Improving Phosphorus Availability and Wheat Yield in Saline Soil of the Lake Urmia Basin through Enriched Biochar and Microbial Inoculation

To reduce requirements for conventional chemical fertilizer and alleviate salinity stress in soils, a glasshouse experiment was conducted to assess the effects of enriched biochar on phosphatase activity, microbial respiration and wheat yield in non-saline and saline soils from the Lake Urmia basin (electrical conductivities 2 dS.m(-1) and 15 dS.m(-1), respectively). Nine treatments were tested: control, 1:1 mixture of apple and grape biochars (BC), phosphate solubilizing bacteria (PSB), BC plus PSB (BC-PSB), BC plus rock phosphate (BC-RP), BC enriched by rock phosphate and bacteria (BC-RP-PSB), BC enriched by rock phosphate and HCl (BC-RP-HCl) or H3PO4 (BC-RP-H3PO4) and chemical fertilizer (TSP). The addition of enriched biochar decreased the soil pH (by 0.5-0.9 units) and increased available phosphorus (>7-fold). In both the saline and non-saline soils, the highest alkaline phosphatase activity was obtained for BC-H3PO4-RP and BC-HCl-RP. Wheat growth parameters were reclaimed after enriched biochar application, indicating superior dry matter yields compared to the control and non-enriched biochar treatments and significantly higher yields compared to TSP. Beneficial effects on soil pH, phosphatase activity, soil respiration and biomass yield demonstrated that enriched biochar could partly substitute chemical fertilizers and increase plant growth in salt stress conditions. However, further field studies are needed to understand the benefits of enriched biochar in different soils and climates

Impact of chlortetracycline and sulfapyridine antibiotics on soil enzyme activities.

Pharmaceutical antibiotics are frequently used in the livestock and poultry industries to control infectious diseases. Due to the lack of proper guidance for use, the majority of administrated antibiotics and their metabolites are excreted to the soil environment through urine and feces. In the present study, we used chlortetracycline and sulfapyridine antibiotics to screen out their effects on dehydrogenase, alkaline phosphatase and urease activity. Factorial experiments were conducted with different concentrations of antibiotic (0, 10, 25 and 100 mg kg-1 of soil) mixed with soil samples, and the enzyme activity was measured at intervals of 1, 4 and 21 days. The results show that the chlortetracycline and sulfapyridine antibiotics negatively affect the dehydrogenase activity, but the effect of sulfapyridine decreases with time of incubation. Indeed, sulfapyridine antibiotic significantly affect the alkaline phosphatase activity for the entire three-time interval, while chlortetracycline seems to inhibit its activity within 1 and 4 days of incubation. The effects of chlortetracycline and sulfapyridine antibiotics on urease activity appear similar, as they both significantly affect the urease activity on day 1 of incubation. The present study concludes that chlortetracycline and sulfapyridine antibiotics have harmful effects on soil microbes, with the extent of effects varying with the duration of incubation and the type of antibiotics used

Interactions between Biochar and Compost Treatment and Mycorrhizal Fungi to Improve the Qualitative Properties of a Calcareous Soil under Rhizobox Conditions

Most calcareous soils have relatively low levels of organic matter. To evaluate the effect of pruning waste biochar (PWB) and pruning waste compost (PWC) combined with arbuscular mycorrhizal fungi (AMF) on the biological indices, a rhizobox study on wheat using a completely randomized design was conducted under greenhouse conditions. The studied factors included the source of organic material (PWB, PWC, and control), the microbial inoculation (+AMF or -AMF), and the zone (rhizosphere and non-rhizosphere soil). At the end of the plant growth period, organic carbon (OC), microbial biomass carbon (MBC), microbial biomass phosphorous (MBP), microbial respiration (BR), substrate-induced respiration (SIR), and alkaline (ALP) and acid (ACP) phosphatase enzyme activities in the rhizosphere and non-rhizosphere soils were determined. Simultaneous application of a source of organic matter and AMF inoculation significantly increased the OC and biological indices of soil relative to those observed when applying organic matter without AMF inoculation. Additionally, MBC, MBP, ACP, and ALP enzymes activities in the rhizosphere zone were significantly higher than in the non-rhizosphere. AMF increased BR and SIR levels in the rhizosphere by 13.06% and 7.95% compared to those in the non-rhizosphere, respectively. It can be concluded that PWC and PWB can improve soil biological properties by increasing microbial activity

Potassium silicate counteracts salt-induced damage associated with changes in some growth characteristics, physiological, biochemical responses, and nutrient contents in two grapevines (Vitis vinifera L.) cultivars

This study investigates the effects of potassium silicate on the growth characteristics, physiological parameters, biochemical parameters, and nutrient content of two grapevine cultivars, 'Bidaneh Ghermez' and 'Sahibi Gird', under NaCl stress conditions. The plants were exposed to NaCl solutions with concentrations of 0, 40, and 80 mM in a hydroponic system. Additionally, the plants were treated with potassium silicate sprays at concentrations of 0, 50, 100, and 200 mg L-1. As NaCl levels increased, both 'Bidaneh Ghermez' and 'Sahibi Gird' cultivars exhibited reduced fresh and dry root weights. However, with potassium silicate application at 200 mg L-1, the rate of root dry weight loss was reduced to 28% and 66.4% for 40 mM and 80 mM NaCl treatments, respectively. The maximum total protein content (1.65 mg L-1 fresh weight) was detected at the 80 mM NaCl level and potassium silicate application at 50 mg L-1. The maximum ascorbate peroxidase activity was observed at a potassium silicate concentration of 50 mg L-1. Based on the results, increasing NaCl levels significantly boosted plant Na+ percentage. In treatments with 40 and 80 mM NaCl (without potassium silicate), nitrate levels decreased by 32.34% and 46.71%, respectively, compared to the control. The amount of leaf iron in the 40 mM salinity treatment increased and by 10.47% with potassium silicate at a concentration of 200 mg L-1. The findings confirmed the role of potassium silicate in modulating the negative effects of NaCl, although more investigations in different grapevine cultivars under NaCl stress are required in this field

Investigation of different methods in siderophore measurement in indigenous Fluorescent Pseudomonads

Introduction:Fluorescent pseudomonads produced a variety of siderophores in which the pyoverdine type siderophore is the main one. These bacteria employ siderophores to increase availability of Iron for their own and plants consumption. Siderophores have a special role in the biological control activity of these bacteria against plant pathogens. Materials and methods: Siderophore production was checked in 21 indigenous Pseudomonads strains, two reference strains and one Bacillus sp. strain by qualitative CAS-Agar, semi-quantitative CAS-AD and quantitative spectrophotometric methods. Results: Colony growth in some of isolates such as UTPF93 has been inhibited in CAS-Agar method because of the detergent compound HDTMA. So, siderophore production was low in these strains. All strains produced siderophore by the CAS-AD method. The highest and the lowest siderophore production were recorded in UTPF76 and UTPF45 with 1.005 and 0.0026 mM of defroxamin equivalent, respectively. The Pyoverdine mutant strain MPFM1 and the Bacillus sp. strain also produce low amounts of siderophore in two recent methods. So, these methods are non-selective to the type of siderophore. In quantitative method only Pyoverdine type siderophore was detectable and the strains MPFM1 and Bacillus sp. did not produce this type of siderophore. The highest amount of pyoverdine was recorded in non-indigenous strain 7NSK2 with 625.29 mM/L followed by UTPF65, UTPF81 and UTPF87. Discussion and conclusion: CAS-AD was the best method for total siderophore measurement and spectrophotometric was the accurate and efficient method for detection of pyoverdine type siderophore in fluorescent pseudomonads

Influence of PGPR Bacteria and Arbuscular Mycorrhizal Fungi on Growth and some Physiological Parameters of Onopordon acanthium in a Cd-Contaminated Soil

Introduction: Heavy metals (HMs) are serious threat for environment due to their dangerous effects. These metals as contaminants that can be accumulated in soil and after absorption by plants, finally will be found in food chains. Cadmium (Cd) is one of the dangerous HMs that threats the health of plants, living organisms and human. Physicochemical remediation methods may cause large changes in different characteristics of soils . Recently environmental-friendly strategies including phytoremediation have been emphasized by researchers. Phytoremediation that refers to the use of plants and their assistance with microorganisms for remediation of contaminated soils is an effective and low cost method for reclamation of heavy metals polluted soils. The most important limitation of phytoremediation is low availability of heavy metals and sensitivity of plants to contamination. There are evidences that soil microbes can help to overcome these limitations through several ways. Plant growth promoting rhizobacteria (PGPR) and arbuscular mycorrhizal fungi (AMF) are known to enhance plant growth and survival in heavy metal contaminated soils through different mechanisms including producing promoting metabolites, auxin, siderophore and antibiotics. In this study the role of some strains of PGPR (a mixture of Pseudomonas species including P. putida, P. fluorescens, and P. aeruginosa) and AMF (a mixture of Glomus species including G. intraradices, G. mosseae and G. fasciculatum), on uptake and accumulation of Cd, Fe, Zn and Cu as well as some physiological properties of Onopordon (Onopordon acanthium L) were evaluated. Materials and Methods:This study was carried out under greenhouse condition as a factorial experiment based on a randomized complete block design with two factors including Cd concentration (four levels) and microbial treatment (three levels) in three replications. Consequently, a soil was selected and spiked uniformly with different concentrations of Cd (0, 10, 30 and 100 mg Cd kg-1 soil) at greenhouse of agricultural college in Urmia University. The contaminated soils were then sterilized and subsequently inoculated with arbuscular mycorrhizal fungi (a mixture of Glomose species including G. intraradices, G. mosseae and G. fasciculatum) and plant growth promoting rhizobacteria (a mixture of Pseudomonas species includeing P. putida, P. fluorescens, and P. aeruginosa). The seeds of Onopordon plants were grown in 2.5 kilogram pots under greenhouse condition. At the end of growing season the shoot dry weight, Cd, Fe, Zn and Cu concentration and element contents and some of physiological parameters of plant as well as microbial properties were analyzed. Furthermore, the effect of soil Pb level on population, activity and efficiency of the inoculated microbes was studied. Results and Discussion: Significant difference was observed for plants’ dry weights. At different Cd levels, the yield of inoculated plants was higher than that of control plants. Furthermore, at elevated Cd concentration, plant height, biomass, relative yield, chlorophyll a, b, carotenoids, relative water content (RWC) decreased significantly (P < 0.05), however, plants inoculated with plant growth promoting rhizobacteria and arbuscular mycorrhizal fungi showed considerable amount of dry matter, chlorophyll a, b as well as RWC. Mycorrizal and bacterial inoculation and Cd treatment also had significant effect on leaf photosynthetic pigments concentration and plant relative water content. In general, concentrations of photosynthetic pigments and RWC were higher in inoculated plants at every level of soil Cd. The microbial inoculation effectively decreased the inhibitory effects of Cd on plant growth. Shoot yield of arbuscular mycorrhizal fungi and plant growth promoting rhizobacteria plants increased by 2.7 and 2.1 times as well as microbial respiration increased by 2.17 and 2.01 times compared to control treatment. The results showed inoculated plant absorbed more Cd than non-inoculated plants. Plant growth promoting rhizobacteria were more effective than arbuscular mycorrhizal fungi inoculation in shoot Cd concentration. Cd contamination reduced soil microbial population and basal respiration. Results showed that with increasing soil Cd concentration shoot Fe, Zn and Cu concentrations significantly decreased. Root colonization rates decreased significantly with 10 mg kg-1 Cd addition for AMF treatments, and drastically with 100 mg kg-1 Cd added. Plant roots in the control and PGPR treatment were not colonized. Conclusion: It is concluded that plant growth promoting rhizobacteria and arbuscular mycorrhizal fungi inoculation could be sustained and promoted plant growth in phytoremediation processes. Therefore, under Cd contamination it can be use PGPR and AMF as growth promoters and finally enhance phytoremediation efficiency

Effect of Air Pollution on Leaf Heavy Metals Concentrations (Fe, Cu, Zn and Mn) of Box Elder (Acer negundo) and Oriental Plane (Platanus orientalis) (Case Study: Urmia City)

Heavy metals are of most important environmental pollutants. Industrial activities and using pesticides are mainly causing environment to be polluted by these elements. This study aims to investigate the effect of air pollution on concentration of leaf heavy metals (Fe, Cu, Zn and Mn) of urban green space&rsquo;s trees and their tolerance in Urmia. For this purpose, leaf samples of Acer negundo and Platanus orientalies individuals were collected in August 2013 and May 2014 from five different regions with different level of air pollution and their heavy metals concentrations were measured. Regarding to increasing of air pollution in the second year comparing to the first year, the accumulation of most elements had been increased by the tree species. In general, P. orientalies was considered as more tolerable species comparing to A. negundo due to higher accumulation even more than permissible defined threshold. Studied species, also, had lower and higher accumulation in the control and polluted places respectively, so it could be possible to use these species to differentiate between the polluted and unpolluted areas. &nbsp

Salinity-induced differences in soil microbial communities around the hypersaline Lake Urmia

Lake Urmia in north-western Iran is one of the largest hypersaline lakes in the world, and agricultural production in the surrounding area is limited by soil salinity. We investigated the effects of salinity on belowground microbial communities in soils collected from fields of cultivated onions (Allium cepa L.) and lucerne (Medicago sativa L.), and sites with the native halophyte samphire (Salicornia europaea L.). We tested the hypotheses that salinity reduces microbial biomass and changes the structure of the microbial community. The physical and chemical properties of soil samples were analysed, and phospholipid fatty acids were identified as signatures for various microbial groups. We found that the organic carbon (OC) content was the dominant determinant of microbial biomass. We also found linear relationships between OC and the biomass of various groups of organisms across the wide salinity gradient studied. Salinity, on the other hand, caused changes in the microbial fatty acid composition that indicated adaptation to stress and favoured saprotrophic fungi over bacteria, and Gram-negative bacteria over Gram-positive. Principal component analysis showed that salinity variables and microbial stress indices formed one group, and OC and microbial biomass another. The importance of OC for high microbial biomass in severely stressed soils indicates that OC amendment may be used to mitigate salt stress and as a method of managing saline soils

Effect of Different Calcium Sources Application on Antioxidant, Enzymatic Activity and Qualitative Characteristics of Apple (Malus domestic)

In order to determine the effect of different Ca sources, in improving enzymatic activity and some qualitative properties of red apple (Malusdomestica) an experiment was carried out in a completely randomized design. Apple trees were sprayed 5 times with CaCl2, CaO, Ca-EDTA and Ca(NO3)2 salts with an interval of 20 days from late June until early October. After harvesting fruits were kept in cold storage at standard condition for 150 days. Nitrogen, phosphorus, potassium, calcium, magnesium, ascorbic acid, total soluble solids, firmness, total acidity, catalase enzyme activity and total antioxidant activity at harvest time, 50, 100 and 150 days after cold storage were measured. The results showed that the effect of foliar application on catalase enzyme activity, total antioxidant, pH, soluble solids, total acidity, calcium, firmness and ascorbic acid was significant. At the end of storage period, calcium amount of fruits at the presence of Ca-EDTA, CaCl2, Ca(NO3)2 and CaO treatments increased by 77.5, 27.5, 22.3 and 10.1 percent, respectively. Catalase enzyme activity in Ca-EDTA treatment increased 91.8 percent after 150 days of storage compared to control. At the end of the storage period, the highest content of ascorbic acid was found in Ca-EDTA treatment (6.04 mg per 100 g FW). It is concluded that spraying of apple fruit with Ca-EDTA can improve and maintain most fruit qualitative properties and increase enzymatic and antioxidant activity during storage time.&nbsp