Calcium and Potassium Supplementation Enhanced Growth, Osmolyte Secondary Metabolite Production, and Enzymatic Antioxidant Machinery in Cadmium-Exposed Chickpea (Cicer arietinum L.)

Chitooligosaccharide application enhanced the growth and phytoremediation efficiency of industrial hemp in Cd-contaminated soils

Hemp has been widely used for cadmium (Cd) remediation. However, its remediation efficiency needs to be improved. Chitooligosaccharides can enhance plant resistance and growth; however, their effects on hemp for Cd-remediation remain unclear. Herein, a greenhouse pot experiment was conducted to investigate the effects of three doses (0, 22.5, and 45 μg m-2) of chitooligosaccharides (COS), chitin-oligosaccharides (NACOS), and hetero-chitooligosaccharides (HTCOS) on the growth and Cd-remediation efficiency of hemp. Results showed that chitooligosaccharides promoted the antioxidant system and aerial biomass (maximum 84 %) depending on doses and types. COS (22.5 μg m-2 under 60 mg cadmium kg-1 soil), NACOS, and HTCOS significantly elevated the Cd concentration in hemp. Consequently, NACOS and HTCOS (45 μg m-2) significantly increased the average Cd removal up to 61 % and 81 %, respectively, compared with the control. Therefore, spraying chitooligosaccharides can enhance growth and phytoremediation efficiency of hemp by elevating aerial biomass and cadmium concentration of hemp.

Calcium Enhances the Effectiveness of Melatonin in Improving Nutritional Properties of Soybean Sprouts and Germination Under Salt and Cadmium Stress

Salinity and cadmium exposure to agrarian land lowers crop yield and imposes toxicity in the food chain, ultimately affecting sustainable agriculture. Melatonin (Mel) and calcium (Ca) have been reported as potent regulators of plant growth and stress resistance. Based on this scenario, this study investigated the sole and combined effects of Mel and Ca on improving the antioxidant properties, mineral content, germination of sprout, and stress tolerance of soybean seedlings under salt and cadmium (Cd) stress. Optimal doses of 20 µM Mel and 1 mM Ca were identified to enhance sprout quality and seed germination. Treatments with Mel > 20 µM inhibited germination, while the combination of Mel (20 µM) and Ca (1 mM) significantly improved germination, mineral content (Ca, P, K), and antioxidant properties, including DPPH(2,2-Diphenyl-1-picrylhydrazyl) activity, polyphenols, flavonoids, and superoxide dismutase (SOD) activity. However, melatonin > 50 µM could completely cease the sprouting, whereas a Ca concentration of up to 10 mM was observed to be normal in sprouting. Additionally, this combination reduced malondialdehyde (MDA) levels and enhanced the proline, indicating decreased oxidative stress in soybean seedlings under stress conditions. Among various treatments tested, the Mel-Ca combination was most effective in enhancing sprout biomass, antioxidant activity, and seed viability under Salt+Cd stress. These findings underscore the synergistic role of Ca in optimizing melatonin pretreatment for stress mitigation in soybean seeds and also address the precaution for a possible negative impact of melatonin effects.

Enhancing cadmium stress resilience in chickpea (Cicer arietinum L.) via exogenous melatonin application

Chickpea (Cicer arietinum L.) productivity is hindered by biotic and abiotic stresses, particularly heavy metal toxicity. The pot experiment was carried out at the botanical garden of The Islamia University of Bahawalpur, Bahawalpur-Pakistan. The experimental treatments comprised of following details: T0 = Control + 0 µM MT, T1 = Control + 15 µM MT, T2= Control + 30 µM MT, T3 = 100 µM Cd + 0 µM MT, T4 = 100 µM Cd + 15 µM MT and T5 = 100 µM Cd + 30 µM MT. A completely randomized design (CRD) with three replicates was used. Cd stress significantly reduced shoot fresh (51.3%) and dry weight (50.4%), total chlorophyll (53.6%), and shoot Ca2+ (56.6%). However, it increased proline (38.3%), total phenolics (74.2%), glycine betaine (46.4%), TSS (67.7%), TSP (50%), SOD (49.5%), POD (107%), and CAT (74.2%). Conversely, 30 µM MT improved shoot fresh (78.5%) and dry weight (76%), total chlorophyll (47%), SOD (26.5%), POD (35.8%), CAT (27.8%), proline (19%), TSS (24.5%), TSP (25.8%), and shoot Ca2+ (56.6%). Results indicated that MT enhanced photosynthetic pigments and antioxidant activities, maintained ion homeostasis, and reduces reactive oxygen species. Desi variety performed better than Kabuli, and 30 µM MT application effectively mitigated Cd toxicity.

Arbuscular mycorrhizal fungi and exogenous Ca2+ application synergistically enhance salt and alkali resistance in perennial ryegrass through diverse adaptive strategies

The challenge of soil salinization and alkalization, with its significant impact on crop productivity, has raised growing concerns with global population growth and enhanced environmental degradation. Although arbuscular mycorrhizal fungi (AMF) and calcium ions (Ca2+) are known to enhance plant resistance to stress, their combined effects on perennial ryegrass' tolerance to salt and alkali stress and the underlying mechanisms remain poorly understood. This study aimed to elucidate the roles of Arbuscular mycorrhizal (AM) fungus Rhizophagus irregularis and exogenous Ca2+ application in molecular and physiological responses to salt-alkali stress. AM symbiosis and exogenous Ca2+ application enhanced antioxidant enzyme activity and non-enzymatic components, promoting reactive oxygen species (ROS) scavenging and reducing lipid peroxidation while alleviating oxidative damage induced by salt-alkali stress. Furthermore, they enhanced osmotic balance by increasing soluble sugar content (Proportion of contribution of the osmotic adjustment were 34∼38 % in shoots and 30∼37 % in roots) under salt stress and organic acid content (Proportion of contribution of the osmotic adjustment were 32∼36 % in shoots and 37∼42 % in roots) under alkali stress. Changes in organic solute and inorganic cation-anion contents contributed to ion balance, while hormonal regulation played a role in these protective mechanisms. Moreover, the protective mechanisms involved activation of Ca2+-mediated signaling pathways, regulation of salt-alkali stress-related genes (including LpNHX1 and LpSOS1), increased ATPase activity, elevated ATP levels, enhanced Na+ extrusion, improved K+ absorption capacity, and a reduced Na+/K+ ratio, all contributing to the protection of photosynthetic pigments and the enhancement of photosynthetic efficiency. Ultimately, the combined application of exogenous Ca2+ and AMF synergistically alleviated the inhibitory effects of salt-alkali stress on perennial ryegrass growth. This finding suggested that exogenous Ca2+ may participate in the colonization of perennial ryegrass plants by R. irregularis, while AM symbiosis may activate Ca2+ pathways. Consequently, the combined treatment of AM and Ca2+ is beneficial for enhancing plant regulatory mechanisms and increasing crop yield under salt-alkali stress.

Application of leaf multispectral analyzer in comparison to hyperspectral device to assess the diversity of spectral reflectance indices in wheat genotypes

Multispectral devices have a huge potential to be utilized in biological, ecological, and agricultural studies, providing valuable information on plant structure and chemical composition. The aim of the study was to assess the reliability and sensitivity of the affordable leaf spectrometer PolyPen (PP) in comparison with the highly sensitive analytical device FieldSpec-4. Measurements at the leaf level were realized on a collection of 24 diverse field-grown wheat (Triticum sp. L.) genotypes in several growth phases during the regular growing season, focusing on whole spectral curves and a set of 41 spectral reflectance indices. As expected, the sensitive analytical device showed a higher capacity to capture genotypic variability and the ability to distinguish seasonal changes compared to a low-cost multispectral device. Nevertheless, the analysis of the data provided by low-cost sensors provided a group of parameters with good sensitivity, including reasonable correlations between the records of the two devices (r > 0.80). Based on the large obtained datasets, we can conclude that the application of a low-cost PP leaf spectrometer in plant and crop studies can be efficient, but the selection of parameters is crucial. Thus, the present study provides valuable information for users of affordable leaf spectrometers in fundamental and applied plant science.

Synergistic effects of combined application of biochar and arbuscular mycorrhizal fungi on the safe production of rice in cadmium contaminated soil

Arbuscular mycorrhizal fungi (AMF) have been shown to effectively mitigate the detrimental effects of heavy metal stress on their plant hosts. Nevertheless, the biological activities of AMF were concurrently compromised. Biochar (BC), as an abiotic factor, had the potential compensate for this limitation. To elucidate the synergistic effects of biotic and abiotic factors, a pot experiment was conducted to assess the impact of biochar and AMF on the growth, physiological traits, and genetic expression in rice plants subjected to Cd stress. The results demonstrated that biochar significantly increased the mycorrhizal colonization rate by 22.19 %, while the combined application of biochar and AMF led to a remarkable enhancement of rice root biomass by 42.2 %. This resulted in a shift in spatial growth patterns that preferentially promoted enhanced underground development. Biochar effectively mitigated the stomatal limitations imposed by Cd on photosynthetic processes. The decrease in IBRv2 (Integrated Biomarker Response version 2) values suggested that the antioxidant system was experiencing a state of remission. An increase of Cd content within the rice root systems was observed, ranging from 33.71 % to 48.71 %, accompanied by a reduction in Cd bioavailability and mobility curtailed its translocation to the aboveground tissues. Under conditions of low soil Cd concentration (Cd ≤ 1 mg·kg-1), the Cd content in rice seeds from the group subjected to the combined treatment remained below the national standard (Cd ≤ 0.2 mg·kg-1). Furthermore, the combined treatment modulated the uptake of Fe and Zn by rice, while simultaneously suppressing the expression of genes associated with Cd transport. Collectively, the integration of biological and abiotic factors provided a novel perspective and methodological framework for safe in-situ utilization of soils with low Cd contamination.

Integrated physio-biochemistry and RNA-seq revealed the mechanism underlying biochar-mediated alleviation of compound heavy metals (Cd, Pb, As) toxicity in cotton

Biochar has been recognised as an efficacious amendment for the remediation of compound heavy metal contamination in soil. However, the molecular mechanism of biochar-mediated tolerance to compound heavy metal toxicity in cotton is unknown. The objective of this research was to investigate the positive impact of biochar (10 g·kg-1) on reducing damage caused by compound heavy metals (Cd, Pb, and As) in cotton (Gossypium hirsutum L.). The results revealed that biochar reduced Cd concentrations by 24.9 % (roots), and decreased Pb concentrations by 37.1 % (roots) and 59.53 % (stems). Biochar maintained ionic homoeostasis by regulating the expression of metal transporter proteins such as ABC, HIPP, NRAMP3, PCR, and ZIP, and genes related to the carbon skeleton and plasma membrane. Biochar also downregulated genes related to photosynthesis, thereby increasing photosynthesis. Biochar re-established redox homoeostasis in cotton by activating signal transduction, which regulated the activity of the enzymes POD, SOD, and CAT activity; and the expression of related genes. This research revealed the molecular mechanism by which biochar confers resistance to the harmful effects of compound heavy metal toxicity in cotton. The application of biochar as a soil amendment to neutralise the toxicity of compound heavy metals is recommended for cash crop production.

Interactive effect of 24-epibrassinolide and silicon on the alleviation of cadmium toxicity in rice (Oryza sativa L.) plants

Cadmium (Cd) pollution is a serious threat to food safety and human health. Minimization of Cd uptake and enhancing Cd tolerance in plants are vital to improve crop yield and reduce hazardous effects to humans. In this study, we investigate the effect of a synergistic system with phytohormone (24-Epibrassinolide, EBL) and silicon (Si) on Cd toxicity and accumulation of rice plants. The results revealed that Si, EBL and their combination rescued Cd-induced growth inhibition, as evidenced by the increased dry weight of root and shoot. The chlorophyll content and photosynthetic performance were improved. The activity of antioxidant enzymes (SOD, POD and CAT) was increased and oxidative stress was alleviated. More importantly, Cd content in root was decreased by 20.25%, 17.72% and 27.84%, while Cd content in shoot decreased by 21.17%, 16.47% and 25.88%, respectively. Moreover, Si, EBL and Si + EBL treatment enriched cell wall-bound Cd and reduced Cd toxicity to functional organelles. Meanwhile, the residual form of Cd was enriched and the highly toxic forms of Cd (inorganic and water-soluble Cd) were decreased. The joint application showed better effects than applying Si and EBL alone. Collectively, this study provides an effective way for Cd toxicity mitigation in rice plants.

Physiological, cytological and multi-omics analysis revealed the molecular response of Fritillaria cirrhosa to Cd toxicity in Qinghai-Tibet Plateau

Fritillaria cirrhosa, an endangered plant endemic to plateau regions, faces escalating cadmium (Cd) stress due to pollution in the Qinghai-Tibet Plateau. This study employed physiological, cytological, and multi-omics techniques to investigate the toxic effects of Cd stress and detoxification mechanisms of F. cirrhosa. The results demonstrated that Cd caused severe damage to cell membranes and organelles, leading to significant oxidative damage and reducing photosynthesis, alkaloid and nucleoside contents, and biomass. Cd application increased cell wall thickness by 167.89% in leaves and 445.78% in bulbs, leading to weight percentage of Cd increases of 76.00% and 257.14%, respectively. PER, CESA, PME, and SUS, genes responsible for cell wall thickening, were significantly upregulated. Additionally, the levels of metabolites participating in the scavenging of reactive oxygen species, including oxidized glutathione, D-proline, L-citrulline, and putrescine, were significantly increased under Cd stress. Combined multi-omics analyses revealed that glutathione metabolism and cell wall biosynthesis pathways jointly constituted the detoxification mechanism of F. cirrhosa in response to Cd stress. This study provides a theoretical basis for further screening of new cultivars for Cd tolerance and developing appropriate cultivation strategies to alleviate Cd toxicity.

Unravelling the halophyte Suaeda maritima as an efficient candidate for phytostabilization of cadmium and lead: Implications from physiological, ionomic, and metabolomic responses

Cadmium (Cd) and lead (Pb) are among the most toxic heavy metals affecting human health and crop yield. Suaeda maritima (L.) Dumort is an obligate halophyte that is well adapted to saline soil. The inbuilt salinity tolerance mechanisms of halophytes help them to survive in heavy metal-contaminated rhizospheric soil. In the present study, growth and ionomic responses, reactive oxygen species (ROS) accumulation, modulations of phytochelatins, antioxidative defense, and metabolomic responses were studied in S. maritima imposed to Cd and Pb stresses with an aim to elucidate Cd and Pb tolerance mechanisms and phytoremediation potential of this halophyte. Our results showed a reduction of biomass in S. maritima, which may serve as an energy conservation strategy for survival under heavy metal stress. The increased accumulation of ROS with concomitant higher expression of various antioxidative enzymes suggests the efficient scavenging of ROS. The metabolite profiling revealed significant up-regulation of sugars, sugar alcohols, amino acids, polyphenols, and organic acids under Cd and Pb stresses suggesting their possible role in osmotic balance, ionic homeostasis, ROS scavenging, and signal transduction for stress tolerance. In S. maritima, the translocation factors (Tf) are <1 in both Cd and Pb treatments, which indicates that this halophyte has high phytostabilization potential for Cd and Pb in roots and through restricted translocation of heavy metal ions to the aboveground part. The findings of this study offer comprehensive information on Cd and Pb tolerance mechanisms in S. maritima and suggest that this halophyte can detoxify the HMs through physiological, ionic, antioxidative, and metabolic regulations.

Heat-stress-responsive HvHSFA2e gene regulates the heat and drought tolerance in barley through modulation of phytohormone and secondary metabolic pathways

KEY MESSAGE

The heat stress transcription factor HSFA2e regulates both temperature and drought response via hormonal and secondary metabolism alterations. High temperature and drought are the primary yield-limiting environmental constraints for staple food crops. Heat shock transcription factors (HSF) terminally regulate the plant abiotic stress responses to maintain growth and development under extreme environmental conditions. HSF genes of subclass A2 predominantly express under heat stress (HS) and activate the transcriptional cascade of defense-related genes. In this study, a highly heat-inducible HSF, HvHSFA2e was constitutively expressed in barley (Hordeum vulgare L.) to investigate its role in abiotic stress response and plant development. Transgenic barley plants displayed enhanced heat and drought tolerance in terms of increased chlorophyll content, improved membrane stability, reduced lipid peroxidation, and less accumulation of ROS in comparison to wild-type (WT) plants. Transcriptome analysis revealed that HvHSFA2e positively regulates the expression of abiotic stress-related genes encoding HSFs, HSPs, and enzymatic antioxidants, contributing to improved stress tolerance in transgenic plants. The major genes of ABA biosynthesis pathway, flavonoid, and terpene metabolism were also upregulated in transgenics. Our findings show that HvHSFA2e-mediated upregulation of heat-responsive genes, modulation in ABA and flavonoid biosynthesis pathways enhance drought and heat stress tolerance.

Exogenous GABA Enhances Copper Stress Resilience in Rice Plants via Antioxidant Defense Mechanisms, Gene Regulation, Mineral Uptake, and Copper Homeostasis

The importance of gamma-aminobutyric acid (GABA) in plants has been highlighted due to its critical role in mitigating metal toxicity, specifically countering the inhibitory effects of copper stress on rice plants. This study involved pre-treating rice plants with 1 mM GABA for one week, followed by exposure to varying concentrations of copper at 50 μM, 100 μM, and 200 μM. Under copper stress, particularly at 100 μM and 200 μM, plant height, biomass, chlorophyll content, relative water content, mineral content, and antioxidant activity decreased significantly compared to control conditions. However, GABA treatment significantly alleviated the adverse effects of copper stress. It increased plant height by 13%, 18%, and 32%; plant biomass by 28%, 52%, and 60%; chlorophyll content by 12%, 30%, and 24%; and relative water content by 10%, 24%, and 26% in comparison to the C50, C100, and C200 treatments. Furthermore, GABA treatment effectively reduced electrolyte leakage by 11%, 34%, and 39%, and the concentration of reactive oxygen species, such as malondialdehyde (MDA), by 9%, 22%, and 27%, hydrogen peroxide (H2O2) by 12%, 38%, and 30%, and superoxide anion content by 8%, 33, and 39% in comparison to C50, C100, and C200 treatments. Additionally, GABA supplementation led to elevated levels of glutathione by 69% and 80%, superoxide dismutase by 22% and 125%, ascorbate peroxidase by 12% and 125%, and catalase by 75% and 100% in the C100+G and C200+G groups as compared to the C100 and C200 treatments. Similarly, GABA application upregulated the expression of GABA shunt pathway-related genes, including gamma-aminobutyric transaminase (OsGABA-T) by 38% and 80% and succinic semialdehyde dehydrogenase (OsSSADH) by 60% and 94% in the C100+G and C200+G groups, respectively, as compared to the C100 and C200 treatments. Conversely, the expression of gamma-aminobutyric acid dehydrogenase (OsGAD) was downregulated. GABA application reduced the absorption of Cu2+ by 54% and 47% in C100+G and C200+G groups as compared to C100, and C200 treatments. Moreover, GABA treatment enhanced the uptake of Ca2+ by 26% and 82%, Mg2+ by 12% and 67%, and K+ by 28% and 128% in the C100+G and C200+G groups as compared to C100, and C200 treatments. These findings underscore the pivotal role of GABA-induced enhancements in various physiological and molecular processes, such as plant growth, chlorophyll content, water content, antioxidant capacity, gene regulation, mineral uptake, and copper sequestration, in enhancing plant tolerance to copper stress. Such mechanistic insights offer promising implications for the advancement of safe and sustainable food production practices.

Comprehensive bioremediation effect of phosphorus-mineralized bacterium Enterobacter sp. PMB-5 on cadmium contaminated soil-crop system

Phosphate-mineralizing bacteria (PMBs) have been widely studied by inducing phosphate heavy metal precipitation, but current researches neglect to study their effects on soil-microbe-crop systems on cadmium (Cd) contaminated. Based on this, a strain PMB, Enterobacter sp. PMB-5, was inoculated into Cd contaminated pots to detect soil characteristics, Cd occurrence forms, soil biological activities, plant physiological and biochemical indicators. The results showed that the inoculation of strain PMB-5 significantly increased the available phosphorus content (85.97%-138.64%), Cd-residual fraction (11.04%-29.73%), soil enzyme activities (31.94%-304.63%), plant biomass (6.10%-59.81%), while decreased the state of Cd-HOAc (11.50%-31.17%) and plant bioconcentration factor (23.76%-44.24%). These findings indicated that strain PMB-5 could perform the function of phosphorus solubilization to realize the immobilization of Cd in the complex soil environment. Moreover, SEM-EDS, FTIR, XPS, and XRD analysis revealed that strain PMB-5 does not significantly alter the soil morphology, structure, elemental distribution, and chemical composition, which suggested that remediation of Cd contamination using strain PMB-5 would not further burden the soil. This research implies that PMB-5 could be a safe and effective bioinoculant for remediating Cd-contaminated soils, contributing to the sustainable management of soil health in contaminated environments.

Fulvic acid alleviates cadmium-induced root growth inhibition by regulating antioxidant enzyme activity and carbon-nitrogen metabolism in apple seedlings

Introduction

Substantial previous studies have reported that fulvic acid (FA) application plays an important role in Chinese agricultural production. However, little is known about the mechanisms for using FA to increase apple trees resistance to Cd toxicity. In order to clarify the mechanism underlying FA alleviation in Cd-induced growth inhibition in apple seedlings.

Methods

Herein, we treated M9T337 seedlings to either 0 or 30 µM/L Cd together with 0 or 0.2 g/L FA and analyzed the root growth, antioxidant enzyme activities, carbon (C) assimilation, nitrogen (N) metabolism, and C and N transport.

Results

The results presented that, compared with CK (without Cd addition or FA spraying application), Cd poisoning significantly inhibited the root growth of apple seedlings. However, this Cd-induced root growth inhibition was significantly alleviated by FA spraying relative to the Cd treatment (Cd addition alone). On the one hand, the mitigation of inhibition effects was due to the reduced oxidative damage by enhancing antioxdiant enzyme (SOD, POD, and CAT) activities in leaves and roots. On the other hand, this growth advantage demonstrated compared to the Cd treatment was found to be associated with the strengthen of photosynthetic performance and the elevation of C and N metabolism enzymes activities. Meanwhile, we also found that under Cd stress condition, the distribution of C and N nutrients in apple seedlings was optimised by FA spraying application relative to the Cd treatment, according to the results of 13C and 15N tracing.

Conclusion

Conclusively, our results suggested that the inhibitory effect of Cd on apple seedlings root growth was alleviated by FA through regulating antioxdiant capacities and C and N metabolism.

Combined passivators regulate physiological, antioxidant potential and metals accumulation in potato grown in metals contaminated soil

To solve the problem of excessive heavy metals in farmland soil, there is a dire need for research effort to screen for the soil passivator materials. This study aimed to develop a practical novel approach for improving the potato growth and remedial effectiveness of the metals by optimal combination and dosage of various passivators. Experimental treatments were comprised of various levels of passivating agents (sepiolite, quicklime and calcium magnesium phosphate) in individual and combined form. Results showed that application of passivating agents significantly enhanced growth by optimizing photosynthetic attributes, enzymatic antioxidants, and soil health. Balanced application of passivators effectively reduce the bioavailability of metals, curbing their uptake by potato plants. Sole application of all the agents results statistically similar outcomes as compared with combined form. Additionally, passivators indirectly enhance the activity of essential antioxidant enzymes. Synergistic effect of all the agents significantly improved the tuber quality by decreasing the accumulation of proline, malondialdehyde content, and bioaccumulation of Cu, Pb, Cd, and As in potato parts. In crux, combined usage of passivating agents proved to be of better growth, improvement in antioxidative defense system, and better quality of potato. By mitigating heavy metal contamination, passivators not only enhance crop quality and yield but also ensure heavy metal-free potatoes that meet stringent food safety standards.

The combination of nanotechnology and potassium: applications in agriculture

Potassium fertilizer is indispensable for ensuring crop production, which in turn supports global food supply and safe farming practices. Potassium resources are primarily located in the Northern Hemisphere, leading to a current shortage of affordable potash and severe soil deficiencies in certain regions of the Southern Hemisphere. There is a shift away from mined salts in favor of locally available potassium resources. Utilizing potassium-rich silicates, for instance, could be a viable option to address this situation. The imperative of enhancing crop productivity and quality necessitates either increasing potassium availability or utilizing potassium more efficiently. Geneticists may find the development of plants that use potassium more effectively to be a valuable pursuit. Nanomaterials are increasingly becoming part of people's professional lives as a novel material category. This technology is gradually finding applications in agriculture to boost crop yields while reducing environmental pollution. This paper reviews the applications of common potassium-containing materials, explores the effects and mechanisms of nano-fertilizers on plants, and offers insights into future applications of nano-potassium fertilizers in agriculture. All in all, the application of nanotechnology in the production and utilization of potassium fertilizers is both necessary and effective. However, there are still many gaps in the current field of nano-potassium fertilizer application that require further research. It is hoped that this review can serve as a valuable reference for researchers working in this field.

Investigating Mineral Accumulation and Seed Vigor Potential in Bottle Gourd (Lagenaria siceraria) through Crossbreeding Timing

Bottle gourd (Lagenaria siceraria) is a well-known cucurbit with an active functional ingredient. A two-year field experiment was carried out at the Research Farm of Seed Science and Technology, CCS HAU, Hisar, in a randomized block design during the Kharif season (Kharif is one of the two major cropping seasons in India and other South Asian countries, heavily reliant on monsoon rains with the other being Rabi) and the summer season. Five different crossing periods (CP), viz. CP1, CP2, CP3, CP4, and CP5, were considered to illustrate the effects of agro-climatic conditions on the quality and biochemical components of two bottle gourd parental lines and one hybrid, HBGH-35. The average mean temperature for the Kharif season in 2017 was 31.7 °C, and for the summer season, it was 40.1 °C. Flowers were tagged weekly from the start of the crossing period until the end and harvested separately at different times. The fruits harvested from different crossing periods under different environmental conditions influenced the bottle gourd's qualitative and biochemical traits and showed significant variations among the five crossing period environments. A positive significance and correlation were observed between weather variables and different biochemical characteristics. Henceforth, the CP4 crossing period at a temperature of 31.7 °C retained high-quality seed development, which may be essential in enhancing agricultural productivity and the national economy.

NPs-Ca promotes Cd accumulation and enhances Cd tolerance of rapeseed shoots by affecting Cd transfer and Cd fixation in pectin

The use of rapeseed (Brassica napus) as a hyperaccumulator plant has shown great promise for the remediation of cadmium (Cd) contaminated soils. Nanosized materials (NPs) have been shown to mitigate heavy metal toxicity in plants, but it is unknown how l-aspartate nano-calcium (NPs-Ca) affects Cd uptake, transport, and tolerance in rapeseed. A soil pot experiment was conducted with two treatments: a control treatment (CK) with 2.16 g CaCl2 and NPs-Ca treatment with 6.00 g NPs-Ca, to evaluate the effects and mechanisms of NPs-Ca on Cd tolerance in rapeseed. Compared to CaCl2, NPs-Ca promoted Cd transportation from roots to shoots by up-regulating the expression of Cd transport genes (ABCC12, HMA8, NRAM6, ZIP6, CAX4, PCR2, and HIP6). Therefore, NPs-Ca increased Cd accumulation in rapeseed shoots by 39.4%. Interestingly, NPs-Ca also enhanced Cd tolerance in the shoots, resulting in lower hydrogen peroxide (H2O2) accumulation and proline content, as well as higher antioxidant enzyme activities (POD, CAT). Moreover, NPs-Ca reduced the activity of pectin-degrading enzymes (polygalacturonase: PG, β-galactosidase: β-GAL), promoted the activity of pectin methyl esterase (PME), and changed transcription levels of related genes (PME, PMEI, PG, PGIP, and β-GAL). NPs-Ca treatment also significantly increased the Cd content in cell walls by 59.8%, that is, more Cd was immobilized in cell walls, and less Cd entered organelles in shoots of NPs-Ca treatment due to increased pectin content and degree of pectin demethylation. Overall, NPs-Ca increased Cd accumulation in rapeseed shoots by promoting Cd transport from roots to shoots. And meantime, NPs-Ca enhanced Cd tolerance of shoots by inhibiting pectin degradation, promoting pectin demethylation and increasing Cd fixation in pectin. These findings suggest that NPs-Ca can improve the potential of rapeseed as a hyperaccumulator for the remediation of Cd-contaminated soil and the protection of the environment. Furthermore, the study provides a theoretical basis for the application of NPs-Ca in the phytoremediation of Cd-contaminated soils with hyperaccumulating plants.

Establishing the Relationship Between Flavonoid Content, Mycorrhization, and Soil Nutritional Content in Different Species of the Genus Passiflora in Colombia

The genus Passiflora comprises more than 500 species distributed in tropical and semitropical regions. With a great diversity of species, it is estimated that one-third is found in Colombian territory. Besides the food importance, Passiflora species are important sources of biologically active compounds, such as flavonoids. The most important symbiosis between soil fungi and vascular plants related to plant nutrition and tolerance to stress conditions is mycorrhizae. Passiflora species form arbuscular mycorrhizae, with several species of Glomeromycota. This association has been reported to alter the production of secondary metabolites. Thus, the objective of this study was to determine the relation between flavonoid content, mycorrhization, and soil nutritional content of Passiflora alata, Passiflora quadrangularis, Passiflora maliformis, and Passiflora ligularis in Colombian crops. The extracts were prepared and analyzed using UPLC/PDA-MS, and total flavonoids were quantified with the method of AlCl3. Soil characteristics, including nutritional content and percentage of colonization by arbuscular mycorrhizal fungi, were also determined. All variables were analyzed using Spearman's correlation and principal component analysis. Chromatographic analysis of the extracts allowed us to visualize the different flavonoid compositions of each extract, identifying several C-glycosylflavonoids. In this paper, we report for the first time the presence of luteolin-8-C-rhamnosyl-4'-O-glucoside, apigenin-6-C-arabinosyl-7-O-glucoside, and orientin for P. maliformis. Statistical analysis showed a negative correlation between available phosphorus (ρ = -0.90, p = <0.05) and magnesium (Mg) saturation (ρ = -0.70, p = <0.05) on flavonoid content, whereas the calcium magnesium (Ca/Mg) ratio was positively correlated (ρ = 0.70, p = <0.01). There was a nonsignificant correlation between mycorrhization and flavonoid content (ρ = -0.70, p = >0.1). These results contribute to understanding the relationship between flavonoid-mycorrhization-soil nutritional content on Passiflora spp.

Identification of Dioscorea opposite Thunb. CDPK gene family reveals that DoCDPK20 is related to heat resistance

Temperature affects the growth and yield of yam (Dioscorea opposite Thunb.), and calcium-dependent protein kinases (CDPKs) play an important role in the plant stress response. However, there has been a lack of system analyses of yam's CDPK gene family. In this study, 29 CDPK transcriptome sequences with complete open reading frames (ORFs) were identified from yam RNA sequencing data. The sequences were classified into four groups (I-VI) using phylogenetic analysis. Two DoCDPK genes were randomly selected from each group and the gene patterns of yam leaves were determined using quantitative real-time PCR (qRT-PCR) under high and low temperature stress in order to show their unique functions in mediating specific responses. Among them, DoCDPK20 was significantly induced in high temperatures. The pPZP221-DoCDPK20 was transformed into tobacco leaves using an agrobacterium-mediated method. Under high temperature stress, DoCDPK20 overexpression reduced photosynthesis and improved heat tolerance in transgenic tobacco. Our research offers meaningful perspectives into CDPK genes and new avenues for the genetic engineering and molecular breeding of yam.

GhCYS2 governs the tolerance against cadmium stress by regulating cell viability and photosynthesis in cotton

Cysteine, an early sulfur-containing compound in plants, is of significant importance in sulfur metabolism. CYS encodes cysteine synthetase that further catalyzes cysteine synthesis. In this investigation, CYS genes, identified from genome-wide analysis of Gossypium hirsutum bioinformatically, led to the discovery of GhCYS2 as the pivotal gene responsible for Cd2+ response. The silencing of GhCYS2 through virus-induced gene silencing (VIGS) rendered plants highly susceptible to Cd2+ stress. Silencing GhCYS2 in plants resulted in diminished levels of cysteine and glutathione while leading to the accumulation of MDA and ROS within cells, thereby impeding the regular process of photosynthesis. Consequently, the stomatal aperture of leaves decreased, epidermal cells underwent distortion and deformation, intercellular connections are dramatically disrupted, and fissures manifested between cells. Ultimately, these detrimental effected culminating in plant wilting and a substantial reduction in biomass. The association established between Cd2+ and cysteine in this investigation offered a valuable reference point for further inquiry into the functional and regulatory mechanisms of cysteine synthesis genes.

Cadmium induced a non-coding RNA microRNA535 mediates Cd accumulation in rice

Identifying key regulators related to cadmium (Cd) tolerance and accumulation is the main factor for genetic engineering to improve plants for bioremediation and ensure crop food safety. MicroRNAs (miRNAs), as fine-tuning regulators of genes, participate in various abiotic stress processes. MiR535 is an ancient conserved non-coding small RNA in land plants, positively responding to Cd stress. We investigated the effects of knocking out (mir535) and overexpressing miR535 (mir535 and OE535) under Cd stress in rice plants in this study. The mir535 plants showed better Cd tolerance than wild type (WT), whereas the OE535 showed the opposite effect. Cd accumulated approximately 71.9% and 127% in the roots of mir535 and OE535 plants, respectively, compared to WT, after exposure to 2 µmol/L Cd. In brown rice, the total Cd accumulation of OE535 and mir535 was about 78% greater and 35% lower than WT. When growing in 2 mg/kg Cd of soil, the Cd concentration was significantly lower in mir535 and higher in OE535 than in the WT; afterward, we further revealed the most possible target gene SQUAMOSA promoter binding-like transcription factor 7(SPL7) and it negatively regulates Nramp5 expression, which in turn regulates Cd metabolism. Therefore, the CRISPR/Cas9 technology may be a valuable strategy for creating new rice varieties to ensure food safety.

Expression of TaNCL2-A ameliorates cadmium toxicity by increasing calcium and enzymatic antioxidants activities in arabidopsis

Cadmium (Cd) is a heavy metal that occurs naturally in the environment and is toxic to both animals and plants. The impact of Cd toxicity is shown to be reduced by the exogenous application of calcium (Ca) in crop plants. The sodium/calcium exchanger-like (NCL) protein is involved in Ca enrichment in the cytoplasm by transporting it from the vacuole in the exchange of cytosolic sodium (Na). However, it has not been utilized to ameliorate the Cd toxicity, to date. An elevated expression of TaNCL2-A gene in the root and shoot tissues of bread wheat seedlings, and a higher growth rate of recombinant yeast cells, suggested its role in Cd stress response. The TaNCL2-A expressing transgenic Arabidopsis lines exhibited significant Cd tolerance with increased Ca (∼10-fold) accumulation. The proline content and antioxidant enzymes activities were increased while oxidative stress-related molecules such as H2O2 and MDA were reduced in the transgenic lines. In addition, the growth and yield parameters of transgenic lines such as seed germination rate, root length, leaf biomass, leaf area index, rosette diameter, leaf length and width, and silique count, along with various physiological indicators like chlorophyll, carotenoid, and relative water contents were also improved in comparison to the control plants. Further, the transgenic lines exhibited significant salinity and osmotic stress tolerance, as well. Taken together, these results suggested that the TaNCL2-A could mitigate Cd toxicity along with salinity and osmotic stress. This gene may also be utilized for phytoremediation and Cd sequestration in future studies.

Integrated physio-biochemical and transcriptomic analysis revealed mechanism underlying of Si-mediated alleviation to cadmium toxicity in wheat

Cadmium (Cd) contamination has resulted in serious reduction of crop yields. Silicon (Si), as a beneficial element, regulates plant growth to heavy metal toxicity mainly through reducing metal uptake and protecting plants from oxidative injury. However, the molecular mechanism underlying Si-mediated Cd toxicity in wheat has not been well understood. This study aimed to reveal the beneficial role of Si (1 mM) in alleviating Cd-induced toxicity in wheat (Triticum aestivum) seedlings. The results showed that exogenous supply of Si decreased Cd concentration by 67.45% (root) and 70.34% (shoot), and maintained ionic homeostasis through the function of important transporters, such as Lsi, ZIP, Nramp5 and HIPP. Si ameliorated Cd-induced photosynthetic performance inhibition through up-regulating photosynthesis-related genes and light harvesting-related genes. Si minimized Cd-induced oxidative stress by decreasing MDA contents by 46.62% (leaf) and 75.09% (root), and helped re-establish redox homeostasis by regulating antioxidant enzymes activities, AsA-GSH cycle and expression of relevant genes through signal transduction pathway. The results revealed molecular mechanism of Si-mediated wheat tolerance to Cd toxicity. Si fertilizer is suggested to be applied in Cd contaminated soil for food safety production as a beneficial and eco-friendly element.

Uncovering the impact of AM fungi on wheat nutrient uptake, ion homeostasis, oxidative stress, and antioxidant defense under salinity stress

The growth of wheat (Triticum aestivum) is constrained by soil salinity, although some fungal species have been shown to enhance production in saline environments. The yield of grain crops is affected by salt stress, and this study aimed to investigate how arbuscular mycorrhizal fungus (AMF) mitigates salt stress. An experiment was conducted to assess the impact of AMF on wheat growth and yield in conditions of 200 mM salt stress. Wheat seeds were coated with AMF at a rate of 0.1 g (10⁸ spores) during sowing. The results of the experiment demonstrated that AMF inoculation led to a significant improvement in the growth attributes of wheat, including root and shoot length, fresh and dry weight of root and shoot. Furthermore, a significant increase in chlorophyll a, b, total, and carotenoids was observed in the S2 AMF treatment, validating the effectiveness of AMF in enhancing wheat growth under salt stress conditions. Additionally, AMF application reduced the negative effects of salinity stress by increasing the uptake of micronutrients such as Zn, Fe, Cu, and Mn while regulating the uptake of Na (decrease) and K (increase) under salinity stress. In conclusion, this study confirms that AMF is a successful strategy for reducing the negative effects of salt stress on wheat growth and yield. However, further investigations are recommended at the field level under different cereal crops to establish AMF as a more effective amendment for the alleviation of salinity stress in wheat.

Cadmium uptake and membrane transport in roots of hyperaccumulator Amaranthus hypochondriacus L

Hyperaccumulator Amaranthus hypochondriacus L. has huge potential in the remediation of cadmium (Cd)-contaminated soils and is necessary to understand the mechanism of Cd uptake by the roots. In this study, the mechanism of Cd uptake into the root of A. hypochondriacus was investigated using the non-invasive micro-test technology (NMT) by analyzing the rate of Cd²⁺ fluxes at different regions of the root tip; also we assessed the impact of different channel blockers and inhibitors on the Cd accumulation in the roots, the real-time Cd²⁺ fluxes, and the distribution of Cd along the roots. The results showed that the Cd²⁺ influx was greater near the root tip (within 100 μm of the tip). All the inhibitors, ion-channel blockers, and metal cations had different degrees of inhibition on the absorption of Cd in the roots of A. hypochondriacus. The net Cd²⁺ flux in the roots was significantly decreased by the Ca²⁺ channel blockers lanthanum chloride (LaCl₃) by up to 96% and verapamil by up to 93%; as for the K⁺ channel blocker tetraethylammonium (TEA), it also caused a 68%-reduction on the net Cd²⁺ flux in the roots. Therefore, we infer that the uptake by A. hypochondriacus roots is mainly through the Ca²⁺ channels. The Cd absorption mechanism appears to be related to the synthesis of plasma membrane P-type ATPase and phytochelatin (PC), which is reflected by the inhibition of Ca²⁺ upon addition of inorganic metal cations. In conclusion, access of Cd ions into the roots of A. hypochondriacus is achieved through various ion channels, with the most important being the Ca²⁺ channel. This study will further enhance the literature regarding Cd uptake and pathways of membrane transport in roots of Cd hyperaccumulators.

How heavy metal stress affects the growth and development of pulse crops: insights into germination and physiological processes

The current work is an extensive review addressing the effects of heavy metals in major pulse crops such as Chickpea (Cicer arietinum L.), Pea (Pisum sativum L.), Pigeonpea (Cajanus cajan L.), Mung bean (Vigna radiata L.), Black gram (Vigna mungo L.) and Lentil (Lens culinaris Medik.). Pulses are important contributors to the global food supply in the world, due to their vast beneficial properties in providing protein, nutritional value and health benefits to the human population. Several studies have reported that heavy metals are injurious to plants causing inhibition in plant germination, a decrease in the root and shoot length, reduction in respiration rate and photosynthesis. Properly disposing of heavy metal wastes has become an increasingly difficult task to solve in developed countries. Heavy metals pose one of the substantial constraints to pulse crops growth and productivity even at low concentrations. This article attempts to present the morphological, biochemical and various physiological changes induced on the pulse crops grown under various heavy metal stress such as As, Cd, Cr, Cu, Pb, and Ni.

Synergistic effects of calcium and melatonin on physiological and phytochemical attributes of Dracocephalum kotschyi genotypes under salinity stress

Since regulatory roles of calcium (Ca) and melatonin (MT) in physiological responses of plants to salinity stress are lacking, various Dracocephalum kotschyi genotypes (Bojnord, Urmia, Fereydunshahr, and Semirom) were pretreated with exogenous Ca (5 mM), MT (100 μM), and Ca + MT in the presence of salt (75 mM NaCl). In addition measuring the concentration of phenolic compounds by high performance liquid chromatography (HPLC), histochemical evaluations of essential oils and phenolic compounds in glandular trichomes of leaf samples were performed by light microscope. Salt stress reduced shoot fresh (SFW) and dry weight (SDW), leaf area (LA), relative water content (RWC), and maximum efficiency of photosystem II (F_v /F_m ), but enhanced total phenolic content (TPC) and total flavonoids content (TFC), phenolic compounds concentrations, DPPH radical scavenging capacity, electrolyte leakage (EL), proline and hydrogen peroxide (H₂ O₂ ) concentrations, and Na⁺ /K⁺ and essential oils and TPC of the glandular trichomes of leaves in all D. kotschyi genotypes. Foliar spraying of Ca, MT, and particularly Ca + MT on D. kotschyi seedlings improved SFW, SDW, RWC, TPC, TFC, proline and phenolic compounds concentrations, F_v /F_m , and DPPH radical scavenging capacity, but reduced H₂ O₂ , EL, and Na⁺ /K⁺ in the leaves and essential oils and TPC in the glandular trichomes of all genotypes under both non-stress and salt stress conditions. These findings indicate that the crosstalk between MT and Ca synergistically improves salt tolerance, TPC and TFC, phenolic compounds concentration, and essential oils accumulation in glandular trichomes of different D. kotschyi genotypes.

Calcium and L-glutamate present the opposite role in managing arsenic in barley

Arsenic contamination in agricultural soils has posed tremendous threat to sustainable crop production and human health via food chain. Calcium and Glutamate have been well-documented in metal(loid)s detoxification, but it is poorly understood how they regulate arsenic-induced toxicity to plants. In this study, the effect of glutamate and calcium at high concentration on arsenic toxicity and accumulation in barley seedling was accessed in terms of plant growth, photosynthetic efficacy, arsenic uptake, translocation and accumulation, antioxidant defense, nutrient uptake and the expression of As transporters. Our results have demonstrated that calcium could effectively ameliorate arsenic toxicity to barley seedlings, which is mainly attributed to its beneficial effect on increasing nutrient uptake, reducing the aboveground arsenic accumulation and enhancing antioxidative defense capacity. However, it is unexpected that glutamate considerably exacerbated the arsenic toxicity to barley seedlings. More importantly, for the first time, glutamate was observed to tremendously facilitate the root-to-shoot translocation of arsenic by 41.8- to 60.8-fold, leading to 90% of the total amount of As accumulating in barley shoots. The reason of this phenomenon can be well explained by the glutamate-triggered enormous upregulation of genes involved in arsenic uptake (HvPHT1;1, HvPHR2 and HvNIP3;2), reduction (HvHAC1;1), translocation (HvABCC7, HvNIP1;1 and HvNIP3;3) and intracellular sequestration (HvABCC1). These findings suggest that calcium and glutamate function as the opposite player in managing arsenic, with calcium being an effective alleviator of arsenic stress to ensure the safe production of crops; while glutamate being a highly efficient phytoextraction agent for phytoremediation of arsenate-contaminated soils.

Nitric oxide promotes adventitious root formation in cucumber under cadmium stress through improving antioxidant system, regulating glycolysis pathway and polyamine homeostasis

Cadmium (Cd) as a potentially toxic heavy metal that not only pollutes the environment but also interferes with plant growth. Nitric oxide (NO) regulates plant growth and development as well as abiotic stress response. However, the mechanism underpinning NO-induced adventitious root development under Cd stress remains unclear. In this study, cucumber (Cucumis sativus 'Xinchun No. 4') was used as the experimental material to investigate the effect of NO on the development of adventitious roots in cucumber under Cd stress. Our results revealed that, as compared to Cd stress, 10 μM SNP (a NO donor) could considerably increase the number and length of adventitious roots by 127.9% and 289.3%, respectively. Simultaneously, exogenous SNP significantly increased the level of endogenous NO in cucumber explants under Cd stress. Our results revealed that supplementation of Cd with SNP significantly increased endogenous NO content by 65.6% compared with Cd treatment at 48 h. Furthermore, our study indicated that SNP treatment could improve the antioxidant capacity of cucumber explants under Cd stress by up-regulating the gene expression level of antioxidant enzymes, as well as reducing the levels of malondialdehyde (MDA), hydrogen peroxide (H₂O₂) and superoxide anion (  O 2    · - ) to alleviate oxidative damage and membrane lipid peroxidation. Application of NO resulted in a decrease of the  O 2    · - , MDA, and H₂O₂ level by 39.6%, 31.4% and 60.8% as compared to Cd-alone treatment, respectively. Besides that, SNP treatment significantly increased the expression level of related genes involved in glycolysis processes and polyamine homeostasis. However, application of NO scavenger 2-(4-carboxy -2-phenyl)-4, 4, 5, 5-tetramethy limidazoline -1-oxyl -3-oxide (cPTIO) and the inhibitor tungstate significantly reversed the positive role of NO in promoting the adventitious root formation under Cd stress. These results suggest that exogenous NO can increase the level of endogenous NO, improve antioxidation ability, promote glycolysis pathway and polyamine homeostasis to enhance the occurrence of adventitious roots in cucumber under Cd stress. In summary, NO can effectively alleviate the damage of Cd stress and significantly promote the development of adventitious root of cucumber under Cd stress.

Bio-priming with salt tolerant endophytes improved crop tolerance to salt stress via modulating photosystem II and antioxidant activities in a sub-optimal environment

Abiotic stress is one of the major constraints which restrain plant growth and productivity by disrupting physiological processes and stifling defense mechanisms. Hence, the present work aimed to evaluate the sustainability of bio-priming salt tolerant endophytes for improving plant salt tolerance. Paecilomyces lilacinus KUCC-244 and Trichoderma hamatum Th-16 were obtained and cultured on PDA medium containing different concentrations of NaCl. The highest salt (500 mM) tolerant fungal colonies were selected and purified. Paecilomyces at 61.3 × 10^-6 conidia/ml and Trichoderma at about 64.9 × 10^-3 conidia/ml of colony forming unit (CFU) were used for priming wheat and mung bean seeds. Twenty- days-old primed and unprimed seedlings of wheat and mung bean were subjected to NaCl treatments at 100 and 200 mM. Results indicate that both endophytes sustain salt resistance in crops, however T. hamatum significantly increased the growth (141 to 209%) and chlorophyll content (81 to 189%), over unprimed control under extreme salinity. Moreover, the reduced levels (22 to 58%) of oxidative stress markers (H₂O₂ and MDA) corresponded with the increased antioxidant enzymes like superoxide dismutase (SOD) and catalase (CAT) activities (141 and 110%). Photochemical attributes like quantum yield (F_V/F_M) (14 to 32%) and performance index (PI) (73 to 94%) were also enhanced in bio-primed plants in comparison to control under stress. In addition, the energy loss (DI_O/RC) was considerably less (31 to 46%), corresponding with lower damage at PS II level in primed plants. Also, the increase in I and P steps of OJIP curve in T. hamatum and P. lilacinus primed plants showed the availability of more active reaction centers (RC) at PS II under salt stress in comparison to unprimed control plants. Infrared thermographic images also showed that bio-primed plants were resistant to salt stress. Hence, it is concluded that the use of bio-priming with salt tolerant endophytes specifically T. hamatum can be an effective approach to mitigate the salt stress cosnequences and develop a potential salt resistance in crop plants.

Weighted gene co-expression network analysis revealed the key pathways and hub genes of potassium regulating cotton root adaptation to salt stress

Soil salinization is one of the main abiotic stresses affecting cotton yield and planting area. Potassium application has been proven to be an important strategy to reduce salt damage in agricultural production. However, the mechanism of potassium regulating the salt adaptability of cotton has not been fully elucidated. In the present research, the appropriate potassium application rate for alleviating salt damage of cotton based on different K⁺/Na⁺ ratios we screened, and a gene co-expression network based on weighted gene co-expression network analysis (WGCNA) using the transcriptome data sets treated with CK (0 mM NaCl), S (150 mM NaCl), and SK8 (150 mM NaCl + 9.38 mM K₂SO₄) was constructed. In this study, four key modules that are highly related to potassium regulation of cotton salt tolerance were identified, and the mitogen-activated protein kinase (MAPK) signaling pathway, tricarboxylic acid (TCA) cycle and glutathione metabolism pathway were identified as the key biological processes and metabolic pathways for potassium to improve cotton root salt adaptability. In addition, 21 hub genes and 120 key candidate genes were identified in this study, suggesting that they may play an important role in the enhancement of salt adaptability of cotton by potassium. The key modules, key biological pathways and hub genes discovered in this study will provide a new understanding of the molecular mechanism of potassium enhancing salinity adaptability in cotton, and lay a theoretical foundation for the improvement and innovation of high-quality cotton germplasm.

Potassium silicate and zinc oxide nanoparticles modulate antioxidant system, membranous H+-ATPase and nitric oxide content in faba bean (Vicia faba) seedlings exposed to arsenic toxicity

Current research focused on the potential role of zinc oxide nanoparticles (ZnONPs) and potassium (K+ ) in mitigation of arsenic (As) toxicity in Vicia faba L. seedlings. Faba bean seedlings were grown for 30days in potted soil. As stress curtailed root and shoot length, chlorophyll (Chl) content and net photosynthetic rate in V. faba seedlings. However, ZnONPs and K+ curtailed As stress in faba bean seedling through enhanced activity of superoxide dismutase (SOD), ascorbate peroxidase (APX), catalase (CAT) and peroxidase (POD) enzyme. Furthermore, ZnONPs and K+ significantly enhanced cysteine (Cys) content and serine acetyletransferase (SAT) activity in faba bean seedling exposed to As-toxificated soil. Application of ZnONPs and K+ curtailed superoxide ionic content and hydrogen peroxide (H2 O2 ) accumulation in V. faba seedlings exposed to As-polluted soil. Nitric oxide (NO) content also increased in faba bean seedlings treated with ZnONPs and K+ in normal and As-polluted soil. As stress alleviation was credited to reduce As uptake in faba bean seedlings treated with synergistic application of ZnONPs and K+ . It is proposed that K+ interaction with nanoparticles can be exploited at molecular level to understand the mechanisms involved in abiotic stress tolerance.

Effects of Salt Stress on the Antioxidant Activity and Malondialdehyde, Solution Protein, Proline, and Chlorophyll Contents of Three Malus Species

Understanding the different physiological responses of Malus species under salt stress in the seedling stages will be useful in breeding salt-tolerant dwarfing apple rootstocks. Seedlings of Malus Zumi (Mats.) Rehd. (M. zumi), Malus sieversii (Led.) Roem. (M. sieversii), and Malus baccata (L.) Borkh. (M. baccata) were treated with solution of 0, 0.20%, 0.40%, and 0.60% salinity. Physiological parameters of their leaves and roots were measured at 0 d, 4 d, 8 d and 12 d after salinity treatments. Superoxide dismutase (SOD), peroxidase (POD), catalase (CAT), malondialdehyde (MDA), solution protein (SP), and proline (PRO) initially increased and then decreased. The activities and contents of these parameters were higher in the 0.40% and 0.60% NaCl treatments than in the 0.20% treatment and in the 0% control. M. zumi was the most resistant to salt stress, showing the lowest content of MDA in the leaves and roots, which increased slightly under salt stress. M. baccata had the highest increase in both the content and proportion of MDA. High enzyme activity was shown to play an important role in the salt resistance of M. zumi. Moreover, it can be speculated that there are other substances that also play a major role. We found that osmotic regulation played a key role in response to salt stress for M. baccata even though it was sensitive to salt stress. For M. sieversii, both the osmotic regulation and enzymatic antioxidants were observed to play a major role in mitigating salt stress.

Relative Water Content, Proline, and Antioxidant Enzymes in Leaves of Long Shelf-Life Tomatoes under Drought Stress and Rewatering

Some physiological, oxidative, and antioxidant enzymatic patterns were assessed in plants of three local Sicilian landraces of long shelf-life tomatoes ('Custonaci', 'Salina', and 'Vulcano'), as compared to the commercial tomato hybrid 'Faino' (control). Three water treatments were considered in open-field: DRY (no irrigation); IRR (long-season full irrigation); REW (drought/rewatering cycles). During the growing season, soil water deficit (SWD) was estimated, and relative water content (RWC), specific leaf area (SLA), proline and malondialdehyde (MDA) content, and glutathione peroxidase (GPX), catalase (CAT), and superoxide dismutase (SOD) activities were measured in leaves. Differently from control, RWC in local landraces exhibited a similar pattern in REW and DRY, indicating a low capacity to re-hydrate after rewatering. Positive correlation of proline content vs. SWD in all local landraces highlights an osmotic adjustment occurring in these tomatoes in response to limited soil water content. Long shelf-life tomatoes suffered minor oxidative stress due to severe soil water deficit, as revealed by the lower levels of MDA with respect to the control. Significant correlation of CAT vs. SWD for all tomatoes indicates that this antioxidant enzyme, among those analyzed, may be considered as a biomarker for a water stress condition more than for oxidative stress due to water deficit.

Calcium Supplementation Ameliorates Cerebellar Oxidative Stress in Lactational Aluminum-induced Neurotoxicity in Rats

Introduction

The neurotoxic effects of aluminum exposure during the critical period of neurodevelopment have been well documented. This study investigated the known protective effects of calcium supplementation on the cerebellum of juvenile Wistar rats following aluminum-induced neurotoxicity during lactation.

Methods

Four groups of juvenile rats were exposed via lactation to distilled water (control group), aluminum (40 mg/kg/d), calcium supplement (50 mg/kg/d), and a combination of both aluminum and calcium from postnatal day 4 to day 28. The cerebella of the animals were excised to access the levels of antioxidant enzymes (superoxide dismutase [SOD], glutathione peroxidase [GPx]), lipid peroxidation (malondialdehyde), histomorphological alterations (hematoxylin and eosin staining), Nissl profile (cresyl fast violet staining), and glial activation (glial fibrillary acidic protein immunohistochemistry).

Results

Lactational aluminum significantly decreased the activities of superoxide dismutase and glutathione peroxidase while exacerbating lipid peroxidation and reactive astrocyte in cerebellar lysates. Lactational calcium supplementation normalized the activities of SOD and GPx, thereby preventing excessive lipid peroxidation and glial activation. Despite no apparent changes in the general histology of the cerebellum, aluminum-induced chromatolysis changes in the Purkinje cell layer, which was counteracted by the antioxidant propensities of calcium supplementation.

Conclusion

These findings support that calcium supplementation significantly protects the cerebellum against aluminum-induced oxidative stress, chromatolysis, and neuroinflammation.

Increasing the lycopene content and bioactive potential of tomato fruits by application of encapsulated biological and chemical agents

Plant secondary metabolites play an important part in the human diet. This research investigated the effect of alginate microspheres loaded with chemical (calcium or copper ions) or chemical and biological (Trichoderma viride) agents on plant secondary metabolites synthesis of two tomato varieties ('Vasanta' and 'Abellus') in two types of greenhouse cultivation, hydroponic and soil. Targeted and controlled release of active agents facilitates the root of plants to respond to the encapsulated agents and stimulate the synthesis of investigated plant metabolites both in hydroponic and soil types of cultivation. A significant increase in lycopene (up to 230%), total polyphenols content (up to 61%), and the overall antioxidant activity (up to 77%) of the tomato fruits was found for all of the treatments, respectively. Encapsulated chemical and biological agents remarkably stimulate the synthesis of plant secondary metabolites in tomato fruits indicating its great potential in the production of value-added foods.

Zinc oxide nanoparticles improve lettuce (Lactuca sativa L.) plant tolerance to cadmium by stimulating antioxidant defense, enhancing lignin content and reducing the metal accumulation and translocation

Cadmium (Cd) contamination is a serious global concern that warrants constant attention. Therefore, a hydroponic study was conducted to evaluate the effect of different concentrations (0, 1, 2.5, 5, 10, 15 mg/l) of zinc oxide nanoparticles (ZnONPs) on the Cd content in lettuce (Lactuca sativa L.) under Cd stress conditions. The results showed that Cd stress triggered a decrease in plant biomass, an increase in relative electrolyte conductivity (REC), a decrease in root activity, accumulation of reactive oxygen species (ROS) accumulation, and nutrient imbalance. The application of ZnONPs reduced the toxicity symptoms of lettuce seedlings under Cd stress, with the most pronounced effect being observed 2.5 mg/l. ZnONPs promoted the growth of lettuce under Cd stress, mainly in terms of increase in biomass, chlorophyll content, antioxidant enzyme activity, and proline content, as well as reduction in Cd content, malondialdehyde, and reactive oxygen species (ROS) in plant tissues. ZnONPs also enhanced the uptake of ions associated with photosynthesis, such as iron, manganese, magnesium, and zinc. In addition, ZnONPs increase the amount of lignin in the roots, which blocks or reduces the entry of Cd into plant tissues.

Induction of resilience strategies against biochemical deteriorations prompted by severe cadmium stress in sunflower plant when Trichoderma and bacterial inoculation were used as biofertilizers

Background

Cadmium (Cd) is a highly toxic heavy metal. Its emission is suspected to be further increased due to the dramatic application of ash to agricultural soils and newly reclaimed ones. Thereby, Cd stress encountered by plants will exacerbate. Acute and chronic exposure to Cd can upset plant growth and development and ultimately causes plant death. Microorganisms as agriculturally important biofertilizers have constantly been arising as eco-friendly practices owing to their ability to built-in durability and adaptability mechanisms of plants. However, applying microbes as a biofertilizer agent necessitates the elucidation of the different mechanisms of microbe protection and stabilization of plants against toxic elements in the soil. A greenhouse experiment was performed using Trichoderma harzianum and plant growth-promoting (PGP) bacteria (Azotobacter chroococcum and Bacillus subtilis) individually and integrally to differentiate their potentiality in underpinning various resilience mechanisms versus various Cd levels (0, 50, 100, and 150 mg/kg of soil). Microorganisms were analyzed for Cd tolerance and biosorption capacity, indoleacetic acid production, and phosphate and potassium solubilization in vitro. Plant growth parameters, water relations, physiological and biochemical analysis, stress markers and membrane damage traits, and nutritional composition were estimated.

Results

Unequivocal inversion from a state of downregulation to upregulation was distinct under microbial inoculations. Inoculating soil with T. harzianum and PGPB markedly enhanced the plant parameters under Cd stress (150 mg/kg) compared with control plants by 4.9% and 13.9%, 5.6% and 11.1%, 55.6% and 5.7%, and 9.1% and 4.6% for plant fresh weight, dry weight, net assimilation rate, and transpiration rate, respectively; by 2.3% and 34.9%, 26.3% and 69.0%, 26.3% and 232.4%, 135.3% and 446.2%, 500% and 95.6%, and 60% and 300% for some metabolites such as starch, amino acids, phenolics, flavonoids, anthocyanin, and proline, respectively; by 134.0% and 604.6% for antioxidants including reduced glutathione; and by 64.8% and 91.2%, 21.9% and 72.7%, and 76.7% and 166.7% for enzymes activity including ascorbate peroxidase, glutathione peroxidase, and phenylalanine ammonia-lyase, respectively. Whereas a hampering effect mediated by PGP bacterial inoculation was registered on levels of superoxide anion, hydroxyl radical, electrolyte leakage, and polyphenol oxidase activity, with a decrease of 0.53%, 14.12%, 2.70%, and 5.70%, respectively, under a highest Cd level (150 mg/kg) compared with control plants. The available soil and plant Cd concentrations were decreased by 11.5% and 47.5%, and 3.8% and 45.0% with T. harzianum and PGP bacterial inoculation, respectively, compared with non-inoculated Cd-stressed plants. Whereas, non-significant alternation in antioxidant capacity of sunflower mediated by T. harzianum action even with elevated soil Cd concentrations indicates stable oxidative status. The uptake of nutrients, viz., K, Ca, Mg, Fe, nitrate, and phosphorus, was interestingly increased (34.0, 4.4, 3.3, 9.2, 30.0, and 1.0 mg/g dry weight, respectively) owing to the synergic inoculation in the presence of 150 mg of Cd/kg.

Conclusions

However, strategies of microbe-induced resilience are largely exclusive and divergent. Biofertilizing potential of T. harzianum showed that, owing to its Cd biosorption capability, a resilience strategy was induced via reducing Cd bioavailability to be in the range that turned its effect from toxicity to essentiality posing well-known low-dose stimulation phenomena (hormetic effect), whereas using Azotobacter chroococcum and Bacillus subtilis, owing to their PGP traits, manifested a resilience strategy by neutralizing the potential side effects of Cd toxicity. The synergistic use of fungi and bacteria proved the highest efficiency in imparting sunflower adaptability under Cd stress.

Under cadmium stress, silicon has a defensive effect on the morphology, physiology, and anatomy of pea (Pisum sativum L.) plants

Soil pollution with cadmium (Cd) is a serious threat to plant growth and development. On the other hand, silicon (Si) can support plants to cope with Cd stress. However, the Cd stress mitigating impact of Si reduction in pea (Pisum sativum L.) is not known. The objective of this study is to see if and how Si can reduce Cd toxicity. To the end, a greenhouse pot experiment was performed twice during the 2018/2019 and 2019/2020 seasons to investigate the effect of Si on the growth, anatomy, and biochemistry of Cd stressed peas plants. Cd exposure increased the contents of Cd ions in the root and shoot of pea plants. Consequentially, Cd accumulation in pea tissue significantly reduced plant growth i.e., plant height, leaf area, and shoot and root dry weights. The effect of Cd was concentration-dependent, where at low concentration (50 mg/kg soil), the plant height was 94.33 and 97.33cm and at high concentration (100 mg/kg soil), it was 89.0 and 91.0 cm in the two seasons, respectively. This growth reduction can be explained by the decrease in plants' photosynthesis, whereas plants exposed to Cd toxicity had lower chlorophyll levels. At the anatomy level, high Cd concentrations resulted in anatomical abnormalities such as an unusual vascular system, abnormal lignification in the pith parenchyma, and enlarged cortical cells. Moreover, all Cd concentrations resulted in a highly significant decrease in stomatal area and stomatal density (the number of stomata per mm²). In addition to growth inhibition, Cd-induced oxidative damage to pea plants as indicated by increased hydrogen peroxide (H₂O₂) and Malondialdehyde (MDA) levels. To reduce stress toxicity, plants treated with Cd at 50 and 100 (mg/kg) showed a significant increase in antioxidant capacity. Peroxidase (POD) enzyme activity was significantly increased by 41.26%, 28.64%, 77.05%, and 60.77% in both seasons, respectively. Si at 300 ppm under Cd (100 mg/kg) stress conductions considerably reduced (MDA) contents by 29.02% and 29.12%, in the two seasons, respectively. The findings pointed out that Si's ability to protect pea against the oxidative stress caused by Cd toxicity.

Systemic H2O2 signaling mediates epigallocatechin-3-gallate-induced cadmium tolerance in tomato

Toxic heavy metal cadmium (Cd) reduces crop yield and threatens human health via the food chain. The bioactive flavonoid 'Epigallocatechin-3-gallate' (EGCG) affects plant stress response; however, the function of EGCG in Cd tolerance and the molecular pathways remain largely unknown. Here, we revealed that root application of EGCG alleviated Cd stress in tomato plants. While Cd stress decreased Fv/Fm, Ф_PSII, photosynthetic rate, root growth, root vitality and biomass accumulation by increasing reactive oxygen species (ROS) accumulation and lipid peroxidation, exogenous EGCG minimized excessive ROS accumulation and oxidative stress by promoting the activity of antioxidant enzymes and redox poise in roots and leaves. Moreover, EGCG induced the transcript of RESPIRATORY BURST OXIDASE HOMOLOG1 (RBOH1) and decreased Cd content and photoinhibition in leaves. Interestingly, similar to EGCG, exogenous H₂O₂ application also enhanced Cd tolerance; however, the application of an NADPH oxidase inhibitor, diphenyleneiodonium (DPI), aggravated Cd phytotoxicity and attenuated the beneficial effects of EGCG on plant tolerance to Cd stress, suggesting that root applied EGCG-induced expression of RBOH1 and associated H₂O₂ signaling mediate the EGCG-induced enhanced Cd tolerance. This work elucidates a fundamental mechanism behind EGCG-mediated Cd tolerance and contributes to our existing knowledge of stress resistance properties of EGCG in plants.

Modulation of osmoprotection and antioxidant defense by exogenously applied acetate enhances cadmium stress tolerance in lentil seedlings

To examine the potential role of acetate in conferring cadmium (Cd) stress tolerance in lentil (Lens culinaris), several phenotypical and physio-biochemical properties have been examined in Cd-stressed lentil seedlings following acetate applications. Acetate treatment inhibited the translocation of Cd from roots to shoots, which resulted in a minimal reduction in photosynthetic pigment contents. Additionally, acetate-treated lentil showed higher shoot (1.1 and 11.72%) and root (4.98 and 30.64%) dry weights compared with acetate-non-treated plants under low-Cd and high-Cd concentrations, respectively. Concurrently, acetate treatments increase osmoprotection under low-Cd stress through proline accumulation (24.69%), as well as enhancement of antioxidant defense by increasing ascorbic acid content (239.13%) and catalase activity (148.51%) under high-Cd stress. Acetate-induced antioxidant defense resulted in a significant diminution in hydrogen peroxide, malondialdehyde and electrolyte leakage in Cd-stressed lentil seedlings. Our results indicated that acetate application mitigated oxidative stress-induced damage by modulating antioxidant defense and osmoprotection, and reducing root-to-shoot Cd transport. These findings indicate an important contribution of acetate in mitigating the Cd toxicity during growth and development of lentil seedlings, and suggest that the exogenous applications of acetate could be an economical and new avenue for controlling heavy metal-caused damage in lentil, and potentially in many other crops.

An In Vitro and In Silico Perspective Study of Seed Priming with Zinc on the Phytotoxicity and Accumulation Pattern of Arsenic in Rice Seedlings

Arsenic (As) contamination of the rice agro-ecosystem is a major concern for rice farmers of South East Asia as it imposes a serious threat to human and animal life; thus, there is an unrelenting need to explore the ways by which arsenic stress mitigation could be achieved. In the present investigation, we explore the effect of zinc (Zn²⁺) supplementation using the seed priming technique for the mitigation of As-induced stress responses in developing rice seedlings. In addition to the physiological and biochemical attributes, we also studied the interactive effect of Zn²⁺ in regulating As-induced changes by targeting antioxidant enzymes using a computational approach. Our findings suggest that Zn²⁺ and As can effectively modulate redox homeostasis by limiting ROS production and thereby confer protection against oxidative stress. The results also show that As had a significant impact on seedling growth, which was restored by Zn²⁺ and also minimized the As uptake. A remarkable outcome of the present investigation is that the varietal difference was significant in determining the efficacy of the Zn²⁺ priming. Further, based on the findings of computational studies, we observed differences in the surface overlap of the antioxidant target enzymes of rice, indicating that the Zn²⁺ might have foiled the interaction of As with the enzymes. This is undoubtedly a fascinating approach that interprets the mode of action of the antioxidative enzymes under the metal/metalloid-tempted stress condition in rice by pointing at designated targets. The results of the current investigation are rationally significant and may be the pioneering beginning of an exciting and useful method of integrating physiological and biochemical analysis together with a computational modelling approach for evaluating the stress modulating effects of Zn²⁺ seed priming on As-induced responses in developing rice seedlings.

Response of Yam (Dioscorea alata) to the Application of Rhizophagus irregularis and Potassium Silicate under Salinity Stress

Yam (Dioscorea alata) is a tropical plant that is considered critical for food security. The use of high fertilizer, low soil fertility, and insect pest infestation reduce yam tuber yield and quality. The present study was performed to determine the effect of potassium silicate and arbuscular mycorrhizal fungi (AMF) on yam cultivated under salinity stress. This study revealed that the combination of Rhizophagus irregularis (AMF) and Potassium silicate was more effective than their individual application on yam and were beneficial for overall analyzed characters. We observed the days to emergence and the average days to first leaf emergence decreased by 33.46% and 26.78%, respectively, the number of leaves increased by 45.23%, number of sprouts per seed tuber by 50%, vine length by 60.8%, vine length at harvest by 40.53%, the average leaf width by 53.79%, petiole length by 31.74%, tuber length by 43.84%, average diameter of tuber by 56.58%, and average number of tuber per vine by 46.15% in T5 treated plants. We also recorded that starch content increased by 21.89%, ascorbic acid by 61.51%, average moisture by 8.36%, TSS by 50%, and total sugar by 69.53% in T5 treated plants. The total phenol was found to be 1.53% higher in T3 applied plants, while the dry matter was 36.37% higher in T5 treatment. Furthermore, the enzymatic evaluation of MDA in leaves was found to be enhanced by 142% in T2. The enzyme 8-OHdG from the leaves sample was reported to be increased after T5 by 621.15%. Moreover, the amount of CAT was higher by 53.46% in T2 treated plants. Likewise, the amount of enzyme SOD and POX in leaves of D. alata enhanced by 30.91% and 51.15% T2 treatments respectively.

Calcium in Photosynthetic Restoration and Growth of Annona emarginata after Mechanical Damage

Calcium, an essential element with structural function in the cell wall and plasma membrane, in addition to being a secondary messenger, is responsible for the regulation of physiological processes in plant development and responses to biotic and abiotic stresses. This study investigated the effects of calcium variation on photosynthetic performance, growth, and enzymatic antioxidant defense system in A. emarginata subjected to mechanical damage. The experimental design was in 6 × 5 factorial randomized blocks. A. emarginata plants were submitted to the six treatments: plants grown in solution with 0 mM Ca2+ without mechanical damage, 0 mM Ca2+ with mechanical damage, 2 mM Ca2+ without mechanical damage, 2 mM Ca2+ with mechanical damage, 4 mM Ca2+ without mechanical damage, and 4 mM Ca2+ with mechanical damage, as well as five evaluation periods at 0, 15, 30, 60, and 90 days after mechanical damage. The fluorescence of chlorophyll a, gas exchange, total dry mass, quantitative growth, and lipid peroxidation was studied. It is concluded that the A. emarginata plants showed better performance in restoration after mechanical damage in the presence of Ca2+ and was more sensitive in the absence of the mineral. Cultivation of the species with 2 mM Ca2+ in complete nutrient solution was sufficient to guarantee the efficiency of the enzymatic antioxidant defense system, and photosynthetic restoration of plants subjected to mechanical damage.

Exogenously applied calcium regulates antioxidative system and reduces cadmium-uptake in Fagopyrum esculentum

Calcium (Ca) being macronutrient plays a prominent role in signal transduction during various abiotic stresses. However, their involvements to alleviate heavy metal stress in plants remain evasive. In the present investigation, we found that application of exogenous Ca to Cd-stressed common buckwheat plants reversed the toxic effects of Cd by enhancing root and shoot length, biomass accumulation and reduced Cd-uptake as revealed by the translocation factor (<1), indicating more Cd is restrained in the roots. Moreover, present data also revealed that exogenous Ca significantly alleviated the Cd-induced oxidative damage by enhancing proline by 66.12% and 47.20% respectively in roots and shoots than control. The decline in the total chlorophyll content upon Ca application in Cd-treated plants was found less (38.96%) compared to buckwheat plants treated with Cd-stress alone (80.2%). APX and POD activities increased by 1.97 and 1.44 times in shoots, respectively, and increased by 2.81and 1.33 times in roots, respectively compared to the Cd-treated plants alone. The mineral content (Ca, K, Mg, Fe, P and S) that were suppressed in Cd-treated plants in both root and shoot were restored upon exogenous Ca application. Further, the correlation analysis showed significant positive correlation among proline and GSH synthesis in the Ca + Cd treatment. The correlations of Ca revealed to be positive with enhanced levels of APX and POD activity. Our data showed that exogenous application of Ca minimizes the Cd-toxicity and modulates the physiological and biochemical pathway in common buckwheat to withstand Cd-induced oxidative stress.

Red-seaweed biostimulants differentially alleviate the impact of fungicidal stress in rice (Oryza sativa L.)

Red seaweed-derived biostimulants facilitate plant health and impart protection against abiotic stress conditions by their bioactive compounds and plant nutrients. The potency of red seaweed biostimulants (LBS6 and LBD1) on rice cv. IR-64 in response to fungicides induced stress was investigated in this study. Foliar application of LBS6 maintained the stomatal opening and leaf temperature under the fungicidal stress condition. Reactive Oxygen Species (ROS) such as hydrogen peroxide and superoxide radicals were significantly reduced in LBS6-treated stressed plants. After applying seaweed biostimulants, ROS production was stabilized by antioxidants viz., CAT, APX, SOD, POD, and GR. LBS-6 application increased the Ca⁺ and K⁺ levels in the stressed plants, which perhaps interacted with ROS and stomatal opening signalling systems, respectively. In the rice plants, fungicidal stress elevated the expression of stress-responsive transcriptional factors (E2F, HSFA2A, HSFB2B, HSFB4C, HSFC1A, and ZIP12). A decline in the transcript levels of stress-responsive genes was recorded in seaweed treated plants. For the first time, we present an integrative investigation of physicochemical and molecular components to describe the mechanism by which seaweed biostimulants in rice improve plant health under fungicidal stress conditions.

Slaked lime improves growth, antioxidant capacity and reduces Cd accumulation of peanut (Arachis hypogaea L.) under Cd stress

Slaked lime has been used to remediate contaminated agricultural soils as an in situ chemical immobilization amendment for a long time. However, the effects of slaked lime on peanut and soil cadmium (Cd) levels remain poorly understood with respect to remediating Cd-contaminated soil. In this study, six rates of slaked lime (e.g., 0, 300, 600, 900, 1200 and 1500 kg ha-1) were applied to evaluate the effects of slaked lime treatments on soil pH and the growth, Cd accumulation and physiology characteristics of peanut, which were in Cd-contaminated soil, and 0 kg ha-1 was taken as the control. The results indicated that slaked lime application significantly increased soil pH and reduced total Cd contents in peanut tissues at all growth stages. As the rates of slaked lime were increased, kernel biomass increased in the maturity stage, which increased peanut yields. The irregular variations in catalase, peroxidase, and superoxide dismutase activities and chlorophyll and malondialdehyde contents that were observed at all growth stages may be due to the interactions among soil pH, Ca nutrients and Cd, etc. In summary, slaked lime is suitable as an in situ chemical immobilization amendment to increase Cd immobilization and peanut yields in Cd-contaminated soil.

Root morphology ion absorption and antioxidative defense system of two Chinese cabbage cultivars (Brassica rapa L.) reveal the different adaptation mechanisms to salt and alkali stress

Salt stress and alkali stress are major factors that affect the growth and production of Chinese cabbage. To explore their tolerant mechanism to salt and alkali stress, three salinity levels (0, 50, 100 mmol/L NaCl) and three different pH levels (pH6.5, pH7.5, pH8.5) were interactively applied on Qinghua (salt-tolerant-alkali-sensitive) and Biyu (salt-sensitive-alkali-tolerant) cultivars; the root morphology, ion content and antioxidant enzymes were determined. The results showed that the root morphology and root water content of Qinghua under S₀pH_7.5 and S₀pH_8.5 were seriously affected, and the content of H₂O₂ and MDA increased by 143%, 190% and 234%, 294%, respectively, compared with S₀pH_6.5; when Biyu was under S₅₀pH_6.5 and S₁₀₀pH_6.5 stress, the content of H₂O₂ and MDA increase to 152%, 208% and to 240%, 263%, respectively, but the activities and genes expression of SOD, POD, CAT, AAO, APX, DHAR and MDHAR did not change. The root and the contents of H₂O₂ and MDA were not affected when Qinghua was treated with salt and Biyu was treated with alkali, but the activities of the antioxidant enzymes increased to 150-200%, and their relative expression was overexpressed and 2.5-3.5-fold of the S₀pH6.5. The increase of Na⁺ in Qinghua was limited under salt stress, Mg²⁺ in Biyu increased significantly under alkali stress. These all indicated that the adaptability of roots could reflect the degree of tolerance; Chinese cabbage with high salt and alkali tolerance enhanced the regulation of their absorption of ions and increased the relative expression and activities of related antioxidant enzymes.