought inhibits the plant photosynthesis causing changes of chlorophyll contents, damage the photosynthetic apparatus and decreases plant growth and development. Generally, the environmental stresses, especially drought stress, give rise to accumulation of soluble carbohydrates, proline and free amino acids as well as antioxidant compounds. Triazoles are the active ingredient of fungicides (propoconazole, penconazole, epixiconazole) and some growth regulators. The fungicidal properties of triazoles depend on inhibition of the C4-demethylase reactions in sterol biosynthesis of fungi. However, triazole-based fungicides induce a suite of morphological and physiological adaptations and allow plants to tolerate a broad range of environmental stresses including drought, herbicide treatment and elevated temperatures. The growth inhibitor paclobutrazol (PBZ) is a triazole and has been reported to protect plants against several environmental stresses, i.e. drought, low and high temperature. The purpose of this study was to evaluate the effect of palobutrazol on vegetative, physiological and gas exchange characteristics of pear (Pyrus communis cv. ShahMive) under different irrigation regimes.
Materials and Methods: In March, 2011, 1-year-old pear (Pyrus communis cv. ShahMive) saplings 80±2 cm high were planted in 20-l plastic pots filled with loamy sand soil (8% clay, 15% silt, 77% Sand) in experimental greenhouse. Paclobutrazol was added to soil at the same time with sapling cultivation at rates of 0, 0.15 and 0.3 g active ingredient per pot. PBZ was diluted in 500 ml distilled water and solution applied to the soil at the base of the saplings on pots. The control saplings were treated with distilled water of equal volume. Vegetative (stem growth, stem diameter, leaf number, shoot dry weight, root dry weight and plant dry weight), physiological and biochemical (leaf relative water content (RWC), total soluble sugar(TSS), proline and membrane stability index (MSI)) and gas exchange (Photosynthetic rate, sub-stomatal CO2, stomata conductance (gs) and transpiration) characteristics were measured.
Results and Discussion: The results showed that paclobutrazol treatments had significant effect on growth parameters, except root dry weight. Paclobutrazol significantly reduced stem height and stem diameter increment, mean leaf area, shoot dry weight and whole plant dry weight. Root: shoot ratio was increased in paclobutrazol-treated saplings. No significant differences in any characteristic were found between 0.15 and 0.3 g active ingredient PBZ per pot for growth parameter. Waters stress decreased leaf relative water content (RWC), photosynthetic rate, stomatal conductance and transpiration rate, membrane stability index and chlorophyll content and increased leaf proline content, total soluble sugar and sub-stomatal CO2. Significant interaction between PBZ and irrigation regimes was seen for RWC, proline and sub-stomatal CO2. PBZ-treated saplings had higher RWC than untreated ones. The effects of treatments on physiological and gas exchange traits were significant. RWC was high in all non-water-stressed (with or without paclobutrazol) treatments and decreased in water stressed treatments. It was higher in PBZ-treated than PBZ-untreated treatments in similar water stress condition. But there was not significant differences between 0.15 and 0.3 g PBZ in a given water stress condition. For example, RWC was 89.76 and 85.56 percent in -0.4 MPa water stress plus 0.15 and 0.3 gr PBZ treatments, respectively. The results showed that leaf proline content was increased under water stress condition. Leaf proline content of the PBZ-untreated sapling, subjected to water stress increased to 32.13 and 61.82 µmol.gr-1DW in -0.4 and -0.8 MPa water stress conditions, respectively. The PBZ-treated saplings accumulated less proline content than the PBZ-untreated ones. The highest proline concentration was founded in PBZ-untreated and -0.8 MPa water stress treatment. TSS was decreased in water stress treatments. TSS concentration was increased in water stress treatments. The highest TSS concentration was founded in PBZ-treated and untreated -0.8 MPa water stress treatments. PBZ- treated saplings had more TSS than untreated ones in -0.4 MPa treatments. Water stress was decreased leaf chlorophyll (a, b and total) content of saplings. PBZ-treated saplings had higher leaf chlorophyll content than PBZ-untreated ones in non-water stress treatments. The interaction of PBZ treatment and water stress moderated the negative effect of water stress on the chlorophyll b and total chlorophyll.
Conclusions: Generally, the results showed that PBZ allowed plants to tolerate water stress by morphological and physiological traits modification. On the other hand, paclobutrazol stimulated a more efficient stomatal regulation, which affected photosynthesis, but permitted significantly better levels of water status in treated plants.
Rohollah Ameri; Majid Azizi; Ali Tehranifar; Vahid Rowshan
Abstract
In order to study the effect of natural antitranspirant compound and water stress on growth, development and essential oil content of Ocimumbasilicum a factorial experiment based on completely randomized design with three replicates was conducted. 3 levels of water stress (500 as control, 375 and 250 ...
Read More
In order to study the effect of natural antitranspirant compound and water stress on growth, development and essential oil content of Ocimumbasilicum a factorial experiment based on completely randomized design with three replicates was conducted. 3 levels of water stress (500 as control, 375 and 250 ml/day) and 3 antitranspirant compound (chitosan, plantago mucilage and psyllium mucilage) in 3 levels of 0.5, 1 and 1.5% (m/v) and applied during the plant growth. Photosynthesis, transpiration, stomatal conductance, stomatal chamber CO2, leaf temperature, fresh and dry weight of herb, essential oil percentage and content were measured. The results showed that water stress and antitranspirant application had a significant effect on all measured traits (P≤0.05 and P≤0.01). The highest values of these traits were observed in control for water stress treatment and different levels of antitranspirant compounds. Transpiration levels from leaf were significantly decreased by antitranspirant compounds application. Chitosan (1 and 1.5%) decreased transpiration by 200% over control. Photosynthesis was also increased up to 30% by chitosan treatment (0.5 and 1) in comparison to control.Also, antitranspirant compounds increasing dry matter yield in water stress condition but reducing essential oil % and yield in comparison with control. In general, according to the result of this experiment, antitranspirant compounds with natural origin are safe, biodegradable, easy available, low cost and alternatives which can be used in substitution with common chemical types.
Majid Esmaeilizade; Ali Reza Talaie; Hossein Lesani; Amanollah Javanshah; Hossein Hokmabadi
Abstract
In order to prevent of inflorescence bud abscission and reduce of alternate bearing in pistachio cv. ‘Ohadi’ an experiment with 12 treatments including of girdling, fruit thinning, application of urea (0.5%), sucrose (3 and 5%) and their combination with urea, zinc sulfate (0.05 and 0.1% of pure ...
Read More
In order to prevent of inflorescence bud abscission and reduce of alternate bearing in pistachio cv. ‘Ohadi’ an experiment with 12 treatments including of girdling, fruit thinning, application of urea (0.5%), sucrose (3 and 5%) and their combination with urea, zinc sulfate (0.05 and 0.1% of pure zinc) and also their combination with urea in 3 replication and during 2 stages, was conducted in 2007 and 2008. The treatments were applied in two different stages of fruit growth and development including: 1- Initiation of rapid growth of nut endosperm and 2- Endosperm completion and initiation of rapid nut embryo growth. The results showed that girdling reduced inflorescence bud abscission, leaf chlorophyll content and photosynthesis rate significantly, but it didn't have any effect on qualitative and quantitative nut characteristics. The other treatments increased kernel weight and nut dehiscent and reduced ounce (No. of nuts per ounce), blankness, nut deformity and inflorescence bud abscission, but they didn't have any effect on early splitting. With the exception of zinc sulfate treatments, the others increased leaf chlorophyll content, meanwhile sucrose or combination of sucrose with urea reduced photosynthesis rate, but the other treatments increased it.
Fariborz Habibi; Mohammad Esmaeil Amiri
Abstract
In this experiment, physiological responses of two citrus rootstocks [sour orange (Citrus aurantium L.) and trifoliate orange (Poncirus trifoliata Raf.)] were investigated under in vitro salt stress conditions. This study was conducted on a completely randomized factorial design. Explants (Nucellar seedling ...
Read More
In this experiment, physiological responses of two citrus rootstocks [sour orange (Citrus aurantium L.) and trifoliate orange (Poncirus trifoliata Raf.)] were investigated under in vitro salt stress conditions. This study was conducted on a completely randomized factorial design. Explants (Nucellar seedling obtained from seeds) of both rootstocks were transferred to Murashige and Skoog (MS) solid proliferation medium containing 8.9 µM BA and 0.5 µM NAA with different concentrations 0, 50, 100, 150, 200 mM of sodium chloride (NaCl) whit six replicates. Results show that leaf chlorophyll index, photosynthesis rate, stomatal conductance, internal CO2 concentration (Ci), total protein content decreased in both rootstocks by increasing salinity levels, although there was no significant difference for above-mentioned characteristics in the interaction of salinity and rootstock. The amounts of reduction in total protein content, chlorophyll loss and internal CO2 concentration (Ci), in trifoliate orange genotype were greater than the sour orange. Also, peroxidase enzyme activity increased by increasing salinity level in both rootstocks, but, the rate of increase in the trifoliate orange was higher than the sour orange. By increasing salinity levels in the cultural medium, the uptake of sodium (Na+) and chlorine (Cl-) significantly increased in both rootstocks over 6 weeks culture period. Comparison in to trifoliate orange, sour orange less sodium and chlorine were taken up. Based obtained results, can be declared, salt tolerance has a negative correlation with Na+ and Cl- content in plant tissues, and the plant have a less Na+ and Cl- in tissues are more resistant. Thus, sour orange was more tolerant than trifoliate orange to salt stress and could be has more resistant to high concentration salinity.
Mehri Yusefi; Seyyed Jalal Tabatabaie; Jafar Hajilou; Naser Mahna
Abstract
Salinity affects the yield and quality of fruits crops as result of modifying water and nutrient uptake. In split root system, it should be possible to reduce the deleterious effect of salinity on the plant growth. Therefore, an experiment was conducted on strawberry with different concentration of NaCl ...
Read More
Salinity affects the yield and quality of fruits crops as result of modifying water and nutrient uptake. In split root system, it should be possible to reduce the deleterious effect of salinity on the plant growth. Therefore, an experiment was conducted on strawberry with different concentration of NaCl (0, 30, 60 and 90 mM) in a completely randomized blocks design in studding hydroponic greenhouse. The roots were divided into two portions and either even or uneven salinity was applied to the root portions. The treatments consist of 0:0, 0:30, 0:60, 0:90, 30:30, 60:60 and 90:90 with three replications. In general, the increased salinity reduced photosynthesis rate but in uneven salinity the photosynthesis rate was increased. Proline concentration was reduced in 0:0 treatments but increased in 0:30 and 30:30 treatments. Ca, N, P and K concentrations were reduced by increasing salinity, but were increase in uneven salinity. The highest concentrations of Cl and Na were observed in 60:60 and 90:90 salinity treatments. Na and Cl concentrations were reduced in uneven salinity in the root zone so that in 0:30 treatments, the concentration of Na were 20% lower than that in 30:30 treatments. Based on the results of this study the application of uneven salinity in a concentration of 30 mM could be recommended for growing strawberry in salinity stress conditions.
Mohsen Mahmoodnia; Mohammad Farsi; Seyyed Hassan Marashi; Parviz 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 ...
Read More
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.
