The yield potential and growth responses of licorice (Glycyrrhiza glabra L.) to mycorrhization under Pb and Cd stress.

The effects of mycorrhization (inoculation and non-inoculation) on growth and quality of two ecotypes (Baft and Ramjerd) of Glycyrrhiza glabra L. under heavy metals stress (0, 300 Pb + 20 Cd (H1) and 600 Pb + 40 Cd (H2) (mg kg-1) was investigated. Higher concentration of heavy metals decreased shoot dry weight in Baft (7.05%) and Ramjerd (43.34%) than control. Root dry weight increased in mycorrhizal Baft (28.23%) and Ramjerd (31.84%) ecotypes under H2 than non-mycorrhizal plants. In mycorrhizal plants, root colonization percentage decreased 37.07% in H2 than control. Increasing heavy metals concentration led to increase of total antioxidant activity and total phenol content. Mycorrhizal Ramjerd showed the lowest shoot Pb concentration in both heavy metals concentrations and the highest root Pb concentration (107.25% higher than non-mycoorhizal one) in H2. For both ecotypes, the lowest shoot Cd concentration observed in mycorrhizal plants under H1 and mycorrhizal plants had more root Cd concentration (33.83 mg kg-1 dry matter) than non-mycorrhizal ones. In both concentrations of heavy metals, the lowest Pb (0.026) and Cd (0.153) translocation factor (TF) observed in mycorrhizal plants. Based on the results, licorice with TF< 1 is not a hyperaccumulator plant but stabilizes Cd and Pb in root. Novelty statement: Licorice is a well-known medicinal plant that its root and rhizome contains diverse applications in pharmaceutical and food industries. The main source of licorice supply is through harvesting from natural habitats of Iran (one of the first exporters of licorice in the world), which during the last years have been exposed to heavy metals contamination. Therefore, the growth response of the plant in polluted habitats and most importantly, the concentration of heavy metals especially in belowground parts of the plant need more consideration. Hence, this research was carried out with an objective to investigate growth and yield potential response of two ecotypes of licorice to mycorhization under heavy metal stress (Cd and Pb) and the mechanism of heavy metal management in above and belowground parts of licorice in order to achieve its potential for further sustainable phytoremediation programs and most importantly considering the heavy metal accumulation in rhizomes and roots in accordance with world standards for medicinal and edible consumption.

Investigation of Different Selenium Sources and Supplying Methods for Selenium Enrichment of Basil Vegetable (A Case Study under Calcareous and Non-calcareous Soil Systems).

BACKGROUND: Selenium (Se) is a crucial component of selenoaminoacids and selenoproteins. Therefore, Se-enriched agricultural products can reduce health complications induced by Se deficiency. OBJECTIVE: This research was carried out to investigate the effects of Se bio-enrichment on Basil grown in calcareous and non-calcareous soil systems and also to evaluate the changes in Se concentration in the soil after harvesting. METHODS: The experiment executed in two calcareous and one non-calcareous soil systems, and different Se application methods (control, soil application, seed inoculation, foliar application, and soil + foliar application) were administered. Selenobacteria, a plant growth-promoting rhizobacteria (PGPR), derived from the soil was used as a biofertilizer, compared to the other Se sources. RESULTS: The results showed that both soil types and the methods of Se application had significant effects (P ˂ 0.01) on root and shoot dry weights and concentrations of P, K, Zn, Fe, and Se in both of the root and shoot. Shoot dry weight of plants treated with foliar Se was maximum in the calcareous soil. Compared to the control treatment, foliar application of Se increased shoot Se content in both calcareous and non-calcareous soils by 242% and 204%, respectively. Furthermore, the increase in shoot Se concentration in calcareous soil induced by Se application increased the concentration of other nutrients in the shoot and root. Plant growth parameters and concentrations of nutrients were significantly increased by using selenobacter inoculum. CONCLUSION: The application of Se-containing compounds can improve vegetable quality. Considering the daily requirement of the human body for minerals and nutrients, enriching basil with Se can play an important role in community health. Moreover, some patents have reported the effectiveness of endophyte bacteria.

The potential use of Cordia myxa in the remediation of crude oil pollution.

This study investigated the effects of hydrocarbon-degrading bacteria and organic matter on a crude oil-polluted soil by Cordia myxa. The treatments consisted of crude oil at two levels (3 and 6% w/w), municipal waste compost at two levels (5 and 10% v/v), and two different bacterial strains (Pseudomonas sp.141 and Pseudomonas sp. 27ps). At the end of the growth period, the plants were harvested and prepared for the laboratory analyses. The greatest population of oil degrading-bacteria (4.6 × 106 CFU/g soil) was observed in the treatment containing 10% compost, 6% crude oil, and Pseudomonas sp.141. The highest crude oil degradation (76.49%) was recorded in the soil polluted with 6% crude oil, amended with 10% compost, and inoculated with Pseudomonas sp.141. The investigation on the degradation of the chains of C10-C35 compounds indicated that, in various treatments, the most abundant compound was among those with fewer carbon atoms (C12-C25), so the application of organic matter boosted the degradation of crude oil. In conclusion, C. myxa seedlings has an acceptable efficiency in the remediation of the oil-contaminated soil affected by biological factors (compost and Pseudomonas bacteria), which is because of their high tolerance to the pollution and their ability to penetrate deeper soil layers.

Phosphate-solubilizing bacteria and silicon synergistically augment phosphorus (P) uptake by wheat (Triticum aestivum L.) plant fertilized with soluble or insoluble P source.

Phosphorus (P) deficiency is one of the major problems in agricultural soils for crop production around the world. Use of silicon (Si) and phosphate-solubilizing bacteria (PSB) is known as one of the most effective and economical ways for increasing P availability and improving P use efficiency under low P conditions. However, little is known about the alleviative role of Si and PSB together in mitigating P-deficiency stress and in improving P use efficiency in Triticum aestivum L. (wheat), as one of the most important crop plants worldwide. Consequently, aim of the research was to study the combined and single effects of Si (0, 150, 300, and 600 mg kg-1 added as silicic acid) and PSB (B0, Bacillus simplex UT1, and Pseudomonas sp. FA1) on P uptake by wheat plant fertilized with soluble or insoluble P (Esfordi rock phosphate, RP) in a completely randomized design with factorial arrangement through a perlite potted experiment. In addition, the effects of various treatments on wheat shoot and root dry weight, activity of catalase, superoxide dismutase, and peroxidase enzymes, and the uptake of Si and potassium (K) by this plant were also investigated. Both shoot and root biomass of wheat plants were markedly reduced when grown in RP-fertilized medium compared with those grown in soluble P-fertilized medium. The PSB strains and Si levels independently improved all the aforementioned parameters. Application of Si to wheat plants grown in soluble P or insoluble P medium markedly enhanced P use efficiency. According to the results of this study, Si not only increased the uptake of P from sparingly soluble-P source (RP), but also enhanced uptake of P from water-soluble P source. Both Pseudomonas sp. FA1 and B. simplex UT1 showed a considerable role in improvement of root and shoot biomass and uptake of P (and K and Si) under both soluble and insoluble P fertilization conditions with Pseudomonas sp. FA1 being more effective than B. simplex UT1. However, the combined application of the PSB with Si resulted in the greatest enhancement in wheat plant P uptake and other measured parameters. Addition of 600 mg Si kg-1 and Pseudomonas sp. FA1 significantly increased the P shoot concentration of wheat plant fertilized with RP to an adequate level (>0.3%) in the range of P-fertilized plants. Therefore, in addition to PSB application, Si should be considered as soil amendment in agricultural soils deficient in plant available Si as a means of sustainable agriculture with respect to possible savings of scarce P resources (P-fertilizers). The information on the availability of P following PSB and Si addition to plant growth medium may help in better management of P fertilization.

Assessing the effect of industrial wastewater on soil properties and physiological and nutritional responses of Robinia pseudoacacia, Cercis siliquastrum and Caesalpinia gilliesii seedlings.

The main aim of this study is to investigate the physical and chemical properties, including soil salinity, acidity, concentrations of macro-nutrients (phosphorus, potassium, and Calcium-Magnesium) and sodium adsorption ratio to the soil, physiological and nutritional traits of three plant species including Caesalpinia gilliesii, Robinia pseudoacacia, and Cercis siliquastrum. First, some sample were taken from the agricultural soils irrigated with wastewater. The results of initial soil test revealed that the irrigation with wastewater significantly increased sodium adsorption ratio (SAR), electrical conductivity (ECe), cation exchange capacity (CEC) of the soil (p < 0.05). Secondly, the effect of industrial wastewater on the responses of three plants were investigated. According to the results, the highest shoot fresh weight was observed in C. gilliesii seedlings treated with T100%, which is 35% higher than the control treatment. The highest concentration of shoot phosphorus in the three plants was respectively 0.54, 0.72, and 1% in those treated with T100% and 0.41, 0.48, and 0.83% in the control treatment. The amount of shoot potassium in the three plants treated with T100% was respectively 0.84, 0.48, and 1%, while it was 0.43, 0.4, and 0.1 in the control treatment, respectively (p < 0.05). According to the current concerns about increased EC, SAR, and Na in C. gilliesii treated with T100%, as compared to the control treatment (50, 386, and 412), and the positive effects of wastewater on soil properties (CEC, pH, and K) and morpho-physiological responses of the plant, it is recommended to use wastewater with continuous monitoring to prevent the pollution of water and soil resource.