Foliar exposure of zinc oxide nanoparticles improved the growth of wheat (Triticum aestivum L.) and decreased cadmium concentration in grains under simultaneous Cd and water deficient stress.

A pot study was conducted to explore the effectiveness of zinc oxide nanoparticles (ZnO NPs) foliar exposure on growth and development of wheat, zinc (Zn) and cadmium (Cd) uptake in Cd-contaminated soil under various moisture conditions. Four different levels (0, 25, 50, 100 mg/L) of these NPs were foliar-applied at different time periods during the growth of wheat. Two soil moisture regimes (70% and 35% of water holding capacity) were maintained from 6 weeks of germination till plant harvesting. The results revealed that the growth of wheat increased with ZnO NPs treatments. The best results were found in 100 mg/L ZnO NPs under normal moisture level. The lowest Cd and highest Zn concentrations were also examined when 100 mg/L NPs were applied without water deficit stress. In grain, Cd concentrations decreased by 26%, 81% and 87% in normal moisture while in water deficit conditions, the Cd concentrations decreased by 35%, 66% and 81% compared to control treatment when ZnO NPs were used at 25, 50 and 100 mg/L. The foliar exposure of ZnO NPs boosted up the leaf chlorophyll contents and also decreased the oxidative stress and enhanced the leaf superoxide dismutase and peroxidase activities than the control. It can be suggested that foliar use of ZnO NPs might be an efficient way for increasing wheat growth and yield with maximum Zn and minimum Cd contents under drought stress while decreasing the chances of NPs movement to other environmental compartment which may be possible in soil applied NPs.

Hydrogen sulfide alleviates chromium stress on cauliflower by restricting its uptake and enhancing antioxidative system.

The present study evaluated the physiological and biochemical mechanisms through which exogenous sodium hydrosulfide (H2 S donor) mitigates chromium (Cr) stress in cauliflower. The different levels of Cr included 0, 10, 100 and 200 µM. Results reported that Cr exposure reduced growth and biomass, chlorophyll (Chl) contents, gas exchange parameters and enzymatic antioxidants. Chromium stress enhanced the production of electrolyte leakage (EL), hydrogen peroxide (H2 O2 ) and malondialdehyde (MDA) contents and increased Cr content in the roots, stem, leaf and flowers. Exogenous H2 S improved the physiological and biochemical attributes of Cr-stressed cauliflower. Hydrogen sulfide decreased Cr content in different parts of Cr-stressed plants, whereas it increased the Chl contents and gas exchange attributes. H2 S reduced the EL, H2 O2 and MDA concentrations, enhancing the antioxidant enzymes activities in Cr-stressed roots and leaves compared to the Cr treatments alone. Collectively, our results provide an insight into the protective role of H2 S in Cr-stressed cauliflower and suggest H2 S as a potential candidate in reducing Cr toxicity in cauliflower and other crops.

Interactive effect of 24-epibrassinolide and silicon alleviates cadmium stress via the modulation of antioxidant defense and glyoxalase systems and macronutrient content in Pisum sativum L. seedlings.

BACKGROUND: This study assessed the effects of 24-epibrassinolide (EBL, 10-7M) and silicon (2 mM) on the alleviation of cadmium (Cd, 150 mg L-1) toxicity in Pisum sativum L. seedlings via the modulation of growth, antioxidant defense, glyoxalase system, and nutrient uptake. RESULTS: Shoot and root lengths declined by 46.43% and 52.78%, respectively, following Cd stress. Shoot and root dry weights also declined with Cd toxicity. Biochemical and physiological aspects exhibit significant decline including total chlorophyll (33.09%), carotenoid (51.51%), photosynthetic efficiency (32.60%), photochemical quenching (19.04%), leaf relative water content (40.18%), and gas exchange parameters (80.65%). However, EBL or Si supplementation alone or in combination modulates the previously mentioned parameters. Cadmium stress increased proline and glycine betaine (GB) contents by 4.37 and 2.41-fold, respectively. Exposure of plants to Cd stress increased the accumulation of H2O2, malondialdehyde content, electrolyte leakage, and methylglyoxal, which declined significantly with EBL and Si supplementation, both individually and in combination. Similarly, Cd stress adversely affected enzymatic and non-enzymatic antioxidants, but EBL and/or Si supplementation maintained antioxidant levels. Glyoxalase I (GlyI) accumulated after Cd stress and increased further with the application of EBL and Si. However, GlyII content declined after Cd stress but increased with supplementation of EBL and Si. Cadmium accumulation occurred in the following order: roots > shoots>leaves. Supplementation with EBL and Si, individually and in combination reduced Cd accumulation and enhanced the uptake of macronutrients and micronutrients in shoots and roots, which declined with Cd toxicity. CONCLUSION: The application of 24-EBL and Si, individually and in combination, alleviated the adverse effects of Cd by improving growth, biochemical parameters, nutrient uptake, osmolyte accumulation, and the anti-oxidative defense and glyoxalase systems in Pisum sativum seedlings.

Analysis of ibuprofen and its main metabolites in roots, shoots, and seeds of cowpea (Vigna unguiculata L. Walp) using liquid chromatography-quadrupole time-of-flight mass spectrometry: uptake, metabolism, and translocation.

A liquid chromatography quadruple time-of-flight mass spectrometry (LC-QqTOF-MS/MS) method was developed for simultaneous quantitative analysis of ibuprofen (IBU), 1- and 2-hydroxyibuprofen (1-OH IBU and 2-OH IBU), and carboxyibuprofen (CBX IBU) while preserving the ability of the instrument to get precursor and product ion mass spectra of non-target compounds. The trigger was the precursor ions reaching 100 cps intensity. Sample preparation was carried out by ultrasound solid-liquid extraction with methanol as extraction solvent at pH < 2 followed by solid-phase extraction (SPE) clean-up using STRATA-X cartridges and methanol as an eluent. Linearity was obtained in the range 50-10,000 ng mL-1 for IBU, each OH IBU and CBX IBU (r ≥ 0.99). The proposed method was satisfactorily validated showing absolute recoveries of > 70% for all target analytes at low and high concentration levels. The lowest limit of quantification was < 50 ng g-1 in plant. This method was applied to investigate IBP behavior in cowpea (Vigna unguiculata (L.) Walp) treated at high IBU concentrations and its presence in vegetables irrigated with treated water. Up to 46 metabolites, mostly hydroxylated metabolites and conjugates with hexosides and amino acids, were identified. The most abundant metabolites were also identified in an eggplant sample. Graphical Abstract ᅟ Ibuprofen metabolite identification.

Melatonin Alleviates High Temperature-Induced Pollen Abortion in Solanum lycopersicum.

Melatonin is a pleiotropic signal molecule that plays critical roles in regulating plant growth and development, as well as providing physiological protections against various environmental stresses. Nonetheless, the mechanisms for melatonin-mediated pollen thermotolerance remain largely unknown. In this study, we report that irrigation treatment with melatonin (20 µM) effectively ameliorated high temperature-induced inactivation of pollen and inhibition of pollen germination in tomato (Solanum lycopersicum) plants. Melatonin alleviated reactive oxygen species production in tomato anthers under high temperature by the up-regulation of the transcription and activities of several antioxidant enzymes. Transmission electron micrograph results showed that high temperature-induced pollen abortion is associated with a premature degeneration of the tapetum cells and the formation of defective pollen grains with degenerated nuclei at the early uninuclear microspore stage, whilst melatonin protected degradation of organelles by enhancing the expression of heat shock protein genes to refold unfolded proteins and the expression of autophagy-related genes and formation of autophagosomes to degrade denatured proteins. These findings suggest a novel function of melatonin to protect pollen activity under high temperature and support the potential effects of melatonin on reproductive development of plants.

Deciphering genetic diversity analysis of saffron (Crocus sativus L.) using RAPD and ISSR markers.

The existence of genetic diversity in Crocus sativus has globally remained a mystery till date. The study investigated PCR based DNA amplification profile of saffron using ISSR and RAPD based primers. A total of 38 amplicons were generated by ISSR primers in the range from 7 to 12 with an average of 9.50 bands per primer. 20 bands were found to be polymorphic and 18 were monomorphic with an average percentage of polymorphism as 52.48%. RAPD based amplification revealed a total 161 amplicons, 107 as polymorphic and 54 as monomorphic with an average percentage of polymorphism as 66.44%. Cumulative results of RAPD and ISSR demonstrated that Nei-Li's similarity index ranged between 0.70 and 0.97. The results of AMOVA has revealed 9% of variance among populations and 91% of variance within populations, Φ PT was found as 0.089, which indicates existence of genetic differences though limited. In conclusion, the results indicate that saffron accessions are minimally genetically differentiated, which could be capitalized in future breeding programmes to ameliorate this precious crop.

Jasmonic acid (JA) and gibberellic acid (GA3) mitigated Cd-toxicity in chickpea plants through restricted cd uptake and oxidative stress management.

Cadmium stress is one of the chief environmental cues that can substantially reduce plant growth. In the present research, we studied the effect of jasmonic acid (JA) and gibberellic acid (GA3) applied individually and/or in combination to chickpea (Cicer arietinum) plants exposed to 150 µM cadmium sulphate. Cadmium stress resulted in reduced plant growth and pigment contents. Moreover, chickpea plants under cadmium contamination displayed higher levels of electrolytic leakage, H2O2, and malonaldehyde, as well as lower relative water content. Plants primed with JA (1 nM) and those foliar-fed with GA3 (10-6 M) showed improved metal tolerance by reducing the accumulation of reactive oxygen species, malonaldehyde and electrolytic leakage, and increasing relative water content. . Osmoprotectants like proline and glycinebetaine increased under cadmium contamination. Additionally, the enzymatic activities and non-enzymatic antioxidant levels increased markedly under Cd stress, but application of JA as well as of GA3 further improved these attributes. Enzymes pertaining to the ascorbate glutathione and glyoxylase systems increased significantly when the chickpea plants were exposed to Cd. However, JA and GA3 applied singly or in combination showed improved enzymatic activities as well as nutrient uptake, whereas they reduced the metal accumulation in chickpea plants. Taken together, our findings demonstrated that JA and GA3 are suitable agents for regulating Cd stress resistance in chickpea plants.

Nitric oxide donor, sodium nitroprusside, mitigates mercury toxicity in different cultivars of soybean.

The present study reveals the effect of mercury (Hg) and sodium nitroprusside (SNP) on plant growth and metabolism in soybean cultivars (Pusa-24, Pusa-37and Pusa-40). Mercury stress decreased growth and biomass yield, and gas exchange attributes in all soybean cultivars. External supplementation of SNP mitigated Hg toxicity by improving growth and gas exchange parameters. Electrolyte leakage (EL) increased accompanied with elevated levels of malondialdehyde (MDA) and H2O2 under Hg stress, however, they were found to be reduced in all cultivars upon the exogenous application of SNP. The activities of anti-oxidative enzymes, superoxide dismutase and catalase (SOD and CAT) and those enzymes involved in the ascorbate-glutathione pathway were impaired by Hg stress, but they were regulated by the application of SNP. Accumulation of Hg and NO in the shoots and roots were also regulated by the application of NO. Although, all three cultivars were affected by Hg stress, Pusa-37 was relatively less affected. Mercury stress affected the growth and development of different soybean cultivars, but Pusa-37 being tolerant was less affected. Pusa-37 was found to be more responsive to SNP than Pusa-24, Pusa-40 under Hg toxicity. The external supplementation of SNP could be a sustainable approach to economically utilize Hg affected soils.

The impact of different weed management strategies on weed flora of wheat-based cropping systems.

The world population will rise in future, which would demand more wheat production to fulfil dietary needs of wheat-dependent population of the world. Food security in wheat-dependent regions will greatly rely on wheat productivity. Weed infestation is a major constraint reducing wheat productivity globally. Nonetheless, cropping systems and weed management strategies strongly influence weed infestation in modern agriculture. Herbicides are the key weed management tool in conventional agriculture. However, frequent use of herbicides have resulted in the evolution of herbicide-resistance weeds, which made weed management a challenging task. Sustainable and eco-friendly weed management strategies shift weed-crop competition in the favour of crop plants. Limited studies have evaluated the interactive effect of cropping systems and weed management strategies on weed flora of wheat-based cropping systems (WBCSs). This two-year study evaluated the impact of different weed management strategies (WMSs) on weed flora of WBCSs, i.e., fallow-wheat (FW), rice-wheat (RW), cotton-wheat (CW), mungbean-wheat (MW) and sorghum-wheat (SW). The WMSs included in the study were, false seedbed, allelopathic water extracts and herbicide application, while weed-free and weedy-check were maintained as control treatments. Data relating to diversity and density of individual and total broadleaved and narrow-leaved weeds were recorded. The WBCSs, WMSs and their interaction significantly altered diversity and density of individual, total, broadleaved and narrow-leaved weeds. Weed-free and weedy-check treatments recorded the lowest and the highest values of diversity and density of individual, total, broadleaved and narrow-leaved weeds. Herbicide application effectively reduced density and diversity of weeds. Allelopathic water extracts and false seedbed proved less effective than herbicides. On the other hand, SW cropping system not only reduced weed density but also limited the weed flora. It is concluded that false seedbed and SW cropping system can be efficiently used to manage weeds in WBCSs. However, long-term studies are needed to infer the impact of SW cropping system and false seedbed on soil properties, soil microbes and productivity of wheat crop.

Synthesis and Characterization of Na-Zeolites from Textile Waste Ash and Its Application for Removal of Lead (Pb) from Wastewater.

Massive production of carcinogenic fly ash waste poses severe threats to water bodies due to its disposal into drains and landfills. Fly ash can be a source of raw materials for the synthesis of adsorbents. Rag fly ash as a new class of raw materials could be a cheap source of Al and Si for the synthesis of Na-zeolites. In this work, NaOH activation, via a prefusion- and postfusion-based hydrothermal strategy, was practiced for the modification of rag fly ash into Na-zeolite. Morphology, surface porosity, chemical composition, functionality, mineral phases, and crystallinity, in conjunction with ion exchangeability of the tailored materials, were evaluated by SEM, ICP-OES, XRF, FTIR, XRD, and cation exchange capacity (CEC) techniques. Rag fly ash and the synthesized Na-zeolites were applied for the removal of Pb (II) from synthetic wastewater by varying the reaction conditions, such as initial metal ion concentration, mass of adsorbent, sorption time, and pH of the reaction medium. It was observed that Na-zeolite materials (1 g/100 mL) effectively removed up to 90-98% of Pb (II) ions from 100 mg/L synthetic solution within 30 min at pH ≈ 8. Freundlich adsorption isotherm favors the multilayer heterogeneous adsorption mechanism for the removal of Pb (II). It is reasonable to conclude that recycling of textile rag fly ash waste into value-added Na-zeolites for the treatment of industrial wastewater could be an emergent move toward achieving sustainable and green remediation.

Effect of potassium fertilizer on the growth, physiological parameters, and water status of Brassica juncea cultivars under different irrigation regimes.

Abiotic stress, especially a lack of water, can significantly reduce crop yields. In this study, we evaluated the physiological and biochemical effects of potassium sulfate (K2SO4) fertilizer and varied irrigation regimes on the economically significant oilseed crop, Brassica juncea L, under open field conditions. Two cultivars (RH-725 and RH-749) of B. juncea were used in a randomized complete block design experiment with three replicates. Irrigation regimes consisted of a control (double irrigation: once at the 50% flowering and another at 50% fruiting stages), early irrigation (at 50% flowering only), late irrigation (at 50% fruiting only) and stress (no irrigation). The K2SO4 applications were: control (K0, no fertilization); K1, 10 kg ha-1; and K2, 20 kg ha-1. We measured growth via fresh and dry plant weight, plant height, root length, and leaf area. All the growth parameters were higher in RH-749. The physiological attributes, including the membrane stability index and relative water content, were higher at the 50% flowering stage in RH-749. The amount of antioxidant enzymes (catalase (CAT), guaiacol peroxidase (POX), ascorbate peroxidase (APX), and superoxide dismutase (SOD)) was enhanced when both plants were fertilized during water stress. All of these enzymes had higher activity in RH-749. The total chlorophyll content and photosynthesis rate were considerably higher in RH-749, which leaked fewer electrolytes and maintained a less destructive osmotic potential under limited water conditions. The results indicated that it is water-stress tolerant when given a high concentration of K2SO4, which alleviated the adverse effects of water stress on growth and physiology.

Zinc oxide nanoparticles (ZnO-NPs) induce salt tolerance by improving the antioxidant system and photosynthetic machinery in tomato.

Zinc oxide nanoparticles (ZnO-NPs) has been demonstrated to positively regulate plant tolerance to multiple environmental stresses. However, till date little information has been gained regarding the role of ZnO-NPs in the salt stress regulation in plants. Hence, the objective of our study was to investigate the role of ZnO-NPs in the regulation of salt tolerance in tomato (Lycopersicon esculentum Mill.). In this regard, the tomato plants were subjected to salt stress by using NaCl (150 mM) at the time of transplantation [15 days after sowing (DAS)]. Foliar application of ZnO-NPs at different levels viz., 10, 50 and 100 mg/L in the presence/absence of NaCl (150 mM) was carried out at 25 DAS and sampling was done at 35 DAS. Results of our study revealed that foliar spray of ZnO-NPs significantly increased shoot length (SL) and root length (RL), biomass, leaf area, chlorophyll content and photosynthetic attributes of tomato plants in the presence/absence of salt stress. Besides, the application of ZnO-NPs mitigates the negative impacts of salt stress on tomato growth, and enhanced protein content and antioxidative enzyme activity such as peroxidase (POX), superoxide dismutase (SOD) and catalase (CAT) under salt stress. In conclusion, the ZnO-NPs plays an important role in the alleviation of NaCl toxicity in tomato plants. Hence, the ZnO-NPs can be used to boost the growth performance and mitigate the adverse effects caused by NaCl in tomato.

Biochar as a tool for effective management of drought and heavy metal toxicity.

Drought and heavy metal stress undesirably disturb soil fertility and plant growth. Heavy metals pose severe biological toxic effects. Biochar, a carbon rich source application ameliorates this stress by increasing the plant growth, biomass, nutrient uptake and improves gaseous exchange in drought stress. Application of biochar reduces drought stress by increasing water holding capacity of soil through modification of soil physio-chemical properties that in turn increases water availability to plants and also enhances mineral uptake and regulation of stomatal conductance. Biochar mediates the retention of moisture, nutrients, inhibits harmful bacteria, absorbs heavy metals, pesticides, prevents soil erosion, increases soil pH, improves cationic exchange and boosts soil fertility. Drought and heavy metal stress often lead to production of reactive oxygen species. However, biochar significantly modifies the Reactive Oxygen Species (ROS) scavenging enzymes and provides an efficient electron transferring mechanism to tackle the toxic effects of ROS in plants. Biochar is regarded as a tool for the effective management of agricultural productivity and various environmental issues. This review provides insights on the potential role of biochar in ameliorating drought and heavy metal stress.

Influence of ecological and edaphic factors on biodiversity of soil nematodes.

Nematodes are the most diverse and highly significant group of soil-inhabiting microorganisms that play a vital role in organic material decomposition and nutrient recycling. Diverse geographical locations and environmental gradients show a significant impact on the diversity of nematodes. Present study aims to assess the effects of ecological (altitude, temperature, moisture) and edaphic (soil pH, nutrients, soil patches) factors on the soil nematode diversity and structure at five different landscape patches (forests, apple orchards, rice fields, pastures, and alpine zone) from ten different sites of Kashmir valley (India). Differences in the altitudinal gradients results in the shift of generic nematode population. Among the soil patches, highest nematode diversity was observed in forest soil and least in alpine soil; however, bacteriovorous nematodes dominated all the soil patches. The temperature and moisture have a significant effect on nematode diversity, the highest nematode trophic levels were observed above 21°C temperature, and 30% moisture. Nematode abundance decreased from alkaline to acidic pH of the soil. Soil nutrients such as, nitrogen (N) and phosphorus (P) have shown a detrimental effect in nematode richness at each site, where nematode diversity and richness of genera were higher at abundant soil N and P but decreased at low soil nutrients. Ecological indices like diversity index (DI), Shannon-Wiener Index (H'), enrichment index (EI), and maturity Index (MI) values demonstrated forest soil more favourable for nematodes and high soil health status than other soil patches. This study suggested that these indices may be helpful as soil monitoring tools and assessing ecosystem sustainability and biodiversity.

Effect of green and chemically synthesized titanium dioxide nanoparticles on cadmium accumulation in wheat grains and potential dietary health risk: A field investigation.

A field study was designed to explore the impacts of foliar-applied chemically and green synthesized titanium dioxide nanoparticles (TiO2 NPs) on cadmium (Cd) uptake in wheat plants. The wheat was grown in field which was contaminated with Cd and plants were subjected to foliar episodes of TiO2 NPs during plant growth period. Leaf extracts of two plant species (Trianthema portulacastrum, Chenopodium quinoa) were used for green synthesis while sol-gel method was used for chemical preparation of TiO2 NPs. Results showed that TiO2 NPs significantly enhanced the plant height, length of spikes photosynthesis, and straw and grain yield compared to control. TiO2 NPs minimized the oxidative burst in leaves and improved the enzyme activities than control. Cadmium concentrations of straw, roots and grains decreased after TiO2 NPs treatments than control. The grain Cd contents were below recommended threshold (0.2 mg Cd /kg grain DW) for cereals upon NPs exposure. The health risk index by the dietary use of grains for adults was below threshold upon NPs exposure. Overall, foliar use of TiO2 NPs prepared from plant extracts was appropriate in minimizing Cd contents in wheat grains, thereby reducing risk of Cd to human health via food chain.

Impact of bovine serum albumin - A protein corona on toxicity of ZnO NPs in environmental model systems of plant, bacteria, algae and crustaceans.

Zinc oxide nanoparticles (ZnO NPs) are widely applied in industrial, household and medical areas that lead to its discharge and accumulation in ecosystem. Here, the toxic effect of ZnO NPs in presence and absence of bovine serum albumin (BSA) was analyzed. The difference in toxicity of bare ZnO and BSA interacted ZnO was studied with different environmental models. P. aeruginosa and S. aureus were used as model bacterial systems. Toxicity against bacteria was determined by employing plate count method. C. pyrenoidsa was used as algal system for evaluating toxicity and it was determined by chlorophyll estimation assay. Daphnia sp. was chosen as crustacean system model. A. cepa root cells were chosen as plant model. ZnO NPs increased the ROS formation, lipid peroxidation and oxidative stress and it reduced in the presence of BSA. The cytotoxicity, chromosomal aberrations and micronuclei (MN) index of A. cepa were increased after ZnO NPs treatment. Same time the toxic effect was decreased in case of BSA coated ZnO NPs. The NPs toxic potential on the organisms decreased in the order of P. aeruginosa (LC50-0.092 mg/L) > S. aureus (LC50-0.33 mg/L) > Daphnia sp (LC50-0.35 mg/L) > C. pyrenoidosa (LC50-8.17 mg/L). LC50 in presence of BSA was determined to be 18.45, 26.24, 17.27 and 53.97 mg/L for P. aeruginosa, S. aureus, Daphnia sp and C. pyrenoidosa respectively. Therefore, the report suggests that BSA stabilized ZnO NPs could be more amenable towards applications in biotechnology and bioengineering.

Ecotoxicological Effects of Ibuprofen on Plant Growth of Vigna unguiculata L.

Despite the prevalence of the common pharmaceutical ibuprofen (IBU) in water and sediments worldwide, the effects of IBU on plants are largely unknown. This study was designed to assess the ecotoxicological effects of emerging pharmaceutical pollutant IBU on plant growth and development in a series of toxicity experiments using cowpea (Vigna unguiculata). Plant growth parameters (morphological and physicochemical) were investigated under a series of IBU concentrations (0, 400, 800, 1200, 1600, 2000 ppm IBU). IBU exposure reduced the shoot and root lengths, fresh and dry weights, leaf area, and chlorophyll a and b, carotenoid, total chlorophyll, mineral (K and Mg), glutathione reductase, and soluble protein contents. Simultaneously, increases in Ca and Mn contents, sodium translocation from roots to shoots, H2O2, malondialdehyde, superoxide dismutase, catalase, ascorbate peroxidase, and IBU uptake were observed. The amount of bioaccumulated IBU varied between 7% and 8%. IBU was translocated from roots to shoots with a translocation factor of 3-16%. The IC50 values for biomass and plant length were 1253 and 1955 ppm IBU, respectively, which is much higher than the reported levels of IBU in the environment. This study demonstrates that cowpea plants develop several morphological and physicochemical adaptations to cope under ibuprofen stress; environmentally relevant concentrations of IBU are unlikely to produce negative impacts.

Zinc Oxide Nanoparticles Application Alleviates Arsenic (As) Toxicity in Soybean Plants by Restricting the Uptake of as and Modulating Key Biochemical Attributes, Antioxidant Enzymes, Ascorbate-Glutathione Cycle and Glyoxalase System.

Accumulation of arsenic (As) in soils is increasing consistently day-by-day, which has resulted in increased toxicity of this element in various crop plants. Arsenic interferes with several plant metabolic processes at molecular, biochemical and physiological levels, which result in reduced plant productivity. Hence, the introduction of novel ameliorating agents to combat this situation is the need of the hour. The present study was designed to examine the effect of zinc oxide nanoparticles (ZnO-NPs) in As-stressed soybean plants. Various plant growth factors and enzymes were studied at varying concentrations of As and ZnO-NPs. Our results showed that with the application of ZnO-NPs, As concentration declined in both root and shoot of soybean plants. The lengths of shoot and root, net photosynthetic rate, transpiration, stomatal conductance, photochemical yield and other factors declined with an increase in external As level. However, the application of ZnO-NPs to the As-stressed soybean plants resulted in a considerable increase in these factors. Moreover, the enzymes involved in the ascorbate-glutathione cycle including superoxide dismutase (SOD), catalase (CAT), ascorbate peroxidase (APX) and glutathione reductase (GR) showed a significant increase in their activity with the application of ZnO-NPs to the As-stressed plants. Hence, our study confirms the significance of ZnO-NPs in alleviating the toxicity of As in soybean plants.

Exogenously Applied Ascorbic Acid-Mediated Changes in Osmoprotection and Oxidative Defense System Enhanced Water Stress Tolerance in Different Cultivars of Safflower (Carthamus tinctorious L.).

The present study was conducted to examine the effect of exogenously applied ascorbic acid (AsA) on osmoprotectants and the oxidative defense system in four cultivars (16171, 16183, 16207 and 16246) of safflower under well-watered and water deficit conditions. Water stress (60% field capacity) significantly decreased the shoot and root fresh and dry weights, shoot and root lengths and chlorophyll contents in all four safflower cultivars, while it increased the leaf free proline, total phenolics, total soluble proteins, hydrogen peroxide content and activities of catalase, superoxide dismutase and peroxidase enzymes. Foliar-applied (100 mg L-1 and 150 mg L-1) ascorbic acid caused a marked improvement in shoot and root fresh and dry weights, plant height, chlorophyll and AsA contents as well as the activity of peroxidase (POD) enzyme particularly under water deficit conditions. It also increased the accumulation of leaf proline, total phenolics, total soluble proteins and glycine betaine (GB) content in all four cultivars. Exogenously applied AsA lowered the contents of MDA and H2O2, and the activities of CAT and SOD enzymes. Overall, exogenously applied AsA had a positive effect on the growth of safflower plants under water deficit conditions which could be related to AsA-induced enhanced osmoprotection and regulation of antioxidant defense system.

Foliar Spray of Fe-Asp Confers Better Drought Tolerance in Sunflower as Compared with FeSO4: Yield Traits, Osmotic Adjustment, and Antioxidative Defense Mechanisms.

Different techniques are being employed to reduce the adverse effects of water stress on seed yield and quality of crop plants. The current study aimed to improve the water stress tolerance of field-grown sunflower by foliar-supplied ecofriendly iron-chelated aspartate (Fe-Asp) in comparison with FeSO4. Water stress decreased the plant growth and yield, accompanied with disturbed water relations, nutrient acquisition, accumulation of amino acids, and antioxidative defense mechanisms. However, lipid peroxidation, total anthocyanin, and photosynthetic pigments were increased. Fertigation of FeSO4 and Fe-Asp as foliar sprays proved effective to reduce the negativities of limited irrigation on biomass production and seed yield, accompanied with a reduction in lipid peroxidation and improvements in water relations, antioxidative defense mechanisms, and leaf photosynthetic pigments. In comparison with FeSO4, foliary applied Fe-Asp better improved the plant water relations with more accumulation of essential amino acids and nutrient acquisition, especially leaf aspartate (Asp) and Fe accumulation which showed better translocation. Overall, foliary applied Fe-Asp proved better for induction of drought tolerance in sunflower plants as compared with FeSO4. The study recommended the use of the ecofriendly Fe-Asp as a foliar spray for better growth and production of sunflower under limited irrigation.