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Although biochar (BC) is expected to improve soil properties and plant growth, few studies have confirmed its effect on Helianthus annuus L. (sunflower). The effects of four different concentrations of birch-derived BC (2.5, 5, 7.5, and 10%) on the biometric growth parameters of sunflower were studied in a 60-day pot-scale experiment. In addition, the physicochemical properties and elemental composition of the birch-derived BC and peat substrates were examined. It is noted that birch-derived BC was characterized by a slightly acidic pH (about 6.4), lower electrical conductivity and 3.4 times higher water-holding capacity compared to the control substrate. Moreover, the percentage of carbon in BC was 1.4 times higher, while the content of hydrogen and oxygen, on the contrary, was lower in 1.5 and 2.0 times than in the control substrate. In most cases, adding BC to the peat substrate improved H. annuus growth parameters such as shoot height, root length, leaf area, as well as total fresh and dry biomass. The best results were obtained by adding 5% BC, which had a positive effect on all biometric parameters of H. annuus plants, while 10% BC had the least impact.

The use of plant growth-promoting rhizobacteria (PGPR) along with additional biofortification of agricultural plants with scarce essential elements, such as iodine, is a promising area of agricultural biotechnology. The seeds of Pisum sativum L. (var. Madras) pre-inoculated for two hours with PGPR Arthrobacter sp. strain CTF1 (108 CFU/mL) were grown for 14 days in a hydroponic culture at foliar spraying with iodine solution (0.01% KI or KIO3) on the 7th day of the vegetation. Growth parameters such as the length of shoot, fresh and dry biomass of seedlings were studied, the germination percentage and vigor index were calculated, and the content of photosynthetic pigments in pea leaves was assessed. The results showed inoculation of pea seeds with PGPR strain CTF1 had a positive effect on the biomass of two-week-old pea microgreens and their vigor index. At the same time, a significant increase in photosynthetic pigments was also observed in the leaves of pea seedlings, especially chlorophyll a (by almost 25%) and carotenoids (by almost 40%). Additionally, application of iodine via foliar spraying, irrespective of its form (KI or KIO3), resulted in nearly a 26-fold surge in amount of microgreens. However, the significant effect of such iodine treatment had a positive effect only on the content of carotenoids.

Biofortification of plant food products including microgreens is one of the most promising approaches to combat with the problem of balanced nutrition for the human population. This study introduces the microbiological biofortification using plant growth-promoting (PGP) bacteria, specifically three strains of zincsolubilizing Pseudomonas sp. (STF10, STF14, STF16) isolated from the rhizosphere of Tussilago farfara L. The research explores their impact on growth parameters and photosynthetic pigments in pea (Pisum sativum L.) microgreens following iodine spraying, providing groundbreaking insights. The experimental results indicate that inoculation of pea seeds with these rhizobacteria significantly increased the fresh and dry biomass of 14-day-old microgreens (by 22 and 15%, respectively, on average) compared to non-inoculated plants. At the same time the content of chlorophylls and carotenoids in seedlings increased on average by 18 and 36%, respectively. Spraying with one form of iodine (0.01% KI or KIO3) slightly increased fresh and dry biomass (by 8% on average) and did not alter the content of photosynthetic pigments. Wherein iodine content in pea microgreens increased by 4.4 and 3.8 times, after KI and KIO3 spraying, respectively. By conducting experiments in a hydroponic nutrient solution, this study provides a robust platform for evaluating the biofortification potential of the three Pseudomonas strains along with foliar iodine feeding, marking a significant stride towards enhancing the nutritional profile of pea microgreens. [ABSTRACT FROM AUTHOR]

Metal contamination coupled with aridity is a major challenge for remediation of abiotic stressed soils throughout the world. Both biochar and beneficial bacteria showed a significant effect in bioremediation; however, their conjugate study needs more exploration. Two rhizobacteria strains Serratia sp. FV34b and Pseudomonas sp. ASe42b isolated from multi-metal and drought stressed sites showed multiple plant-growth-promoting attributes (phosphate solubilization, indole-3-acetic acid, siderophore, and ammonia production). Both strains were able to tolerate a high concentration of Cd along with being resistant to drought (−0.05 to −0.73 MPa). The seldom studied biomass of Amaranthus caudatus L. was used for biochar preparation by pyrolyzing it at 470 °C for 160 min under limited oxygen and then using it for the preparation of biochar-based microbial cell composites (BMC)s. To check the efficiency of BMC under Cd stress (21 mg kg−1 soil) and drought, a pot-scale study was conducted using Brassica napus L. for 47 days. Both the BMC5 (Biochar + Serratia sp. FV43b) and BMC9 (Biochar + Pseudomonas sp. ASe42b) improved the seed germination, plant biometrical (shoot and root biomass, length of organs) and physiological (photosynthetic pigments, proline, malondialdehyde, and relative water content) parameters under drought (exerted until it reaches up to 50% of field capacity) and Cd-spiked soil. However, for most of them, no or few significant differences were observed for BMC9 before and after drought. Moreover, BMC9 maximized the Cd accumulation in root and meager transfer to shoot, making it a best bioformulation for sustainable bioremediation of Cd and drought stressed soils using rapeseed plant. [ABSTRACT FROM AUTHOR]

The interest to bacterial biofertilizers (BFs) is currently increasing since their application is environment friendly and cheaper in comparison with chemical fertilizers. BFs application reduces the metals availability in the soil through chelation, thereby reducing the toxicity of pollutants. The aim of the research was to study the effect of BF based on biochar and metal tolerant plant growth promoting rhizobacteria (PGPR) on growth parameters, copper accumulation and lipid peroxidation level in Brassica oleracea L. Bacillus altitudinis strain TF16a isolated from the rhizospheric soil of Tussilago farfara L. growing close to copper smelter was used to prepare the inoculum. To obtain BF, liquid inoculum of PGPR (108 CFU mL-1) was mixed with sterile substrate. Plants were grown in pot for 30 days. In the control substrate and with the addition of BF, the copper content was two times lower than the maximum permissible concentration for Russia. It was found that combined action of BF with Cu had a positive effect on the growth parameters in B. oleracea. Copper application led to the significant increase in its accumulation in shoot and root which was accompanied by the increase in malondialdehyde content in cabbage leaves. The combined action of BF and Cu reduced Cu accumulation and mitigated peroxidation processes. Thus, it can be concluded that biochar based biofertilizer promoted growth and alleviated copper toxicity in B. oleracea. [ABSTRACT FROM AUTHOR]

Metal tolerant plant growth-promoting (PGP) rhizobacteria are promising for enhancing plant productivity under copper (Cu) stress. Present pot scale experiment was conducted on Brassica napus L. to check the efficiency of rhizobacteria isolated from the rhizosphere of Tussilago farfara L. growing on Cu-contaminated soils. Out of fifty Cu tolerant strains, three isolates which showed multiple PGP traits such as indole-3-acetic acid (IAA) synthesis, phosphate (PS) solubilization, siderophore and ammonia production were identified preliminarily by morphological and physiological characteristics followed by 16S rRNA gene sequencing. The best Bacillus altitudinis strain TF16a which showed IAA: 15.5 mg L−1, PS: 215 mg L−1, siderophore halo zone ratio of 3.0 with high ammonia production was selected to prepare a biochar-based biofertilizer (BF). Seedling test showed maximum growth of B. napus shoot and root in presence of 5% of BF and this concentration was selected for further experiment. The pot experiment included four treatments: control (soil), 100Cu (100 mg Cu kg−1 soil), 5%BF (v/v), and 5%BF+100Cu, which were carried out for 30 days, after which the morphological, physiological, and biochemical parameters of B. napus were studied. The Cu treatment caused its accumulation in shoot and root up to 16.9 and 30.4 mg kg−1 DW, respectively, and increased malondialdehyde (MDA) content by 20%. Application of BF with copper led to the decrease in the Cu accumulation by 20% for shoot and 28% for root while MDA content was the same as in the control. Both treatments of BF with and without Cu increased chlorophyll a and b content by 1.3 times on average as well as non-enzymatic antioxidants such as soluble phenolic compounds (1.3 times) and free proline (1.6 times). Moreover, BF + Cu led to the increase in the biomass of shoot and root by 30 and 60%, respectively, while there was no significant effect on the growth characteristics of plants after the addition of BF without Cu. The study elucidates that BF based on B.altitudinis strain TF16a and biochar can be a promising bioformulation which could increase rapeseed growth under the moderate Cu concentration in soil. [ABSTRACT FROM AUTHOR]

This paper reviews research on phytoremediation (2002–2021), particularly for the estimation of plant efficiency and soil pollution indices, examining the extraction of metals from soil and plants growing under both artificial (spiked with specific metal) and natural conditions. From the analysis of >200 published experimental results, it was found that contamination factor and geo-accumulation index as well as translocation and bioconcentration factors are the most important soil pollution and plant efficiency metrices, respectively, which are gaining importance to assess the level of metal pollution and its transfer from soil to plant to find a better metal clean-up strategy for phytoremediation. To access the metal concentration, it was found that the most widely accepted extractants to dissolve and extract the metals from the soil and plant were HNO3 and HClO4 (mainly in 5:1; v/v or 4:1; v/v), which are used both in natural and artificial metal contamination studies. Moreover, plants such as Pteris vittata, Monochoria korsakowi, Lolium perenne, Festuca rubra, Poa pratensis, Ricinus communis, and Siegesbeckia orientalis can act as hyperaccumulators under both natural and artificial experiments and can be directly implemented into the fields without checking their further efficiency in phytoremediation. [ABSTRACT FROM AUTHOR]

Conversion of low-density wood into biochar faces many problems and results in ash formation. Development of three-container indirect heating retort can help to combat with this problem and could lead to production of good quality biochar. To validate, the Amaranthus spp. biomass has been dried, ground <0.1 mm and put it in a small container which was placed in a bigger container and finally surrounded by a large stainless-steel container which was filled with feedstock and allowed to combust for two hours under limited oxygen condition. Analysis of prepared biochar showed alkaline pH, high water holding capacity and electrical conductivity. Pot scale study was performed on Amaranthus caudatus L. var. gibbosus rubra which showed that application of 1% biochar has not only enhanced fresh and dry shoot biomass but also improved biometric growth parameters (length of shoot and number of leaves) as compared to control plants. The study showed that the application of a low dose of biochar from Amaranthus spp. improved the growth of A. caudatus plants and thus increased the lignocellulose content which can be used for bioenergy production. [ABSTRACT FROM AUTHOR]

We examined the uptake of five heavy metals (Cu, Fe, Ni, Zn, and Mn) inCeratophyllum demersumL. (hornwort) andPotamogeton alpinusBalb. (pondweed) from Iset’ river, Ural region, Russia. This study was conducted in a territory that is highly urbanized where the surface waters are contaminated by a wide spectrum of pollutants. The environmental situation in this territory drastically deteriorated due to anthropogenic activity. The water quality in most of the water bodies in the Ural region is rather poor. In a comparative study ofC. demersumandP. alpinus,differential accumulation pattern was noted for heavy metals (HMs). Higher amounts of HMs accumulated inC. demersumcompared toP. alpinus. Also it was shown that in leaves ofC. demersumthere were high amount of total phosphorus, nitrogen, organics acids and ash; high activity of guaiacol peroxidase; high content of non-enzymatic antioxidants viz., flavonoids, ascorbate, glutathione and proline; high amount of thiols (soluble and membrane bound) compared toP. alpinus. [ABSTRACT FROM AUTHOR]

This paper analyzes the effect of exogenous urea in increased concentration gradient (0, 100, 500 and 1,000 mg L) on photosynthetic pigments (measured spectrophotometrically), uptake of CO (using radioisotope), and urease activity (by measuring ammonia with Nessler's reagent) in leaves of Elodea densa Planch. We have observed that low concentration of urea (100 mg L) stimulates the accumulation of photosynthetic pigments and intensifies photosynthesis in E. densa, whereas high concentration (1,000 mg L) suppresses these processes. Urease activity increased by approximately 2.7 and 8 fold when exogenous urea concentrations were 100 and 500 mg L, respectively. However, exogenous urea in high concentration (1,000 mg L) decreased urease activity by 1.5 fold compared to the control. The necessity of mitigating urea and other nitrogen-containing compounds (NH from urea) in water bodies has been discussed with emphasis on the potential for phytoremediation of urea using common water weed viz. E. densa. [ABSTRACT FROM AUTHOR]

Copper (Cu) is an essential element, however it's excess into the environment causes detrimental effect on plant and risks for public health. Four Cu and drought tolerant 1-aminocyclopropane-1-carboxylate (ACC) deaminase producing rhizobacteria were isolated from the roots of Trifolium repens L. growing on Cu smelter contaminated soils, characterized and identified based on 16S rRNA gene sequencing. A consortium of high ACC deaminase (53.74 μM α-ketobutyrate mg−1 protein h−1) producing bacteria Pseudomonas sp. strain TR15a + siderophore producing Bacillus aerophilus strain TR15c significantly (p < 0.05) produced better results for multiple-metal tolerance including Cu (1750 mg kg−1), antibiotic resistance (ampicillin, kanamycin, chloramphenicol, penicillin, tetracycline, and streptomycin) and plant growth promoting attributes (phosphate solubilization: 315 mg L−1, indole-3-acetic acid (IAA) production: 8 mg L−1, ammonia and hydrogen cyanide production) as compared to individual isolates. Pot scale experiment (enriched with 100 mg Cu kg−1) showed inoculation of Helianthus annuus seeds with consortium of TR15a + TR15c had significantly (p < 0.05) improved seed germination by 32%, total dry biomass by 64%, root Cu by 47% and shoot Cu by 75% as compared to uninoculated control whereas 0.2−7 fold higher results were observed for above stated parameters as compared to four individual isolates studied. The result suggests consortium of ACC deaminase producing Pseudomonas sp. TR15a and siderophore producing B. aerophilus TR15c could play a vital role in enhanced Cu uptake and improvement of biomass and may provide a better alternative for decontamination of Cu contaminated natural ecosystem than individual isolates. [Display omitted] • Pseudomonas sp. TR15a and Bacillus aerophilus TR15c produced high ACC deaminase. • Consortium of TR15a + TR15c showed high resistance to multiple metals and antibiotics. • Siderophore production and ACC deaminase activity were improved for consortium. • Growth and Cu concentration in sunflower enhanced after application of consortium. • Consortium act as better phytostabilizer than single inoculant for Cu remediation. [ABSTRACT FROM AUTHOR]

Organic fertilizers became a better alternative to chemical fertilizers in modern agricultural practices however, contamination of copper (Cu) from organic fertilizer is still a major concern for the globe. Plant growth promoting (PGP) microorganisms showed their efficiency to combat with this problem and thus Cu tolerant PGP endophytes from roots of Odontarrhena obovata (Alyssum obovatum) growing on Cu smelter contaminated serpentine soil were explored in present study. Out of twenty-four isolates, Pseudomonas lurida strain EOO26 identified by 16s rRNA gene sequencing was selected to check its efficacy for Cu-remediation. The strain EOO26 showed multi-metal tolerance, drought resistance and exhibited PGP attributes such as 1-aminocyclopropane-1-carboxylic acid (ACC) deaminase, siderophore and ammonia production. Significant production of indole-3-acetic acid and phosphate-solubilization under different Cu concentration (0–100 mg L−1) at varying pH (5.0–8.0) suggests potentiality of this strain to work effectively under wide range of abiotic stress conditions. Plant growth experiment (pH 6.8 ± 0.3) in copper spiked soil suggested a significant increase in length and dry weight of root and shoot of sunflower (Helianthus annuus) after inoculation with strain EOO26. Plants inoculated with strain EOO26 resulted in increase in Cu uptake by 8.6-fold for roots and 1.9-fold for leaves than uninoculated plants. The total plant uptake in inoculated Cu treatment was 2.6-fold higher than uninoculated one, which is much higher than the previously reported Cu accumulating plants. The excellent adaptation abilities and promising metal removal efficiency strongly indicate superiority of strain EOO26 for phytoremediation of Cu-contamination and may work effectively for Cu removal from contaminated soils. • Pseudomonas lurida strain EOO26 is a potential metal and drought tolerant endophyte. • EOO26 showed various PGP traits and Cu enhances IAA production over control. • Produces IAA and solubilizes phosphate under wide range of pH and Cu content. • EOO26 improved biometric growth parameters of Helianthus annuus. • EOO26 enhanced Cu accumulation in roots and leaves, and total Cu uptake. [ABSTRACT FROM AUTHOR]