Wheat Straw Burial Improves Physiological Traits, Yield and Grain Quality of Rice by Regulating Antioxidant System and Nitrogen Assimilation Enzymes under Alternate Wetting and Drying Irrigation

Wheat straw burial has great potential to sustain rice production under alternate wetting and drying(AWD)irrigation.A field experiment was conducted with three wheat straw burial treatments,including without straw burial(NSB),with light straw burial of 300 kg/hm^(2)(LSB)and dense straw burial of 800 kg/hm^(2)(DSB),as well as three AWD regimes:alternate wetting/moderate drying(AWMD),alternate wetting/severe drying(AWSD)and alternate wetting/critical drying(AWCD).The rice growth and grain quality were higher in LSB and NSB than those in NSB under the same AWD regime.The AWMD×DSB treatment resulted in the highest yield,brown rice rate,milled rice rate,amylose content and protein content.Conversely,the AWCD×NSB treatment led to the lowest yield,brown rice rate,milled rice rate,amylose content and protein content.The active absorption area and nitrate reductase activity of roots were higher in the AWMD×DSB treatment than those in the AWCD×NSB treatment,as the former increased organic carbon and nitrogen contents in the rhizosphere,whereas the latter reduced their availability.Total soluble protein content and glutamine synthetase activity were greater in the AWMD×DSB treatment than those in the AWCD×NSB treatment.The activities of superoxide dismutase and catalase were higher in the AWMD×DSB treatment compared with the AWCD×NSB treatment,leading to the amelioration of oxidative cell injury,as shown by a lower malonaldehyde level.This study suggested that farmers should implement AWMD irrigation after leaving the straw residues in the field,followed by deep tillage to improve soil quality and mitigate the drought stress cycles of AWD.This approach can improve rice growth and grain quality and alleviate the problems of disposal of straw residues and water scarcity for sustainable rice production.

Effects of Bioorganic Fertilizers on the Leaf Antioxidant Enzyme Activity and the Photosynthetic Characteristics of Replanted Szechuan Pepper, Zanthoxylum simulans

Continuous cropping obstacles hamper the efficient growth and yield of Szechuan pepper,Zanthoxylum simulans.The current study investigated the impact of different levels of bioorganic fertilizer on the leaf physiological and photosynthetic characteristics of Z.simulans to provide a theoretical reference for continuous Z.simulans crop cultivation.A bioorganic fertilizer was used to treat seedlings growing in 25-year-old continuous cropping soil.Five fertilizer treatments were applied.The impacts of the treatments on the activity of defense enzyme and photosynthetic parameters of Z.simulans leaves were determined.The different concentrations of bioorganic fertilizer reduced to varying degrees the malondialdehyde(MDA)content and intercellular CO2 concentration(Ci),and increased the activity of peroxidase(POD),superoxide dismutase(SOD),and ascorbate peroxidase(APX),as well as the chlorophyll content,net photosynthetic rate(Pn),stomatal conductance(Gs)and transpiration rate(Tr)of Z.simulans leaves.The results showed that most significant increases or decreases were achieved with 100 g/L bioorganic fertilizer(Y2).Thus,the application of bioorganic fertilizer at a rate of 100 g/L can significantly improve the activity of relevant defense enzymes and photosynthetic parameters of Z.simulans,and reduce the MDA content,enhancing the stress resistance of the plants,promoting their growth and addressing,to some extent,obstacles associated with continuous cultivation.

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.

Exogenous Glycine Betaine Reduces Drought Damage by Mediating Osmotic Adjustment and Enhancing Antioxidant Defense in Phoebe hunanensis

Drought stress negatively impacts growth and physiological processes in plants.The foliar application of glycine betaine(GB)is an effective and low-cost approach to improve the drought tolerance of trees.This study examined the effect of exogenously applied GB on the cell membrane permeability,osmotic adjustment,and antioxidant enzyme activities of Phoebe hunanensis Hand.-Mazz under drought stress.Two levels(0 and 800 mL)of water irrigation were tested under different applied GB concentrations(0,50,100,and 200 mM).Drought stress decreased the relative water content by 58.5%while increased the electric conductivity,malondialdehyde,proline,soluble proteins,soluble sugars,and antioxidant enzyme activities(superoxide dismutase,catalase,peroxidase)by up to 62.9%,42.4%,87.0%,19.1%,60.5%,68.3%,71.7%,and 83.8%,respectively,on the 25^(th) day.The foliar application of GB,especially at 100 mM,increased the relative water content of P.hunanensis leaves under drought stress.The concentration of GB from 50 to 100 mM effectively alleviated the improvement of cell membrane permeability and inhibited the accumulation of membrane lipid peroxidation products.Under drought stress,the concentrations of proline,soluble proteins,and soluble sugars in the leaves of P.hunanensis increased as the applied GB concentration was increased and the water stress time was prolonged.Exogenously applied GB decreased oxidative stress and improved antioxidant enzyme activities as compared with treatments without GB application.Furthermore,the physiological and biochemical indexes of P.hunanensis showed a certain dose effect on exogenous GB concentration.These results suggest that GB helps maintain the drought tolerance of P.hunanensis.

Effects of Water-retaining Agents on Growth, Development, Yield and Quality of Soybean under Drought Stress

[Objectives]The paper was to explore the effects of different doses of water-retaining agent on the growth and development indicators,yield and quality of soybean plants subjected to drought stress.[Methods]The effects of drought stress(MDS)and drought stress with low(MDS-L),medium(MDS-M)and high doses(MDS-H)of the water-retaining agent on the growth and development indicators,root activity,MDA content,antioxidant enzyme activity,yield and quality of soybean were studied by field plot test,with the normal water supply serving as the control(CK).[Results]In response to drought stress,the plant height,stem diameter,and yield of soybean exhibited a notable decline.Additionally,the contents of protein,fat,linoleic acid,and linolenic acid in seeds demonstrated a significant reduction.Conversely,the root activity and antioxidant enzyme activity exhibited a noticeable decline,while the MDA content exhibited an increase.The application of varying doses of the water-retaining agent was found to significantly enhance soybean growth,stimulate root activity,and elevate antioxidant enzyme activity,while concurrently reducing MDA content.The observed effects were found to be dose-dependent,with the greatest effects observed at the highest dose.In comparison to MDS,the yields of soybean in the MDS-L,MDS-M,and MDS-H treatments exhibited a 18.38%,25.58%,and 46.26%increase,respectively.Additionally,the content of protein,fat,linoleic acid,and linolenic acid in seeds demonstrated a notable enhancement.[Conclusions]The application of the water-retaining agent has been demonstrated to significantly promote the growth of soybean plants under conditions of drought stress,resulting in an improvement in both the yield and the quality of the soybean crop.The recommended dosage of the water-retaining agent is 3.3 kg/667 m 2.

Effects of temperature on keeping-alive without water and antioxidant enzyme of the rock scallop Crassadoma gigantea

Temperature was one of the key factors for the living environment of aquatic organisms, especially for shellfish. The effects of temperature was studied on the survival rate and the median lethal time （LT50） of the rock scallop Crassadoma gigantea, and the effects of temperature stress on the antioxidant enzymes of rock scallop Crassadoma gigantea were studied in order to explore the effects of temperature on keeping-alive without water and antioxidant system of the rock scallop Crassadoma gigantea. The rock scallop Crassadoma gigantea （shell length （39.7± 5） mm） at different temperatures （5℃ and 15℃）, humidity （moisture treatment, not moisturizing treatment） and oxygen （aerobic treatment, not aerobic treatment） in laboratory was studied by the survival analysis and the analysis of factors affecting the effects of the median lethal time （LTso） in order to investigate the effects of temperature on the survival rate and the median lethal time of the rock scallop Crassadoma gigantea. Results showed that low temperature, moisture and aerobic treatment can significantly improve the survival rate and the median lethal time of the rock scallop Crassadoma gigantea （P〈0.05）. The effect of temperature on the survival rate and the median lethal time of the rock scallop Crassadoma gigantea was most significant, followed by the effect of oxygen, and that of humidity was the most weakest. Interaction between temperature and humidity, temperature and oxygen significant interaction（P〉0.05）, and interaction between humidity and oxygen interaction was not significant （P〈0.05） in the interaction of three factors. It provided an important basis for the determination of the rock scallop Crassadoma gigantea in the seedling transportation time. In the article, the rock scallop Crassadoma gigantea larvae antioxidant enzymes activity was detected, including SOD activity,CAT activity ,T-A℃ activity （superoxide dismutase activity, catalase activity, total antioxidant capacity） changes through raising the temperature from the low temperature （5℃, 10℃, 15℃, 20℃, 25℃）, to explore the change of the antioxidant enzymes activity under the influence of temperature on the rock scallop Crassadoma gigantea larvae. The SODactivity was significantly lower than that of the other groups （P〈0.05） at 5℃, and the CAT activity had no significant difference between groups （p=0.05）, and the T - AOC level was the lowest significantly below 15℃, 25℃ （P〈0.05）.The SOD and CAT activity had no significant difference in the same experimental time （P〉0.05）, and the T - AOC activity temperature was significantly higher than the rest of the group （P=〈0.05） when temperature at 10℃ and 20℃. The SOD activity had no significant difference （P〉0.05）between groups at 25℃, and the CAT activity was significantly higher than 5℃ 10℃, 15℃ group （P〈0.05）. The T-AOC activity was only lower than 15℃ group （P〉0.05）. It indicated that the high temperature had a clear inducing effect on the CAT activity in the rock scallop Crassadoma gigantea larvae, and had a significant inhibitory effect on the T-AOC activity. The low temperature had a significant inhibitory effect on the activity of T-AOC in the tissue fluid of the scallop. The above results showed that the high and low temperature had a significant effect on the antioxidant enzymes activity of the rock scallop Crassadoma gigantea larvae.

Effects on antioxidant enzyme activities and osmolytes in Halocnemum strobilaceum under salt stress

The seedlings of Halocnermum strobilaceum were cultivated in 0.5% hoagland nutrient solution containing 0.0%, 0.9%, 2.7% and 5.4% of NaC1 as well as composite salt （Na^＋, Ca^2＋, K^＋, Si^4＋） for 20 days; all the contents are in weight ratio. Succulent level, inorganic ions （Na^＋, K^＋）, organics such as betaine, proline, malondialdehyde, and antioxidant enzyme activities including superoxide dismutase （SOD）, catalase （CAT）, peroxidase （POD）, betaine aldehyde dehydrogenase （BADH） were measured to reveal its salt tolerance mechanism. When the composite salt concentration reaches 5.4%, SOD activity level, and MDA content is five times the control group; when it reaches 2.7%, the succulent level of seedlings, and the content ofK＋ in roots is nearly two times the NaCl treatment; the dry weight is more than three times the control group; with the NaCl treatment, MDA is three times the contrast; when the salt concentration is 2.7%, POD reaches the maximum. Results indicate that Si^4＋, K^＋, and Ca^20 from composite salt in the roots of H. strobilaceum improved the water-holding capacity. The activities of antioxidant enzyme were raised by the accumulation ofproline and betaine, which increased the salt tolerance. The absorption of K^＋ promoted the high ratio of K^＋/Na^＋ and alleviated the damage of cell membranes of H. strobilaceum, which is associated with osmotic contents such as betaine and proline.

Study on Growth,Serum Biochemical and Antioxidant Enzyme Indices of Juvenile Siganus guttatus Fed with Enteromorpha prolifra and Artificial Feed

In order to provide reference for using Sigartus guttatus to control overgrowth of Ertteromorpha prolifra, the growth, serum biochemical and antioxidant enzyme indices of juvenile S. guttatus respectively fed with E. prolifra and artificial feed were studied. One hundred and eighty individuals were cultivated for 90 days in six 2.5 m × 1.5 m × 1.5 m cages （30 ind. per cage） which mesh size were 0.5 mm. The experimental animals were divided into two dietary groups （ three cages for each group） that were fed with E. prolifra and artificial feed respectively. During the culture period, temperatures ranged from 23.0 to 26.5℃, pH was between 7.8 and 8.2, dissolved oxygen was more than 5.0 mg/L. The weight gain rate, specific growth rate, relative growth rate, hepato-somatic index of juvenile S. guttatus fed with E. prolifra were significantly lowe than that fed with artificial feed （P 〈 0.05）. The total protein （TP）, urea nitrogen （UN） and alkaline phosphatase （AKP） of juvenile S. guttatus fed with E. Prolifra were significantly higher than that fed with artificial feed （P 〈0.05）, while glutamic oxalacetie transaminase （AST/GOT） and glutamic-pyruvic transaminase （ALT/GPT） of juvenile S. guttatus fed with E. prolifra were significantly lower than that fed with artificial feed （P 〈 0.05 ）. SOD, GPX and anti-superoxide anion radical activity in liver, kidney, gill and muscle of juvenile S. guttatus fed with E. prolifra were higher than that fed with artificial feed, and these antioxidant enzyme activities in kidney of juvenile S. gtatatus fed with E. prolifra was significantly higher than that fed with artificial feed （P 〈 0.05）, while CAT and hydroxyl radical-inhibiting activity in liver of juvenile S. guttatus fed with arti- ficial feed were significantly higher than that fed with E. prolifra （P 〈 0.05 ）. Juvenile S. guttatus fed with E. prolifra showed poor growth performance but better antioxidant defense system. S. guttatus is easily raised and has stronger ability of digestion and absorption of E. Prolifra. The technique that uses S. gtatatus to control E. prolifra deserves deeply study.

Antioxidant metabolic system and comparative proteomics analysis in winter turnip rape(Brassica rapa L.)under cold stress

Winter turnip rape(Brassica rapa L.)is widely cultivated in winter in Northwest China,however,its cold-tolerant mechanism remains insufficiently understood.In this study,winter turnip rape cultivar Longyou 7,a cold-tolerant variety,was used as material,whose accumulation of H_(2)O_(2) and O_(2)^(·-),antioxidant enzyme activity as well as differences in protein expression based on two-dimensional gel electrophoresis(2-DE)technique under -4℃ stress were analyzed.Results showed that,production of H_(2)O_(2) and O_(2)^(·-) were increased in Longyou 7 leaves,simultaneously,SOD and POD activities were also obviously rosed up,but the activities of CAT and APX were gradually reduced with the temperature.Thirty-six differential protein spots were successfully identified between control and treatments group by using mass spectrometry analysis.Among them,4 differential protein spots were induced under cold stress,and 2 were inhibited at-4℃.Functional analysis found that these identified proteins mainly participated in photosynthesis,carbohydrate metabolism,defense,protein synthesis,enzyme activity,redox and membrane metabolism,respectively.Additionally,13 proteins'function were still unknown.In conclusion,strong antioxidant capacity and cell defense ability might play important roles in Longyou 7 response to cold stress.

Participation of H_2O_2 in Enhancement of Cold Chilling by Salicylic Acid in Banana Seedlings

The possible physiological mechanism of enhancement of cold tolerance by salicylic acid (SA) in banana seedlings ( Musa acuminata cv. Williams 8188) was explored. Measurements of leakage electrolyte after 2 d of recovery at 30/22 ℃ (day/night) following 3 d of cold stress at 7 ℃ showed that pretreatment with hydroponic solution containing SA 0.3-0.9 mmol/L as foliar spray under normal growth conditions (30/22 ℃) could significantly enhance cold tolerance of banana plants. The highest enhancing effect of SA occurred at 0.5 mmol/L and it showed the lowest leakage rate of electrolyte or smaller leaf wilting area after 2 d of recovery at normal temperature from 3 d of 7 ℃ or 5 ℃ cold stress. Higher concentrations (≥2.5 mmol/L) of SA, however, caused more electrolyte leakage, indicating that they aggravated chilling damage. Enhanced cold tolerance by SA could be related to H 2O 2 metabolism. Compared with water_treated seedlings (control), SA 0.5 mmol/L treatment inhibited activities of catalase (CAT) and ascorbate peroxidase (APX), increased peroxidase (POX) activity, but did not affect the activity of superoxide dismutase (SOD) under normal growth conditions, and these changes might lead to an accumulation of H 2O 2, whereas SA pretreatment enhanced the activities of CAT and APX, and reduced the increase in productions of H 2O 2 and thiobarbituric acid_reaction substances (TBARS) during subsequent 7 ℃ cold stress and recovery periods. Exogenous H 2O 2 treatments (1.5 -2.5 mmol/L) also increased cold tolerance of banana seedlings. Furthermore, pretreatment of banana seedlings with dimethylthiourea (a trap for H 2O 2) significantly inhibited cold tolerance induced by SA. These results suggested that endogenous H 2O 2 may be required for SA_enhanced cold tolerance. The significance of the interaction of SA, H 2O 2 and H 2O 2_metabolizing enzymes during cold stress has been discussed.

Effects of Ozone Stress on Physiological and Biochemical Characteristics Dwarfing Rootstock M9T337

[Objective] To investigate the effects of different ozone concentrations （30, 60, 80, 100 and 120 μg/L） on the physiological and biochemical characteristics of M9T337, so as to provide theoretical basis for breeding anti-ozone dwarfing root- stocks. [Method] The effects of different concentrations of ozone on chlorophyll con- tent, antioxidant enzyme activity, malondialdehyde （MDA） and soluble protein content of M9T337 were studied by potting dwarfing rootstock M9T337 as test material. [Result] With the increase of ozone concentration, the content of chlorophyll in M9T337 leaves decreased gradually. The activity of SOD （superoxide dismutase） and CAT （catalase） increased first and then decreased, while POD （Peroxidase） ac- tivity and MDA （malondialdehyde） content were gradually increased. [Conclusion] The comprehensive analysis of the indicators indicated that the potted M9T337 could tolerate the low concentration （〈80 μg/L） ozone stress in the short time （〈3 h）, and it would cause serious injury to M9T337 when the ozone concentration ex- ceeded 80 μg/L.

Physiological characteristics of Ficus tikoua under antimony stress

A greenhouse culture experiment was used to evaluate the effects of antimony(Sb)stress on Ficus tikoua(F.tikoua).Theresults showed that the growth of F.tikoua leaves was significantly inhibited when Sb concentration was higher than30μmol/L,andno significantly inhibitory effect of Sb on the roots and stems of F.tikoua was found in all the treatments,implying that leaves weremore sensitive to Sb toxicity than roots and stems.Antimony concentration in the roots was higher than that in the stems and leaves.To reduce reactive oxygen species(ROS)level in the F.tikoua,the activities of superoxide dismutase(SOD),peroxidase(POD)andcatalase(CAT)increased with Sb treatments,but the SOD and CAT were more early active than POD.Although the decrease ofchlorophyll content with high Sb treatments(450μmol/L)was observed at the end of the experiments,the positive impact onchlorophyll content was observed with all the Sb treatments at the early period.No significant difference of the maximum quantumefficiency of PSII and quantum yield of PSII electron transport values with different Sb treatments was observed at the end of thisexperiment,suggesting that the photosynthesis was not inhibited with Sb concentration below450μmol/L.The results implied acertain tolerance to Sb stress for F.tikoua.This meets the essential condition for utilization in Sb contamination environments.

The protection of Thymus vulgaris leaves alcoholic extract against hepatotoxicity of alcohol in rats

Objective:This study was performed to investigate the protective effect of Thymus vulgaris(T.vulgaris) leaves 70%alcoholic extract against alcohol-mediate hepatotoxicity rats.Methods:The protective effect of extract was investigated at dose of 500 mg/kg/day orally against alcohol-mediate hepatotoxicity using adult male Wister albino rats during 21 days.Protective effect of T.vulgaris extract was evaluated comparing with silymarin standard drug al recommended dose(25 mg/kg/day) orally for 21 days.Results:Alcohol-mediate hepatotoxicity rats(alcohol-control) showed hepatocytes distortion represented as marked increment on liver biomarkers;alkaline phosphatase(ALP),aspartate transaminase(AST) and alanine transaminase(ALT) activities,as well as pronounced reduction on total protein and its fractions albumin and globulin corresponding to normal ranges.Addition to oxidative stress status as depletion on glutathione concentration,catalase(CAT),superoxide dismutase(SOD),glutathione reductase(GR),glutathione-S-transferase(GST) and glutathione peroxidase(GPx)activities,concurrence with augmentation oxidative stress parameters;malondyaldchydc(MDA) and hydrogen peroxide(H_2O_2) concentrations comparing to normal values.Alcohol administration elevated total cholesterol(TC),low density lipoprotein cholesterol(LDL-C) and high density lipoprotein cholesterol(HDL-C) comparing to normal ranges.Co-administration T.vulgaris extract with alcohol showed protective effect on hepatocytes manifested as minimizing on ALP.AST and ALT activities and increment on total protein,albumin and globulin production compared to alcohol-control.Antioxidant enzymes activities;CAT.SOD.GR,GST and GPx were significantly magnified,while MDA and H_2O_2 concentration were lessened corresponding to alcohol-control.Also,lipid profile was markedly improved and risk ratio was lowered compared to alcohol-control.These results were confirmed by normalization of degenerated and fibrotic liver tissue as of alcohol-control.Conclusion:T.vulgaris extract appeared hepatoprotective,hypolipidemic and antioxidant activities on alcohol-mediate hepatotoxicity rats compared to silymarin.

Influence of water potential and soil type on conventional japonica super rice yield and soil enzyme activities

We carried out a pool culture experiment to determine the optimal water treatment depth in loam and clay soils during the late growth stage of super rice. Three controlled water depth treatments of 0-5, 0-10 and 0-15 cm below the soil surface were established using alternate wetting and drying irrigation, and the soil water potential （0 to -25 kPa） was measured at 5, 10 and 15 cm. A 2-cm water layer was used as the control. We measured soil enzyme activities, root antioxidant enzyme activities, chlorophyll fluorescence parameters, and rice yield. The results showed that the 0-5-cm water depth treatment significantly increased root antioxidant enzyme activities in loam soil compared with the control, whereas soil enzyme activities, chlorophyll fluorescence parameters and yield did not differ from those of the control. The 0-10- and 0-15-cm water depth treatments also increased root antioxidant enzyme activities, whereas soil enzyme activities, chlorophyll fluorescence parameters and yield decreased. In clay soil, the soil enzyme activities, root antioxidant enzyme activities, chlorophyll fluorescence parameters, and yield did not change with the 0-5-cm water treatment, whereas the 0-10- and 0-15-cm water treatments improved these parameters. Therefore,the appropriate depths for soil water during the late growth period of rice with a 0 to -25 kPa water potential were 5 cm in loam and 15 cm in clay soil.

Microalgae(Chlorella vulgaris Beijerinck)alleviates drought stress of broccoli plants by improving nutrient uptake,secondary metabolites,and antioxidative defense system

Microalgae,such as Chlorella vulgaris Beijerinck(green algae),are beneficial microscopic organisms that may help plants to improve nutrient uptake,growth,and abiotic tolerance to stressors.The current study was performed to investigate the effectiveness of algae(Chlorella vulgaris Beijerinck)foliar applications[1%,3%,or 5%(v/v)]on mitigation of drought stress in broccoli plants subjected to water deficit at 25%of field capacity.The results showed that the broccoli plants grown under drought stress alone exhibited severe disturbance in growth with considerable reductions in the shoot length,and fresh and dry weights,leaf area,relative water content,leaf water potential,and photosynthetic pigment contents and elevated levels of the lipid peroxidation product malondialdehyde in the leaves.Additionally,the foliar application of microalgae mitigated the detrimental effects of drought,leading to better growth performance(increase of 9%–132%)when compared with the drought-stressed plants that had not received an application of microalgae.Microalgae-mediated beneficial effects were particularly evident in the enhancement of the photosynthetic pigment contents,including chlorophyll-a(6%–60%),chlorophyll-b(19%–55%),and total carotenoids(26%–114%).Exogenous microalgae also contributed to the reduction of membrane damage,as proven by significantly decreased levels of malondialdehyde(10%–39%)in the leaves of the broccoli plants exposed to drought stress.The application of microalgae increased the total flavonoid and phenolic contents,and nutrition uptake.Furthermore,the activities of enzymatic antioxidants like ascorbate peroxidase,catalase,glutathione reductase,and superoxide dismutase increased in response to mediation,resulting in significant alleviation of drought-induced oxidative damage.The most effective application concentration of microalgae was determined as 5%.Overall investigations revealed that the foliar application of microalgae could be recommended as a sustainable strategy to improve the defense system of drought-stressed broccoli plants.

5-Aminolevulinic acid alleviates herbicide-induced physiological and ultrastructural changes in Brassica napus

It is well known that application of 5-aminolevuJinic acid （ALA） could promote the plant growth under abiotic stress in oilseed rape （Brassica napus L.）. However, the specifics of its physiological and ultrastructural regulation under herbi- cide stress conditions are poorly understood. In the present study, alleviating role of ALA in B. napus was investigated under four levels of herbicide propyl 4-（2-（4,6-dimethoxypyrimidin-2-yloxy） benzylamino） benzoate （ZJ0273） （0, 100, 200 and 500 mg L-1） with or without 1 mg L-1 ALA treated for 48 or 72 h. Results showed that after 48 h of herbicide stress, the growth of rape seedlings was significantly inhibited with the successive increases of the ZJ0273 concentrations from 0 to 500 mg L-1, but this inhibition was obviously alleviated by exogenous application of ALA. However, when treatment time prolonged to 72 h, the recovery effects of ALA could not be evaluated due to the death of plants treated with the highest concentration of ZJ0273 （500 mg L-1）. Further, the root oxidizability and activities of antioxidant enzymes （superoxide dismutase, perox- idase and ascorbate peroxidase） were dramatically enhanced by the application of 1 mg L-1 ALA under herbicide stress. Therefore, plants treated with ALA dynamically modulated their antioxidant defenses to reduce reactive oxygen species （ROS） accumulation and malondialdehyde （MDA） content induced by herbicide stress. Additionally, exogenously applied ALA improved the ultrastructure＇s of chloroplast, mitochondria and nucleus, and induced the production of stress proteins. Our results suggest that ALA could be considered as a potential plant growth regulator for the improvement of herbicide tolerance through alleviation of the physiological and ultrastructural changes induced by the herbicide in crop production.

Changes in extreme high-temperature tolerance and activities of antioxidant enzymes of sacred lotus seeds

Sacred lotus (Nelumbo nucifera Gaertn. ‘Tielian’) seed is long-lived and extremely tolerant of high temperature. Water content of lotus and maize seeds was 0.103 and 0.129 g H2O [g DW] ?1, respectively. Water content, germination percentage and fresh weight of seedlings produced by surviving seeds gradually decreased with increasing treatment time at 100℃. Germination percentage of maize (Zea mays L. ‘Huangbaogu’) seeds was zero after they were treated at 100℃ for 15 min and that of lotus seeds was 13.5% following the treatment at 100℃ for 24 h. The time in which 50% of lotus and maize seeds were killed by 100℃ was about 14.5 h and 6 min, respectively. With increasing treatment time at 100℃, relative electrolyte leakage of lotus axes increased significantly, and total chlorophyll content of lotus axes markedly decreased. When treatment time at 100℃ was less than 12 h, subcellular structure of lotus hypocotyls remained fully intact. When treatment time at 100℃ was more than 12 h, plasmoly-sis gradually occurred, endoplasmic reticulum became unclear, nuclei and nucleoli broke down, most of mitochondria swelled, lipid granules accumulated at the cell periphery, and organelles and plas-molemma collapsed. Malondialdehyde (MDA) content of lotus axes and cotyledons decreased during 0-12 h of the treatment at 100℃ and then increased. By contrast, the MDA content of maize embryos and endosperms increased during 5-10 min of the treatment at 100℃ and then decreased slightly. For lotus seeds: (1) activities of superoxide dismutase (SOD) and glutathione reductase (GR) of axes and cotyledons and of catalase (CAT) of axes increased during the early phase of treatment at 100℃ and then decreased; and (2) activities of ascorbate peroxidase (APX) and dehydroascorbate reductase (DHAR) of axes and cotyledons and of CAT of cotyledons gradually decreased with increasing treat-ment time at 100℃. For maize seeds: (1) activities of SOD and DHAR of embryos and endosperms and of GR of embryos increased during the early phase of the treatment at 100℃ and then decreased; and (2) activities of APX and CAT of embryos and endosperms and of GR of endosperms rapidly decreased with increasing treatment time at 100℃. With decrease in seed germination, activities of SOD, APX, CAT, GR and DHAR of axes and cotyledons of lotus seeds decreased slowly, and those of embryos and endosperms of maize seeds decreased rapidly.

Physiological Response of Paspalum notatum’s Leaf and Root under Persistent Drought Stress

To investigate the correlation and difference between Paspalum notatum’s leaf and root under drought adversity,this study tested the physiological responses of wild Paspalum notatum’s leaf and root under 0(CK),1,3,5,7,14,21,and 28 d drought stress treatment.These physiological responses include osmotic regulating substance,antioxidant enzyme activity,malonaldehyde content,cell membrane permeability,and chlorophyll content.According to the results,the soluble protein content,proline concentration,malonaldehyde content,cell membrane permeability and CAT activity in Paspalum notatum’s leaf and root tended to increase with the prolongation of drought stress;the soluble sugar content and SOD activity first increased and then decreased;POD dropped gradually;the contents of chlorophyll a,b and total chlorophyll first declined,then mounted,and lastly dropped again.During the early stage of drought stress,SOD and CAT acted as the main antioxidant enzymes in Paspalum notatum’s leaf and root.However,with the aggravation of drought stress the predominant antioxidant enzymes became SOD in the root system whereas CAT and POD in the leaf.It implicates drought has a strong influence on root’s CAT and leaf’s SOD and POD.Leaf is the major organ regulating the osmosis and photosynthesis of Paspalum notatum.The findings can provide a useful theoretical basis for improving Paspalum notatum’s drought tolerance.

Effect of Light Intensity on Leaf Photosynthetic Characteristics and Accumulation of Flavonoids in Lithocarpus litseifolius (Hance) Chun. (Fagaceae)

The active compounds in herb drugs are mainly secondary metabolites, which are greatly influenced by external conditions. Particularly, light intensity has a great influence on the photosynthesis and accumulation of secondary metabolites. In this study, the light intensity was changed, and the influence of the light intensity on leaf photosynthetic characteristics, antioxidant enzyme activity and flavone contents of Lithocarpus litseifoliusp (Hance) Chun. was discussed. The results showed that (1) L. litseifolius is a typical heliophyte. As the light intensity decreased, the contents of chlorophyll a (Chl a), chlorophyll b (Chl b) and total chlorophyll (Chl a + b) all increased. However, the Chl a/b ratio gradually decreased. The daily variation of net photosynthetic rate changed from a double-peak curve under natural light to single-peak curve under 20% full light two shading nets. (2) As the light intensity decreased, the SOD and POD activities and the soluble proteins content decreased in the leaves. In contrast, the malondialdehyde content increased. (3) The flavone content was the highest in leaves at one shading nets 60% of full light, and the lowest occurred in leaves at two shading nets 20% of full light. A comprehensive analysis indicated that an appropriate shading could induce shade tolerance in the leaves of L. litseifolius, which promoted the accumulation of flavonoids. L. litseifolius should be planted in the lower position of sunny slope or the upper position of shady slope to increase the content of flavone in the leaves.

Amelioration of altered antioxidant enzyme activity by Satureja khuzistanica essential oil in alloxan-induced diabetic rats

AIM: To examine the possible protective effect of Satureja khuzistanica essential oil(SKE) on antioxidant enzyme activity in alloxan-induced Type 1 diabetic rats. METHOD: Thirty Sprague-Dawley male rats were divided into three groups randomly; group one as control, group two diabetic, with no treatment, and group three treatment with SKE at 500 ppm in drinking water, respectively. Diabetes was induced in the second and third groups by alloxan injection subcutaneously. After eight weeks, animals were anaesthetized. Blood samples were also collected before killing to measure antioxidant enzymes activity. RESULTS: SKE significantly increased the serum level of glutathione and the serum activity of glutathione peroxidase, superoxide dismutase, and catalase in the treated group compared with the diabetic untreated group. CONCLUSION: The findings showed that SKE exerts beneficial effects on the antioxidant enzymes activity in alloxan-induced Type 1 diabetic rats.