نشریه مدیریت خاک و تولید پایدار
سال یازدهم شماره 4 (پیاپی 38، زمستان 1400)

One of the serious problems of biological communities is environmental pollution caused by heavy metals due to increase of industrial activities regardless of environmental considerations. According to the nature of these contaminants and considerable persistence in environmental components, especially soil, modification of contaminated soils to mitigate the negative effects of these contaminants on plants as a food chain initiator, is necessary. Considering the importance of using waste to recover them and also the different reaction of mycorrhiza in the face of heavy metals, this study aimed to investigate the effect of eggshell and mycorrhiza on changes in hazard index in basil plant.

This experiment was conducted in factorial completely randomized design consist of soil factors (non-contaminated, contaminated), eggshell waste (0, 3 and 5% w/w) and mycorrhiza (non-inoculated, inoculated with combined Funneliformis mosseae and Rhizophagus irregularis) in 3 replications (36 experimental units). Basil (Ocimum basilicum L.) was selected as an experimental plant due to its high leaf area and production of suitable dry matter. Finally, growth parameters, concentrations of zinc, copper, lead and cadmium in the plant tissue, transfer coefficient, translocation factor, hazard quotient and hazard index of the plant were evaluated.

Increasing the level of soil pollution reduced the height of the shoot by 54% and the fresh weight of the shoot by 70%. The use of eggshell waste by 5% w/w as compared to the control treatment in contaminated soil caused 32% increase in plant shoot height and 16.5% increase in fresh shoot weight. In contrast, root inoculation increased shoot height by 25.7% and shoot fresh weight by 4.47%. A relatively similar trend was observed in case of shoot and root dry weight. Under soil contamination conditions, application of 5% of eggshell waste reduced the amount of zinc, copper and cadmium in the shoots of the plant by 11.7%, 4.16% and 16.7%, respectively. In contaminated soil, application of mycorrhiza caused a significant reduction in concentration of zinc, copper, lead and cadmium in the shoots by 33.8%, 2.87, 25.9% and 43.3%, respectively. In contaminated soil, the highest hazard index (2.14) was observed in the treatment without eggshell and not inoculation with mycorrhiza. Because of eggshell application at the rate of 5% and mycorrhiza inoculation, hazard index decreased by 14.9% and 36%, respectively. According to the results, the use of eggshell waste and mycorrhiza inoculation reduced the hazard index in the contaminated soil, which the effects were different according to the type of element. However, in the case of both treatments, according to the level of contaminants, the value of basil hazard index did not fall below the allowable level, so that in 5% eggshell treatment, the hazard index was 1.54 and in mycorrhiza inoculation treatment, 1.31 was reported. The lowest hazard index in contaminated soil (1.16) was observed in treatment of mycorrhiza inoculated along with 5% eggshell.

Basil cultivated in contaminated soil, despite the effectiveness of treatments in reducing the hazard index, was still at the risk of consumption. Considering the type and concentration of heavy metals in the optimal use of recycled materials such as eggshell waste as well as bioremediators such as mycorrhiza can be of particular importance.

Wind erosion is a serious problem in arid and semi-arid area. In order to control wind erosion , some technical measures should be focused on the soil surface. Straw checkerboard barrier method as a cheap, effective and easy technology plays an important role in trapping dust and reducing wind erosion. Therefore, the objective of this research was to study the effect of straw checkerboard barriers method on physicochemical properties of soil and probable reduction of dust in lands exposed to wind erosion of Shahrekord meadow.

Straw checkerboard barriers were arranged in 1 m × 1 m checkerboard pattern in January, 2018 in a part of the “Margh” meadow of Shahrekord, the capital of Chaharmahal and Bakhtiari province. Rice straw materials were buried in the soil to a depth of 15 cm horizontally and protruded 20 cm above the soil surface. The study was carried out on a 20 × 25 m land area. The same area was also dedicated for control as bare ground. In order to determine the role of this technique on the wind erosion and its control, vertical sediment traps with a circular cross section of PVC pipe (PVC), 5 sediment traps were randomly installed in the bare ground, 5 in the first area of the checkered barrier, 5 in the middle and 5 at the end of the barrier in the direction of the prevailing wind. Sampling began in late July and was performed every 30 days in five stages. The height of the trap was divided into four parts: 0-12, 12-24, 36-24 and 48-36 cm and the amounts of sediments collected in the installed traps were compared with each other. Wind speed and direction were also measured in the mentioned months and the wind rose was drawn subsequently. Data were analyzed in RCBD design with 5 replications. Sediment trap position was considered as the first factor in three levels and trap height class were considered as the second factor. Also, during two consecutive years after the establishment of straw checkerboard barriers, soil properties including aggregate stability, percentage of clay, silt and sand, organic carbon, total nitrogen, available phosphorus were measured.

Results showed that checkerboards reduced the amounts of sediments significantly. This trend was observed in the five sampling month especially for the traps at the end of the barriers. The wind speed in the collision of barriers decreased significantly with lower amounts of energy, resulted to lowest amount of sediment at the end of barriers. Amount of sediments in the first, middle and end area of the checkerboard barriers in July, August, September and October decreased with the height of the trap drawer. But in November the sediments increased till height of 24 cm that may be due to higher rates of winds and particle movements. The highest mean weight diameter of aggregates was observed in border of barriers which may be associated with significant increase in organic carbon in the borders. Organic carbon, total nitrogen and available phosphorus contents were affected by straw checkerboard barriers and increased in the borders. Fine particles of soil included silt and clay were increased inside the squares accounts for unloading of particles and or deposition of them from the air.

The establishment of straw checkerboard barriers reduced the amount of wind sediments significantly compared to the bare ground. On the other hand, effective particle stabilization and dust deposition increased in checkerboards. Also checkerboard improved the physicochemical properties and increase some nutrients might promising for better microclimate for plant establishment and growth, leading to biodiversity and sustainability return.

The efficiency of phosphorus (P) chemical fertilizers in agriculture is relatively low (5-25%). This has led to more P fertilizers’ application which not only increases production costs but also threatens the environment. Therefore, it was necessary to introduce suitable alternatives to replace part of these fertilizers consumption. Phosphate solubilizing bacteria have been identified as a promising option to reduce P chemical fertilizers’ application due to their ability to solve insoluble P in soil environment. These bacteria can assimilate part of the solubilized P, known as the microbial biomass P. This mechanism allows natural ecosystems to be self-sustainable, without the application of phosphate fertilizers. Given the role of potent bacterial strains in dissolving insoluble phosphates and the importance of microbial biomass P in providing part of the plant needed P in the long term, this study was aimed to select efficient strains by quantitative measurement of dissolved P and microbial biomass P after inoculation of bacteria in sperber medium with different phosphate sources.

This study was conducted as factorial experiment in a completely randomized design format using two factors in three replications. The first factor was bacteria inoculation including strains: Curtobacterium flaccumfaciens Tkd/4, Pantoea agglomerans Ggd/4 and Sphingobium yanoikuyae Rpd/4, all isolated from Giroud Shemshak Phosphate mine, Bacillus pumilus RPY isolated from Yazd Asfordi Phosphate mine, Pseudomonas putida Ps/14 prepared from Soil and Water Research Institute (isolated from maize farm soil) and blank (contains phosphate sources without bacteria inoculation) and the second factor was three phosphate sources: tricalcium phosphate (TCP), calcium phytate (CPhy) and phosphate main soil (PMS). The measured traits were included pH, EC, dissolved P and microbial biomass P. Total solubilized P from the phosphate source (sum of dissolved P and microbial biomass P), the ratio of dissolved P to microbial biomass P and biosorption percentage of P were calculated as well.

The effect of bacteria strain, posphate source and their interactions was significant on all measured traits (P ≤0.01). The ability of Ps/14 strain to dissolve phosphate was higher than other strains in all three phosphate sources. All strains absorbed more phosphorus from TCP than the other two phosphate sources. Microbial biomass P was higher in phosphate soil treatments inoculated with all strains except Tkd/4 strain than in CPhy treatments inoculated with those strains. The lowest pH (3) and the highest EC (1.53 dS m-1) were observed in the PMS and TCP treaments inoculated with Ps/14 strain, respectively.

The studied strains had different effects on both dissolved P and microbial biomass P properties from different P sources. The ability of Ps/14 strain to dissolve P from all three phosphate sources was higher than the other strains. The results revealed that the strain that has more potential in dissolving P from one source does not necessarily have the same potential in assimilating P from the same source. This can be attributed to the solubility nature of material and the solubilizing capability of the microorganisms. The results of this study also showed that the total solubilized P could be more strongly attributed to dissolved P rather than microbial biomass P. Overall, the results showed that the potent of some of the studied bacteria in both dissolved P and microbial biomass P properties can be considered as a promising option in reducing the application of P fertilizers and increasing their effectiveness.

Potato is the fifth agricultural crop in the world that is an origin of carbohydrates, proteins and essential amino acids for humans. Agricultural inputs have special performance in increasing the quality and quantity of potatoes. But, the excessive use of chemical fertilizers sometimes leads to many health and biological problems. Useful soil microorganisms can have special efficiency in improving plant growth, harvesting agricultural products and subsequently reducing its costs. In addition to physical and chemical properties, soil condition is closely related to its biological properties. The aim of this study was to investigate the application of 10 strains of potassium, phosphorus and iron solubilizing bacteria on the growth parameters of Geely potato cultivar and to produce Geely’s healthier product.

The research was done in the greenhouse of Hamadan Agricultural Research Center in 1398. It was conducted in a completely randomized design with three replications. The treatments included 10 identified potassium, phosphorus and iron solubilizing bacteria, 1 Potabarvar biofertilizer and 1 control treatment (without any biofertilizer and bacteria). The measured traits were tuber wet weight, number of tubers, biological production, plant height, root dry weight, shoot dry weight, dry matter percentage, concentrations of phosphorus, potassium, iron and zinc in roots, shoots, tubers and soil.

The results showed that the application of potassium, phosphorus and iron solubilizing bacteria increased the growth parameters of the potato plants, the uptake of phosphorus, potassium, iron and zinc by potatoes significantly. The most efficient bacterium in this study was Pseudomonas frederiksbergensis that was more potent than other bacteria for most plant growth parameters and nutrient uptake . For this treatment, root dry weight was obtained 17.66 g/pot, which was 103.92% higher than the control. By the treatment with this bacterium, the maximum shoot dry weight was 47 g/pot which was 88% higher than the control. The concentrations of zinc in roots, and phosphorus, potassium, iron and zinc in shoots, that were obtained from inoculation with Pseudomonas frederiksbergensis, were 0.034, 6.666, 333.16, 460, 0.041, 3.86, 24.20 mg/kg, respectively; These values showed significant differences with the control and other treatments. In this study, Enterobacter ludwigii and Brevundimonas vesicularis were the most inefficient bacteria.

The results of the study showed that application of potassium solubilizing bacteria as biofertilizers can improve plant growth and increase its performance. It can be said that the use of biofertilizers along with chemical fertilizers might be helpful to reduce environmental pollution and to decrease costs.

Overused chemical fertilizers not only is associated with negative impacts on the environment and human health, but also by reducing of agricultural lands yield and crops quality. Therefore, the combined use of organic fertilizers with chemicals ones has been considered as a method of integrated plant nutrition management. The objective of this study was to investigate the effect of separate and combined application of different organic, biological and chemical fertilizers on the concentration of nutrients in the seeds and leaf of transplanted rapeseed (Brassica napus L.) and soil under cultivation.

An experiment in a randomized complete block design with eleven treatments and three replications in the field crop year 2019-2020 on the lands of the Iraqi Agricultural Research Station (IARS) in Gorgan (Gorgan, northern Iran) was performed. Treatments included: 1) Control (T1), 2) NPK chemical fertilizer (T2), 3) NPK+Fe+Zn chemical fertilizers (T3), 4) poultry manure (T4), 5) Compost (T5), 6) Biofertilizer + Fe and Zn chemical fertilizers (T6), 7) NPK chemical fertilizer+ humic acid (T7), 8) 50% poultry manure + 50% Compost + 50% NPK+ Fe and Zn chemical fertilizers (T8), 9) 25% poultry manure + 25% Compost + 100% NPK + Fe and Zn chemical fertilizers (T9), 10) 50% poultry manure + 50% Compost + 50% NPK + Fe and Zn chemical fertilizers + Biofertilizer (T10) and 11) direct sowing of seeds + NPK chemical fertilizer (T11). At the end of the cultivation period, macroelements (N, P, K) and microelements (Fe and Zn) in plants and soil were measured.

The results showed that the application of biofertilizer + Zn + Fe (T6) increased the production of N and soil phosphorus, and decreased pH and EC and the combined application of organic and biofertilizers with chemical fertilizers (T8, T9 and T10) increased the availability of K, Fe and Zn in soil. Also, application of biofertilizer + Fe + Zn (T6) caused a significant increase (P<0.05) in N, P, K and Zn on the leaf and also the content of N, P and K of seed compared to other treatments and control by the lowest amount of these elements. Concentrations of Fe in rapeseed leaf and seeds increased significantly (P<0.05) compared to the control treatment with the combined use of organic and biological and chemical fertilizers (T8, T9 and T10).

T6, T8, T9 and T10 treatments were the most effective treatments in increasing nutrient production and nutritional needs of rapeseed. Therefore, the combined application of chemical fertilizers with organic and biofertilizers probably due to the improvement of physical conditions, biodiversity and availability of plant nutrients, caused soil fertility, environmental health and rapeseed nutritional needs.

The demand for wheat as the most important grain used by humans is increasing. Due to climate change and improper soil and water management, salinity stress reduces wheat yield. The use of plant growth promoting rhizobacteria is a nature-friendly way to reduce the effects of salinity stress on wheat yield. The aim of this study was to evaluate the effect of plant growth promoting bacteria isolated from the rhizosphere of several saline plants in Yazd province on total biomass and yield components of wheat (var. Ghods).

Plant growth promoting characteristics and salinity resistance of bacteria isolated from rhizosphere of Atriplex lentiformis, Seidlitzea rosmarinus, Tamarix ramosissima and Halostachys belangeriana were investigated. Wheat seeds were inoculated with superior bacteria including Bacillus safensis, B. pumilus and Zhihengliuella halotolerans and after planting in the pots in greenhouse conditions was irrigated with water with salinities of 4, 8, and 16 ds/m.

All three bacteria were able to produce auxin. The highest amount of auxin production was measured in B. safensis (29.72 μg / ml). All three bacteria were able to produce hydrogen cyanide and the highest amount of hydrogen cyanide production was observed in Z. halotolerans with grade 5 (very high). All three bacteria were able to produce siderophore. ACC deaminase production was observed in all three bacteria and the highest amount was measured in B. pumilus at 8 μg / ml. Ability to dissolve phosphate in Z. halotolerans was more than twice that of B. safensis. Salinity reduced all the measured indices in wheat. In bacterial inoculated treatments at all salinity stress levels (4, 8 and 16 ds/m), the average of total biomass, amylose and amylopectin increased up to 52.5, 21.3 and 10.3%, respectively, compared to the average of these indices in control treatments (without bacteria) in the same salinity levels. Also, bacteria in these levels increased spike weight, seed weight and number of seeds up to a maximum of 22, 74.6 and 66.6%, respectively, compared to the control (without bacteria) of these salinity levels.

the plant growth promoting bacteria increased yield components of wheat under salinity stress, therefore to reduce the effects of salinity on wheat under saline irrigation conditions; the bacteria studied in this experiment can be used. Z. halotolerans was more efficient than other two bacteria in all of the studied indices. Since the experiment was performed under greenhouse conditions, it is recommended that this experiment be performed in the field.

The existence of agricultural wastes, especially wood and degradation-resistant wastes and time-consuming composting of these residues, shows the importance of using degrading microorganisms as bioactivators. By inoculating microorganisms into hard-to-decompose agricultural residues, it is possible to increase their composting rate and produce quality compost. The aim of this study was to isolate, identify and determine the efficacy of cellulolytic and ligninolytic bacteria and fungi.

Samples were taken from semi-rotten tissues of trees, organic matter including compost, vermicompost, animal manure, animal samples such as termites, earthworms, amur fish and commercial samples containing bioactivators. In order to isolate bacterial and fungal isolates with the ability to produce cellulose and ligninase enzymes, after preparing a series of dilutions from the extracts of each sample, culture was performed on common culture media. After purification of bacteria and fungi, the efficiency in terms of cellulase and ligninase activity was determined by measuring the diameter of the transparent halo on specific culture media. Molecular identification of selected bacterial and fungal isolates was performed by amplification of 16S rDNA region and ITS1-5.8S-ITS2 region, respectively.

A total of 83 bacterial isolates and 18 fungal isolates capable of producing cellulase were identified. BB12 and CCB9 isolates showed the highest cellulase activity with a ratio of halo diameter to colony diameter of 9.5 and 7.5, respectively. In fungal isolates, the highest cellulolytic activity was related to WF2 and WF4 isolates; the ratio of halo diameter to colony diameter in each of these two isolates was 4.57 and 2.4, respectively. Regarding ligninolytic activity, it was found that Chapak culture medium containing one gram of methyl blue is the best medium to study ligninolytic activity and the highest ratio of halo diameter to colony diameter in Chapak medium was in WB6 and WB5 bacterial isolates, respectively in the amount of 10 and 7. In fungal isolates, ligninolytic activity was observed only in WF2 and WF4 isolates; So that the ratio of halo diameter to colony diameter was 2.17 and 2, respectively. The results of molecular identification showed that the selected bacterial isolates were most similar to Bacillus halotolerans, Bacillus siamensis, Bacillus paralicheniformis, Bacillus subtilis, Bacillus atrophaeus, Bacillus amyloliquefaciens, Bacillus circulans, Bacillus sercatus, Bacillus sp. The fungi were more similar to Penicillium corylophilum and Pseudogymnoascus pannorum. The maximum parsimony tree with 1000 bootstrap replications showed that bacterial and fungal isolates were located in 9 and 2 clades, respectively.

Examination of cellulolytic activity showed that Bacillus amyloliquefaciens showed the highest amount of cellulolytic activity and the highest ligninolytic activity was seen in Serratia marcescens. In fungal isolates, the highest cellulolytic and ligninolytic activities were observed in Penicillium corylophilum and Pseudogymnoascus pannorum. Based on the results of this study, further investigation is suggested about the possibility of using a combination of selected microorganisms to prepare initial formulations for faster conversion of agricultural waste into compost.

Rhizobium is terrestrial bacteria that can coexist and form nodules in the leguminous family. The legume-rhizobia symbiosis results in great quantities of nitrogen fixation throughout the world. Rhizobial populations become non-target microbiomes for the herbicide applied in the field. Various herbicides such as Trifluralin and Imazethapyr can affect legume-rhizobia symbiosis negatively or in hermetic way. Hormesis is a dose-response relationship phenomenon characterized by a low-dose stimulation and a high-dose inhibition. This study aimed to investigate the effect of Imazethapyr and Trifluralin herbicides at two pH value (5.5 and 7) on the growth of Mezorhizobium ciceri at in vitro conditions.

To investigate the effect of Imazethapyr and Trifluralin herbicides on M. ciceri bacteria, an experiment was conducted as a completely randomized design in Gonbad Kavous University. M. ciceri strain were grown and maintained on yeast extract mannitol agar medium. Yeast extract manitol broth medium was used at two pH equal to 5.5 and 7. Moreover, Imazethapyr (0.021, 0.042, 0.084, 0.168, 0.336, and 0.672 g.L-1) and Trifluralin (0.337, 0.675, 1.35, 2.7, 5.4, and 10.8 g.L-1) herbicides accompanied with no-herbicide control added to the medium containing of 105 cell.ml-1 of M. ciceri at in vitro condition and the measurement of bacterial population was calculated at 600 nm light absorption, using spectrophotometer. The experiment was carried out with 4 replications and repeated two times. Population trends at different herbicide were fitted using three and four parameters logistic models and the Brain-Cousens equation was used when the hormesis response was observed.

The bacterial population of M. ciceri affected by Imazethapyr and Trifluralin concentrations in pH=5.5 followed the three parameter logarithm logistic model and in pH=7 followed the five parameter Brain-Cousense model. The maximum bacterial populations in pH=5.5 and pH=7 were 22.8×106 from zero concentration and 378.5×106 from 0.021 dose of Imazethapyr, respectively. At 0.021 and 0.042 g.L-1 of Imazethapyr doses, the bacterial population increased by 25.6% and 10.25%, respectively, compared to the control, which indicates the bacteria's hormetic behavior. The amount of hormesis in Trifluralin from doses (0.337 and 0.675 g.L-1) was recorded equal to 1.01×108 cell.mL-1. The increasing percentage of bacterial population from these doses compared to the control was 20.92 and 16.14, respectively. The value of “e” parameter, which indicates the amount of herbicide required for 50% reduction of the bacterial population, in pH=5.5 was obtained from Imazethapyr equivalent to 1.03 10-1 g.L-1 and from Trifluralin equal to 2.93 g.L-1.

This study showed statistical evidence of M. ciceri growth stimulation against minimum doses of Imazethapyr and Trifluralin in neutral acidity as Hormesis. This bacterium's population growth reaction in both herbicides under acidic conditions followed the logarithmic logistic model, and no hormesis was observed. In general, with increasing the dose of herbicides used in this experiment, M. ciceri bacterial population growth decreased. However, depending on the culture medium's pH, the bacterial reaction process was different so that in neutral acidity and sub-lethal doses was accompanied by an increase in population growth and then as the doses increased the growth rate decreased.