Processing Effects on Selected Antioxidant Activities and Metabolizing Enzyme Inhibition of M. Koneigii (Curry Leaves) Extracts

Curry leaves, scientifically termed Murraya koenigii, are renowned in South Asian cuisine for their flavor enhancement and potential health benefits, including antioxidative, anti-inflammatory, and antidiabetic properties. This study aimed to evaluate the impact of thermal processing methods on curry leaves by analysing Total Phenolic Content (TPC), Total Flavonoid Content (TFC), antioxidant activity, and metabolizing enzyme inhibition. Fresh curry leaves were subjected to thermal treatments: Oven-dried at 60˚C and Air-dried at 25˚C for 2 weeks. Extracts were prepared using Ethanol and water solvents. Results indicated that Air-dried leaves exhibited significantly higher TPC (5132.65 mg GAE/100 g) and TFC (243.13 mg CE/100 g) compared to Fresh and Oven-dried leaves. Antioxidant assays show that oven-dried curry leaves at 60˚C displayed higher results in NORS, FRAP, and TEAC assays compared to Fresh and Air-dried leaves. Ethanol extracts showed better extraction of bioactive compounds than aqueous extracts. Moreover, Lipase inhibition activity was notably high, indicating potential health benefits. This study provides valuable insights into the effects of processing methods on curry leaf extracts, emphasizing the importance of solvent selection for optimal extraction of bioactive compounds.

Study on Antioxidant Enzyme Activity and Physiology and Biochemistry of Solanum nigrum L. under Glyphosate Stress

[Objectives] This study was conducted to investigate the scientific prevention and control of Solanum nigrum L. [Methods] Through experiments on S. nigrum from different sources, it was found that glyphosate stress had significant effects on antioxidant enzyme activity and oxidative damage of sensitive S. nigrum plants. [Results] Sensitive S. nigrum showed oxidative damage under glyphosate stress, while resistant S. nigrum responded to adversity damage by improving its antioxidant enzyme activity. The experimental results showed that the antioxidant enzymes and reduced glutathione of S. nigrum had certain metabolic detoxification effects under glyphosate stress. [Conclusions] This study provides a theoretical basis for scientific prevention and control of S. nigrum , and has a certain reference value for revealing the glyphosate resistance mechanism of S. nigrum .

Sodium nitroprusside as a signal molecule for up-regulating membrane characteristics,antioxidant defense system to improve flax productivity under water stress

Water stress is a critical environmental adversity that significantly impacts the growth,development,and yield of flax plants.In this study,flax seeds were cultivated under different water irrigation requirements(WIR)(100%,75%,and 50%)to investigate the effects of exogenously supplied nitric oxide(NO)donor sodium nitroprusside(SNP)as foliar treatments at concentrations of 0.0 mmol/L,0.5 mmol/L,1.0 mmol/L,and 2.0 mmol/L.Drought stress led to a significant decrease in plant growth,photosynthetic pigments,yield components such as oil and total carbohydrate percentage.It also resulted in an increase in leaf H2O2 production,lipid peroxidation levels and activities of enzymatic antioxidants including polyphenol oxidase,superoxide dismutase,and nitrate reductase enzymes.However,foliar application of SNP improved photosynthetic pigments and antioxidant defense system which mitigated the negative impact of water stress on growth and yield productivity by reducing oxidative damage caused by reactive oxygen species accumulation.The use of SNP also decreased H_(2)O_(2) accumulation levels,lipid peroxidation levels,and improved membrane stability.SNP treatment at concentration of 2 mmol/L showed superior results compared to other concentrations with extremely significant increases observed in yield characteristics such as oil content,total carbohydrate percentages,and unsaturated fatty acids to saturated fatty acids ratio.

Effect of powdery mildew on interleaf microbial communities and leaf antioxidant enzyme systems

Chinese peony(Paeonia lactiflora Pall.)is both medicinally and aesthetically beneficial.Powdery mildew is a common fungal disease that seriously jeopardizes the value of numerous species,including peonies as a crop.In order to provide a basis for the prevention and treatment of peony powdery mildew,we examined the microbial diversity,the malondialdehyde(MDA)concentrations and antioxidant enzyme activities of peony leaves infected with three levels of powdery mildew to determine any modifications to the leaf's antioxidant enzyme systems and microbial community structure following the onset of disease.The results show that the MDA content rose as the degree of infection became worse.Antioxidant enzyme activity rose and then declined.Following the initiation of powdery mildew,fungal community diversity decreased,whereas there was not any appreciable change in bacterial communities according to microbial diversity sequencing.The relative abundance of more than half of fungal species decreased,with the bacterial genera displaying both abundant and diminished communities with less pronounced alterations in their community structure after the disease spread.Significant different taxa that were critical to the organization of each microbiome were found.Correlation analysis showed that the relative abundance of powdery mildew pathogenic fungal genus Erysiphe was correlated with those of 11 fungal genera and one bacterial genus.Among them,Aureobasidium,Neosetophoma and Sclerostagonospora showed significant positive correlations with Erysiphe and MDA.

Osmotic Regulation,Antioxidant Enzyme Activities and Photosynthetic Characteristics of Tree Peony(Paeonia suffruticosa Andr.)in Response to High-Temperature Stress

Tree peony(Paeonia suffruticosa Andr.)is a traditional Chinese flower,which prefers cool weather.However,high temperature in summer in the middle and lower reaches of the Yangtze River restricts its growth and development.In this study,osmotic regulation,antioxidant enzyme activities,and photosynthetic characteristics of tree peony in response to high-temperature stress were investigated.The results showed that high-temperature stress had destroyed the cell membrane,manifested as the increased relative electrical conductivity and malondialdehyde content.Moreover,high-temperature stress led to excessive accumulation of reactive oxygen species,thereby,activating antioxidant enzyme activities.Also,photosynthetic parameters and chlorophyll fluorescence parameters directly reflected the damage to the photosystem II reflection center under high-temperature stress.In addition,high-temperature stress led to stomatal closure and chloroplast damage.This study revealed the physiological responses of tree peony to high-temperature stress,laying a foundation for the promotion of tree peony in high-temperature areas and the improvement of high-temperature resistance.

Effect of Sodium Chloride and Cadmium on the Growth, Oxidative Stress and Antioxidant Enzyme Activities of Zygosaccharomyces rouxii

Zygosaccharomyces rouxii is a salt-tolerant yeast species capable of removing cadmium(Cd) pollutant from aqueous solution. Presently, the physiological characteristics of Z. rouxii under the stress of sodium chloride(NaCl) and Cd are poorly understood. This study investigated the effects of NaCl and Cd on the growth, oxidative stress and antioxidant enzyme activities of Z. rouxii after stress treatment for 24 h. Results showed that NaCl or Cd alone negatively affected the growth of Z. rouxii, but the growth-inhibiting effect of Cd on Z. rouxii was reduced in the presence of NaCl. Flow cytometry assay showed that under Cd stress, NaCl significantly reduced the production of reactive oxygen species(ROS) and cell death of Z. rouxii compared with those in the absence of NaCl. The activities of superoxide dismutase(SOD), catalase(CAT), and peroxidase(POD) of Z. rouxii were significantly enhanced by 2%–6% NaCl, which likely contributed to the high salt tolerance of Z. rouxii. The POD activity was inhibited by 20 mg L-1Cd while the SOD and CAT activities were enhanced by 8 mg L-1 Cd and inhibited by 20 mg L-1 or 50 mg L-1 Cd. The inhibitory effect of high-level Cd on the antioxidant enzyme activities of Z. rouxii was counteracted by the combined use of NaCl, especially at 6%. This probably accounted for the decrease in Cd-induced ROS production and cell death of Z. rouxii after incubation with NaCl and Cd. Our work provided physiological clues as to the use of Z. rouxii as a biosorbent for Cd removal from seawater and liquid highly salty food.

Effects of mechanical damage and herbivore wounding on H2O2 metabolism and antioxidant enzyme activities in hybrid poplar leaves

The changes of hydrogen peroxide （H2O2） metabolism and antioxidant enzyme activities in a hybrid poplar （Populus simonii xp. pyramidalis ＇Opera 8277＇） in response to rnechanical damage （MD） and herbivore wounding （HW） were investigated to determine whether H2O2 could function as the secondary messenger in the signaling of systemic resistance. Results show that H2O2 was generated in wounded leaves through MD and HW treatments and systemically in unwounded leaves around the wounded leaves. The activities of antioxidant enzymes such as superoxide dismutase （SOD）, catalase （CAT） and ascorbate peroxidase （APX） were also enhanced. However, the H2O2 accumulation and antioxidant enzyme activities were inhibited in MD leaves through the pretreatment with DPI （which is a specific inhibitor of NADPH oxidase）. The results of this study suggest that H2O2 could be systemically induced by MD and HW treatments, and H2O2 metabolism was closely related to the change in SOD, APX and CAT activities. A high level of antioxidant enzymes could decrease membrane lipid peroxidation levels and effectively induce plant defense responses.

Distribution of Calcium in Bagged Apple Fruit and Relationship between Antioxidant Enzyme Activity and Bitter Pit

[Objective]The aim was to study the distribution of Ca in bagged apple fruit and the relationship between antioxidant enzyme activity and bitter pit disease,which will provide a basis for resolving Ca metabolism disorder in apple cultivation. [Method]With Fuji Apple as the tested material,the changes of Ca2＋ content and antioxidant enzyme activity in different parts of apple fruit after picking bags and storage period were determined. [Result]The results showed that Ca contents in the light surface of fruits were higher than that in the backlight surface. The Ca contents of stalk cavity were higher than that of calyx-end. The activities of SOD,POD,CAT and APX in the light surface of fruits were higher than that in the backlight surface. The activities of SOD,POD,CAT and APX of stalk cavity were higher than that of calyx-end. The contents of MDA in the light surface of fruits were lower than that in the backlight surface. The contents of MDA of stalk cavity were lower than that of calyx-end. [Conclusion]The incidence rate of bitter pit in the light surface of fruits were lower than that in the backlight surface,and the incidence rate of bitter pit of stalk cavity were lower than that of calyx-end.

Effect of Different Arbuscular Mycorrhizal Fungi Strains on Mineral Nutrition and Antioxidant Enzymes of Chrysanthemum morifolium

[Objective] The purpose was to study the effects of different arbuscular mycorrhizal fungi strains（AMF）on the mineral nutrition and antioxidant enzymes of Chrysanthemum morifolium.[Method] The pot experiment was conducted in the greenhouse,C.morifolium ＇Jinba＇ was inoculated with five kinds of AMF,N,P,K,malondial dehyde（MDA）content,as well as the superoxide dismutase（SOD）,peroxidase（POD） and catalase（CAT） activity in roots,leaves and petals of C.morifolium were measured at seedling and flowering stages.[Result] The G.i,G.e and G.m treatments could promote mineral nutrient absorption,increase N,P,K content in roots,leaves and petals of C.morifolium compared with the control without inoculation.The G.d、G.e and G.m treatments could significantly reduce MDA content in roots and petals,thus alleviating membrane permeability and lipid peroxidation.The G.i treatments could also improve the SOD,POD and CAT activities of C.morifolium,thereby increasing the capability of scavenging oxygen free radicals.[Conclusion] According to the comprehensive analysis,G.i was screened out as the best strain to improve mineral nutrition and antioxidant enzyme activities of C.morifolium.

Research on Oxidative Stress Induced by Tenuazonic Acid from Alternaria augustiovoide and Changes in Antioxidant Enzyme Activities in Leaves of Echinochloa crus-galli

[Objective] The aim of the study was to determine whether phytotoxicity of TeA against Echinochloa crus-galli leaves was correlated with oxidative stress caused by generation of reactive oxygen and the changes of antioxidant enzymes activity.[Method] The changes of malondialdehyde（MDA）content,hydrogen peroxide（H2O2）,and activities of superoxide dismutase（SOD）,glutathione reductase（GR）and catalase（CAT）were studied by leaf segment method in vitro.[Result] After the treatment of 500 μmol/L TeA,the content of MDA and H2O2 increased by 247.86% and 67.00%,respectively,indicating that the accumulation of MDA and H2O2 in E.crus-galli leaves was due to the reactive oxygen burst induced by TeA.TeA induced a significant increase in activities of SOD,GR and CAT.At 500 μmol/L TeA,activities of SOD,GR and CAT increased more than one fold compared with the control.[Conclusion] TeA could not only cause oxidative stress in leaves of E.crus-galli through the induction of reactive oxygen,but also induce the increasing of antioxidant enzyme activity.

Extraction of Pumpkin Polysaccharide by Complex Enzyme Method and Its Antioxidant Research

[Objective] This paper aims to study a new method of extracting pumpkin polysaccharide from pumpkin. Single factor experiments were conducted to examine the effects of extracting time,temperature,the solid-liquid ratio and pH value on the extraction yield of polysaccharide from pumpkin. [Method] The best enzyme ratio and extraction conditions for complex enzymes extraction were determined through orthogonal tests. Scavenging ·OH and O-2 activities of pumpkin polysaccharides were also investigated by salicylic acid and improved self-oxidation of o-pheno methods respectively. [Results] The results showed that the biggest extraction yield of polysaccharide from pumpkin can be got when adding 1% cellulose enzyme,1.5% pectinase,1.0% papain and Na2HPO4-citric acid buffer solution (pH was 4.6),and oscillating for 30 min under water at 40 ℃ with the solid-liquid ratio of 1:30. In addition,pumpkin polysaccharides had a strong activity of eliminating ·OH,but very weak activity to scavenge O-2. [Conclusion] This study provided basic data for research and application of Pumpkin polysaccharide.

Effects of Chitosan and Organosilicon on Antioxidant Enzyme Activity of Tomato Seedlings Diseased with Botrytis cinerea

[Objective] The aim was to explore effects of chitosan and organosilicon on tomato resistance against Botrytis cinerea. [Method] With leaf spraying method adopted, four groups were set in the test, including control group, groups treated with Botrytis cinerea, with chitosan and Botrytis cinerea, and with chitosan, organosilicon, and Botrytis cinerea, in order to study on effects of chitosan and organosilicon on antioxidant enzyme activities of tomato. [Result] Antioxidant enzyme activities of tomato seedlings were improved in groups with chitosan, organosilicon, and Botrytis cinerea and with chitosan and Botrytis cinerea compared with the group treated with Botrytis cinerea. On the 6th d, activities of PAL, SOD, POD, PPO and CAT in groups with chitosan and Botrytis cinerea, and with chitosan, organosilicon, and Botrytis cinerea increased by 27.36%, 52.07%, 43.55%, 82.02% and 71.82%, and 18.91%, 30.22%, 57.14%, 38.09% and 53.64%, respectively. [Conclusion] Antioxidant enzyme activities of tomato seedlings could be improved by chitosan and organosilicon.

Effects of Relative Soil Water Content on Antioxidant Enzyme System in Malus sieversii(Lebed.) Roem

By pot experiment under artificially simulated water stress conditions, soluble protein content, MDA content and SOD, POD, CAT and APX activities in Malus sieversfi leaves were determined to reveal the response mechanism of M. sieversii to changes of relative soil water content. According to the results, with the decrease of relative soil water content, MDA content in M. sieversii leaves increased by mem- brane lipid peroxidation. Cells resist water stress-induced membrane lipid peroxidation and clear the increased reactive oxygen species by improving soluble protein content and SOD, POD, CAT and APX activities. However, various enzymes were involved in the response to water stress under different moisture conditions. In addition, the results indicated that M. sieversii had a good adaptability to higher relative soil water contents.

Melatonin mitigates cold-induced damage to pepper seedlings by promoting redox homeostasis and regulating antioxidant profiling

This study assessed the influence of exogenous ME in the mitigation of cold damage in pepper seedlings. Melatonin(ME) is a dynamic molecule that helps plants cope with stress in several ways. Cold stress(CS) is one of the most important environmental factors that restrict plant growth and yield. Pepper(Capsicum annuum L.) is a valuable commercial crop, highly sensitive to CS. Thus, identifying an efficient strategy to mitigate cold damage is critical for long-term pepper production. For this purpose, the roots of pepper seedlings were pretreated with ME(5 μmol · L^(-1)) and exposed to CS for 7 d. The results indicated that CS suppressed pepper growth, hampered photosynthetic capacity, and damaged root architecture in pepper plants. In contrast, the production of reactive oxygen species(ROS), malondialdehyde(MDA), electrolyte leakage(EL), proline, and soluble sugars were enhanced in plants under CS. ME(5 μmol · L^(-1)) pretreatment reduced the negative effects of CS by recovering plant growth, root traits, gas exchange elements, and pigment molecules compared to CS control treatment. Furthermore, ME application efficiently reduced oxidative stress markers [hydrogen peroxide(H_(2)O_(2)), superoxide ion(O_(2)^(·-)), EL, and MDA] while increasing proline and soluble sugar content in pepper leaves. ME application combined with CS further increased antioxidant enzymes and related gene expression. Collectively, our results confirmed the mitigating potential of ME supplementation for CS by maintaining pepper seedling growth,improving the photosynthesis apparatus, regulating pigments, and osmolyte content.

Ellagic Acid Enhances Antioxidant System Activity and Maintains the Quality of Strawberry Fruit during Storage

Ellagic acid(EA)is a natural antioxidant,widely present in a lot of forms’soft fruits,nuts,and other plant tissues,and helpful for promoting human health;however,its protective effect on postharvest fruit and improving the quality index of postharvest fruit have rarely been studied.In this experiment,the strawberries were soaked in 0,100,200,300,400,and 500 mg L^(−1) EA,respectively,and the influential EA on fruit quality and the antioxidant system of strawberries were studied.Compared with the control,EA treatment can reduce the browning degree and rotting rate of strawberry fruit during storage and augment the soluble solid content(SSC).EA treatment can also increase the content of related stuff and enzyme activity in antioxidant systems;the gene expression level of polyphenol oxidase(PPO)in strawberries treated with EA was always down-regulated,correspondingly,the expression of other antioxidant enzyme genes was enhanced.Among the strawberry fruits treated with EA of different concentrations,300 mg L^(−1) EA had the best effect in the process of strawberry preservation.The results suggested that the proper concentration of exogenous EA at 300 mg L−1 could maintain strawberries’quality and enhance the antioxidant system by improving the activities of antioxidative enzymes and the ascorbateglutathione(AsA-GSH)cycle during storage.

Effects of Potassium-Solubilizing Bacteria on Growth, Antioxidant Activity and Expression of Related Genes in Fritillaria taipaiensis P. Y. Li

This study aimed to examine the effects of inoculating Fritillaria taipaiensis P.Y.Li leaves with different strains ofpotassium-solubilizing bacteria (KSB), or combinations thereof, focusing on aspects of photosynthesis and physiologicaland biochemical characteristics. At present, some studies have only studied the rhizosphere microbialcommunity characteristics of F. taipaiensis and have not discussed the effects of different microbial species on thegrowth promotion of F. taipaiensis. This paper will start from the perspective of potassium-solubilizing bacteria toconduct an in-depth study. Seed cultivation commenced at the base with three different KSBs in early October2022. The growth of F. taipaiensis leaves was observed after different treatments. Both single-plant and compoundinoculations were executed. A total of eight treatment groups were established, with aseptic fertilizer and sterilizedsoil functioning as the control group. The results reveal that intercellular CO_(2) concentration (Ci), stomatal conductance(Gs), and transpiration rate (Tr) were at their apex in the S7 group. Most treatment groups exhibited anincrease in leaf area, photosynthetic pigment content, soluble sugar, soluble protein, Superoxide Dismutase(SOD), Peroxidase (POD), Catalase (CAT) activities, and proline content. The expression levels of POD, SOD,and CAT genes were evaluated, following inoculation with different KSB. The highest was the S7 group. Theinoculation with various KSB, or combinations thereof, appears to bolster the growth and development of F. taipaiensis.The composite inoculation group S7, comprising Bacillus cereus, Burkholderia cepacia, and Bacillus subtilis,manifested the most favorable impact on the diverse indices of F. taipaiensis, thereby furnishing valuableinsights for the selection of bacterial fertilizer in the artificial cultivation of F. taipaiensis.

Effects of Heavy-ion Beams Irradiation on Survival Rate and Antioxidant Enzymes of Sweet Sorghum Seedlings

[Objective] This study aimed to investigate the effects of heavy-ion beams irradiation on the seed germination potential, survival rate, antioxidant enzyme activi- ties and lipid peroxidation of sweet sorghum. [Method] The dry seeds were irradiated by ＇2（36. heavy ion beams with absorbed doses： 0, 40, 80, 120, 160 and 200 Gy, respectively. Then, the seed germination potential, survival rate, antioxidant enzyme activities and lipid peroxidation of sweet sorghum were measured. [Result] Heavy-ion beams irradiation exhibited different influence on germination potential and survival rates. Germination rate showed a downward trend, but the corresponding survival curve of seedlings was saddle-shaped. The activities of SOD, POD, CAT and ASA- POD changed in different trends as well. The MDA content rose toward increasing irradiation dose, suggesting that high dose of heavy-ion beams irradiation enhanced the damage to membrane of sweet sorghum seedlings. [Conclusion] After being irra- diated, germination potential and survival rates of sweet sorghum were decreased, and antioxidant enzymes activity changed greatly. This study laid the basis for fur- ther work on breeding and improvement of sweet sorghum irradiated by ,^（12）C^（6＋） heavy ion beams.

Effect of Botryosphaeria berengeriana f.sp.piricola and Biocontrol Bacteria on the System of Antioxidant Enzymes in Pears

[Objective] The aim was to understand defense mechanism of pear after inoculated Botryosphaeria berengeriana f. sp. piricolan and mechanism of antioxidant enzymes of biocontrol bacteria. [Method] Pears were treated by Botryosphaeria berengeriana f. sp. piricolan and bio control bacteria, and the change of antioxidant enzymes were determined. [Result] The biocontrol bacteria had little effect on MDA;the content of MDA treated by B. berengeriana reached high peak in 48 h, was 10.22nmol/g which was 1.86 times of CK; the content of MDA treated by B. berengeriana and biocontrol bacteria reached high peak in 24 h, was 8.92 nmol/g which was1.62 times of CK. The content of SOD treated by biocontrol bacteria reached high peak in 48 h, was 126.69 U/[g（FW）·min] which was 1.54 times of CK; the contents of SOD treated by B. berengeriana as well as B. berengeriana and biocontrol bacteria reached high peak in 24 h, were 122.10 and 135.32 U/[g（FW）·min] which were 1.48 and 1.65 times of CK respectively; the contents of POD on biocontrol bacteria treatment, B. ana treatment as well as B. berengeriana and biocontrol bacteria treatment reached high peak in 24 h, were 385.34, 342.50 and 290.00 U/[g（FW）·min] which were 1.83, 1.62 and 1.38 times of CK respectively. The contents of CAT on biocontrol bacteria treatment, B. rengeriana treatment as well as B. berengeriana and biocontrol bacteria treatment reached high peak in 6 h, were 133.33,114.17 and 113.35 U/[g（FW）·min] which were 1.33, 1.14 and 1.13 times of CK respectively. The biocontrol bacteria had little difference in CK; the content of PPO of B. berengeriana treatment reached high peak in 12 h, was 81.86 U/[g（FW）·min]which was 1.76 times of CK; B. berengeriana and biocontrol bacteria treatment reached high peak in 24 h, was 70.00 U/[g（FW）·min] which was 1.50 times of CK.[Conclusion] B. berengeriana and biocontrol bacteria had more effect on MDA; both B. berengeriana and biocontrol bacteria could increase the excitation of SOD enzyme activity; both B. berengeriana and biocontrol bacteria could increase the excitation of POD enzyme activity; both B. berengeriana and biocontrol bacteria could increase the excitation of CAT enzyme activity; using biocontrol bacteria alone had not obvious effect on PPO, B. berengeriana could increase the excitation of PPO enzyme activity.

Phytotoxicity of cadmium on protein, proline and antioxidant enzyme activities in growing Arachis hypogaea L. seedlings

Phytotoxicity of cadmium on growing Arachis hypogaea L. seedlings was studied. Seeds were exposed to 25, 50, and 100 μmol/L CdCl2 concentrations, for a period of 10, 15, 20 and 25 d. The extent of damage to chlorophyll, protein, proline, nitrate and nitrite reductase, antioxidant enzyme activity in leaves and roots were evaluated after 10 d of cadmium stress. The higher concentration of cadmium （100 μmol/L） resulted （leaves and roots） total chlorophyll 91.01%, protein 79.51%, 83.61%, nitrate reductase 79.39%, 80.72% and nitrite reductase 77.07%, 75.88% activity decreased with increase in cadmium concentrations and exposure periods. Cadmium caused significant changes in the activity of antioxidative enzymes. Contrastingly Cd treated plant tissues showed an increase in proline 159.87%, 239.6%, gluthion reductase （GR） 337.72%, 306.14%, superoxide disumutase （SOD） 688.56%, 381.72%, ascorbate peroxidase （APX） 226.47%, 252.14%, peroxidase （POD） 72.19%, 60.29% and catalase （CAT） 228.96%, 214.74% as compared to control. Cadmium stress caused a significant increase in the rate of SOD activity in leaves and roots of plant species. Results show the crop A. hypogaea is highly sensitive even at very low cadmium concentrations.

Physiological responses of Brassica napus to fulvic acid under water stress: Chlorophyll a fluorescence and antioxidant enzyme activity

The ameliorative effect of fulvic acid(0, 300, and 600 mg L-1) on photosystem II and antioxidant enzyme activity of the rapeseed(Brassica napus L.) plant under water stress(60, 100, and 140 mm evaporation from class A pan) was studied using split plots in a randomized complete block design with three replications. Results indicated that application of fulvic acid(FA) improved the maximum quantum efficiency of PSII(Fv/Fm)and performance index(PI) of plants under both well-watered and limited-water conditions. The time span from Foto Fmand the energy necessary for the closure of all reaction centers was significantly increased, but the size of the plastoquinone pool was reduced with increasing water stress levels. Plants treated with FA had higher peroxidase and catalase activities under all irrigation conditions. Activities of ascorbate peroxidase and superoxide dismutase in plants increased with increasing water stress. Malondialdehyde increased under severe water stress, but application of FA significantly decreased lipid peroxidation. Production of reactive oxygen species(ROS) is a common phenomenon in plants under stress. Under this condition, the balance between the production of ROS and the quenching activity of antioxidants is upset, often resulting in oxidative damage. In this study, application of FA significantly increased fluorescence of chlorophyll a, inhibiting ROS production and enhancing antioxidant enzymes activity that destroyed ROS. Thus, ROS in plant cells was reduced under water stress by application of FA and consequently lipid peroxidation was reduced.