Soil fertility, chemical properties, and pollutant removal efficiency of Salicornia europaea in response to different times and duration of wastewater irrigation.

Halophytes are the good candidates in coastal saline areas which could be irrigated with wastewater. The purpose of this study was to evaluate the soil-water-plant system under control and wastewater irrigation (containing toxic elements and organic matter) at three durations (vegetative, flowering, and reproductive stages) and two exposure times (2 and 4 days in each stage). The results obtained in the experimental tests for wastewater irrigation indicated that the Salicornia is efficient for the removal of chemical oxygen demand (61%), biochemical oxygen demand (74%), total suspended solids (47.6%), and ammoniacal nitrogen (64%) at the reproductive stage. At the same time, the average nitrate concentration increased to 51.3 mg L-1 with more solids. Regardless of wastewater irrigation duration, irrigation with wastewater significantly increased organic matter, nitrogen, phosphorus, and potassium of the soil. The Mg2+ and Ca2+ contents in the aboveground biomass of the plants were also high ranged from 0.58 to 1%, and 0.43 to 0.68 mg g-1 DW, respectively. All the exchangeable cations other than Na+ were higher for wastewater irrigation at the flowering stage. Plants maintained noticeably higher Ca2+/Na+ and K+/Na+ ratios in the roots than those in the shoots except for 4 days after the reproductive stage. S. europaea is well adapted to grow in wastewater irrigation and can tolerate hypoxic conditions through improving water and soil quality.

The Salicornia europaea potential for phytoremediation of heavy metals in the soils under different times of wastewater irrigation in northwestern Iran.

The use of wastewater for irrigation usually leads to the buildup of potentially toxic elements (PTEs) in soils. The objective of this study was to assess the capacity of Salicornia europaea L. to uptake heavy metal when irrigated with wastewater at the vegetative, flowering, and reproductive stages of S. europaea for 2 and 4 days (in each stage) in the coastal saline area of Lake Urmia. The concentrations of heavy metals were detected in irrigated water, soil, and plant samples, while transfer factor (TF), bioconcentration factor (BCF), and bioaccumulation factor (BAF) were calculated. The results revealed that metal concentrations in the wastewater were above the permissible limits. The wastewater irrigation caused higher shoot biomass despite the high uptake of PTEs. Levels of Fe and Cu in plants were higher when irrigated with wastewater at the reproductive stage as compared to flowering and vegetative stages. The TF of wastewater-irrigated plants was higher at the flowering stage. TF of different metals at the flowering stage were in order of Zn > Pb > Ni > Cd > Cu, while the BCF increased in the order Cd > Cu > Zn > Ni > Pb. The BAF of the investigated PTEs at the flowering stage increased in the order Cd > Pb > Ni > Zn > Cu. In conclusion, higher Pb and Zn in the shoot indicated that the plant exhibited the phytoextraction mechanism, while Salicornia used a phytostabilization mechanism for roots-Cu, Ni, and Cd.

Improvement of the yield-related response of mycorrhized Lallemantia iberica to salinity through sulfur-oxidizing bacteria.

BACKGROUND: To investigate the effects of salinity as a serious environmental limiter of productivity on the yield-related traits of Lallemantia iberica, a split-plot experiment was performed for 2 years (2017-2018) based on a randomized complete block design with three replications at Urmia University (37°33'09″N, 45°05'53″E). The main plots included salinity stress at two levels (6.72 dS m-1 , and 0.91 dS m-1 as control), and subplots were inoculants at four levels (Funneliformis mosseae, Thiobacillus sp., F. mosseae + Thiobacillus sp., and no inoculation). RESULTS: In the saline condition, serious reductions in yield and yield components (numbers of capsules per plant, seeds per capsule, and seeds per plant, 1000-seed weight, seed and biological yields), concentrations of leaf phosphorus and potassium, and relative mycorrhizal dependency were observed, but against the harvest index the leaf sulfur and sodium contents were increased. Moreover, all morphological traits (plant height, number of branches and leaves, leaf weight, stem weight, and ratio of leaf weight to stem weight) were decreased under salinity conditions. Mycorrhizal inoculation enhanced the salinity-induced reduction of yield and morphological traits to some extent. Inoculation with Thiobacillus had superiority in some of the yield and morphological characteristics compared with those in the non-inoculated plants. CONCLUSION: Salinity stress can significantly affect the yield, morphological characteristics, nutrients content, and mycorrhizal dependency of L. iberica plants. This study exhibited the significant effects of single and simultaneous applications of F. mosseae and Thiobacillus on plant growth and yield in saline soils. © 2020 Society of Chemical Industry.

Mycorrhizal Fungi and Thiobacillus Co-inoculation Improve the Physiological Indices of Lallemantia iberica Under Salinity Stress.

Salinity, a serious environmental pressure on crop production, might be counteracted by free-living and symbiotic inoculants entailing positive synergistic effects. Enhancement in nutrient uptake and/or production of antioxidants under the stress condition, can improve plant growth and yield. In this study, inoculation of Lallemantia iberica with Funneliformis mosseae and the sulfur solubilizing bacterium (Thiobacillus sp. T95 and T40) was evaluated under two salinity levels (6.72 dS/m and 0.91 dS/m as control). The root colonization, spore density, seed and biological yield, total soluble sugars, and nutrients were reduced by salt stress. Antioxidant enzyme activity (catalase, superoxide dismutase, peroxidase and ascorbate peroxidase), proline, contents of sodium and sulfur have increased under salt stress. The enzyme activities as well as the concentrations of nitrogen, phosphorus, potassium, sodium, and sulfur were dropped at the flowering stage (75 days after sowing). Seed and biological yield, antioxidant enzymes activity, proline content, and nutrients were significantly improved in mycorrhizal treatments. Inoculation of Thiobacillus exhibited the positive effect on root colonization, spore density, enzymes activity, and nutrients. Bacterial treatments (dual and single) significantly increased the sulfur and total soluble sugars. Totally, the mycorrhizal plants accumulated more enzymatically produced antioxidants, osmolytes, and showed improved nutrient uptake. Our results provide new insights into the relationship among arbuscular mycorrhizal fungi (AMF), biosulfur bacteria, and plant growth under saline conditions. In conclusion, the Lallemantia iberica inoculation with mycorrhizal fungi, either alone, or in combination with Thiobacillus, is indicated for optimum plant yield through alleviation of the salinity stress.

Arbuscular mycorrhizal fungi and Pseudomonas in reduce drought stress damage in flax (Linum usitatissimum L.): a field study.

Drought stress, which is one of the most serious world environmental threats to crop production, might be compensated by some free living and symbiotic soil microorganisms. The physiological response of flax plants to inoculation with two species of arbuscular mycorrhizal (AM) fungi (Funneliformis mosseae or Rhizophagus intraradices) and a phosphate solubilizing bacterium (Pseudomonas putida P13; PSB) was evaluated under different irrigation regimes (irrigation after 60, 120, and 180 mm of evaporation from Class A pan as well-watered, mild, and severe stress, respectively). A factorial (three factors) experiment was conducted for 2 years (2014-2015) based on a randomized complete block design with three replications at Urmia University, Urmia, located at North-West of Iran (37° 39' 24.82″ N44° 58' 12.42″ E). Water deficit decreased biomass, showing that flax was sensitive to drought, and AM root colonization improved the performance of the plant within irrigation levels. In all inoculated and non-inoculated control plants, leaf chlorophyll decreased with increasing irrigation intervals. Water deficit-induced oxidative damage (hydrogen peroxide, malondialdehyde, and electrolyte leakage) were significantly reduced in dual colonized plants. All enzymatic (catalase, superoxide dismutase, glutathione reductase, and ascorbate peroxidase) and non-enzymatic (glutathione, ascorbic acid, total carotenoids) antioxidants were reduced by water-limiting irrigation. Dual inoculated plants with AM plus Pseudomonas accumulated more enzymatic and non-enzymatic antioxidants than plants with bacterial or fungal inoculation singly. Dual colonized plants significantly decreased the water deficit-induced glycine betaine and proline in flax leaves. These bacterial-fungal interactions in enzymatic and non-enzymatic defense of flax plants demonstrated equal synergism with both AM fungi species. In conclusion, increased activity of enzymatic antioxidants and higher production of non-enzymatic antioxidant compounds in symbiotic association with bacteria and mycorrhiza can alleviate reactive oxygen species damage resulting in improve water stress tolerance.