Potential role of apple wood biochar in mitigating mercury toxicity in corn (Zea mays L.).

Mercury (Hg) is a very toxic decomposition-resistant metal that can cause plant toxicity through bioaccumulation and oxidative damage. Biochar, derived from organic waste and agricultural garbage, is an on-site modification technique that can improve soil health in heavy metals-polluted regions. The present experiment was designed to explore the role of apple biochar in the management of mercury toxicity in corn (Zea mays cv. 'PL535'). Different levels of biochar derived from apple wood (0%, 2.5%, 5.0%, and 7.5% w/w) along with different Hg concentrations (0, 20, 40, and 60 mg/L) were used in the experiment that was based on a completely randomized design. Based on the results, HgCl2 at all rates reduced root and shoot dry weight and length, tolerance index, chlorophyll a and b content, the Hill reaction, and dissolved proteins and increased shoot and root Hg content (up to 72.57 and 717.56 times, respectively), cell death (up to 58.36%), MDA level (up to 47.82%), H2O2 (up to 66.33%), dissolved sugars, and proline. The results regarding enzymatic and non-enzymatic antioxidants revealed increases in total phenol and flavonoids content (up to 71.27% and 86.71%, respectively), DPPH free radical scavenging percentage, and catalase (CAT) and ascorbate peroxidase (APX) activity (up to 185.93% and 176.87%, respectively), in corn leaves with the increase in the Hg rate applied to the culture medium. The application of biochar to the substrate of the Hg-treated corns reduced Hg bioavailability, thereby reducing Hg accumulation in the roots (up to 76.88%) and shoots (up to 71.79%). It also reduced the adverse effect of Hg on the plants by increasing their shoot and root dry weight, photosynthesizing pigments, Hill reaction, and APX activity and reducing cell death, H2O2 content, and MDA content. The results reflected the capability of apple wood biochar at all rates in reducing Hg bioavailability and increasing Hg fixation in Hg-polluted soils. However, it was most effective at the rate of 7.5%.

Effects of malic acid and EDTA on oxidative stress and antioxidant enzymes of okra (Abelmoschus esculentus L.) exposed to cadmium stress.

Environmental stresses, including heavy metal pollution, are increasing at a growing rate and influencing arable lands. Chelators play an essential role in several biochemical pathways in the cells of plants treated with heavy metals. This research evaluated the modifying effect of malic acid (MA) and ethylenediaminetetraacetic acid (EDTA) on the physiological and biochemical parameters of okra plants exposed to Cd stress in which the okra plants were cultivated in hydroponic conditions. At the 4-leaf stage, they were applied with the treatments of cadmium nitrate at three levels (0, 50, and 100 mg/L), EDTA and MA at two levels (0.5 and 1 mM), and Cd + EDTA + MA at different rates for one month. The harvested plants were subjected to the measurement of the physico-biochemical factors. The results revealed that the application of Cd alone reduced leaf area (up to 21.57 %), and dissolved sugars (up to 40.51 % in the shoot and 45.19 % in the root) and increased MDA (up to 66.37 % and 76.43 % in the shoot and root, respectively), H2O2 (up to 67.14 % and 53.28 % in the shoot and root, respectively), proline (up to 52.04 % and 40.93 % in the shoot and root, respectively), and dissolved proteins (up to 14.59 % and 21.90 % in the shoot and root, respectively) contents in both shoots and roots whereas the application of MA and EDTA to the Cd-treated plants increased their leaf area and dissolved sugars and reduced MDA, H2O2, proline, and dissolved proteins content. The antioxidant enzymes, e.g., superoxide dismutase (SOD), catalase (CAT), and ascorbate peroxidase (APX), were significantly higher in the plants treated with MA, EDTA, and Cd, but the application of MA and EDTA to the Cd-treated plants reduced the activity of all these antioxidant enzymes versus the plants only treated with Cd. MA and EDTA are likely to prevent the accumulation of Cd in the cytosol by binding to it and transferring it into vacuoles, thereby mitigating Cd toxicity in the okra plants.

The effect of EDTA and citric acid on biochemical processes and changes in phenolic compounds profile of okra (Abelmoschus esculentus L.) under mercury stress.

The present study aimed to explore the effect of synthetic and naturally occurring chelators, EDTA and citric acid (CA), respectively, on changes in physiological and biochemical factors including cell death, level of mercury ions accumulation, malondialdehyde (MDA) content, total phenol and total flavonoids, anthocyanins and DPPH free radical scavenging activity, in the leaves of okra (Abelmoschus esculentus L.) plants exposed to mercury stress. In addition, polyphenolic compounds profile was assessed by high-performance liquid chromatography. The okras were planted in completely controlled hydroponic conditions (Hoagland solution). After they reached the four-leaf stage, they were treated simultaneously with different concentrations of HgCl2, EDTA and CA chelators, and their combination for one month. At the stage of maturity, the physiological and biochemical factors of the plant leaves were measured. The results showed that with the application of higher concentration of HgCl2, cell death, level of shoot and root Hg2+ content and root MDA, total phenols and total flavonoids, anthocyanin content, and DPPH free radical scavenging activity were increased. Also, the results indicated that okra plants have high biomass and a high rate of Hg mobilization and accumulation in the shoot versus the roots (TF=2.152 for the plants treated with 60 mg L-1 Hg2+), hence, can be considered as Hg hyperaccumulator plant for the phytoremediation of Hg-polluted soils and waters. In the Hg-treated plants changes in their phenolic profile were induced, and the increase of chlorogenic acid, rosmaric acid, apigenin, quercetin and rutin content was observed. The application of EDTA and CA improved the toxic effects of Hg2+, by modifying phenolic compounds, chelating Hg2+, and its proper compartmentation, while EDTA outperformed CA in this respect. Based on the results, it could be concluded that due to the high biomass and growth of okra in the presence of Hg2+, this plant is suitable for phytoremediation of soil and water contaminated with mercury. In addition, EDTA and CA can play a significant role in removing this toxic metal through transferring it from the culture medium to the plant.

Combined Effect of Biological and Organic Fertilizers on Agrobiochemical Traits of Corn (Zea mays L.) under Wastewater Irrigation.

Corn (Zea mays L.) is an important annual grain that is cultivated as a food staple around the world. The current study examined the effect of wastewater and a combination of biological and organic fertilizers on the morphological and phytochemical traits of corn, using a factorial experiment based on a randomized complete block design with three replications. The first factor was biological and organic fertilizers at seven levels, including the control (no fertilization), bacterial biological fertilizers (NPK) along with iron and zinc Barvar biofertilizers, fungal biofertilizers made from Mycorrhiza and Trichoderma, biochar, a combination of bacterial and fungal biofertilizers, and a combination of bacterial and fungal biofertilizers with biochar. The second factor was irrigation at two levels (conventional irrigation and irrigation with wastewater). The traits studied included the morphological yield, phenols, flavonoids, polyphenols, glomalin, cadmium content in plant parts, and translocation factor (TF). The results disclosed that the best treatment in regard to the morphological traits was related to conventional water + biochar + mycorrhiza + Trichoderma + NPK. The highest phenol and flavonoid content were observed when biochar + mycorrhiza + Trichoderma + NPK treatments were used in both water treatments. Also, the wastewater + biochar + mycorrhiza + Trichoderma + NPK treatment demonstrated the highest total glomalin and phenylalanine ammonia-lyase (PAL) activity. The obtained results demonstrate that combined biological and organic fertilizer use on corn plants can effectively alleviate the deleterious effects of cadmium present in wastewater.

The Role of Stress Modifier Biostimulants on Adaptive Strategy of Oregano Plant for Increasing Productivity under Water Shortage.

To investigate the influence of stress modulators on the adaptive physiological responses and biomass traits of oregano under water stress conditions, a two-year (2018 and 2019) randomized complete block-designed factorial research was performed. In this study, oregano plants were treated with five stress modulators levels (CHN: chitosan, AMA: amino acids, SEW: seaweed, ASA: ascorbic acid, SAA: salicylic acid, and CON: control) at three levels of irrigation regimes (Irr40 (40), Irr60 (60) and Irr75 (75) % field capacity). The effects of water shortage and biostimulant application were evaluated on total dry weight (TDW), relative water content (RWC), essential oil production, chlorophyll, nutrient (N, K, and P), proline, total soluble sugar, polyphenol and flavonoid content, and activity of antioxidant enzymes. The result showed that under optimal irrigation conditions, oregano plants sprayed with CHN exhibited the highest dry weight (141.23 g m-2) as a morphological trait, the highest relative water content (79.34%), the most consistent concentrations of nitrogen, phosphorus and potassium (3.14, 0.39, and 1.69%, respectively), chlorophylls a and b (3.02 and 1.95 mg g-1 FW, respectively), and total phenols and total flavonoids (30.72 and 3.17 mg g-1 DW, respectively). The water deficit increased the proline content, with the greatest amount (4.17 µg g-1 FW) observed in control plants. Moreover, under moisture shortage stress conditions, the application of CHN and SEW increased the soluble sugar (27.26 µmol g-1 FW) and essential oil yield (1.80%) production, the catalase, ascorbate peroxidase, and superoxide dismutase activities (3.17, 1.18, and 63.89 µmol min-1 g-1 FW, respectively) compared to control plants. In summary, the study demonstrated that oregano plants respond positively to stress modulator treatments when subjected to moisture shortage stress, especially when treated with chitosan. The results offer promising insights for developing sustainable adaptative strategies aimed at enhancing the oregano's tolerance to water shortage, ultimately improving its productivity and biochemical traits.

Urbanization influences the distribution, enrichment, and ecological health risk of heavy metals in croplands.

The contamination of urban soils with heavy elements due to the rapid development of urbanization and urban services has become a major environmental and human health challenge. This study provides insight into the urbanization controls on combined pollution severity and health risk potential of heavy metals in corn-cultivated urban versus non-urban soils. A multifaceted assessment was conducted using enrichment factor (EF), ecological risk (ER), bioconcentration factor (BCF), transmission factor (TF), hazard index (HI), and carcinogenic risk (CR). The results indicate a significant increase in the concentration of all metals in urban farmlands. When compared to the non-urban soils, EF implies a significant increase of all metals in the urban soil, downgrading this index from minimal enrichment (EF < 2) in the control soils to moderate enrichment (2 ≤ EF < 5) in the urban soils. Likewise, the average ER value showed an increase in the urban soils than in the control soils in the order of Fluvisols (66.6%) > Regosols (66.1%) > Cambisols (59.8%) > Calcisols (47%). The BCF and TF values for different elements decreased in the order of Cd (0.41-0.92) > Cu (0.1-0.23) > Zn (0.1-0.18) > Ni (0.01-0.03) > Pb (0.005-0.011) and Zn (0.75-0.94) > Cu (0.72-0.85) > Pb (0.09-0.63) > Cd (0.17-0.22) > Ni (0.01-0.21), respectively, which indicates that certain metals were not mobilized to the extent that they had been accumulated in the plant roots. The total carcinogenic risk was ranged from 5.88E-05 to 1.17E-04 for children and from 1.17E-04 to 2.30E-04 for adults, which implies a greater associated health risk for children.

Organically vs. Conventionally Grown Vegetables: Multi-elemental Analysis and Nutritional Evaluation.

Vegetables are important contributors to a healthy diet, and their adequate daily intake can help prevent some of the major illnesses. The aim of the study was to examine the content of the major and trace elements in selected organically grown (OG) and conventionally grown (CG) vegetables (cabbage, kohlrabi, Brussels sprout, beetroot, carrot, potato, and onion), taken from city green markets. Multi-elemental analysis was carried out by inductively coupled plasma method with optical emission spectrometry (ICP-OES). Nutritional quality evaluation in comparison to nutritional reference values was done. In studied vegetables, Al, Ca, K, Fe (with the exception of organic kohlrabi), Mg, Na, P, S, and Zn were quantified in all samples, whereas As, Cd, Co, Hg, Se, and V were below the limit of detection for these elements. Macroelements and trace elements were found at higher concentrations in OG and CG vegetables, respectively. Differences in concentrations of studied elements between the same vegetable species produced in two agricultural systems were significant, except for beetroot (p ≤ 0.05). Principal component analysis and hierarchical cluster analysis results showed that the botanical origin had higher influence on sample differentiation than the agronomic practice, which was in accordance with the results obtained by Mann-Whitney U test. Good quality of both OG and CG vegetables in respect of nutritionally beneficial elements was observed.

Multi-elemental Analysis, Pattern Recognition Techniques of Wild and Cultivated Rosehips from Serbia, and Nutritional Aspect.

Twenty-six major and trace elements, in the seed and the mesocarp of wild and cultivated rosehips from different locations in Serbia, were quantified by means of inductively coupled plasma-atomic emission spectroscopy (ICP-AES). The cultivated rosehip was investigated for the first time. In both wild and cultivated rosehips, the most abundant elements were K and Ca. Among trace elements, Mn (in both seed and mesocarp); Fe (in seeds); and B, Ba, and Sr (in mesocarp) were quantified in the highest concentrations. The higher content of Cu, K, Mn, P, and S in the seed of cultivated rosehip, as well as Ca, Mg, and Sr in the mesocarp of wild rosehip, was observed, both significant at p < 0.05. Additionally, differences between the seed and the mesocarp of studied rosehip were noticed in the content of B, Cu, Fe, K, Ni, P, S, Sr, and Ti (p < 0.05). Nutritional assessment revealed that both wild and cultivated rosehips are a valuable source of essential elements (Ca, Cu, K, Mg, Mn, and P). The absence of toxic and potentially toxic elements additionally contributes to the quality of studied Serbian rosehip. A high impact of factors such as variety, location, as well as their interaction on the content of elements in cultivated rosehip mesocarp and seed was observed. Pattern recognition techniques, principal component analysis (PCA), and hierarchical cluster analysis (HCA) were applied in order to provide insight into similarities among the analyzed samples.

Combined bio-chemical fertilizers ameliorate agro-biochemical attributes of black cumin (Nigella sativa L.).

Nigella sativa L. is a medicinal plant with extensive, nutritional, pharmaceutical, and health applications. Nowadays, reducing the application of chemical fertilizers (synthetic fertilizers) is one of the main goals of sustainable agriculture to allow the production of safe crops. Therefore, the combined effect of urea and biofertilizers was studied on the quantitative and qualitative traits of N. sativa L. in a randomized complete block design with 10 treatments and three replications. The treatments included control (no fertilization), U (100% chemical fertilizer as urea at 53.3 kg ha-1, Nb (Biofertilizer, Azotobacter vinelandii), Pb (Biofertilizer, Pantoea agglomerans and Pseudomonas putida), Kb (Biofertilizer, Bacillus spp.), NPKb (NPK, biofertilizer), Nb + 50% U, Pb + 50% U, Kb + 50%U and NPKb + 50% U. The NPK(b) + U50% was related to the highest quantity of plant height, branch diameter, capsule (follicle) number per plant, auxiliary branches, seed yield per plant, thousand-seed weight, essential oil content, total phenolic compounds, flavonoid content, DPPH free radical scavenging, nitric oxide (NO) radical scavenging, superoxide radical scavenging, chain-breaking activity, phosphorus content, and potassium content, along with U for the highest biological yield and (Pb) + U50% for the highest essential oil percentage which is close to (NPKb) + U50%. The lowest value was observed in all traits related to the control treatment except for branch diameter that was related to (NPKb). Hence, the application of (NPKb) + U50% as bio-chemical fertilizers improved N. sativa L. Traits, so it can be recommended.

Winter Cultivation and Nano Fertilizers Improve Yield Components and Antioxidant Traits of Dragon's Head (Lallemantia iberica (M.B.) Fischer & Meyer).

Balangu (Lallemantia sp.) is a medicinal herb with a variety of applications, all parts of which have economic uses, including leaf for extraction of essential oils, as a vegetable and potherb, seed for extraction of mucilage and edible or industrial oil. To investigate the effect of cultivation season and standard chemical and nano fertilizers (n) on the yield components and antioxidant properties of Dragon's head, a factorial experiment based on randomized complete block design was conducted with 12 treatments and three replications. Experimental treatments consisted of two seasons (spring and winter cultivation) and six levels of fertilizer (control, NPK-s, NPK-n, Fe-chelated-n, NPK-n + Fe-chelated-n, NPK-s + NPK-n + Fe-chelated-n). The traits included grain yield per plant, essential oil percentage and yield, mucilage percentage and yield, antioxidant properties in the seeds and leaves, including total phenols and flavonoids content, DPPH radical scavenging, and nitric oxide and superoxide radical scavenging. The results showed that winter cultivation had a noticeable advantage over spring cultivation across all of the traits. The highest grain yield per plant was obtained in winter cultivation using NPK-n + Fe-chelated-n fertilizer treatment. The highest essential oil percentage was in NPK-n + Fe-chelated-n. The highest mucilage percentage was observed in NPK-s + NPK-n + Fe-chelated-n fertilizer treatment, which was not statistically different to NPK-n + Fe-chelated-n treatment. The combined effects of winter cultivation and NPK-n + Fe-chelated-n fertilizers resulted in improving antioxidant activity traits. Overall, the results indicated that the combination of winter cultivation and NPK-n + Fe-chelated-n fertilizers are the most appropriate treatment to acquire highest qualitative and quantitative yield of Dragon's head, in the Azerbaijan region (Iran).

Phytomanagement of trace metals in mangrove sediments of Hormozgan, Iran, using gray mangrove (Avicennia marina).

Trace elements (Zn, Cu, Pb, and Cd) in root and leaf tissues of the gray mangrove (Avicennia marina) and in corresponding sediment samples were studied. Samples were taken from the inflow/outflow points in two distinct habitats, i.e., the Hara Protected Area and the Azini Bay, of Hormozgan Province in south Iran. Heavy metal concentrations (µg g-1 of dry weight) in the sediments of the Hara Protected Area ranged from 16.0 to 68.0 for Pb, 15.0 to 52.0 for Zn, 9.0 to 27.0 for Cu, and 1.0 to 3.3 for Cd. In the Azini Bay, these concentrations ranged from 7.1 to 27.5 for Pb, 17.1 to 55.9 for Zn, 12.1 to 37.9 for Cu, and 0.2 to 2.3 for Cd. The accumulation trend of heavy metal concentrations in the roots of A. marina was in the order Pb (16.1) > Zn (15.8) > Cu (9.3) > Cd (1.3) µg g-1 of dry weight in the Hara Protected Area and in the order Zn (13.7) > Cu (9.4) > Pb (5.5) > Cd (0.6) µg g-1 of dry weight in the Azini Bay. The value of translocation factor (TLF) was smaller than 1 in both regions. It was estimated from 0.44 to 0.62 in the Hara Protected Area and from 0.51 to 1.01 in the Azini Bay. The enrichment coefficient for root (ECR) varied from 0.32 to 0.93 in the Hara Protected Area and from 0.32 to 0.51 in the Azini Bay. The ratio of heavy metals in leaves/sediments (ECL) also varied from 0.01 to 0.67 in the Hara Protected Area and from 0.01 to 0.47 in the Azini Bay. The enrichment coefficient for leaf (ECL) was always lower than ECR in both regions. Based on the above findings, A. marina can be regarded as an excluder for the heavy metals examined in this study, given its low efficiency in translocating and accumulating the heavy metals in the shoots. Apart from serving as a baseline for the study area, findings could be useful for mitigating heavy metal contamination in these sensitive ecosystems through possible phytomanagement using gray mangrove.