Soil science
J. Al-Jomah; A. Halajnia; A. Lakzian; A.R. Astaraei
Abstract
Introduction
Saline soils resulting from natural and/or anthropogenic processes are very diverse and widely distributed under all climates. Soil salinity as a serious environmental problem has negative effects on plant growth and development in arid and semi-arid as well as humid regions. Since increasing ...
Read More
Introduction
Saline soils resulting from natural and/or anthropogenic processes are very diverse and widely distributed under all climates. Soil salinity as a serious environmental problem has negative effects on plant growth and development in arid and semi-arid as well as humid regions. Since increasing global food security is a fundamental goal to feed the growing world population, it is necessary to develop suitable and efficient techniques for the rehabilitation of salt-affected soils and their exploitation. Chemical fertilizers are usually used to provide nutrients required for plant growth in order to increase crop yield, but application of these chemical components has negative environmental effects and reduces the quality of soils and agricultural products. The use of beneficial microorganisms (bacteria and fungi) as fertilizers and biological amendments has a high potential to improve productivity in saline soils. The aim of this study was to investigate the effect of using Acidithiobacillus bacteria along with mycorrhiza on the production of some photosynthetic and biochemical metabolites in maize under salt stress and comparing it with control conditions.
Materials and Methods
To perform this experiment, a surface soil sample was collected from a depth of 30 cm from the campus of Ferdowsi University of Mashhad, and some physical and chemical properties of the soil were measured by usual laboratory methods. To prepare saline soil a mixture of four compounds MgSO4.7H2O, Na2SO4, NaCl, and CaCl2. 2H2O were used. The mycorrhizal fungus (Funneliformis mosseae) and mesophilic Acidithiobacillus bacteria species two types of bacteria, Acidithiobacillus thiooxidans PTCC No: 1692 (DSM 504) and Acidithiobacillus ferrooxidans PTCC No: 1646 (DSM 583), were purchased from Turan Biotechnology Company (Semnan Science and Technology Park) and Iran Microbial Scientific and Industrial Research Center (PTCC), respectively. In this research, the effect of biological treatments including: two levels of mycorrhiza (inoculation and non-inoculation), two levels of salinity (0.96 and 6 d/m) and four levels of Acidithiobacillus control (C), Acidithiobacillus thiooxidans (T), Acidithiobacillus Ferrooxidans (F), Acidithiobacillus thiooxidans and Ferrooxidans (T+F) were compared with each other on some photosynthetic and biochemical characteristics of Zea mays under greenhouse conditions in the form of a completely randomized design with factorial arrangement with three replications. 10 gr of salt mixture (this amount of salt was obtained to reach electrical conductivity of 6 in the pre-experiment) was added to 5 kg of soil and the soil moisture of the pots was kept for one month in the field capacity. Bacterial treatments were inoculated with 30 mL of cell suspension per pot (approximately 107 CFU mL-1). In the simultaneous use of two bacteria, 15 ml of each bacterial cell suspension (15+15) was added to each pot. Single-cross 704 variety of maize was grown in pots and soil moisture was maintained during the growth period in the field capacity by weighing. Chlorophyll a, b and carotenoid, concentrations of flavonoids, anthocyanins and proline and electrical leakage were measured in fresh leaf samples (third leaf on the stem).
Results and Discussion
The results showed that salinity decreased the percentage of root colonization and chlorophyll a and b content in leaves. Salinity decreased chlorophyll a, b and carotenoid in leaves by 27.9, 68.42% and 50%, respectively. Salinity increased proline concentration (42.62%), electrolyte leakage (33.30%), anthocyanins concentration (96.36%) and leaf flavonoids (84.73%) compared to control soil. Inoculation with mycorrhiza compared to no inoculation had a remarkable and significant effect on all investigated parameters in both saline and control soils. In saline soil, mycorrhizal inoculation reduces electrolyte leakage (56.75%) and increases chlorophyll a (2.3 times), chlorophyll b (6.6 times), carotenoid (1.3 times), proline concentration (24.39%), anthocyanins amount (24.07) and flavonoids (20.4%) in the plant. The effect of bacterial treatments on the investigated parameters in plants inoculated with mycorrhiza was greater than non-inoculated treatments. The effectiveness of the simultaneous application of both bacteria was greater than the effect of each of them alone. In saline soil, simultaneous inoculation of mycorrhizae with both bacteria species reduces electrolyte leakage (14.72%) and increases chlorophyll a (39.80%), chlorophyll b (106%), carotenoid (50%), proline concentration (10.12%), the amount of anthocyanins (14.17%) and flavonoids (4.06%) compared to mycorrhiza treatment alone. The results showed that these bacteria can probably be considered as helping mycorrhizal bacteria.
Conclusion
The objective of this study was to examine the impact of simultaneous inoculation of mycorrhizae and Acidithiobacillus bacteria on select photosynthetic and biochemical metabolites of maize subjected to salinity stress conditions. Confirming the results of other studies, the results of this research also showed the clear and distinct effect of mycorrhiza on increasing chlorophyll and producing metabolites effective in increasing plant resistance to salt stress. In addition, the results showed that although the use of each species of Acidithiobacillus ferrooxidans and Acidithiobacillus thiooxidans alone was effective on the measured parameters in both saline and control soils, the simultaneous inoculation of both Acidithiobacillus bacteria species and mycorrhiza had the greatest effect on increasing chlorophyll, production of proline, anthocyanins and flavinoids and reducing electrolyte leakage and as a result, increasing tolerance to salt stress. In other words, these bacteria can be considered as mycorrhiza helper bacteria, whose activity can improve the function of mycorrhiza. On the other hand, mycorrhiza symbiosis may have increased the efficiency of these bacteria by changing the soil conditions and the environment around the roots. However, further greenhouse and field experiments with other plant species are necessary to confirm these findings.
Soil science
S. Mohammadi; A. Sepehry; M. Farzam; H. Barani
Abstract
IntroductionThe aim of the present study was to investigate the effect of soil conditioners on physiological responses (stomatal resistance, leaf temperature, chlorophyll, percentage of root colonization, carotenoids, proline) of Lycium depressum Stocks to drought stress. The experiments were performed ...
Read More
IntroductionThe aim of the present study was to investigate the effect of soil conditioners on physiological responses (stomatal resistance, leaf temperature, chlorophyll, percentage of root colonization, carotenoids, proline) of Lycium depressum Stocks to drought stress. The experiments were performed in semi-controlled greenhouse conditions.Materials and MethodsThe experiment was conducted as a factorial experiment based on a completely randomized design including the main factor, irrigation at 4 levels (100, 75, 50 and 25% of field capacity) and the sub-factor of soil conditioners. In each combined treatment, 5 repetitions of irrigation and soil remediation and a total of 160 pots were used. Subsoil treatments including hydrogel and nitrobacter, mycorrhiza and zeolite were added to each pot. 500 cuttings of the target plant were planted in the greenhouse. The grown cuttings were transferred to the pots where the experiments were carried out. At each irrigation level, 40 pots containing 4 kg of vegetation soil of the target species were considered and the agricultural capacity (FC) of the target soil was determined in the soil laboratory. A total of 160 pots were placed in the greenhouse for testing. The main treatment of the experiment included irrigation levels (100, 75, 50 and 25% of the crop capacity) and sub-treatments of soil conditioners including Stacosorb hydrogel in the amount of 3 grams per kilogram of soil in each pot in the lower part of the plant roots. Zeolite with the industrial name of mineral zeolite (Mineral Zeolite) was added in the amount of 8 grams in each pot in the lower part of the root of the plant. Nitrobacter (a collection of strains of Azotobacter sp, Azospirillum sp and Bacillus sp with the brand name Nitrobacter Diane) was added to the amount of 3 cc in each pot in the upper region of the plant roots. Addition of mycorrhiza (the mycorrhiza used in this experiment was Glomus mosseae and was prepared as soil containing mosseae fungi) in the amount of 10 grams per pot in the lower part of the plant roots. After adding soil conditioners, irrigation was done according to the crop capacity in 4 irrigation levels, in the determined treatments.Results and DiscussionMeasurement of physiological characteristics showed different responses in each of the variables. Carotenoid changes in 50% irrigation showed the lowest value (p<0.05) and the control treatment without mycorrhiza showed the highest value in the measurement of chlorophyll and carotenoid at 100 and 75% irrigation levels. The results of measuring colonization percentage, stomatal resistance and leaf temperature showed the lowest value in 25% irrigation. In the control treatment, proline parameters and root colonization percentage increased under the influence of drought stress, and stomatal resistance parameters, leaf temperature and chlorophyll decreased under the influence of drought stress. With intensification of drought stress, chlorophyll and carotenoid contents of the plant increased and the amount of proline decreased in Nitrobacter treatment with mycorrhiza, which was significantly different from the control treatment. In the control treatment with mycorrhiza, with increasing drought stress, the leaf temperature increased and the amount of proline decreased, which was different from the control treatment. Aperture resistance decreased from 48 m2 / mol.s 100% irrigation level to 44 m2 / mol.s 25% irrigation, leaf temperature at 100% irrigation level in mycorrhizal-free hydrogel modifier from 26 ° C Decreased to 21.57 ° C in 25% irrigation, at 100% irrigation level in non-mycorrhizal zeolite modifier the amount of chlorophyll b + a from 0.6 mg / g to 1.20 mg / g in 25% irrigation increased. The amount of carotenoids at 100% irrigation level in zeolite modifier with mycorrhiza increased from 0.1 mg / g to 0.2 mg / g in 25% irrigation in control treatment with mycorrhiza at 100% irrigation level compared to the level Irrigation increased by 50% and root colonization by 1.5%. The amount of proline in mycorrhiza-free hydrogel treatment was measured at 100% 2.77 μmol / g irrigation and at 50% irrigation level 2.66 μmol / g. Reduction of proline at 50% irrigation level indicates that the hydrogel modifier has increased the resistance of Lycium depressum Stocks to drought stress.ConclusionThe results of this study showed that the increase in drought causes changes in the physiological performance of the plant and the use of soil conditioners under drought stress due to the improvement of the physiological parameters, will increase the resistance of the plant by 50%. Nitrobacter treatments without mycorrhiza, hydrogel and zeolite with mycorrhiza and without mycorrhiza, due to further improvement of physiological parameters, is recommended to plants in nature.
R. Khodadadi; Reza Ghorbani nasrabadi; M. Olamaee; S.A. Movahedi Naini
Abstract
Introduction: Worldwide studies have shown that inappropriate land uses over the past 45 years have resulted in salinization of 6% of the world's land. Salinity has negative effects on soil physicochemical properties and microbial activities. The imbalance in nutrient uptake, ion toxicity and ...
Read More
Introduction: Worldwide studies have shown that inappropriate land uses over the past 45 years have resulted in salinization of 6% of the world's land. Salinity has negative effects on soil physicochemical properties and microbial activities. The imbalance in nutrient uptake, ion toxicity and decreasing water consumption due to high osmotic pressure are resulted from high accumulation of solutes in soil solution. One of the strategies to mitigate soil salinity is the inoculation of crops with different types of beneficial soil bacteria and fungi. Plant growth promoting bacteria (PGPB) are a diverse group of bacteria capable of promoting growth and yield of many crops. The most important growth promoting mechanisms of bacteria are the ability to produce plant hormones, non-symbiotic nitrogen fixation, solubilization of insoluble phosphate and potassium, biocontrol of plants pathogens through producing hydrogen cyanide and siderophore production. Plant inoculation with growth promoting bacteria causes an increase in several indices such as shoot fresh and dry weight, root dry weight and volume as well as chlorophyll content. The synergetic effect of Azotobacter and Azospirillum on the plant has been documented by increasing the absorption of nutrients, production of hormones that stimulate plant growth such as auxin, and influencing the root morphology. Due to the wide area of saline soils, appropriate methods to reduce the negative effects of salinity are of great significance. Given the importance of using bacteria adapted with climatic conditions and soil ecosystems in each region, as well as the efficiency of the combined application of growth promoting bacteria, this study was conducted to investigate the effect of growth promoting bacteria as a single and combined application at two levels of salinity calculated based on the threshold of barley yield reduction (Karoon cultivar) and 50 % reduction in barley yield.
Materials and Methods: In order to record the Azotobacter isolates, 15 soil samples were collected from salt affected lands of Golestan province. Thirty two Azotobacter isolates were isolated by physiological and biochemical tests and cyst production in old culture. Then, their ability to grow in different concentrations of salinity, drought stress tolerance, polysaccharide production, auxin production, phosphorus and potassium solubilization, hydrogen cyanide synthesis and biological fixation of molecular nitrogen were investigated. Based on physiological and growth stimulation tests, Az13 isolate was selected as the superior isolate of Azotobacter for greenhouse test. Azospirillum superior isolate was then prepared from the microbial bank of Soil Science Department, Gorgan University of Agricultural Sciences and Natural Resources. A soil with 16 dS/m salinity was selected to determine the effects of experimental treatments at two threshold salinity levels of yield reduction and 50 % reduction of barley yield. Then, soil salinity was reduced to 8 dS/m (yield reduction threshold) by leaching. After reaching to the desired salinity, the soil was removed from the pots and air dried. The sample was sifted through a 2 - mm sieve and again transferred to the pots. The barley seeds, Karoon cultivar, were used. To prepare the inoculum, firstly the bacterial isolates were grown in the pre-culture nutrient broth medium, and then incubated at 120 rpm in a shaking incubator at 28°C for 48 hours. Afterwards, each seed was inoculated with one milliliter of the bacterial inoculant with a population of 109 CFU/ml. This experiment was conducted as factorial in a completely randomized design with three replications in the greenhouse at Gorgan University of Agricultural Sciences and Natural Resources. The treatments included four levels of bacteria (without inoculation, Azotobacter inoculation, Azospirillum inoculation, combined inoculation of Azotobacter and Azospirillum) and two levels of salinity (8 and 16 dS/m). After 70 days (late vegetative growth period), some growth and physiological indices and concentration of nutrients uptake were measured.
Results and Discussion: The results showed that salinity stress had a significant (p < 0.01) negative effect on growth and physiological traits and nutrient uptake of the plant. The combined application of Azotobacter and Azospirillum bacteria showed a positive significant influence (p < 0.01) on growth, dry weight, and root dry weight in the plant under salinity stress. The combined application of bacteria increased the chlorophyll a, b and a + b content at a salinity level of 16 dS/m by 136.49, 117.86 and 127.97 %, respectively. The combined application of bacteria resulted in a 65.39 and 55.94 % increase in proline amino acid content at salinity levels of 8 and 16 dS/m, respectively. The results revealed that nitrogen, phosphorus and potassium levels increased by 81.97, 80 and 66.67%, respectively, at 16 dS/m salinity level in combined application of both bacteria. Sodium ion accumulation in all bacterial treatments decreased in both salinity levels compared to control treatment and the highest reduction was observed in combined bacterial inoculation. These findings underline the positive effect of bacterial inoculation, particularly their combined application, on the growth and nutrients uptake of barley under salt stress.
Conclusion: Our results indicate that increasing salinity level significantly decreased shoot dry weight, root dry weight, plant height, chlorophyll content and nutrient concentrations of barley. Inoculation of salt-resistant bacteria, including Azotobacter and Azospirillum, reduced the adverse effects of salinity on growth and physiological traits, which was more pronounced in Azotobacter than Azospirillum. The combined application of Azotobacter and Azospirillum had a significant effect on root dry weight, plant height, chlorophyll content, increasing nutrient concentration efficiency (nitrogen, phosphorus, and potassium) and decreased sodium concentration at both salinity levels (8 and 16 dS/m) compared with the individually inoculated bacteria. Hence, the application of Azotobacter and Azospirillum isolates is an appropriate method for pot experiments with saline soils. To apply these results, field experiments in saline soils must be carried out to evaluate the effect of these bacterial isolates on the crop growth, yield and physiological characteristics.
K. Kiani Jam; M.R. Bihamta; D. Habibi; A. Asgharzadeh; A. Saremirad
Abstract
Introduction: Nowadays, increasing soil contamination by heavy metals is one of the most important issues around the world, and is the focus of attention. Lead as the most dangerous heavy metal and persistent chemical pollutant affects the environment, especially the metabolic and physiological activities ...
Read More
Introduction: Nowadays, increasing soil contamination by heavy metals is one of the most important issues around the world, and is the focus of attention. Lead as the most dangerous heavy metal and persistent chemical pollutant affects the environment, especially the metabolic and physiological activities of organisms and ultimately cause serious damage to the environment and human health. The purpose of this study was to investigate the effect of mycorrhizal fungus (Rhizophagus irregularis) on some biochemical traits of 10 wheat genotypes in three different concentrations of lead heavy metal (0, 218 and 437 ppm) in soil.
Material and Methods: The present study was conducted as factorial experiment based on randomized complete block design with three replications. The factors included lead in three concentrations (0, 218 and 437 mg / kg), mycorrhizal inoculum (addition and no addition), and 10 wheat genotypes (Shiraz, Sepahan, Sirvan, Back Cross Roshan, Marvdasht, Sivand, Bahar, Pars, Roshan, and Pishtaz). Soil samples were prepared from a depth of 0-25 cm of the research farm of Islamic Azad University, Karaj Branch. Samples were taken randomly. After soil drying and passing through a 2 mm sieve, they were transferred to the soil science laboratory to determine some of the physical and chemical properties. According to the soil test results, the soil was sandy loam, a semi-light soil with 25% clay, 25% silt and 50% sand, with pH = 7.49 and salinity of 1.63 dS. m-1, and also free of heavy metals. The soil was sterilized for four hours by an autoclave at the temperature of 121 °C and a pressure of 1.5 atm. After soil preparation, the lead was added to the soil at three concentrations of 0, 218 and 437 ppm, and stored in a pre-embedded bag with 60% moisture content to achieve a two-week equilibrium. In order to inoculate the mycorrhizal fungus, after removal of 3-4 cm from the soil surface, Rhizophagus irregularis (35 g) was added to the soil surface, then 30 to 40 seeds were placed on the soil surface and covered with soil. In the control samples without mycorrhizal fungus, a certain amount of mycorrhizal fungus placed at 105 ºC to kill the fungus and then added to the pots.
Results and Discussion: Malondialdehyde concentration increased by increasing the concentration of lead. The highest concentrations of proline were belonged to the level 218 ppm of lead, in Pars cultivar in both treatments of with and without mycorrhiza fungus as well as Sirvan cultivar in the treatment of without fungi, respectively. The activity of Catalase was highest in the treatment of 218 ppm of lead without fungus. Roshan cultivar also showed high levels of ascorbate peroxidase activity in 218 ppm of lead. Similar to cultivar, BC Roshan and Pishtaz cultivars also showed high ascorbate peroxidase activity in this concentration of lead. The amount of hydrogen peroxide was reduced by changing the concentration of lead from 0 to 218 ppm, while its amount increased at 437 ppm concentration. With increasing lead concentration, the amount of chlorophyll a decreased while chlorophyll b increased. Using mycorrhizal fungus, the amount of malondialdehyde, proline and hydrogen peroxide and catalase content decreased compared with control. It seems that lead, due to its concentration in the environment, leads to the induction of oxidative stress and the formation of free radicals and thus change in the amount of biochemical traits of wheat such as malondialdehyde, proline, hydrogen peroxide and chlorophyll a and b and activity of catalase and ascorbate peroxidase. The genotype of the plant is very important factor in tolerating the toxicity of lead, and it deals with various protective mechanisms. Not only the plant genotype but also environmental factors such as the use of mycorrhizal fungus are effective in reducing the harmful effects of lead, and helps plants tolerate the stress caused by lead toxicity.
Conclusion: Lead in the soil causes changes in the biochemical content of wheat cultivars. The amount of change depends on the plant's genotype, lead concentration, and other factors in the soil, such as symbiotic fungi. As shown in the present study, mycorrhizal fungus was effective in eliminating the negative effects of lead during symbiotic with wheat. It is suggested further studies to determine the concentration of lead and even other heavy metals in wheat genotypes and to compare with Iranian national standards in order to overcome the concerns about the entry of these metals into the diet.
tahereh raiesi; bijan moradi; Behruz Golein
Abstract
Introduction: Citrus is the main fruit group grown in tropical as well as sub-tropical climate of more than 150 countries in the world. In Iran, the total area under citrus crops is 0.284 M ha with a production of 4.345 M ton and a productivity of 17 ton per ha. Citrus is also one of the most important ...
Read More
Introduction: Citrus is the main fruit group grown in tropical as well as sub-tropical climate of more than 150 countries in the world. In Iran, the total area under citrus crops is 0.284 M ha with a production of 4.345 M ton and a productivity of 17 ton per ha. Citrus is also one of the most important horticultural products in Mazandaran, with 112,000ha devoted to its cultivation. Drought stress is frequent in Iran and is common in the dry summer periods in Mazandaran. Therefore, irrigation is essential during mentioned periods in this province. Irrigation scheduling and water requirement of the citrus crops are one of the main concerns of the citrus fruit production. Irrigating based on soil water potential (tensiometer) is one of the irrigation scheduling methodologies. In addition, fertilization is used to promote quantity and quality of fruit production. Potassium has a key role in the osmotic adjustment of plants and alleviate the effects of drought stress. Until now, studies on citrus to evaluate the effects of potassium fertilization to mitigate the negative effects of drought stress have not been conducted. In the present study, we hypothesised that K applications via soil could contribute to osmotic adjustment of citrus and alleviate the effects of drought stress. Thus, the objective of the present study was to evaluate the effects of different soil water potential and rate of potassium (K) application on biochemical indices and growth responses of Thomson navel (Citrus, sinensis (L.) osbeck) orange seedlings on Citrumelo rootstock.
Materials and Methods: This study site was located at the Citrus and Subtropical Fruit Research Center of Horticultural Science Research Institute (36°54′11″N, 50°39′30″E), with a mean annual rainfall of 1200 mm. Thomson navel trees (Citrus, sinensis (L.) were planted at 7 × 6m distances. Soil had a pH (soil-to-water suspension ratio of 1:2) of 6.2 and contained 14.3 g kg−1 organic C and CaCO3<1%. The texture of soil was clay loam. A two-year field study was conducted in a factorial experiment based on randomized complete block design with four selected ranges of soil water potential, two levels of K application, and four replicates. Irrigations were scheduled using soil moisture tensiometers. The irrigation treatments were scheduled when soil water tensions reached 20, 40, and 60 kilopascal (kPa) on the tensiometers per treatment and results were compared with control (none irrigation) treatment. Soil water tensions of 20, 40, and 60 kPa correspond to soil water depletions of 17, 35, and 52%, respectively, of the available soil water for the studied soil. Levels of K fertilizer were 50 (k1) and 100 (K2) g K × age of tree. Potassium fertilizer was broadcast below the tree canopy in March. At the end of each year, yield, available K and some growth indices were measured. In addition, in the last year, proline, ionic leakage and electrical conductivity were also measured. All data were represented as mean of four replicates. Differences in yield, canopy diameter and available K among fertilizer and irrigation treatments and sampling years were analyzed using general linear model two-way analysis of variance (ANOVA) in SAS 9.1. Since the mentioned attributes were measured during two years to take into account annual variation, we used ANOVA procedure for a combined analysis of data. The significance of differences between the mean of treatments were determined by using Duncan test. All the statistical analyzes were performed by SAS 9.2.
Results and Discussion: The results showed that irrigation increased the canopy diameter (P<0.05). Under K1 application, the tree yield was not significantly different (P≥0.05) between irrigation at different water potentials (I1, I2 and I3). However, the K effects on tree yield depended on soil water potential and the positive effects of K2 application were evident only in the I2 and I3 treatments. However, K2 application reduced the yield in irrigation treatments including I0 and I1 significantly (P<0.05) compared with K1 application. In addition, the results of the last year showed that proline and ionic leakage were increased (P<0.05) by reduce of water potential in irrigation time. However, double application of K (K2) increased (P<0.05) proline and decreased ionic leakage as compared with normal application of K (K1). Moreover, available K and electrical conductivity were increased (P<0.05) by excessive application of K and reduce of soil water potential.
Conclusion: In summary, regarding this experiment, irrigation at 60 kPa (depletion coefficient =52%) and potassium application rate of 50 g K × age of tree was the best treatment.
k. dalvand
Abstract
Introduction: Among wide variety of soil pollutants including heavy metals, acidic precipitation and other toxicants, the importance of heavy metals due to their pollution capacity has received growing attention in recent years. Heavy metals are important environmental pollutants and their toxicity is ...
Read More
Introduction: Among wide variety of soil pollutants including heavy metals, acidic precipitation and other toxicants, the importance of heavy metals due to their pollution capacity has received growing attention in recent years. Heavy metals are important environmental pollutants and their toxicity is a problem of increasing significance for ecological, evolutionary, nutritional, and environmental reasons. Of all non-essential heavy metals, cadmium (Cd) is perhaps the metal that has attracted the most attention in soil science and plant nutrition due to its potential toxicity to humans, and also its relative mobility in the soil–plant system. The uptake of ions takes place in competition with that of elements such as Zn, P, Cl–, Ca, and Cu. Soil, environmental, and management factors impact the amount of Cd accumulated in plants (Hart et al., 1998). Much of the Cd taken up by plants is retained in the roots, but a portion is translocated to the aerial portions of the plant and into the seed. The amount of Cd accumulated and translocated in plants varies with species and with cultivars within species. Cd toxicity causes inhibition and abnormalities of general growth in many plant species. After long-term exposure to Cd, roots are mucilaginous, browning, and decomposing; reduction of shoots and root elongation, rolling of leaves, and chlorosis can occur. Cd was found to inhibit lateral root formation while the main root became brown, rigid, and twisted. The changes in the leaf included alterations in chloroplast ultrastructure, low contents of chlorophylls, which caused chlorosis, and restricted activity of photosynthesis. Radish (Raphanus sativus) is a root vegetable grown and consumed all over the world and is considered as a part of the human diet, even though it is not common among some populations. Usually, people eat radishes raw as a crunchy vegetable, mainly in salad, while it also appears in many European dishes. Some people, at least in the Middle East, prefer to drink its juice in pursuit of certain health benefits. Radishes have different skin colors (red, purple, black, yellow, and white through pink), while its flesh is typically white. In addition, the edible root of radish varies in its flavor, size, and length throughout the world.
Materials and Methods: In this study, we investigated the influence of Cd application rates on vegetative parameters, and physiological and biological indexes of radish. The experimental design was a factorial with randomized block with two treatments and three replications carried out at the Research Farm of College of Agriculture, Shahid Chamran University. Treatments included three rates of Cd application of 0 (control), 30 and 60 mg kg-1, and two harvesting dates of commercial maturity (CM) and a week after CM, hereafter referred to as 1st and 2nd harvesting dates. Measurements included vegetative parameters such as wet and dry weights, leaf area, length and width of leaves, leaf numbers and root length. Physiological indexes of electrolyte leakage and relative humidity, and biochemical indexes of chlorophyll a, b and total, Cartonoeid, Proline and vitamin C were also determined.
Results and Discussion: The results indicated that the Cd application reduced all of the vegetative parameters. Application of 60 mg kg-1 of Cd increased the electrolyte leakage by 28.2% and Proline concentration by 48.8 mg g-1. Cd application increased the relative humidity. All biochemical indexes decreased as the Cd application rates increased. The maximum concentration of Cd in plant was observed at 60 mg kg-1 Cd contamination. It seems that decrease of physiological indices due to increased Cd concentration reduced the growth properties.
Conclusion: Application of different Cd concentrations affected the vegetative, physiological and biochemical properties. By increasing Cd concentration of soil, the Cd accumulation in the plant increased. Increasing the Cd concentration increased the electrolyte leakage and proline concentration and reduced the content of relative humidity, chlorophyll, vitamin C in radish. In addition, it decreased yield including fresh and dry weights, root length, leaf area, leaf length and width, and number of radish leaves. Further, the effects of degradation on vegetative, physiological and biochemical characteristics of radish were one week after commercial maturity more than the first time (commercial maturity). Therefore, the phosphorus-containing Cd for the cultivation of vegetables, especially tubers, such as radishes, as well as harvest management, should be carefully applied.
vahid mozafari; fariba khaleghi
Abstract
Introduction: Salinity is one of the main problems which limits crop production, especially in arid and semi-arid areas such as Iran. Iran is the most important producer of pistachio in the world. However, its performance is low in many areas. Most pistachio plantations are irrigated with saline water ...
Read More
Introduction: Salinity is one of the main problems which limits crop production, especially in arid and semi-arid areas such as Iran. Iran is the most important producer of pistachio in the world. However, its performance is low in many areas. Most pistachio plantations are irrigated with saline water and with low quality (28). On the other hand, nitrogen is a dynamic element which is a constituent of amino acids, proteins, nucleic acids and Enzymes and it has a vital role in plant physiology, growth, chlorophyll formation and production of fruit and seeds (34). Gibberellic acid is known as phytohormon which varied physiological responses in plants under stress. acid gibberellic increases the photosynthesis and growth under stress and impact on the physiology and metabolism of plant (29). Based on previous studies, production and activity of plant hormones are affected by natural factors and plant nutrient requirements and the nitrogen has an important influence on production and transmission of acid gibberellic plant shoot. Therefore, in this study the effect of acid gibberellic and nitrogen on some characteristics of physiology parameters and micronutrient pistachio seedlings (Cv. Qazvini) under saline conditions was studied.
Materials and methods: Experiment under greenhouse condition and factorial in a completely randomized design with three replications was conducted in greenhouse agriculture college, Vali-E-Asr University of Rafsanjan. Treatments consisted of three levels of salinity (0, 1000 and 2000 mg of sodium chloride per kg of soil), three levels of nitrogen (0, 75 and 150 mg per kg of ammonium nitrate source) and three acid gibberellic levels (0, 250 and 500 mg per liter). Adequate soil with little available salinity conditions was collected from the top 30-cm layer of a pistachio-culture region of Kerman province. After air drying and ground through passing a 2 mm sieve, some of the physical-chemical properties of this soil include pH (7/63), Tissue (Sandy loam), electrical conductivity (ECe) (1 dS m-1), Silt (23.1%), Clay (5.5%), Organic matter (0.5%), Olsen phosphorus (P) (5.35 mg kg-1), Ammonium acetate-extractable K (100 mg kg-1) were determined. Nitrogen treatments 3 weeks after planting, dissolved in irrigation water was added to pots. Salinity, after the establishment of the plant (5 weeks after planting), divided into two equal parts and one-week interval dissolved with irrigation water was added to the pot. as well acid gibberellic treatments, as spray after salt treatment was applied at three times and at intervals of one week.
Results and discussion: The results showed that the salinity content of carotenoid and Chlorophyll fluorescence parameters significantly reduced but with increasing acid gibberellic and nitrogen application, mentioned parameters were significantly increased, compared to controls. The ability of photosynthesis improved and increased productivity. Mozafari et al studied the pistachio, reported that with increasing salinity from zero to 150 and 300 mM NaCl, carotenoids decreased more than 16% and 22% compared to control respectively. Carotenoids play a most important role in light, protecting plants against stress condition. Salinity application increased leaf proline, but with application of 150 mg nitrogen and 500 mg per liter foliar application of acid gibberellics, this parameter increased by 55 and 26 percent, respectively. Also, combined use of these two treatments increased proline content by 79 percent compared to control. The researchers stated that the increasing gibberellin concentration caused leaf proline increased, so spraying 100 and 200 mg per liter gibberellin significantly increased leaf proline compared with the non-application of gibberellin. The results also showed with increasing salinity increased iron, manganese and zinc concentrations shoots and roots and decreased copper concentrations, but using 150 mg of nitrogen and acid gibberellic consumption concentrations of copper element increased. Hojjat nooghi and Mozafari (28) reported, the used salinity of 60 mM NaCl increased shoot Fe concentration, but by applying the same amount of salinity in the root iron concentration decreased compared with the control. Research has shown that the copper concentration in the leaves and shoot of corn planted in soil decreased with increasing salinity. Micronutrient absorption reduction such as copper in salt condition can result in greater absorption of nutrients such as sodium, magnesium and calcium. The researchers in the study reported that with increasing nitrogen in the form of nitrate and ammonium, zinc concentration in plant tissues increased along with increasing salinity and lower shoot dry weight, zinc concentration was increased in two wheat cultivars too.
Conclusion: The results of this experiment showed that under saline conditions, acid gibberellic and nitrogen applied alone or in combination improved physiology parameters and increased nutrient concentration of pistachio seedling.
Afsaneh Tongo; A. Mahdavi; E. Saiad
Abstract
To study the effect of Aquazorb super absorbent polymer (SAP) on reducing Drought stress of Acacia victoriae seedling, a split plot experiment based on the completely randomized design was conducted. In this research, stressed treatment as the main plots and amount of superabsorbent were considered as ...
Read More
To study the effect of Aquazorb super absorbent polymer (SAP) on reducing Drought stress of Acacia victoriae seedling, a split plot experiment based on the completely randomized design was conducted. In this research, stressed treatment as the main plots and amount of superabsorbent were considered as sub plot. Treatments were applied consisted of four levels of drought stress (15, 30, 60 and 100% of field capacity) and four levels of superabsorbent (0, 0.2, 0.4 and 0.6 wt%) Were studied. The results showed that survival of seedlings at the end of growth season between different treatments was the same, but the Acacia growth was responsed to the water stress and reduced growth traits were found. Using of the superabsorbent polymer had a significant effect on collar diameter, seedling height, fresh and dry root weight, relative water content of leaf and proline. According to the comparison of the means simple effects, in all of growth indices except the leaf area and root fresh weight the most means was obtained in 0.2% superabsorbent polymer treatment and also, in comparison the effect of diferent factors in most of the traits the highest means compared with 100% irrigation level without applying SAP related was to 60% irrigation level with 0.2 % SAP. That represents water savings is about 40%.
samaneh ahmadi gheshlaghi
Abstract
Glomalin is a glycoprotein produced by arbuscular mycorrhizal (AM) fungi, and is a major component of soil organic matter, which plays an important role in soil aggregation and carbon sequestration. Glomalin is produced only by the AM fungi. On the other hand, stressful environments such as salinity ...
Read More
Glomalin is a glycoprotein produced by arbuscular mycorrhizal (AM) fungi, and is a major component of soil organic matter, which plays an important role in soil aggregation and carbon sequestration. Glomalin is produced only by the AM fungi. On the other hand, stressful environments such as salinity can affect the AM fungi .The purpose of this study was to investigate the effect of NaCl salinity on glomalin production by Glomerales in symbiosis with corn plant. A factorial experiment was conducted in completely-randomized design (CRD) with four replications in a greenhouse. Factors were NaCl salinity with three levels (S0: 1.34, S1:4 and S2: 8 dS/m) and mycorrhizal fungi with four levels (non mycorrhizal, Glomus versiforme, G. intraradices, G. etunicatum). The results showed that the interaction of salinity and mycorrhizal fungi on plant dry weight, leaf proline, root colonization percentage, EEG and TG was significant at p
