Soil science
Maryam Ghorbani; shahram kiani; Ali Moharrery; Sina Fallah
Abstract
IntroductionThe gradual decrease in the fertile soils surface due to environmental pollution and urbanization phenomena has reduced the possibility of sufficient fodder production. In addition, the strict dependency of the agricultural sector on water resources in an age of drastic climate change ...
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IntroductionThe gradual decrease in the fertile soils surface due to environmental pollution and urbanization phenomena has reduced the possibility of sufficient fodder production. In addition, the strict dependency of the agricultural sector on water resources in an age of drastic climate change necessitates providing novel solutions for agricultural production. One of the methods that has gained attention for providing fodder is its production through soilless culture techniques. Maize can be a suitable option for fodder production in soilless culture due to high starch and sugar content, low seed cost, high biomass production, and rapid growth. Proper nutritional management of maize in soilless culture is highly important for increasing the quantity and quality of forage greenery. Little information is available regarding the impact of nitrogen form on the growth, yield and chemical composition of forage plants including maize in soilless culture. This experiment was conducted to investigate the effect of nitrogen form on the chemical composition, leaf photosynthetic pigments concentration and yield of two fodder maize (Zea mays L.) cultivars in soilless culture. Materials and MethodsA factorial experiment based on randomized complete block design was conducted with the two factors of ammonium to nitrate ratio in the nutrient solution (0:100, 12.5:87.5, 25:75, 37.5:62.5 and 50:50) and maize cultivars (i.e., single cross hybrid 704 and single cross 410) and four replications in hydroponic culture at the greenhouse of Shahrekord University. After seed germination and emergence of the first two leaves, the maize seedlings were transferred to 10-liter plastic pots containing perlite (0.5-5 mm) and were manually fertigated with different ammonium to nitrate ratios on a daily basis. Before harvesting, chlorophyll a, b and (a+b), and carotenoids were quantified in leaves of plants. At the end of the tasseling stage, the plants were harvested. After harvesting, the root, stem, and leaf parts were separated, and the fresh weights of the samples were measured. Plant samples were dried in an oven at 60 °C. Then, dry weights of samples were measured and samples (root and leaf + stem) were ground for nutrient analysis including of N, P and K. Analysis of variance was performed using SAS software version 9.4. Means comparison was conducted using Duncan's multi-range test at p <0.05. Results and DiscussionThe results showed that in single-cross hybrid 704 and single-cross 410 cultivars, respectively, increasing the applied ammonium to 37.5% and 50% in the nutrient solution caused a significant increase in the shoot nitrogen concentration. Application of ammonium in the nutrient solution led to an increase in shoot and root phosphorus concentration in both maize cultivars compared to the nutrient solution without ammonium. The highest concentration of phosphorus in shoot (18.02 g.kg-1) was observed in the single-cross hybrid 704 cultivar when maize plants fed with a nutrient solution containing 50 percent ammonium, which was 3.2 times higher than the shoot phosphorus concentration in plants fed with nutrient solution without ammonium. Furthermore, at the 50:50 ammonium to nitrate ratio in the nutrient solution, the lowest root potassium concentration was recorded in both maize cultivars. In single-cross hybrid 704 cultivar, application of nutrient solution with ammonium to nitrate ratio of 50:50 resulted in a significant 31% decrease in leaf chlorophyll a concentration compared to plants fed with a nutrient solution containing 25% ammonium (with the highest chlorophyll content). The leaf chlorophyll a concentration in single-cross 410 cultivar showed an increasing trend with increasing ammonium in the nutrient solution up to 25 percent, and then a decreasing trend with further increase in the ammonium proportion. Moreover, a 31.4% significant decrease in chlorophyll b concentration was observed in plants fed with a 50:50 ammonium to nitrate ratio compared to plants fed with a 37.5: 62.5 ammonium to nitrate ratio. The highest leaf carotenoid concentration was recorded in single-cross hybrid 704 cultivar and at 25:75 ammonium to nitrate ratio, which was 1.4 times higher than the leaf carotenoid concentration compared to plants fed with nutrient solution without ammonium. The highest relative leaf moisture content was observed in the plants nourished with ammonium to nitrate ratio of 25:75, which showed a significant 20% increase compared to the ammonium-free nutrient solution. The results also indicated that the application of 50% of nitrogen in the form of ammonium in the nutrient solution led to a significant decrease in the leaf surface area of maize. The highest shoot and root fresh weights were obtained in the plants nourished with 25:75 ammonium to nitrate ratio and in the single-cross hybrid 704 cultivar. The results showed that the highest water (solution) use efficiency based on fresh weight was recorded in plants fed with 25:75 ammonium to nitrate ratio and in the single-cross hybrid 704 cultivar. ConclusionBased on the results of the present study, the highest shoot and root fresh weights of both maize cultivars were obtained in plants fed with 25:75 ammonium to nitrate ratio. Given the limitations of water resources and rainfall, optimal use of minimum water to produce maximum agricultural crops must be cnsidered. According to the results of this research, application of nutrient solution with ammonium to nitrate ratio of 50:50 led to ammonium toxicity and a reduction in forage yield in both maize cultivars. Therefore, replacing 25% nitrate in the nutrient solution with ammonium and selecting the single-cross hybrid 704 cultivar (due to higher yield compared to single cross 410 cultivar) is recommended to achieve maximum fodder yield in soilless culture under conditions similar to this study.
Soil science
T. Nazari; M. Barani Motlagh; S.O. Rastegar; M.H. Sedri
Abstract
IntroductionPhosphorus is an essential element for all living organisms, and it cannot be replaced by any other element. Phosphorus has however a limited resource, and it is estimated that the extracted phosphorus resources (Apatite) will last for another 50 to 100 years. One of the most widely used ...
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IntroductionPhosphorus is an essential element for all living organisms, and it cannot be replaced by any other element. Phosphorus has however a limited resource, and it is estimated that the extracted phosphorus resources (Apatite) will last for another 50 to 100 years. One of the most widely used technologies for recycling phosphorus is the precipitation of phosphorus from sewage sludge and leachate. Phosphorus Recovery as struvite (NH4MgPO4.6H2O) from sewage sludge has attracted special attention due to its potential for use as an ecological and slow release fertilizer. Struvite is a white, grain-like solid, odor-free and sludge–free ingredient, composed of magnesium, ammonium and phosphate at equal molar concentrations. Therefore, this study is designed to examine the effect of struvite replacement with triple superphosphate fertilizer on some physiological parameters and phosphorus availability in wheat plants in calcareous soils deficient in phosphorus. Methods and MaterialsSoil with phosphorus deficiency was collected from 0-30 cm depth under arable lands of Hajjiabad-e Seyyedeh located in Ghorveh township, Kurdistan Province, Iran. The soil was air-dried and ground to pass through a 2-mm sieve, followed by laboratory analysis to determine its physico-chemical properties. The struvite used in the research was obtained by optimizing the three main factors of sulfuric acid concentration, solid-to-liquid ratio, and time for the leaching process, and the three key factors of Mg:P ratio, N:P ratio and pH for the precipitation process by Response Surface Methodology. To achieve the aim of this study a factorial experiment was carried based on completely randomized design with 4 replications. The factors included the application of different proportions of struvite replaced with triple superphosphate (S0:P100, S25:P75, S50:P50, S75:P25 and S100:P0) and 4 levels of phosphorus (0, 50, 100 and 150 kg TSP ha-1) and a total of 54 pots. The application rate for struvite was calculated based on total phosphorus (P2O5). Then 10 wheat seeds were planted in each pot at 2-cm depth which after plant emerging and greening, declined to 4 plants in each pot. The pots were randomly moved twice a week during the growth period to eliminate environmental effects. Irrigation and weeding operations were applied by hand. Plants were harvested 60 days after planting (beginning of flowering), washed with distilled water and dried with tissue paper. The samples were air-dried and then oven dried at 70˚C to a constant weight in a forced air-driven oven. Phosphorus concentrations in plant extracts were measured by the molybdenum vanadate or yellow method and chlorophyll content (a, b and ab) and carotenoids using the Arnon method. The statistical results of the data were analyzed using SAS software and LSD test (at 5% level) was used for comparing the mean values. Results and DiscussionBased on the obtained results, all the investigated treatments and their interactions were significant at p<0.01. However, the interaction effect of fresh weight shoots and height was significant at p<0.05. The comparison of the average data showed that the highest amount of fresh weight shoots (7.79 g pot-1), dry weight shoots (1.130 g pot-1) and height (29.66 cm) was obtained from the application of S75:P25 150 kgTSP ha-1. By use of struvite instead of triple superphosphate fertilizer, the phosphorus concentration and uptake of wheat increased at all three fertilizer levels, so that the highest phosphorus concentration (0.174%) was obtained from S75:P25 150 kg TSP ha-1. However, there was no statistically significant difference for S100:P0 (0.169%) treatment. The highest amount of phosphorus uptake in wheat with an average of 0.197 g pot-1 was obtained from the S75:P25 treatment (150 kg TSP ha-1), compared to the treatment of 100% struvite (S100:P0) and 100% triple superphosphate fertilizer (S0:P100) with the averages of 0.158 and 0.109 g pot-1, respectively, showing 19.79 and 44.67 percent increase. Also, the results showed that the treatment of 150 kg TSP ha-1 100% struvite (S100:P0) compared to 100% triple superphosphate fertilizer (S0:P100) increased the amounts of chlorophyll a, b, ab and carotenoids by 7.78, 3.82, 6.44 and 6.84 percent, respectively. ConclusionDespite struvite's low solubility, it is a highly soluble phosphorus fertilizer for plants . However, the reasons for this apparent contradiction and also the specific mechanisms of struvite dissolution are still unclear. Hence, further accurate measurements at different pH and EC conditions with different physical and chemical properties of soil studying phosphorus fractionation in soil will help to better understand the use of struvite. Therefore, it is recommended to optimize the timing and application rate of struvite in relation to the demand for different agricultural and garden crops.
Soil science
M. Bazi Abdoli; M. Barani Motlagh; A. Bostani; T. Nazari
Abstract
IntroductionOrganic matter and alkaline pH are the main causes of nutrient deficiencies in calcareous soils of arid and semi-arid regions. The availability of some nutritional elements, including the micronutrients such as iron, zinc, copper, and manganese is very low in calcareous soils, although the ...
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IntroductionOrganic matter and alkaline pH are the main causes of nutrient deficiencies in calcareous soils of arid and semi-arid regions. The availability of some nutritional elements, including the micronutrients such as iron, zinc, copper, and manganese is very low in calcareous soils, although the total concentration of these elements may be relatively high. Burning crop residues results in substantial loss of nutrients, and may lead to air pollution and human health problems. An alternative approach is to apply crop residues to soil in the form of biochar. The biochar modification with acid may increase the solubility of nutrients (P, Fe, Zn, Cu, Mn) present in biochar, thereby significant improvement in mineral nutrition of plants grown in calcareous soils. Therefore, the object of this study is to investigate the effect of acid-modified biochar from rice residues on the amount of chlorophyll and the micronutrient concentration of quinoa plant (Chenopodium quinoa) in a calcareous soil. Methods and MaterialsThe soil was air-dried and ground to pass through a 2-mm sieve then was analyzed to determine various soil physico-chemical properties using standard methods. To achieve the aim of this study the factorial experiment was carried out based on a completely randomized design in 4 replications. Factors include 3 types of biochar (unmodified, modified by pre-acidic method and modified by post-acidic method) and different levels of biochar (0, 2, and 5% by weight). Then 10 quinoa seeds were planted in each pot at 2-cm depth which after emergence, declined to 3 plants in each pot. The pots were randomly moved twice a week during the growth period to eliminate environmental effects. Irrigation and weeding operations were performed by hand. Determination of chlorophyll content (a, b, and ab) and carotenoids were measured precisely before harvesting in fresh plants using Arnon method. Plants were harvested at 187 days after planting, washed with distilled water and dry with tissue paper. The samples were air-dried and then oven dried at 65˚C to a constant weight in a forced air-driven oven. Then the total micronutrient content of the plant was determined after dry ashing. The statistical results of the data were analyzed using SAS software (9.4) and LSD test (at 5% level) was used for comparing the mean values. Results and DiscussionBased on the variance analysis, all attributes responded positively to different types and levels of biochar and modified biochar (p<0.01). The comparison of the average effect of the studied treatments showed that with the increase in the levels of all three types of biochar, the amount of chlorophyll a, b, total, and carotenoid increased so the highest amount of chlorophyll a, b, total, and carotenoid respectively, with an average of 2.58 and 1.54, 4.13 and 1.36 mg g-1 were obtained from the treatment of 5% post-acidic biochar. The results showed that the highest amount of Fe concentration in shoots with an average of 229.48 mg kg-1 was obtained from the treatment of 5% post-acidic biochar, although there was no statistically significant difference with the treatment of 5% pre-acidic biochar with an average of 220.48 mg kg-1 and its lowest value with an average of 95.95 mg kg-1 was related to unmodified biochar. The highest amount of Zn concentration in shoots with an average of 13.42 mg kg-1 was related to the treatment of 5% post-acidic biochar which showed an increase of 13.24 and 33.26% compared to the treatment of 5% pre-acidic and unmodified biochar, respectively. Also, the highest concentrations of Cu and Mn in shoots were obtained with an average of 3.85 and 23.37 mg kg-1 respectively, from the treatment of 5% post-acidic biochar. ConclusionPost-acidic biochar had better results in terms of physiological indices and the concentration of micronutrients (Fe, Zn, Cu, and Mn) than unmodified biochar in quinoa. The increase of nutrients in quinoa can be attributed to the dissolution of biochar nutrients after being modified with acid and the reduction of pH and the availability of these elements in the soil. Therefore, biochar modified with acid or biochar produced from sources that have acidic properties can be recommended as a suitable method for improving fertility and increasing micronutrients in calcareous soils affected by salt.
Irrigation
M. Behdarnejad; H. Piri; M. Delbari
Abstract
Introduction
In sustainable farming systems, the use of organic fertilizers is of particular importance in increasing crop production and maintaining sustainable soil fertility. Nowadays, the consumption of organic foods is introduced to consumers as an alternative. The result of the application of ...
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Introduction
In sustainable farming systems, the use of organic fertilizers is of particular importance in increasing crop production and maintaining sustainable soil fertility. Nowadays, the consumption of organic foods is introduced to consumers as an alternative. The result of the application of chemical products is the crisis of environmental pollution, soil and water resources, and the health risk to human society. Nowadays, in order to reduce the effects of misuse of chemical inputs, chemical fertilizers can be replaced with organic biological fertilizers, including animal manure, compost, and green manure. In this regard, chicken manure has a positive effect on the physical, chemical, and biological characteristics of the soil, and due to its richness in uric acid, the nitrogen contained in it is used by the plant much faster than the nitrogen of other organic fertilizers. Vermicompost is considered a good source of soil fertility due to its organic materials. Organic matter in the soil improves the permeability and drainage of the soil and also prevents excessive dryness of the soil by maintaining sufficient moisture. Despite the fact that vermicompost can be used as a fertilizer in organic farming, high levels of this fertilizer may cause salinity effects in the plant, which affects the growth and development of the plant and even it can cause the death of cucumber as one of the crops sensitive to soil and water salinity. The cucumber (Cucumis sativus L.) is one of the important vegetables that can be produced in a greenhouse all year round. Fresh consumption of cucumber throughout the year has increased its production. The development of technology and the short growth period of this product has made it possible to grow it in most climate zones. Therefore, in this research, the effects of different levels of water deficit with the simultaneous application of vermicompost and chicken manure on cucumber plants in the Behbahan region have been investigated.
Materials and Methods
In this study, different levels of irrigation water, vermicompost, and poultry manure on ground cucumber were investigated. The experiment was performed in the form of split plots based on completely randomized design and the form of stacks. Treatments included three levels of poultry manure (2, 4 and 8 ton ha-1), three levels of vermicompost (3, 6 and 9 ton ha-1) and three levels of water stress (100, 75 and 50% of plant water requirement). Both vermicompost and poultry manure were applied to the soil before planting. Harvest was done every three days. Fruit weight, diameter and length, plant length, the protein of the dry matter of the fruit percentage, and leaf chlorophyll in each plot were carefully measured. Also, the yield and water productivity at the end of the season were calculated.
Water productivity
Referring to the yield to irrigation water ratio, is obtained by the following relation (Payero et al., 2009):
WP=Y/IR (1)
In this equation, WP represents water productivity (kg/m3), Y denotes the yield (kg/ha), and IR shows the amount of irrigation water (m3/ha).
Statistical analysis
The analysis of variance for the results obtained from different treatments was conducted using SAS software (SAS 9.1, SAS Institute, Cary, NC, USA). The mean values of the main factors and interactive effects were compared using the Duncan method at the 1% and 5% levels of significance.
Results and Discussion
The results showed that irrigation, poultry manure and vermicompost had a significant effect on the measured parameters at the level of one and five percent probability. Reduction of water consumption reduced yield and yield components, but in this regard, no significant difference was observed between 100% and 75% of water requirement. The highest yield was obtained in the treatment of 100% of plant water requirement and consumption of 4 ton ha-1 of poultry manure and 6 ton ha-1 of vermicompost, in this regard, no significant difference was observed with the treatment of 75% of water requirement. According to the results obtained from this study, it can be said that there is no significant difference in terms of yield between treatments of 75 and 100% of plant water requirement. Therefore, the amount of water given to the plant can be reduced to 75% of the plant water requirement, and with proper management, less water can be consumed without a significant reduction in crop yield. Examining the effects of irrigation water on the amount of the protein of the dry matter of the fruit showed that the highest amount of the protein of the dry matter of the fruit (56.31%) was obtained in the treatment of 75% of the water requirement and the protein of the dry matter of the fruit was less in other treatments. The interaction effect of vermicompost and poultry manure resulted in the highest percentage of cucumber protein at a treatment of 4 tons ha-1 of poultry manure and 6 tons ha-1 of vermicompost (58.42%). However, when the simultaneous use of 8 tons ha-1 of poultry manure and different levels of vermicompost was employed, the percentage of protein in the fruit's dry matter decreased. The combination of drought stress, poultry manure, and vermicompost, along with their interaction effects, significantly influenced the chlorophyll a and b values at both the 1% and 5% probability levels. As the depth of irrigation water decreased, the amounts of chlorophyll a and b also decreased. The treatment with 100% water requirement of the plant showed the highest amounts of chlorophyll a (0.63 mg/g fresh weight) and chlorophyll b (0.36 mg/g fresh weight). However, no significant difference was observed compared to the 75% treatment. Regarding the interactions between vermicompost and poultry manure, it was found that when using 6 tons ha-1 of vermicompost to reduce yield and its components, the use of poultry manure should be reduced to 4 tons ha-1. On the other hand, when higher levels of vermicompost (9 tons ha-1) are used, the application of poultry manure should be reduced to 2 tons ha-1.
Result
According to the results obtained from this research, it can be said that there is no significant difference in performance between the treatments of providing 75% and 100% of the water requirement of the plant, therefore, the amount of water given to the plant can be reduced to the amount of 75% of the water requirement of the plant. With proper management, less water can be consumed without significantly reducing the yield of the product.
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 ...
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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 ...
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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.
A. Jahandideh; M. Barani; E. Dordipour; R. Ghorbani Nasrabadi
Abstract
Introduction: One of the most important needs in the farm planning is the evaluation of different systems of plant nutrition. By supplying the correct way of plant nutrition, one can preserve the environment and increase the efficiency of agricultural inputs. Humic acid contains many nutrients that increase ...
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Introduction: One of the most important needs in the farm planning is the evaluation of different systems of plant nutrition. By supplying the correct way of plant nutrition, one can preserve the environment and increase the efficiency of agricultural inputs. Humic acid contains many nutrients that increase soil fertility, soil organic matter content, and access to macro- and micro-nutrients by preventing the formation of insoluble salts and chelating properties. Phosphorus and humic acid stimulate vegetative growth, improve reproductive growth, and increase the quantitative and qualitative yield of plants. In this regard, the positive effects depend on the amount and how they are applied. The present study was conducted with the aim of investigating the effects of different levels of humic acid and phosphorus fertilizer on phosphorus availability and photosynthetic pigments (a, b and carotenoids) in canola (cv. Hyola 50).
Methods and Materials: The soil used in this study was collected from 0-30 cm layer of a soil profile passed through a 2-mm sieve after air-drying. The soil chemical and physical properties were then determined. The pot experiment was conducted as factorial based on completely randomized design with three replications. Treatments include phosphorous fertilizer as super phosphate in three levels (0, 50 and 100 mg/kg) and humic acid in three levels (0. 0.5 and 1 gr/kg soil), phosphorous and humic acid application ways. Humic acid and phosphorous treatments were mixed in various forms including simultaneous mixing of humic acid and phosphorous fertilizer in the soil matrix, application of humic acid and phosphorous via irrigation water and coting of phosphorous fertilizer via solid humic acid before soil application. Then 10 canola seeds were planted in each pot at 2-cm depth which were declined to 4 plants in each pot after emerging and greening phases. At the end of the growth period (158 days), the plants were harvested. Determination of phosphorus concentrations of plant extracts by molybdenum vanadate or yellow method and chlorophyll content (a, b and ab) and carotenoids were measured precisely before harvesting using Barnes method. After harvesting the plants, the soil was immediately air-dried and passed through a 2mm sieve. Then, the amount of phosphorus was determined by sodium-DTPA and sodium bicarbonate. The statistical results of the data were analyzed using SAS software and LSD test (at 5% level) was used for comparing the mean values.
Results and Discussion: The interactions of humic acid and phosphorus and its application methods were significant for all measured traits at the 5% level. The results of the triple effects of humic acid levels and its application at the presence of phosphorus treatments showed that the highest chlorophyll (a, b and ab) and carotenoid content was obtained at 100 mg/kg phosphorus and 1 g/kg humic acid along with irrigation water. The highest concentration of plant shoot phosphorus with an average of 0.30% was observed in 1 g/kg humic acid with irrigation water at the level of 100 mg/kg phosphorus, although had no significant difference with 0.5 g/kg of humic acid with irrigation water. Maximum amount of P was extracted by Olsen method with the mean of 16.14 mg/kg and Soltanpour and Schwab method with the mean of 5.24 mg/kg obtained in 100 mg/kg phosphorus and 1 g/kg soil humic acid application. There was a significant correlation between the phosphorus extracted by Olsen method and Soltanpour and Schwab method (r = 0.95), which was significantly correlated with concentration of phosphorus (r = 0.84) and (r = 0.85) (P<0.05). There was also a significant correlation between fresh and dry above-ground biomass, types of chlorophyll (a, b and ab) and carotenoids with phosphorus extracted by Olsen and Soltanpour and Schwab methods at 5% significance level.
Conclusion: P adsorption capacity is a function of many factors. Application of phosphorous fertilizers in calcareous soils, due to the presence of calcium with high activity, results in the formation of calcium phosphates, which becomes insoluble, over time. Humic material in interaction with phosphorus in the soil can reduce phosphorus stabilization and increase plant available phosphorus. The results of this study showed that the use of phosphorus with humic acid, rather than the use of phosphorus alone, could increase the available phosphorus in the soil and also the phosphorus concentration within the plant.
Hassan Mir; Ahmad Gholamalizadeh Ahangar; Noshin Mir
Abstract
Introduction: Increasing the production rate became considerable for farmers in various ways. Modern technologies, such as biotechnology and nanotechnology could play an important role in increasing the production and improving the quality of agricultural products. Research into the direct application ...
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Introduction: Increasing the production rate became considerable for farmers in various ways. Modern technologies, such as biotechnology and nanotechnology could play an important role in increasing the production and improving the quality of agricultural products. Research into the direct application of nanotechnology into agriculture is set to increase in the future. One of the most remarkable plant growth factors is its nutrition. Titanium plays a beneficial role in increasing and stimulating plants growth. Titanium's usage in nutrition solution or spraying on the plant will increase the biomass and growth of different plant species. With respect to Nano technology enhancement in recent years the application of nano-particles is increasing. All the positive effects of titanium dioxide depend on its ability to absorb light and the main disadvantages of this combination are the low ability to absorb visible light from the sun and absorbing more UV light. It is possible to improve its effectiveness due to the high proportion of sunlight in the visible range by absorbing the visible light of nano-particles. To achieve this goal a layer of color will be added on the surface of the nanoparticles, which is called the nanoparticle sensitization by color. Due to the absorption of light by titanium dioxide nano-particles, especially ultraviolet radiation, it is assumed that the creation of a color layer on these nano-particles increases the antibacterial and fungal properties of these nanoparticles. As a result, the goal of this experiment is to investigate the possible increase in light absorption and increase the yield of the sorghum plant by titanium dioxide nano-particles of Dye-Sensitized, which, some of the parameters were investigated by treating the seeds of the plant with both nanoparticles.
Materials and Methods: This research was performed in three replications in a completely randomized design with factorial arrangement and with 12 treatments containing 6 concentrations of titanium dioxide nano-particles (0, 1, 10, 50, 100 and 500 mg.L-1), 6 concentration of titanium dioxide nanoparticles of Dye-Sensitized (0, 1, 10, 50, 100 and 500 mg.L-1). Fresh and dry weight of plants, plant nutrients content (Phosphorus, Potassium, Manganese, and Zinc), activity of ascorbate peroxidase and guaiacol peroxidase and chlorophyll content parameters have been measured.
Discussion and Results: The saffron compounds have significant peaks in the UV-Vis spectrum. The spectrum of titanium dioxide nanoparticles has a specific peak in the ultraviolet range (Area between wavelengths of 200-400 nm) however there is no trace of absorption in visible areas. The spectrum of the saffron solution has two identifiable peaks at 328 and 258 nm, and a double peak at 466 and 442 nm. The observed peak at 258 nm is related to the combination of Picrocrocin, which is the same colorless bitter substance found in saffron. The dual peaks range between 400-500 nm and the peak appearing at 328 nm are related to the carotenoids found in saffron. Crocin also has similar peaks which are likely to be overlapping with trans-isomeric peaks and not separable. The Spectrum of titanium dioxide nano-particles covered with saffron color also represents two peaks at 322 and 260 nm, and a peak at 430 nm with a specific shoulder at 458 nm. What comes from the comparison of two saffron peaks alone and saffron coated on titanium dioxide nano-particles is that the Crocin molecules contained in saffron are attached to nano-particles. According to the results, dry weight and enzymatic activity of Guaiacol peroxide and Ascorbate peroxide showed a significant increase compared to the control and had the highest performance respectively at concentrations of 10, 100 and 500 mg.L-1of titanium dioxide nano-particles of Dye-Sensitized, and showed 1.25, 2.7 and 3.28 fold. The amount of plant nutrients such as phosphorus, potassium, manganese, and zinc at concentrations of 10, 100, 500 and 50 mg.L-1titanium dioxide nanoparticles of Dye-Sensitized had a 72.34, 42.85, 73.95 and 28.17 percent increase, except fresh weight and chlorophyll a. Chlorophyll a at a concentration of 500 mg.L-1of both nano-particles showed the highest amount, but the fresh weight, unlike other parameters, showed the best performance with normal nanoparticles.
Conclusion: It seems that these nano-particles, by coloring, intensify light-related reactions compared to normal nano-particles, which results in better performance.
Taleb Nazari; mojtaba barani; Esmaeil dordipour; Reza Ghorbani nasrabadi; Somayeh Sefidgar shahkolaie
Abstract
Introduction: Fe is the first identified micronutrient for crops and required in higher amount than other micronutrients. Fe plays important roles in enzyme metabolism, protein metabolism, chlorophyll construction, chloroplast evolution, photosynthesis, respiration and reduction-oxidation reaction as ...
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Introduction: Fe is the first identified micronutrient for crops and required in higher amount than other micronutrients. Fe plays important roles in enzyme metabolism, protein metabolism, chlorophyll construction, chloroplast evolution, photosynthesis, respiration and reduction-oxidation reaction as well as organic acids metabolism. Iron, as an essential micronutrient, has great contribution in important antioxidant enzymes activity and through which affects plant tolerance against environmental stresses. Plant enzymes including superoxide dismutase, catalase and glutathione peroxidase are among the most important enzymes scavenging the hydrogen peroxide have iron in their structure, so they affected by iron deficiency. In this study, the effect of soil, foliar and fertigation application of humic acid on iron availability, chlorophyll types and superoxide dismutase, catalase and glutathione peroxidase enzymes in canola (Hyola 308) were evaluated.
Results and Discussion: Results showed that highest total iron content in plant leaves was obtained in 0.4 percent foliar application and the lowest was belonged to control treatment. Highest iron content in plant stem and active iron was obtained in humic acid application through irrigation at 2000 mg L-1 by 85 and 44.86 mg kg-1, respectively, and lowest amounts were obtained in control by 54.62 and 20.40 mg kg-1. Also, greatest concentration of chlorophyll a, chlorophyll b and total chlorophyll were recorded under0.4 percent humic acid foliar application by 3.58, 1.79 and 5.37 and the lowest chlorophyll contents were associated to control. Highest activities for plant enzymes superoxide dismutase and glutathione peroxidase were obtained under0.1 percent foliar application of humic acid by 4.20 and 1.95 (Iu/gr. FW) and the highest activity for catalase enzyme by 4.46 Iu/gr FW in 1000 mg L-1 humic acid through was irrigation and the lowest enzyme activity obtained in control treatment. Findings showed that application of various levels of humic acid increased plant enzyme activity compared to control in all of three application method (soil, foliar and application through irrigation water). Increasing humic acid concentration decreased enzyme activities. Also, there was negative correlation between activity of plant enzymes and concentation of chlorophyll types and active iron.
Conclusions: Active iron and antioxidant enzymes represent iron status within cell cytoplasm. Based on the results of this study, active iron concentration and activity of antioxidant enzymes are appropriate indices for evaluating plant tolerance to iron deficiency compared to assessing total iron content in leaves.
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 ...
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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%.
