Integrative moringa and licorice extracts application improves Capsicum annuum fruit yield and declines its contaminant contents on a heavy metals-contaminated saline soil

Multidimensional role of selenium nanoparticles to promote growth and resilience dynamics of Phaseolus vulgaris against sodium fluoride stress

High fluoride (F) concentrations negatively affect the seed germination, plant growth, development, and yield of crops. Phaseolus vulgaris L. is an F-sensitive crop frequently grown on marginal lands affected by F salts. Selenium (Se) is a vital elicitor of the antioxidative enzymes involved in scavenging free radicals to alleviate abiotic stress. Recent studies have demonstrated that engineered nanoparticles (NPs) have the potential to induce tolerance to abiotic stress in plants. Phytosynthesis of NPs is a novel and sustainable approach to mitigate abiotic stresses. The present study was intended to assess the role of green synthesized Se-nanoparticles (Se-NPs) in improving the physiochemical attributes, growth, and F stress tolerance of P. vulgaris growing in 200 ppm sodium fluoride (NaF) stress. NaF toxicity reduced Chl a, Chl b, and carotenoid content by 88.8%, 95.5%, and 96% compared to control with maximum improvement obtained through phyto-nano seed priming and foliar spray of 70 ppm Se-NPs. The joint treatment of NPs application through seed priming and foliar spray improved stomatal conductance (14.2%) and transpiration rate (11.7%) in plants subjected to NaF stress. The protein content (91.02%) and DPPH activity (33.72%) decreased under NaF stress, which was improved by phyto-nano seed priming and foliar spray (14.10%). Furthermore, the integrated application of Se-NPs seed priming and foliar spray increased nutritional content (P, K, Ca, Mg, and Zn), proline, ascorbic acid, and phenol yet reduced the level of NaF in plants. Se-NPs at 70 ppm were found to be more effective than 60 ppm in all modes of applications. Our results reveal a perception that Se-NPs increase P. vulgaris growth in NaF stress conditions, perhaps through a multipronged approach: improving photosynthetic content, nutrient uptake, and yield of P. vulgaris. Consequently, the findings of this study may be used for breeding and screening F-tolerant cultivars.

Co-application of organic amendments and natural biostimulants on plants enhances wheat production and defense system under salt-alkali stress

Soil alkalinity and salinity are major challenges to wheat production in arid regions. Eco-friendly amendments (organic matter and bio-stimulants) offer promising solutions, but their combined effects are underexplored. This study assessed the effects of organic amendments (vermicompost, compost, and chicken manure) combined with foliar bio-stimulants (licorice root, ginger rhizome, moringa leaf extract (MLE), and potassium humate) on wheat under salt and alkalinity stress. Organic amendments combined with bio-stimulants significantly improved wheat yields by enhancing chlorophyll content, proline levels, photosynthetic pigments, water uptake, and enzyme activities. Vermicompost outperformed compost and chicken manure in improving plant physico-biochemical properties. The combination of vermicompost and MLE was most effective in increasing plant height, leaf area, and photosynthetic rate by 97, 126, and 136%, respectively, while also enhancing catalase, peroxidase, and superoxide dismutase by 65, 97, and 185%, respectively. Consequently, this resulted in 64% increase in straw yield and 27% increase in grain yield compared to controls. Additionally, nutrient uptake (N, P, and K) significantly increased, while sodium uptake decreased. Integrating vermicompost with MLE can significantly enhance wheat productivity under abiotic stress, offering a sustainable solution to improve crop resilience in arid environments. Further research is required to understand the mechanisms and optimize bio-stimulant use in agriculture.

Licorice-root extract and potassium sorbate spray improved the yield and fruit quality and decreased heat stress of the 'osteen' mango cultivar

Heat stress, low mango yields and inconsistent fruit quality are main challenges for growers. Recently, licorice-root extract (LRE) has been utilized to enhance vegetative growth, yield, and tolerance to abiotic stresses in fruit trees. Potassium sorbate (PS) also plays a significant role in various physiological and biochemical processes that are essential for mango growth, quality and abiotic stress tolerance. This work aimed to elucidate the effects of foliar sprays containing LRE and PS on the growth, yield, fruit quality, total chlorophyll content, and antioxidant enzymes of 'Osteen' mango trees. The mango trees were sprayed with LRE at 0, 2, 4 and 6 g/L and PS 0, 1, 2, and 3 mM. In mid-May, the mango trees were sprayed with a foliar solution, followed by monthly applications until 1 month before harvest. The results showed that trees with the highest concentration (6 g/L) of LRE exhibited the maximum leaf area, followed by those treated with the highest concentration (3 mM) of PS. Application of LRE and PS to Osteen mango trees significantly enhanced fruit weight, number of fruits per tree, yield (kg/tree), yield increasing%, and reduced number of sun-burned fruits compared to the control. LRE and PS foliar sprays to Osteen mango trees significantly enhanced fruit total soluble solids ˚Brix, TSS/acid ratio, and vitamin C content compared to the control. Meanwhile, total acidity percentage in 'Osteen' mango fruits significantly decreased after both LRE and PS foliar sprays. 'Osteen' mango trees showed a significant increase in leaf area, total chlorophyll content, total pigments, and leaf carotenoids. Our results suggest that foliar sprays containing LRE and PS significantly improved growth parameters, yield, fruit quality, antioxidant content, and total pigment concentration in 'Osteen' mango trees. Moreover, the most effective treatments were 3 mM PS and 6 g/L LRE. LRE and PS foliar spray caused a significant increase in yield percentage by 305.77%, and 232.44%, in the first season, and 242.55%, 232.44% in the second season, respectively.

Enhancing sweet potato (Ipomoea batatas) resilience grown in cadmium-contaminated saline soil: a synergistic approach using Moringa leaf extract and effective microorganisms application

Raising soil contamination with cadmium (Cd2+) and salinization necessitates the development of green approaches using bio-elicitors to ensure sustainable crop production and mitigate the detrimental health impacts. Two field trials were carried out to study the individual and combined effects of foliage spraying of Moringa leaf extract (MLE) and soil application of effective microorganisms (EMs) on the physio-biochemical, osmolytes, antioxidants, and performance of sweet potato grown in Cd2+-contaminated salty soil (Cd2+  = 17.42 mg kg-1 soil and soil salinity ECe = 7.42 dS m-1). Application of MLE, EMs, or MLE plus EMs significantly reduced the accumulation of Cd2+ in roots by 55.6%, 50.0%, or 68.1% and in leaves by 31.4%, 27.6%, or 38.0%, respectively, compared to the control. Co-application of MLE and EMs reduced Na+ concentration while substantially raising N, P, K+, and Ca2+ acquisition in the leaves. MLE and EMs-treated plants exhibited higher concentrations of total soluble sugar by 69.6%, free proline by 47.7%, total free amino acids by 29.0%, and protein by 125.7% compared to the control. The enzymatic (SOD, APX, GR, and CAT) and non-enzymatic (phenolic acids, GSH, and AsA) antioxidants increased in plants treated with MLE and/or EMs application. Applying MLE and/or EMs increased the leaf photosynthetic pigment contents, membrane stability, relative water content, water productivity, growth traits, and tuber yield of Cd2+ and salt-stressed sweet potato. Consequently, the integrative application of MLE and EMs achieved the best results exceeding the single treatments recommended in future application to sweet potato in saline soil contaminated with Cd2+.

Biochar Loaded with a Bacterial Strain N33 Facilitates Pecan Seedling Growth and Shapes Rhizosphere Microbial Community

Biochar and beneficial microorganisms have been widely used in ecological agriculture. However, the impact of biochar loaded with microbes (BM) on plant growth remains to be understood. In this study, BM was produced by incubating pecan biochar with the bacterial strain N33, and the effects of BM on pecan growth and the microbial community in the rhizosphere were explored. BM application significantly enhanced the biomass and height of pecan plants. Meanwhile, BM treatment improved nutrient uptake in plants and significantly increased the chlorophyll, soluble sugars, and soluble proteins of plants. Furthermore, BM treatment improved the soil texture and environment. Finally, BM application substantially enhanced the diversity of soil fungi and bacteria as well as the relative abundances of the phyla Firmicutes and Chloroflexi, and families Bacillaceae and Paenibacillaceae, as shown by high-throughput sequencing. Together, this study clarified the growth-promotive effects of BM on pecan plants and suggested an alternative to synthetic fertilizers in their production.

Exploiting the role of plant growth promoting rhizobacteria in reducing heavy metal toxicity of pepper (Capsicum annuum L.)

Microorganisms are cost-effective and eco-friendly alternative methods for removing heavy metals (HM) from contaminated agricultural soils. Therefore, this study aims to identify and characterize HM-tolerant (HMT) plant growth-promoting rhizobacteria (PGPR) isolated from industry-contaminated soils to determine their impact as bioremediators on HM-stressed pepper plants. Four isolates [Pseudomonas azotoformans (Pa), Serratia rubidaea (Sr), Paenibacillus pabuli (Pp) and Bacillus velezensis (Bv)] were identified based on their remarkable levels of HM tolerance in vitro. Field studies were conducted to evaluate the growth promotion and tolerance to HM toxicity of pepper plants grown in HM-polluted soils. Plants exposed to HM stress showed improved growth, physio-biochemistry, and antioxidant defense system components when treated with any of the individual isolates, in contrast to the control group that did not receive PGPR. The combined treatment of the tested HMT PGPR was, however, relatively superior to other treatments. Compared to no or single PGPR treatment, the consortia (Pa+Sr+Pp+Bv) increased the photosynthetic pigment contents, relative water content, and membrane stability index but lowered the electrolyte leakage and contents of malondialdehyde and hydrogen peroxide by suppressing the (non) enzymatic antioxidants in plant tissues. In pepper, Cd, Cu, Pb, and Ni contents decreased by 88.0-88.5, 63.8-66.5, 66.2-67.0, and 90.2-90.9% in leaves, and 87.2-88.1, 69.4-70.0%, 80.0-81.3, and 92.3%% in fruits, respectively. Thus, these PGPR are highly effective at immobilizing HM and reducing translocation in planta. These findings indicate that the application of HMT PGPR could be a promising "bioremediation" strategy to enhance growth and productivity of crops cultivated in soils contaminated with HM for sustainable agricultural practices.

Unlocking hormesis and toxic effects induced by cadmium in Polygonatum cyrtonema Hua based on morphology, physiology and metabolomics

Traditional Chinese medicine materials (TCMMs) are widely planted and used, while cadmium (Cd) is a widespread pollutant that poses a potential risk to plant growth and human health. However, studies on the influences of Cd on TCMMs have been limited. Our study aims to reveal the antioxidation-related detoxification mechanism of Polygonatum cyrtonema Hua under Cd stress based on physiology and metabolomics. The results showed that Cd0.5 (total Cd: 0.91 mg/kg; effective Cd: 0.45 mg/kg) induced hormesis on the biomass of roots, tubers and aboveground parts with increases of 22.88%, 27.12% and 17.02%, respectively, and significantly increased the flavonoids content by 57.45%. Additionally, the metabolism of caffeine, glutamine, arginine and purine was upregulated to induce hormesis in Cd0.5, which enhanced the synthesis of resistant substances such as spermidine, choline, IAA and saponins. Under Cd2 stress, choline and IAA decreased, and fatty acid metabolites (such as peanut acid and linoleic acid) and 8-hydroxyguanosine increased in response to oxidative damage, resulting in a significant biomass decrease. Our findings further reveal the metabolic process of detoxification by antioxidants and excessive Cd damage in TCMMs, deepen the understanding of detoxification mechanisms related to antioxidation, and enrich the relevant theories of hormesis induced by Cd.

Pathological effects of feeding aflatoxin-contaminated feed on immune status and reproductive performance of juvenile white leghorn males and its mitigation with ∝-tocopherol and Moringa oleifera

This study was planned to detect the adverse pathological consequences of aflatoxin B1 in White Leghorn (WLH) layer breeder males. Eight-week-old male layer cockerels were separated into six experimental categories: A group was kept as negative control, offered with normal feed only; group B was fed with 400 ppb amount of aflatoxin, while groups F and D fed with normal feed and supplemented with vitamin E 100 ppm and 1% Moringa oleifera, respectively, whereas groups E and C were fed with 400 ppb aflatoxin containing feed and ameliorated with vitamin E 100 ppm and 1% Moringa oleifera, respectively. This study was continued for 2 months and immunologic disorders and reproductive parameters were observed during the trial. To find out immunological status lymphoproliferative response to phytohemagglutinin-P (PHA-P), antibody titers against sheep red blood cells (SRBCs) and carbon clear assay were performed by collecting samples from five birds from each group. The whole data was measured by ANOVA test, and group means were compared by DMR test by using M-Stat C software. Regarding the reproductive status, spermatogenesis, blood testosterone level, testes weight, testes histology, sperm motility, and morphology were negatively affected by aflatoxins, but these deviations positively ameliorated by vitamin E and Moringa. Vitamin E and Moringa found advantageous in boosting the immune status of affected bird. All the immunological parameters including antibody titers against sheed red blood cells, lymphoproliferative response to avian tuberculin and phagocytic potential of macrophages were suppressed by AFB1 however in control, Moringa and vitamin E groups these immunological responses were significantly higher.

Heavy metal stress in plants: Ways to alleviate with exogenous substances

Accumulation and enrichment of excessive heavy metals due to industrialization and modernization not only devastate our ecosystem, but also pose a threat to the global vegetation, especially crops. To improve plant resilience against heavy metal stress (HMS), numerous exogenous substances (ESs) have been tried as the alleviating agents. After a careful and thorough review of over 150 recently published literature, 93 reported ESs and their corresponding effects on alleviating HMS, we propose that 7 underlying mechanisms of ESs be categorized in plants for: 1) improving the capacity of the antioxidant system, 2) inducing the synthesis of osmoregulatory substances, 3) enhancing the photochemical system, 4) detouring the accumulation and migration of heavy metals, 5) regulating the secretion of endogenous hormones, 6) modulating gene expressions, and 7) participating in microbe-involved regulations. Recent research advances strongly indicate that ESs have proven to be effective in mitigating a potential negative impact of HMS on crops and other plants, but not enough to ultimately solve the devastating problem associated with excessive heavy metals. Therefore, much more research should be focused and carried out to eliminate HMS for the sustainable agriculture and clean environmental through minimizing towards prohibiting heavy metals from entering our ecosystem, phytodetoxicating polluted landscapes, retrieving heavy metals from detoxicating plants or crop, breeding for more tolerant cultivars for both high yield and tolerance against HMS, and seeking synergetic effect of multiply ESs on HMS alleviation in our feature researches.

Evaluation of antioxidant activity and heavy metals content in licorice (Glycyrrhiza glabra L.) growing wild in Armenia

In this study, for the first time an analysis of the metal content in extracts obtained from licorice roots grown in the forests of five different regions in Armenia was conducted. Our findings indicated that the concentrations of metals in the extracts did not exceed the permissible limits set by regulatory standards. Furthermore, we investigated the quantitative composition of flavonoids, tannins, and anthocyanins in the licorice roots, which had not been previously studied. Our results revealed that the composition of these substances is significantly influenced by the soil characteristics of the region. To assess the antioxidant properties of the licorice extract, we employed the approach known as the kinetics of competitive reaction method. Our study successfully demonstrated that the extract derived from the roots of the licorice plant, collected from all five regions under study, exhibited notable antioxidant properties.

Integrative application of silicon and/or proline improves Sweet corn (Zea mays L. saccharata) production and antioxidant defense system under salt stress condition

Silicon (Si) and/or proline (Pro) are natural supplements that are considered to induce plants' stress tolerance against various abiotic stresses. Sweet corn (Zea mays L. saccharata) production is severely afflicted by salinity stress. Therefore, two field tests were conducted to evaluate the potential effects of Si and/or Pro (6mM) used as seed soaking (SS) and/or foliar spray (FS) on Sweet corn plant growth and yield, physio-biochemical attributes, and antioxidant defense systems grown in a saline (EC = 7.14dS m-1) soil. The Si and/or Pro significantly increased growth and yield, photosynthetic pigments, free proline, total soluble sugars (TSS), K+/Na+ratios, relative water content (RWC), membrane stability index (MSI), α-Tocopherol (α-TOC), Ascorbate (AsA), glutathione (GSH), enzymatic antioxidants activities and other anatomical features as compared to controls. In contrast, electrolytes, such as SS and/or FS under salt stress compared to controls (SS and FS using tap water) were significantly decreased. The best results were obtained when SS was combined with FS via Si or Pro. These alterations are brought about by the exogenous application of Si and/or Pro rendering these elements potentially useful in aiding sweet corn plants to acclimate successfully to saline soil.

Spirulina platensis extract improves the production and defenses of the common bean grown in a heavy metals-contaminated saline soil

Plants have to cope with several abiotic stresses, including salinity and heavy metals (HMs). Under these stresses, several extracts have been used as effective natural biostimulants, however, the use of Spirulina platensis (SP) extract (SPE) remains elusive. The effects of SPE were evaluated as soil addition (SA) and/or foliar spraying (FS) on antioxidant defenses and HMs content of common bean grown in saline soil contaminated with HMs. Individual (40 or 80 mg SPE/hill added as SA or 20 or 40 mg SPE/plant added as FS) or integrative (SA+FS) applications of SPE showed significant improvements in the following order: SA-80+FS-40 > SA-80+FS-20 > SA-40+FS-40 > SA-40+FS-20 > SA-80 > SA-40 > FS-40 > FS-20 > control. Therefore, the integrative SA+FS with 40 mg SP/plant was the most effective treatment in increasing plant growth and production, overcoming stress effects and minimizing contamination of the edible part. It significantly increased plant growth (74%-185%) and yield (107%-227%) by enhancing net photosynthetic rate (78.5%), stomatal conductance (104%), transpiration rate (124%), and contents of carotenoids (60.0%), chlorophylls (49%-51%), and NPK (271%-366%). These results were concurrent with the marked reductions in malondialdehyde (61.6%), hydrogen peroxide (42.2%), nickel (91%-94%), lead (80%-9%), and cadmium (74%-91%) contents due to the improved contents of glutathione (87.1%), ascorbate (37.0%), and α-tocopherol (77.2%), and the activities of catalase (18.1%), ascorbate peroxidase (18.3%), superoxide dismutase (192%), and glutathione reductase (52.2%) as reinforcing mechanisms. Therefore, this most effective treatment is recommended to mitigate the stress effects of salinity and HMs on common bean production while minimizing HMs in the edible part.

Biochar loaded with bacteria enhanced Cd/Zn phytoextraction by facilitating plant growth and shaping rhizospheric microbial community

Biochar and metal-tolerant bacteria have been widely used in the remediation of heavy metal contaminated soil. However, the synergistic effect of biochar-functional microbes on phytoextraction by hyperaccumulators remains unclear. In this study, the heavy metal-tolerant strain Burkholderia contaminans ZCC was selected and loaded on biochar to produce biochar-resistant bacterial material (BM), and the effects of BM on Cd/Zn phytoextraction by Sedum alfredii Hance and rhizospheric microbial community were explored. The results showed that, BM application significantly enhanced the Cd and Zn accumulation of S. alfredii by 230.13% and 381.27%, respectively. Meanwhile, BM alleviated metal toxicity of S. alfredii by reducing oxidative damage and increasing chlorophyll and antioxidant enzyme activity. High-throughput sequencing revealed that BM significantly improved soil bacterial and fungal diversity, and increased the abundance of genera with plant growth promoting and metal solubilizing functions such as Gemmatimonas, Dyella and Pseudarthrobacter. Co-occurrence network analysis showed that BM significantly increased the complexity of the rhizospheric bacterial and fungal network. Structural equation model analysis revealed that soil chemistry property, enzyme activity and microbial diversity contributed directly or indirectly to Cd and Zn extraction by S. alfredii. Overall, our results suggested that biochar- B. contaminans ZCC was able to enhance the growth and Cd/Zn accumulation by S. alfredii. This study enhanced our understanding on the hyperaccumulator-biochar-functional microbe interactions, and provided a feasible strategy for promoting the phytoextraction efficiency of heavy metal contaminated soils.

Thyme essential oil fostering the efficacy of aqueous extract of licorice against fungal phytopathogens of Capsicum annuum L

Capsicum annuum L. production is impeded by various biotic factors, including fungal diseases caused by Colletotrichum capsici, Pythium aphanidermatum, and Fusarium oxysporum. Various plant extracts and essential oils are increasingly used to control different plant diseases. In this study, licorice (Glycyrrhiza glabra) cold water extract (LAE) and thyme (Thymus vulgaris) essential oil (TO) were found to be highly effective against the C. annuum pathogens. LAE at 200 mg ml^-1 demonstrated the maximum antifungal activity of 89.9% against P. aphanidermatum, whereas TO at 0.25 mg ml^-1 showed 100% inhibition of C. capsici. However, when used in combination, much lower doses of these plant protectants (100 mg ml^-1 LAE and 0.125 mg ml^-1 TO) exhibited a synergistic effect in controlling the fungal pathogens. Metabolite profiling using gas chromatography-mass spectrometry and high resolution-liquid chromatography-mass spectrophotometry analysis showed the presence of several bioactive compounds. Enhanced cellular components leakage revealed damage to the fungal cell wall and membrane due to and LAE treatment, which can be attributed to the TO lipophilicity and triterpenoid saponins of LAE. TO and LAE treatments also caused a reduction in ergosterol biosynthesis might be due to the presence of thymol and sterol components in the botanicals. Although the aqueous extracts have a low preparation cost, their uses are limited by modest shelf life and lacklustre antifungal effect. We have shown that these limitations can be bypassed by combining oil (TO) with the aqueous extract (LAE). This study further opens the avenues for utilizing these botanicals against other fungal phytopathogens.

Effects of multiwalled carbon nanotube and Bacillus atrophaeus application on crop root zone thermal characteristics of saline farmland

Presently, the effects of crop roots on crop root zone thermal characteristics are poorly understood, and new fertilizers are rarely considered from the perspective of changing crop root zone thermal characteristics. This study explored the effect of applying two new fertilizers, multiwalled carbon nanotubes (MWCNTs) and Bacillus atrophaeus (B. atrophaeus), on the crop root zone thermal characteristics of saline farmland soils through in situ measurements. The results showed that MWCNTs and B. atrophaeus could indirectly affect crop root zone thermal characteristics by changing the crop root growth. Combined application of MWCNTs and B. atrophaeus could promote both to induce positive effects, promote crop root growth, and significantly alleviate the adverse effects of soil salinization. The thermal conductivity and heat capacity of the shallow root zone were reduced due to the presence of crop roots, while the opposite was true in the deep root zone. For example, the thermal conductivity of the 0-5 cm rich root zone in the MWCNT treatment was 0.8174 W m^-1 ·K^-1, and the thermal conductivity of the poor root zone was 13.42% higher than that of the rich root zone. MWCNTs and B. atrophaeus can also change the spatial distribution of soil moisture, soil salt, and soil particle size characteristics by influencing the root-soil interactions and indirectly affecting crop root zone thermal characteristics. In addition, MWCNTs and B. atrophaeus could directly affect the root zone thermal characteristics by changing the soil properties. The higher the soil salt content was, the more obvious the effect of the MWCNTs and B. atrophaeus on the crop root zone thermal characteristics. The thermal conductivity and heat capacity of the crop root zone were positively correlated with the soil moisture content, soil salt content and soil particle specific surface area and negatively correlated with the soil particle size and the fresh and dry root weights. In summary, MWCNTs and B. atrophaeus significantly affected crop root zone thermal characteristics directly and indirectly and could adjust the temperature of the crop root zone.

Interplay of silymarin and clove fruit extract effectively enhances cadmium stress tolerance in wheat (Triticum aestivum)

Introduction

Osmoprotectant supplementation can be used as a useful approach to enhance plant stress tolerance. However, the effect of silymarin and clove fruit extract (CFE) on wheat plants grown under cadmium (Cd) stress has not been studied.

Methods

Wheat seeds were planted in plastic pots filled with ions-free sand. A ½-strength Hoagland's nutrient solution was used for irrigation. Pots were treated with eight treatments thirteen days after sowing: 1) Control, 2) 0.5 mM silymarin foliar application [silymarin], 3) 2% CFE foliar application [CFE], 4) CFE enriched with silymarin (0.24 g silymarin L-1 of CFE) [CFE-silymarin], 5) Watering wheat seedlings with a nutritious solution of 2 mM Cd [Cd]. 6) Cadmium + silymarin, 7) Cadmium + CFE, and 8) Cadmium + CFE-silymarin. The experimental design was a completely randomized design with nine replicates.

Results and discussion

The Cd stress decreased grain yield, shoot dry weight, leaf area, carotenoids, chlorophylls, stomatal conductance, net photosynthetic rate, transpiration rate, membrane stability index, nitrogen, phosphorus, and potassium content by 66.9, 60.6, 56.7, 23.8, 33.5, 48.1, 41.2, 48.7, 42.5, 24.1, 39.9, and 24.1%, respectively. On the other hand, Cd has an Application of CFE, silymarin, or CEF-silymarin for wheat plants grown under Cd stress, significantly improved all investigated biochemical, morphological, and physiological variables and enhanced the antioxidant enzyme activities. Applying CFE and/or silymarin enhanced plant tolerance to Cd stress more efficiently. Our findings suggest using CFE-silymarin as a meaningful biostimulator for wheat plants to increase wheat plants' tolerance to Cd stress via enhancing various metabolic and physiological processes.

Rebalancing Nutrients, Reinforcing Antioxidant and Osmoregulatory Capacity, and Improving Yield Quality in Drought-Stressed Phaseolus vulgaris by Foliar Application of a Bee-Honey Solution

Bee-honey solution (BHS) is considered a plant growth multi-biostimulator because it is rich in osmoprotectants, antioxidants, vitamins, and mineral nutrients that can promote drought stress (DtS) resistance in common bean plants. As a novel strategy, BHS has been used in a few studies, which shows that the application of BHS can overcome the stress effects on plant productivity and can contribute significantly to bridging the gap between agricultural production and the steady increase in population under climate changes. Under sufficient watering (SW (100% of crop evapotranspiration; ETc) and DtS (60% of ETc)), the enhancing impacts of foliar application with BHS (0%, 0.5%, 1.0%, and 1.5%) on growth, productivity, yield quality, physiological-biochemical indices, antioxidative defense ingredients, and nutrient status were examined in common bean plants (cultivar Bronco). DtS considerably decreased growth and yield traits, green pod quality, and water use efficiency (WUE); however, application of BHS at all concentrations significantly increased all of these parameters under normal or DtS conditions. Membrane stability index, relative water content, nutrient contents, SPAD (chlorophyll content), and PSII efficiency (Fv/Fm, photochemical activity, and performance index) were markedly reduced under DtS; however, they increased significantly under normal or DtS conditions by foliar spraying of BHS at all concentrations. The negative impacts of DtS were due to increased oxidants [hydrogen peroxide (H₂O₂) and superoxide (O₂^•-)], electrolyte leakage (EL), and malondialdehyde (MDA). As a result, the activity of the antioxidant system (ascorbate peroxidase, glutathione reductase, catalase, superoxide dismutase, α-tocopherol, glutathione, and ascorbate) and levels of osmoprotectants (soluble protein, soluble sugars, glycine betaine, and proline) were increased. However, all BHS concentrations further increased osmoprotectant and antioxidant capacity, along with decreased MDA and EL under DtS. What is interesting in this study was that a BHS concentration of 1.0% gave the best results under SW, while a BHS concentration of 1.5% gave the best results under DtS. Therefore, a BHS concentration of 1.5% could be a viable strategy to mitigate the DtS impairment in common beans to achieve satisfactory growth, productivity, and green pod quality under DtS.

Exogenous nano-silicon application improves ion homeostasis, osmolyte accumulation and palliates oxidative stress in Lens culinaris under NaCl stress

Lentil is one of the highly nutritious legumes but is highly susceptible to salinity stress. Silicon has been known to reduce the effect of various environmental stresses including salinity. Moreover, silicon when applied in its nano-form is expected to augment the beneficial attributes of silicon. However, very little is known regarding the prospect of nano-silicon (nSi) application for alleviating the effect of salinity stress in non-silicified plants like lentil. In this study, the primary objective was to evaluate the efficacy of nSi in the alleviation of NaCl stress during germination and early vegetative stages. In this context, different concentrations of nSi (0, 1, 5, 10 g L-1) was applied along with four different concentrations of NaCl (0, 100, 200, 300 mM). The results indicated the uptake of nSi which was confirmed by the better accumulation of silica in the plant tissues. Most importantly, the enhanced accumulation of silica increased the K+/Na+ ratio of the NaCl-stressed seedlings. Moreover, nSi efficiently improved germination, growth, photosynthetic pigments, and osmotic balance. On the other hand, the relatively reduced activities of antioxidative enzymes were surmounted by the higher activity of non-enzymatic antioxidants which mainly scavenged the increased ROS. Reduced ROS accumulation in return ensured better membrane integrity and reduced electrolyte leakage up on nSi application. Therefore, it can be concluded that the application of nSi (more specifically at 10 g L-1) facilitated the uptake of silica and improved the K+/Na+ ratio to reclaim the growth and physiological status of NaCl-stressed seedlings.

Integrative application of heavy metal-resistant bacteria, moringa extracts, and nano-silicon improves spinach yield and declines its contaminant contents on a heavy metal-contaminated soil

Microorganism-related technologies are alternative and traditional methods of metal recovery or removal. We identified and described heavy metal-resistant bacteria isolated from polluted industrial soils collected from various sites at a depth of 0-200 mm. A total of 135 isolates were screened from polluted industrial soil. The three most abundant isolate strains resistant to heavy metals were selected: Paenibacillus jamilae DSM 13815T DSM (LA22), Bacillus subtilis ssp. spizizenii DSM 15029T DSM (MA3), and Pseudomonas aeruginosa A07_08_Pudu FLR (SN36). A test was conducted to evaluate the effect of (1) isolated heavy metal-resistant bacteria (soil application), (2) a foliar spray with silicon dioxide nanoparticles (Si-NPs), and (3) moringa leaf extract (MLE) on the production, antioxidant defense, and physio-biochemical characteristics of spinach grown on heavy metal-contaminated soil. Bacteria and MLE or Si-NPs have been applied in single or combined treatments. It was revealed that single or combined additions significantly increased plant height, shoot dry and fresh weight, leaf area, number of leaves in the plant, photosynthetic pigments content, total soluble sugars, free proline, membrane stability index, ascorbic acid, relative water content, α-tocopherol, glycine betaine, glutathione, and antioxidant enzyme activities (i.e., peroxidase, glutathione reductase, catalase, superoxide dismutase, and ascorbate peroxidase) compared with the control treatment. However, applying bacteria or foliar spray with MLE or Si-NPs significantly decreased the content of contaminants in plant leaves (e.g., Fe, Mn, Zn, Pb, Cd, Ni, and Cu), malondialdehyde, electrolyte leakage, superoxide radical ( O 2 · - ) , and hydrogen peroxide (H2O2). Integrative additions had a more significant effect than single applications. It was suggested in our study that the integrative addition of B. subtilis and MLE as a soil application and as a foliar spray, respectively, is a critical approach to increasing spinach plant performance and reducing its contaminant content under contaminated soil conditions.

The Role of Moringa Leaf Extract as a Plant Biostimulant in Improving the Quality of Agricultural Products

Ensuring high-quality agricultural products has become important in agriculture since society’s standard of living has risen. Meanwhile, Moringa oleifera L. leaf extract (MLE) has been used as a plant biostimulant to improve product quality. The effectiveness of MLE is associated with its beneficial components, consisting of nutrients, phytohormones, secondary metabolites, amino acids, and bioactive compounds. Previous studies have been carried out to find the effects of MLE application on the quality of different crops, including basil, kale, spinach, maize, radish, brinjal, pepper, tomato, grape, strawberry, and more. The results are generally positive concerning physical, nutritional, and chemical qualities. This review comprises recent findings regarding MLE application as a plant biostimulant to increase quality attributes, with its underlying mechanism.

Role of microbes in bioaccumulation of heavy metals in municipal solid waste: Impacts on plant and human being

The presence of heavy metals in municipal solid waste (MSW) is considered as prevalent global pollutants that cause serious risks to the environment and living organisms. Due to industrial and anthropogenic activities, the accumulation of heavy metals in the environmental matrices is increasing alarmingly. MSW causes several adverse environmental impacts, including greenhouse gas (GHG) emissions, river plastic accumulation, and other environmental pollution. Indigenous microorganisms (Pseudomonas, Flavobacterium, Bacillus, Nitrosomonas, etc.) with the help of new pathways and metabolic channels can offer the potential approaches for the treatment of pollutants. Microorganisms, that exhibit the ability of bioaccumulation and sequestration of metal ions in their intracellular spaces, can be utilized further for the cellular processes like enzyme signaling, catalysis, stabilizing charges on biomolecules, etc. Microbiological techniques for the treatment and remediation of heavy metals provide a new prospects for MSW management. This review provides the key insights on profiling of heavy metals in MSW, tolerance of microorganisms, and application of indigenous microorganisms in bioremediation. The literatures revealed that indigenous microbes can be exploited as potential agents for bioremediation.

Bacillus atrophaeus WZYH01 and Planococcus soli WZYH02 Improve Salt Tolerance of Maize (Zea mays L.) in Saline Soil

With the increasing shortage of land resources and people's attention to the ecological environment, the application of microbial fertilizer with natural soil microorganisms as the main component has attracted increasing attention in saline agriculture. In this study, two salt-tolerant strains, YL07 (Bacillus atrophaeus) and YL10 (Planococcus soli), were isolated from maize (Zea mays L.) rhizosphere soil with a saturated conductivity (EC_e) of 6.13 dS/m and pH of 8.32 (Xinjiang, China). The effects of B. atrophaeus WZYH01 (YL07) and Planococcus soli WZYH02 (YL10) on the growth and development of maize (Zea mays L.) under salt stress (EC_e = 5.9 dS/m) were further studied. The results showed that compared with uninoculation, inoculation with B. atrophaeus WZYH01 and Planococcus soli WZYH02 significantly improved maize growth performance, biomass yield, and antioxidant levels under salt stress, and the effect of Planococcus soli WZYH02 was more prominent than the effect of B. atrophaeus WZYH01. Moreover, inoculation with B. atrophaeus WZYH01 and Planococcus soli WZYH02 protected maize from salt stress by regulating plant hormone [IAA and abscisic acid (ABA)] levels and increasing nutrient acquisition. In addition, the tested strains were most efficient for maize growth and health, increasing the content of K⁺ accompanied by an effective decrease in Na⁺ in maize tissues. The transcription levels of salt tolerance genes (ZMNHX1, ZMNHX2, ZMHKT, ZMWRKY58, and ZMDREB2A) in inoculated maize were also dramatically higher than the transcription levels of the specified salt tolerance genes in uninoculated maize. In conclusion, B. atrophaeus WZYH01 and Planococcus soli WZYH02 can alleviate the harmful effects of salt stress on crop growth, thereby promoting sustainable agricultural development.

Integrative Seed and Leaf Treatment with Ascorbic Acid Extends the Planting Period by Improving Tolerance to Late Sowing Influences in Parsley

Abnormal production of reactive oxygen species (ROS) is an undesirable event which occurs in plants due to stress. To meet this event, plants synthesize ROS-neutralizing compounds, including the non-enzymatic oxidant scavenger known as vitamin C: ascorbic acid (AsA). In addition to scavenging ROS, AsA modulates many vital functions in stressed or non-stressed plants. Thus, two-season (2018/2019 and 2019/2020) trials were conducted to study the effect of integrative treatment (seed soaking + foliar spray) using 1.0 or 2.0 mM AsA vs. distilled water (control) on the growth, seed yield, and oil yield of parsley plants under three sowing dates (SDs; November, December, and January, which represent adverse conditions of late sowing) vs. October as the optimal SD (control). The ion balance, osmotic-modifying compounds, and different antioxidants were also studied. The experimental layout was a split plot in a completely randomized block design. Late sowing (December and January) noticeably reduced growth traits, seed and oil yield components, and chlorophyll and nutrient contents. However, soluble sugar, proline, and AsA contents were significantly increased along with the activities of catalase (CAT) and superoxide dismutase (SOD). Under late sowing conditions, the use of AsA significantly increased growth, different yields, essential oil fractions, CAT and SOD activities, and contents of chlorophylls, nutrients, soluble sugars, free proline, and AsA. The interaction treatments of SDs and AsA concentrations indicated that AsA at a concentration of 2 mM was more efficient in conferring greater tolerance to adverse conditions of late sowing in parsley plants. Therefore, this study recommends 2.0 mM AsA for integrative (seed soaking + foliar spraying) treatment to prolong the sowing period of parsley seeds (from October up to December) and avoid damage caused by adverse conditions of late sowing.

Soaking Maize Seeds in Zeatin-Type Cytokinin Biostimulators Improves Salt Tolerance by Enhancing the Antioxidant System and Photosynthetic Efficiency

There is an urgent need for innovative strategies to raise the performance of environmentally stressed plants. The seeds of single-cross yellow Zea mays (L.) hybrid Giza-168 were soaked in Cis-(c-Z-Ck) or trans-zeatin-type cytokinin (t-Z-Ck) solutions at a concentration of 50 or 40 µM, respectively. Salinity stress was imposed at 0, 75 or 150 mM NaCl in the Hoagland nutrient solution (full strength) used for irrigation. The total carotenoids content was negatively affected by only 150 mM NaCl, while both 75 and 150 mM NaCl negatively affected the growth and yield components, relative water content, membrane stability index, photochemical activity, gas exchange, K⁺ and chlorophyll contents, K⁺/Na⁺ ratio, and photosynthetic efficiency. However, all of these traits were significantly improved by c-Z-Ck pretreatment and further enhanced by t-Z-Ck pretreatment compared with the corresponding controls. Furthermore, the contents of proline, soluble sugars, ascorbate, and glutathione, as well as enzymatic antioxidant activities, were significantly elevated by both salt stress concentrations and increased more by both biostimulators compared to the control. Compared to c-Z-Ck, t-Z-Ck was superior in mitigating the harmful effects of the high H₂O₂ levels caused by salt stress on the levels of malondialdehyde and ion leakage compared to the control. Under normal or stress conditions, t-Z-Ck pretreatment was better than c-Z-Ck pretreatment, while both positively affected maize hormonal contents. As a result, t-Z-Ck is recommended to enhance the growth and productivity of maize plants by suppressing the effects of oxidative stress caused by saline water irrigation.

Immunological effect of Moringa Oleifera leaf extract on vaccinated and non-vaccinated Hubbard chickens experimentally infected with Newcastle virus

In veterinary medicine plant based medicine is achieving a huge importance worldwide. This research was subjected to rectify the hydrophilic Moringa Oleifera alcoholic leaves extract could improve the immune system in vaccinated and non-vaccinated broiler Hubbard chickens experimentally exposed to Newcastle disease (ND) virus. Seventy five chicks with age one day old were splitted randomly into five groups equally in distribution with fifteen chick in each group. Group I was untreated unvaccinated (control negative group) while group IV was infected group with NDV (control positive group). The experimental Groups II and V were given daily oral treatment of hydrophilic alcoholic leaves extract of M. oleifera at 200 mg/kg body weight until day 21 of age while groups III and V were ND vaccinated with La Sota strain of ND vaccines. The four groups (II, III, IV, V) were infected with ND virus velogenic strain (VNDV) on day 21. Following to infection, Monitoring of birds were done daily for clinical signs, postmortem examination, morbidity and mortality. Cellular, humeral immune response and phagocytic activity were evaluated and the data were statistically analyzed using (SPSS). Total and differential cell numbers as well as Haemagglutination inhibition (HI) titre increased in the extract treated and vaccinated group which give total protection against NDV much more than treated and unvaccinated group. As a result it could be recommended to use M. Olifera extract from the first day of rearing in Hubbard chicken with ND vaccination program as a prophylactic treatment in protection of birds against ND infection.

Exploring the potential of moringa leaf extract as bio stimulant for improving yield and quality of black cumin oil

The history of plants to be utilized as medicines is thousands of years old. Black cumin is one of the most widely examined plant possessing naturally occurring compounds with antimicrobial potential. Foliar application of growth stimulators is a successful strategy to enhance yield and quality in many crops. A field study was planned to apply growth stimulator like moringa leaf extract on black cumin crop grown under field conditions using RCB design with three replications. All other agronomic inputs and practices were uniform. The treatments were moringa leaf extract concentrations (10%, 20%), growth stages (40 days after sowing, 80 DAS, 120 DAS, 40 + 80 DAS, 40 + 120 DAS, 80 + 120 DAS, 40 + 80 + 120 days after sowing) and two controls unsprayed check (i.e. no moringa leaf extract, no water) and sprayed check (no moringa leaf extract + water). Application of 20% moringa leaf extract at stage-7 (40 + 80 + 120 days after sowing) had significantly increased plant height, branches plant⁻¹, essential oil content, fixed oil content, peroxidase value and iodine value of black cumin oil over unsprayed control. Application of moringa leaf extract showed maximum results and improves growth and yield of black cumin when applied at 40 + 80 + 120 days after sowing. As this study was only conducted using moringa leaf extract, it is advisable to conduct an experiment with various bio stimulants along with fertilizer combinations and growth regulators to check their synergistic effects for more reliable and acceptable recommendations in future.

Impact of wastewater discharge on the plant diversity, community structure and heavy metal pollution of range plants in eastern Saudi Arabia

The main objectives of this study were to determine the floristic composition of the vegetation cover and to find the effects of wastewater pollution on the plant community structure in eastern Saudi Arabia. 28 stands which were distributed among polluted and unpolluted sites, were chosen for this study. A total of 42 plant species were recorded (14 in the polluted and 28 in the unpolluted sites). The recorded plants comprised of 13 perennial plant species and 29 annual plant species. Seven vegetation communities were determined using TWINSPAN and DCA classification and ordination techniques. Three in the polluted sites, two in the unpolluted sites and the remaining two were mixed communities. The (Sarcopoterium spinosum – Pistacia len‐tiscus) community in the polluted sites, had the highest values of soil moisture, salinity, sulphate, calcium and potassium. On the other hand, Juniperus phoenicea – Olea europaea community in the unpolluted site, had the lowest value of organic matter, salinity and magnesium. In respect of genetic diversity, the community of Foeniculum vulgare - Nicotiana glauca in the unpolluted site, was the most diverse, while Ricinus communis - Chrysanthemum coronarium in the polluted sites was the least one. Both soil and wastewater heavy metal analysis indicated that Pb, Cd, Cr, Cu and Ni concentrations in the polluted sites were significantly higher than those in the unpolluted ones. The impact of wastewater discharge led to the appearance of new invasive plant species that may significantly affect plant diversity and community structure in eastern Saudi Arabia. Finally wastewater discharge in open rangelands could adversely affect the growth of plant species in the rangelands and thus adversely affect plant community structure and diversity.

Natural Biostimulant Attenuates Salinity Stress Effects in Chili Pepper by Remodeling Antioxidant, Ion, and Phytohormone Balances, and Augments Gene Expression

A biostimulant is any microorganism or substance used to enhance the efficiency of nutrition, tolerance to abiotic stress and/or quality traits of crops, depending on its contents from nutrients. Plant biostimulants like honey bee (HB) and silymarin (Sm) are a strategic trend for managing stressed crops by promoting nutritional and hormonal balance, regulating osmotic protectors, antioxidants, and genetic potential, reflecting plant growth and productivity. We applied diluted honey bee (HB) and silymarin-enriched honey bee (HB- Sm) as foliar nourishment to investigate their improving influences on growth, yield, nutritional and hormonal balance, various osmoprotectant levels, different components of antioxidant system, and genetic potential of chili pepper plants grown under NaCl-salinity stress (10 dS m‒1). HB significantly promoted the examined attributes and HB-Sm conferred optimal values, including growth, productivity, K+/Na+ ratio, capsaicin, and Sm contents. The antioxidative defense components were significantly better than those obtained with HB alone. Conversely, levels of oxidative stress markers (superoxide ions and hydrogen peroxide) and parameters related to membrane damage (malondialdehyde level, stability index, ionic leakage, Na+, and Cl- contents) were significantly reduced. HB-Sm significantly affects inactive gene expression, as a natural biostimulator silencing active gene expression. SCoT primers were used as proof in salt-treated or untreated chili pepper plants. There were 41 cDNA amplicons selected by SCoT-primers. Twenty of them were EcDNA amplicons (cDNA-amplicons that enhanced their genes by one or more treatments) representing 49% of all cDNA amplicons, whereas 7 amplicons for ScDNA (whose genes were silenced in one or more treatments) represented 17%, and 14 McDNA (monomorphic cDNA-amplicons with control) amplicons were represented by 34% from all cDNA amplicons. This indicates the high effect of BH-Sm treatments in expression enhancement of some inactive genes and their silenced effect for expression of some active genes, also confirming that cDNA-SCoT markers succeeded in detection of variable gene expression patterns between the untreated and treated plants. In conclusion, HB-Sm as a natural multi-biostimulator can attenuate salt stress effects in chili pepper plants by remodeling the antioxidant defense system and ameliorating plant productivity.

Foliar Supplementation of Clove Fruit Extract and Salicylic Acid Maintains the Performance and Antioxidant Defense System of Solanum tuberosum L. under Deficient Irrigation Regimes

A field trial was conducted twice (in 2020 and 2021) to evaluate the effect of clove fruit extract (CFE) and/or salicylic acid (SA), which were used as a foliar nourishment, on growth and yield traits, as well as physiological and biochemical indices utilizing potato (Solanum tuberosum L.) plants irrigated with deficient regimes in an arid environment. Three drip irrigation regimes [e.g., well watering (7400 m3 ha−1), moderate drought (6200 m3 ha−1), and severe drought (5000 m3 ha−1)] were designed for this study. The tested growth, yield, and photosynthetic traits, along with the relative water content, were negatively affected, whereas markers of oxidative stress (hydrogen peroxide and superoxide), electrolyte leakage, and peroxidation of membrane lipids (assessed as malondialdehyde level) were augmented along with increased antioxidative defense activities under drought stress. These effects were gradually increased with the gradual reduction in the irrigation regime. However, under drought stress, CFE and/or SA significantly enhanced growth characteristics (fresh and dry weight of plant shoot and plant leaf area) and yield components (average tuber weight, number of plant tubers, and total tuber yield). In addition, photosynthetic attributes (chlorophylls and carotenoids contents, net photosynthetic and transpiration rates, and stomatal conductance) were also improved, and defensive antioxidant components (glutathione, free proline, ascorbate, soluble sugars, and α-tocopherol levels, and activities of glutathione reductase, peroxidase, superoxide dismutase, catalase, and ascorbate peroxidase) were further enhanced. The study findings advocate the idea of using a CFE+SA combined treatment, which was largely efficient in ameliorating potato plant growth and productivity by attenuating the limiting influences of drought stress in dry environments.

Biological silicon nanoparticles improve Phaseolus vulgaris L. yield and minimize its contaminant contents on a heavy metals-contaminated saline soil

The synthesis of biological silicon nano-particles (Bio-Si-NPs) is an eco-friendly and low-cost method. There is no study focusing on the effect of Bio-Si-NPs on the plants grown on saline soil contaminated with heavy metals. In this study, an attempt was made to synthesis Bio-Si-NPs using potassium silica florid substrate, and the identified Aspergillus tubingensis AM11 isolate that separated from distribution systems of the potable water. A two-year field trial was conducted to compare the protective effects of Bio-Si-NPs (2.5 and 5.0 mmol/L) and potassium silicate (10 mmol/L) as a foliar spray on the antioxidant defense system, physio-biochemical components, and the contaminants contents of Phaseolus vulgaris L. grown on saline soil contaminated with heavy metals. Our findings showed that all treatments of Bio-Si-NPs and potassium silicate significantly improved plant growth and production, chlorophylls, carotenoids, transpiration rate, net photosynthetic rate, stomatal conductance, membrane stability index, relative water content, free proline, total soluble sugars, N, P, K, Ca²⁺, K⁺/Na⁺, and the activities of peroxidase, catalase, ascorbic peroxidase and superoxide oxide dismutase. Application of Bio-Si-NPs and potassium silicate significantly decreased electrolyte leakage, malondialdehyde, H₂O₂, O₂^•-, Na⁺, Pb, Cd, and Ni in leaves and pods of Phaseolus vulgaris L. compared to control. Bio-Si-NPs were more effective compared to potassium silicate. Application of Bio-Si-NPs at the rate of 5 mmol/L was the recommended treatment to enhance the performance and reduce heavy metals content on plants grown on contaminated saline soils.

Foliar Nourishment with Nano-Selenium Dioxide Promotes Physiology, Biochemistry, Antioxidant Defenses, and Salt Tolerance in Phaseolus vulgaris

Novel strategic green approaches are urgently needed to raise the performance of plants subjected to stress. Two field-level experimental attempts were implemented during two (2019 and 2020) growing seasons to study the possible effects of exogenous nourishment with selenium dioxide nanoparticles (Se-NPs) on growth, physio-biochemical ingredients, antioxidant defenses, and yield of Phaseolus vulgaris (L.) plant growing on a salt-affected soil (EC = 7.55–7.61 dS m⁻¹). At 20, 30, and 40 days from seeding, three foliar sprays were applied to plants with Se-NPs at a rate of 0.5, 1.0, or 1.5 mM. The experimental design was accomplished in randomized complete plots. The data indicate noteworthy elevations in indicators related to growth and yield; pigments related to effective photosynthesis, osmoprotectant (free proline and soluble sugars), nutrient and Se contents, K⁺/Na⁺ ratio, cell integrity (water content and stability of membranes), all enzyme activities; and all features related to leaf anatomy induced by Se-NPs foliar spray. Conversely, marked lowering in markers of Na⁺ content-induced oxidative stress (superoxide radical and hydrogen peroxide) and their outcomes in terms of ionic leakage and malondialdehyde were reported by foliar nourishment with Se-NPS compared to spraying leaves with water as an implemented control. The best results were recorded with Se-NPs applied at 1.0 mM, which mitigated the negative effects of soil salinity (control results). Therefore, the outcomes of this successful study recommend the use of Se-NPs at a rate of 1.0 mM as a foliar spray to grow common beans on saline soils with EC up to 7.55–7.61 dS m⁻¹.

Antioxidants and Bioactive Compounds in Licorice Root Extract Potentially Contribute to Improving Growth, Bulb Quality and Yield of Onion (Allium cepa)

The increasing culinary use of onion (Alium cepa) raises pressure on the current production rate, demanding sustainable approaches for increasing its productivity worldwide. Here, we aimed to investigate the beneficial effects of licorice (Glycyrrhiza glabra) root extract (LRE) in improving growth, yield, nutritional status, and antioxidant properties of two high-yielding onion cultivars, Shandaweel and Giza 20, growing under field conditions in two consecutive years. Our results revealed that pretreatments of both onion cultivars with LRE exhibited improved growth indices (plant height and number of leaves) and yield-related features (bulb length, bulb diameter, and bulb weight) in comparison with the corresponding LRE-devoid control plants. Pretreatments with LRE also improved the nutritional and antioxidant properties of bulbs of both cultivars, which was linked to improved mineral (e.g., K+ and Ca2+) acquisition, and heightened activities of enzymatic antioxidants (e.g., superoxide dismutase, catalase, ascorbate peroxidase, glutathione peroxidase, and glutathione S-transferase) and increased levels of non-enzymatic antioxidants (e.g., ascorbic acid, reduced glutathione, phenolics, and flavonoids). LRE also elevated the contents of proline, total free amino acids, total soluble carbohydrates, and water-soluble proteins in both onion bulbs. In general, both cultivars displayed positive responses to LRE pretreatments; however, the Shandaweel cultivar performed better than the Giza 20 cultivar in terms of yield and, to some extent, bulb quality. Collectively, our findings suggest that the application of LRE as biostimulant might be an effective strategy to enhance bulb quality and ultimately the productivity of onion cultivars under field conditions.

Exogenous Gibberellic Acid or Dilute Bee Honey Boosts Drought Stress Tolerance in Vicia faba by Rebalancing Osmoprotectants, Antioxidants, Nutrients, and Phytohormones

The use of growth regulators such as gibberellic acid (GA₃) and biostimulants, including diluted bee honey (Db-H) can improve drought tolerance in many crops, including the faba bean (Vicia faba L.). Db-H contains high values of osmoprotectants, mineral nutrients, vitamins, and many antioxidants making it an effective growth regulator against environmental stress effects. Therefore, the present study was planned to investigate the potential improvement in the faba bean plant performance (growth and productivity) under full watering (100% of crop evapotranspiration (ETc)) and drought stress (60% of ETc) by foliar application of GA₃ (20 mg L⁻¹) or Db-H (20 g L⁻¹). The ameliorative impacts of these growth regulators on growth, productivity, physio-biochemical attributes, nutrient status, antioxidant defense system, and phytohormones were evaluated. GA₃ or Db-H attenuated the negative influences of drought stress on cell membrane stability, ion leakage, relative water content, nutrient status, leaf pigments related to photosynthesis (chlorophylls and carotenoids), and efficiency of the photosystem II (PSII in terms of F_v/F_m and performance index), thus improving faba bean growth, green pod yield, and water use efficiency. Drought stress caused an abnormal state of nutrients and photosynthetic machinery due to increased indicators of oxidative stress (malondialdehyde (MDA), hydrogen peroxide (H₂O₂) and superoxide (O₂^•−)), associated with increased osmoprotectants (proline, glycine betaine, soluble sugars, and soluble protein), non-enzymatic antioxidants (ascorbic acid, glutathione, and α-tocopherol), and enzymatic antioxidant activities (superoxide dismutase, catalase, glutathione reductase, and ascorbate peroxidase). However, foliar-applied GA₃ or Db-H mediated further increases in osmoprotectants, antioxidant capacity, GA₃, indole-3-acetic acid, and cytokinins, along with decreased levels of MDA and abscisic acid. These results suggest the use of GA₃ or Db-H at the tested concentrations to mitigate drought-induced damage in bean plants to obtain satisfactory growth and productivity under a water deficit of up to 40%.

Silymarin-Enriched Biostimulant Foliar Application Minimizes the Toxicity of Cadmium in Maize by Suppressing Oxidative Stress and Elevating Antioxidant Gene Expression

For maize, the potential preventive role of foliar spraying with an extract derived from maize grain (MEg, 2%), silymarin (Sm, 0.5 mM), or silymarin-enriched MEg (MEg-Sm) in attenuating the stress effects of cadmium (Cd, 0.5 mM) was examined using a completely randomized design layout. Under normal conditions, foliar spraying with MEg, Sm, or MEg-Sm was beneficial (with MEg-Sm preferred) for maize plants, whereas the benefit was more pronounced under Cd stress. The use of Cd through irrigation water decreased plant growth traits, photosynthetic efficiency, including instantaneous carboxylation efficiency, Fv/Fm, and pigment contents, and hormonal contents (e.g., auxin, gibberellins, cytokinins including trans-zeatin, and salicylic acid). These undesired findings were due to an increase in Cd content, leading to increased levels of oxidative stress (O₂^•− and H₂O₂), ionic leakage, and lipid peroxidation. Therefore, this damage resulted in an increase in the activities of nonenzymatic antioxidants, Sm, antioxidative enzymes, and enzyme gene expression. However, under Cd stress, although foliar spray with MEg or Sm had better findings than control, MEg-Sm had better findings than MEg or Sm. Application of MEg-Sm greatly increased photosynthesis efficiency, restored hormonal homeostasis, and further increased the activities of various antioxidants, Sm, antioxidative enzymes, and enzyme gene expression. These desired findings were due to the suppression of the Cd content, and thus the levels of O₂^•−, H₂O₂, ionic leakage, and lipid peroxidation, which were positively reflected in the growth and accumulation of dry matter in maize plants. The data obtained in this study recommend applying silymarin-enriched maize grain extract (MEg-Sm at 0.24 g Sm L⁻¹ of MEg) as a spray solution to maize plants when exposed to excess Cd in soil or irrigation water.

Sequential Application of Antioxidants Rectifies Ion Imbalance and Strengthens Antioxidant Systems in Salt-Stressed Cucumber

Exogenous antioxidant applications enable salt-stressed plants to successfully cope with different environmental stresses. The objectives of this investigation were to study the effects of sequential treatments of proline (Pro), ascorbic acid (AsA), and/or glutathione (GSH) on 100 mM NaCl-stressed cucumber transplant’s physio-biochemical and growth traits as well as systems of antioxidant defense. Under salinity stress, different treatment of AsA, Pro, or/and GSH improved growth characteristics, stomatal conductance (gs), enhanced the activities of glutathione reductase (GR), superoxide dismutase (SOD), ascorbate peroxidase (APX), and catalase (CAT) as well as increased contents of AsA, Pro, and GSH. However, sequential application of antioxidants (GSH-Pro- AsA) significantly exceeded all individual applications, reducing leaf and root Cd²⁺ and Na⁺ contents in comparison to the control. In plants grown under NaCl-salt stress, growth characteristics, photosynthetic efficiency, membrane stability index (MSI), relative water content (RWC), contents of root and leaf K⁺ and Ca²⁺, and ratios of K⁺/Na⁺ and Ca²⁺/Na⁺ were notably reduced, while leaf contents of non-enzymatic and enzymatic antioxidants, as well as root and leaf Cd²⁺ and Na⁺ concentrations were remarkably increased. However, AsA, Pro, or/and GSH treatments significantly improved all investigated growth characteristics, photosynthetic efficiency, RWC and MSI, as well as AsA, Pro, and GSH, and enzymatic activity, leaf and root K⁺ and Ca²⁺ contents and their ratios to Na⁺, while significantly reduced leaf and root Cd²⁺ and Na⁺ contents.

Multidimensional Evaluation for Detecting Salt Tolerance of Bread Wheat Genotypes Under Actual Saline Field Growing Conditions

Field-based trials and genotype evaluation until yielding stage are two important steps in improving the salt tolerance of crop genotypes and identifying what parameters can be strong candidates for the better understanding of salt tolerance mechanisms in different genotypes. In this study, the salt tolerance of 18 bread wheat genotypes was evaluated under natural saline field conditions and at three saline irrigation levels (5.25, 8.35, and 11.12 dS m-1) extracted from wells. Multidimensional evaluation for salt tolerance of these genotypes was done using a set of agronomic and physio-biochemical attributes. Based on yield index under three salinity levels, the genotypes were classified into four groups ranging from salt-tolerant to salt-sensitive genotypes. The salt-tolerant genotypes exhibited values of total chlorophyll, gas exchange (net photosynthetic rate, transpiration rate, and stomatal conductance), water relation (relative water content and membrane stability index), nonenzymatic osmolytes (soluble sugar, free proline, and ascorbic acid), antioxidant enzyme activities (superoxide dismutase, catalase, and peroxidase), K+ content, and K+/Na+ ratio that were greater than those of salt-sensitive genotypes. Additionally, the salt-tolerant genotypes consistently exhibited good control of Na+ and Cl- levels and maintained lower contents of malondialdehyde and electrolyte leakage under high salinity level, compared with the salt-sensitive genotypes. Several physio-biochemical parameters showed highly positive associations with grain yield and its components, whereas negative association was observed in other parameters. Accordingly, these physio-biochemical parameters can be used as individual or complementary screening criteria for evaluating salt tolerance and improvement of bread wheat genotypes under natural saline field conditions.

Heavy metals-resistant bacteria (HM-RB): Potential bioremediators of heavy metals-stressed Spinacia oleracea plant

Microorganism technologies can provide a potential alternative to traditional methods of removing heavy metals to conserve agricultural soils. This study aimed to identify and characterize heavy metals-resistant bacteria (HM-RB) isolated from industry-affected soil and their desired impact as bioremediators of heavy metals-stressed spinach plants. Three of 135 isolates were selected based on a high level of resistance to heavy metals. Based on morphological and biochemical characteristics, the selected isolates were identified as Bacillus subtilis subsp. spizizenii DSM 15029 T DSM (MA3), Paenibacillus jamilae DSM 13815 T DSM (LA22), or Pseudomonas aeruginosa DSM 1117 DSM (SN36). Experiments were implemented to investigate the three isolated HM-RB ability on improving attributes of growth, physio-biochemistry, and components of the antioxidant defense system of spinach plant exposed to the stress of cadmium (Cd²⁺; 2 mM), lead (Pb²⁺; 2 mM) or 2 mM Cd²⁺+2 mM Pb²⁺. Compared to control, Cd²⁺ or Pb²⁺ stress markedly lowered plant fresh and dry weights, leaf contents of chlorophylls and carotenoids, rates of transpiration (Tr), net photosynthesis (Pn) and stomatal conductance (gs), relative water content (RWC), and membrane stability index (MSI). In contrast, contents of α.tochopherol (α.TOC), ascorbic acid (AsA), glutathione (GSH), proline, soluble sugars, Cd²⁺, and Pb²⁺, as well as activities of enzymatic and non-enzymatic antioxidants were markedly elevated. The application of HM-RB promoted the tolerance to heavy metal stress in spinach plants by improving Tr, Pn, gs, RWC, and MSI, while activities of enzymatic and non-enzymatic antioxidants were suppressed. These results reflected positively in promoting plant growth under heavy metal stress. Therefore, the application of HM-RB as potential bioremediators may be a promising strategy for promoting plant growth and productivity under heavy metal stress.

An overview of plant-based natural biostimulants for sustainable horticulture with a particular focus on moringa leaf extracts

The horticulture sector is facing various challenges in the near future. Aside from maintaining or even improving yields, sustainable horticulture production is crucial to achieve food security. Reducing the reliance on agro-chemicals and/or increasing the efficiency of use under a changing climate is crucial. Natural biostimulants can play an important role in this regard, increasing production at a relatively low cost sustainably. Natural biostimulant feedstocks include leaf, root or seed extracts, either individually or in combination with others. Their positive effect on horticultural production is mostly due to plant growth-enhancing bioactive compounds such as phytohormones, amino acids, and nutrients. Here we review recent progress made in research and applications on plant-derived extracts with an emphasis on the use of these renewable biochemicals as biostimulants in sustainable horticulture. Moringa leaf extracts in particular have been shown to improve seed germination, plant growth and yield, nutrient use efficiency, crop and product quality traits (pre- and post-harvest), as well as tolerance to abiotic stresses. Although horticulture production relies on synthetic fertilisers to maintain and improve production, the use of plant-derived biostimulants such as moringa leaf extracts may be an option to reduce quantities needed and thus contribute in achieving global food security sustainably.

Integrative application of licorice root extract or lipoic acid with fulvic acid improves wheat production and defenses under salt stress conditions

Although different plant extracts and plant growth regulators are used as biostimulants to support plants grown under salt stress conditions, little information is available regarding the use of licorice root extract (LRE) or lipoic acid (LA) as biostimulants. Studies on the application of LRE or LA in combination with fulvic acid (FA) as natural biostimulants have not been performed. Therefore, in this study, two pot experiments were conducted to evaluate the potential effects of LRE (5 g L^-1) or LA (0.1 mM) supplemented as a foliar spray in combination with FA (0.2 mg kg^-1 soil) on osmoprotectants and antioxidants, growth characteristics, photosynthetic pigments, nutrient uptake, and yield as well as on the anatomical features of the stems and leaves of wheat plants irrigated with three levels of saline water (0.70, 7.8, and 14.6 dSm^-1). Moderate (7.8 dSm^-1) and high (14.6 dSm^-1) levels of salinity caused a significant (p ≤ 0.05) increase in the activities of SOD, APX CAT, POX, and GR as well as in electrolyte leakage, malondialdehyde level, and reactive oxygen species (O₂^‒ and H₂O₂) levels compared to those in controls (plants irrigated with tap water). However, the leaf relative water content, membrane stability index, NPK uptake, leaf area, plant height, spike length, straw yield, grain yield, and protein content of wheat grains significantly (p ≤ 0.05) decreased. Addition of LRE or LA and/or HA to wheat plants under saline stress significantly (p ≤ 0.05) enhanced their morphological and physio-biochemical characteristics in parallel with increases in the activities of enzymatic antioxidants. Salinity stress altered (p ≤ 0.05) wheat stem and leaf structures; however, treatment with LRE + FA significantly improved these negative effects. These findings indicate that FA + LRE treatment significantly improved the antioxidant defense system of the plants, thereby reducing ROS levels and increasing wheat growth and production under saline conditions.

Can secondary metabolites extracted from Moringa seeds suppress ammonia oxidizers to increase nitrogen use efficiency and reduce nitrate contamination in potato tubers?

Nitrification inhibition as an alleviation tool to decrease nitrogen (N) losses and increase N use efficiency (NUE) as well as reducing NO₃^- accumulation in plants is a promising technology. No study thus far has directly or indirectly to use the secondary metabolites extracted from Moringa (Moringa oleifera Lam) seeds as nitrification inhibitors. Moringa seed extract (MSE) was studied based on its content of phenolic compounds (PC) and for its antioxidant characteristic. A 2-year field experiment and 30-day incubation experiment were conducted with three treatments of control (CK), N fertilizer (300 kg N ha^-1 and 200 mg N kg^-1 soil for the field and incubation experiment, respectively), and N fertilizer with MSE (500 ppm as a TPC) to investigate the responses of ammonia-oxidizing bacteria (AOB) and archaea (AOA) to MSE and the consequences for NUE and NO₃^- accumulation in potato tubers. Total phenolics amount was 144 mg gallic acid equivalent g^-1 MSE, while flavonoid contents were 76.6 quercetin equivalent g^-1 MSE. MSE showed antioxidant activity that was comparable to the standard antioxidants TBHQ and gallic acid. MSE application with N fertilizer retarded the nitrification process, as indicated by a higher NH₄⁺-N and lower NO₃^--N content, compared with N fertilizer application alone. NH₄⁺-N content reduced to initial CK level on Day 20 under N fertilizer application alone. However, NH₄⁺-N content decreased to initial control level on Day 30 when MSE was applied. The mechanisms resulted from curbing AOB growth by phenolic compounds (TPC, TF, TAC), leading to a delay in nitrification process. AOB increased significantly when N fertilizer was applied alone; on the contrary, AOA was not sensitive to N fertilizer (with and without MSE). Increase in NUE from 37.5% to 66.3% in potato plants under MSE application with N fertilizer was also observed compared with N fertilizer application alone. The highest NO₃^- accumulation (569 mg NO₃^- kg^-1) in tubers was recorded under N fertilizer application without MSE. MSE application significantly decreased NO₃^- accumulation (92 mg NO₃^- kg^-1) in tubers which is lower than the maximum value of accepting tubers (200 mg NO₃^- kg^-1). The highest average of N uptake, fresh and dry weight, carotenoids, chlorophyll a, chlorophyll b and nitrate reductase activity was recorded when MSE was applied with N fertilizer. Accordingly, using of Moringa extracted secondary metabolites to suppress AOB growth in the soil is a significant strategy to reduce nitrification rate and N loss from soils, and therefore increase NUE as well as reducing NO₃^- accumulation in potato tubers.

Compared to antioxidants and polyamines, the role of maize grain-derived organic biostimulants in improving cadmium tolerance in wheat plants

Recently, the strategy of seed soaking has been successfully applied using extracts from different plant parts for healthy growth of plant under different environmental stresses. Compared to antioxidants like ascorbic acid (AsA) and glutathione (GSH) or polyamines (PAs) like spermine (SPM), spermidine (SPD), and putrescine (PUT), the effects of seed soaking using maize grain extract (MGE) on the biomass, productivity, phytohormones, and antioxidant defense system and its different components were examined with Cd²⁺-stressed wheat plants. In a preliminary study, seed soaking using AsA + GSH or PUT + SPD + SPM was more effective in increasing shoot fresh and dry weights, SPAD chlorophyll, and grain yield, and reducing malondialdehyde (MDA) content than individuals. In addition, MGE at 2% was more efficient than other concentrations. Therefore, they were selected for the main study. In the main study, compared to the control, seed soaking in AsA + GSH, PUT + SPD + SPM or MGE had positive effects on plant growth, yield, photosynthetic efficiency, contents and redox states of AsA and GSH, contents of PAs and plant hormones to varying degrees. Proline content and its metabolism enzymes activity, contents of soluble protein, N-compounds, soluble sugars, and α-tocopherol (α-TOC), and activities of antioxidant enzymes were not affected. However, contents of MDA and hydrogen peroxide (H₂O₂) were significantly reduced under normal conditions. Under Cd²⁺ stress (1.2 mM), along with the detrimental increases in the contents of MDA, H₂O₂ and Cd²⁺, contents of N-compounds, soluble sugars, proline content and its metabolism enzymes activities, AsA and GSH and their redox states, and polyamines, and activities of antioxidant enzymes were increased. In contrast, plant growth and yield, photosynthetic efficiency, soluble protein, and plant hormones were significantly reduced compared to the control. However, all of these attributes were significantly improved to varying degrees along with reduced contents of Cd²⁺, MDA, and H₂O₂ by seed soaking in AsA + GSH, PUT + SPD + SPM or MGE compared to the Cd²⁺-stressed control. Compared to AsA + GSH or PUT + SPD + SPM, seed soaking in MGE at 2% conferred the best results. Therefore, it is recommended to soak wheat seeds using MGE to improve plant growth and productivity by restricting the inhibitory influences of oxidative stress induced by Cd²⁺ stress.

Microbial Fortification Improved Photosynthetic Efficiency and Secondary Metabolism in Lycopersicon esculentum Plants Under Cd Stress

Environmental stress including heavy metal pollution is increasing at high speed and is polluting the cultivable land. Consequently, it results in affecting human population through entering into food chain. The current study aims that Cd stress (0.4 mM) led to toxicity and deleterious effects on 45-day-old Lycopersicon esculentum plants. The use of rhizobacterial strains underlines the main hypothesis of the present research that have been exploited in order to alleviate the Cd induced stress in plants and promoting their growth sidewise. The morphological parameters, plant pigments, and gaseous exchange parameters were estimated and found to be reduced in plants due to Cd toxicity. Along with this, the levels of phenolic compounds and osmoprotectants were stimulated in plants raised in Cd spiked soils. In addition, free amino acid content was reduced in plants under Cd treatment. It was revealed that these bacterial strains Pseudomonas aeruginosa (M1) and Burkholderia gladioli (M2) when inoculated to tomato plants improved the morphological characteristics and enhanced photosynthetic attributes. Moreover, the level of phenolic compounds and osmoprotectants were further enhanced by both the inoculating agents independently. However, in situ localization studies of phenol accumulation in root sections was found to be enhanced in Cd treated plants as revealed through higher intensity of yellowish-brown colour. The supplementation of bacterial strains further accumulated the phenols in Cd stressed root sections as evidenced through increased colour intensity. Therefore, the present study suggested that bacterial strains mitigates Cd stress from tomato plants through improving morphological, physiological and metabolite profiles. Consequently, the present research advocates the best utilization of rhizobacteria as stress alleviators for sustainable agriculture.

Stimulating antioxidant defenses, antioxidant gene expression, and salt tolerance in Pisum sativum seedling by pretreatment using licorice root extract (LRE) as an organic biostimulant

Plant extracts have recently been used as exogenous adjuvants to strengthen the endogenous plant defense systems when they grow under different environmental stresses, including salinity. The study aimed at determining the effects of seed soaking using licorice root extract (LRE) on photosynthesis and antioxidant defense systems, including transcript levels of enzyme-encoding genes in pea seedling grown under 150 mM NaCl-salinity. Salt stress reduced seedling growth, photosynthesis attributes, and K+ content, and increased oxidative stress (O2•‒ and H2O2, and MDA), Na+, and Cl-, along with an increase in antioxidative defense activities compared to control. However, LRE pretreatment enhanced seedling growth, photosynthetic attributes (chlorophylls, carotenoids, Fv/Fm, Pn, Tr, and gs), ascorbate and glutathione and their redox states, proline, soluble sugars, α-TOC, and enzyme activities compared to stressed control. LRE pretreatment also upregulated transcript levels of CAT-, SOD-, APX-, GR-, DHAR-, and PrxQ-encoding genes in salt-stressed seedlings, decreasing oxidative stress and Na+ and Cl- contents and increasing K+ content and K+/Na+ ratio.

Mitigation of Salinity Stress Effects on Growth, Physio-Chemical Parameters and Yield of Snapbean (<i>Phaseolus vulgaris</i> L.) by Exogenous Application of Glycine Betaine

Pots experiment was carried out during season 2017 at greenhouse of the Agric. Bot. Dep., Fac. of Agric., Zagazig Univ., Egypt to evaluate the effect of glycine betaine (GB) application under salinity stress (50 and100 mM NaCl) on growth, physio-chemical analysis and yield of snap bean cv. Bronco. A complete randomized blocks design was used in this search with three replications. Growth parameters, chlorophyll content and green pod yield were significantly decreased with subjecting plants to NaCl. However foliar application of GB detoxified the stress generated by NaCl and significantly improved the above mention parameters. Salinity stress increased the electrolyte leakage (EL) and decreased membrane stability index (MSI) and relative water content (RWC). While foliar application of GB was improved MSI and RWC and minimized EL. Proline content and antioxidant enzymes significantly increased in the response to NaCl stress as well as GB application.

Polyamines modulate growth, antioxidant activity, and genomic DNA in heavy metal-stressed wheat plant

A pot experiment was performed to assess the useful effects of seed soaking or seedling foliar spray using 0.25 mM spermine (Spm), 0.50 mM spermidine (Spd), or 1 mM putrescine (Put) on heavy metal tolerance in wheat plants irrigated with water contaminated by cadmium (2 mM Cd²⁺ in CdCl₂) or lead (2 mM Pb²⁺ in PbCl₂). Cd²⁺ or Pb²⁺ presence in the growth medium resulted in significant reductions in growth and yield characteristics and activities of leaf peroxidase (POD), glutathione reductase (GR), ascorbic acid oxidase (AAO), and polyphenol oxidase (PPO) of wheat plants. In contrast, significant increases were observed for Cd²⁺ content in roots, leaves and grains, superoxide dismutase (SOD) and catalase (CAT) activities, radical scavenging activity (DPPH), reducing power capacity, and fragmentation in DNA in comparison to controls (without Cd²⁺ or Pb²⁺ addition). However, treating the Cd²⁺- or Pb²⁺-stressed wheat plants with Spm, Spd, or Put, either by seed soaking or foliar spray, significantly improved growth and yield characteristics and activities of POD, GR, AAO, PPO, SOD, and CAT, DPPH, and reducing power capacity in wheat plants. In contrast, Cd²⁺ levels in roots, leaves, and yielded grains, and fragmentation in DNA were significantly reduced compared with the stressed (with Cd²⁺ or Pb²⁺) controls. Generally, seed soaking treatments were more effective than foliar spray treatments. More specifically, seed priming in Put was the best treatment under heavy metal stress. Results of this study recommend using polyamines, especially Put, as seed soaking to relieve the adverse effects of heavy metals in wheat plants.

Zero-valent silver nanoparticles attenuate Cd and Pb toxicities on Moringa oleifera via immobilization and induction of phytochemicals

Potentials of zero-valent extract of cocoa pod mediated silver nanoparticles (AgNPs) for heavy metals (cadmium and lead) immobilization, attenuation of induced toxicities and influence on phytochemical contents in Moringa oleifera were investigated. M. oleifera seeds were planted in soil spiked and watered with water (control), 0.2 mg AgNPs, 0.5 mg CdCl₂, 0.5 mg PbCl₂, 0.2 mg AgNPs + 0.5 mg CdCl₂, 0.2 mg AgNPs + 0.5 mg PbCl₂, 0.2 mg AgNPs + 0.75 mg CdCl₂ and 0.2 mg AgNPs + 0.75 mg PbCl₂ per g soil designated as groups A, B, C, D, E, F, G and H respectively. Significant (p < 0.05) repression in shoot and root lengths, percentage germination, number of leaves, vigour and growth tolerance indices, relative water contents with attendant inhibition of photosynthetic pigments, total carotenoid contents, total flavonoid contents and total phenolic contents were obtained for M. oleifera planted on Cd and Pb spiked soil. There were marked decrease in ferric reducing, hydrogen peroxide scavenging and free radical scavenging activities with resultant significant increase in lipid peroxidation (MDA) levels for M. oleifera grown on Cd and Pb treated soil compared to control with Pb having more deleterious effects. Conversely, AgNPs significantly enhanced both physiological and biochemical parameters in M. oleifera over control and considerably attenuated suppressions of these parameters in M. oleifera induced by Cd and Pb. Results in this study have shown AgNPs as excellent immobilizing agents and outstanding modulators of heavy metal induced toxicities.