不同储藏条件下糙米品质变化研究

将供试3种糙米(粳米、杂籼米和纯籼米)分别放在低温、常温、高温和真空条件下储藏,定期测定其浸出液电导率和丙二醛含量的变化.随着储藏时间的延长,糙米的浸出液电导率呈增加趋势,低温储藏的增加最小,真空储藏的次之,常温储藏的增加较大,高温储藏的增加最大;低温、常温和真空储藏条件下丙二醛含量随着储藏时间延长而增加,高温条件下先增加后减小.     

不同灌溉方式对寒地粳稻抗旱生理性状的影响

本试验以东农425和东农427为试验材料,在水稻全生育期内以土壤水势为灌水衡量指标,研究了五种不同灌溉方式对寒地粳稻抗旱生理性状的影响,结果表明:在整个生育期内,处理的叶片脯氨酸(Pro)、丙二醛(MDA)积累量、变化幅度基本趋势为:旱作>重干湿交替灌溉>轻干湿交替灌溉>中干湿交替灌溉>常规灌溉,重干湿交替灌溉和旱作处理显著增加了叶片脯氨酸、丙二醛含量。叶片脯氨酸、丙二醛含量与植株抗旱性及产量均呈负相关关系,其中脯氨酸含量相关性显著;重干湿交替灌溉和旱作处理的叶绿素(Chl)含量明显低于常规灌溉及轻干湿交替灌溉、中干湿交替灌溉处理,随着生育进程的推进,轻干湿交替灌溉、中干湿交替灌溉处理的叶片叶绿素含量反而高于其他处理。中干湿交替灌溉处理能够显著增加水稻叶片叶绿素含量,叶片叶绿素含量与植株抗旱性及产量呈显著正相关。中干湿交替灌溉处理是较为合理的灌溉方式,即田间土壤水势灌溉下限不应低于-20kPa。通过对植物抗旱性及抗旱相关生理指标的分析得出东农425的抗旱性较东农427强。     

铜胁迫对弯囊苔草（ Carex dispalata）生长和生理特性的影响

用水培方法研究了弯囊苔草在不同Cu^2＋浓度（1、5、25 mg·L^-1）胁迫下的生长特性和部分生理生化指标的变化。结果表明,不同Cu^2＋浓度胁迫下,弯囊苔草正常生长,但其生长特性表现出高浓度抑制的相关性, 高浓度下没有新生根。弯囊苔草叶片3种抗氧化酶活性都随胁迫时间的延长呈先上升再下降趋势。SOD在处理的第4 d达到峰值,且活性一直显著高于对照（P＜0.05）,3种Cu^2＋浓度处理下的峰值大小顺序为5 mg·L^-1＞25 mg·L^-1＞1 mg·L^-1。POD和CAT活性在处理第7 d达到峰值,POD活性峰值大小顺序为5 mg·L^-1＞1 mg·L^-1＞25 mg·L^-1;CAT活性峰值大小顺序为25 mg·L^-1＞5 mg·L^-1＞1 mg·L^-1。丙二醛（MDA）和可溶性糖含量都是随着胁迫时间的延长而上升,处理结束时的丙二醛（MDA）（r=0.988 0）和可溶性糖含量（r=0.951 2）与Cu^2＋浓度表现出正相关性。脯氨酸（Pro）含量随胁迫时间的延长也呈先上升后下降趋势,1 mg· L^-1和5 mg·L^-1 Cu^2＋浓度处理下脯氨酸（Pro）含量在处理第4 d达到最大值,25 mg·L^-1高浓度处理下脯氨酸（Pro）含量在处理第7 d达到最大值。叶绿素在5、25 mg·L^-1 Cu^2＋浓度处理下随胁迫时间的延长呈先上升后下降的趋势,1mg·L^-1Cu^2＋处理下的叶绿素含量不断上升,实验结束时各处理下叶片的叶绿素含量与处理浓度呈负相关。结果表明弯囊苔草能通过调节体内抗氧化酶活性来增强其抗氧化胁迫能力,这为其作为铜污染水体的修复植物提供了可能。     

Salicylic acid induced alleviation of oxidative stress caused by clethodim in maize (Zea mays L.) leaves

Salicylic acid is used for regulation of oxidative stress in plants subjected to unfavorable environmental conditions. Application of herbicides for the purpose of weed killing can affect not only the weeds but also the main crop as well. Many herbicides have the ability to cause oxidative stress and further degradation of cell components. In this work, SA was used to alleviate the oxidative stress caused in response to clethodim herbicide in maize leaves. The results demonstrated that, spraying of clethodim caused yellowing of leaves and sometimes browning or drying of leaf tips with high clethodim doses. Contrary, leaves showed no injuries when treated with 1 mM SA 3 days prior clethodim application. Elevated amounts of H₂O₂ and MDA were detected in clethodim treated leaves compared with control indicating ROS formation and lipid peroxidation. Excessive ROS formation led to oxidative stress which followed by degradation of membranous structures. In SA treated leaves, the contents of H₂O₂ and MDA were more or less similar to the corresponding controls. A change in the antioxidant enzymes activities due to clethodim and SA treatment was noticed. For example, the activities of POD and APX were induced while SOD and CAT were more or less reduced in response to clethodim. SA treatment prior clethodim application could induce POD but inhibit CAT. Moreover, SOD and APX activities were adjusted to be similar to those of the control. Another mechanism of SA regulation of the oxidative stress occurred through the formation of antioxidants in the form of phenolic compounds. For that, spraying SA with or without clethodim could accumulate phenolic compounds greatly. The DPPH free radical scavenging assay for leaf extracts had confirmed a change in antioxidant status. Furthermore, SA could enhance accumulation of total proteins and free amino acids in clethodim and SA treated leaves compared with the control. This work was to provide evidence for the ability of SA to regulate clethodim herbicide detoxification through regulation of the antioxidant status of maize leaf cells.     

低温弱光对黄瓜幼苗过氧化物酶同工酶和丙二醛含量的影响

为了探讨低温、弱光条件下,不同黄瓜品种对逆境的适应能力,采用聚丙烯酰胺垂直板凝胶电泳法、硫代巴比妥酸法和紫外分光光度法等方法,研究了低温、弱光对祥云丰满园、津研7号、绿玉、新夏丰一号4个品种黄瓜幼苗叶片中的过氧化物酶(POD)同工酶、丙二醛(MDA)含量的影响。结果表明,与正常栽培相比,在低温+弱光胁迫条件下,MDA增幅分别为:祥云丰满园58.93%,津研七号42.16%,新夏丰一号26.26%,绿玉28.24%,其中新夏丰一号的MDA相对增幅最小;POD同工酶的电泳酶谱显示,仅以弱光胁迫时,各品种的POD同工酶谱均无显著变化;经低温+弱光综合胁迫后,POD同工酶谱的条带数均有所增加。试验结果提示,在低温、弱光2种胁迫因素中,低温+弱光的综合胁迫对黄瓜幼苗的POD影响最为显著。4个品种中,新夏丰一号对低温和弱光有良好的抗性。     

Effect of silicon on antioxidant and stomatal response of two grapevine (Vitis vinifera L.) rootstocks grown in boron toxic,saline and boron toxic-saline soil

We investigated individual and combined effects of B toxicity and salinity in the presence or absence of silicon on the shoot growth, concentrations of sodium (Na), chloride (Cl), boron (B) and silicon (Si), and stomatal resistance (SR), lipid peroxidation (MDA), proline accumulation, H₂O₂ accumulation and the activities of major antioxidant enzymes (superoxide dismutase, SOD; catalase, CAT and ascorbate peroxidase, APX) activity grapevine rootstocks of 41B (V. Vinifera × V. Berlandieri) and 1103P (V. Berlandieri × V. Rupestris). Applied Si counteracted the deleterious effects of salinity and boron toxicity on shoot growth by lowering the accumulation of Na in 1103P, and B and Cl in the both rootstocks. Stomatal resistance, MDA, and the concentrations of H₂O₂ and proline were higher in the plants grown in conditions of B toxicity, salinity and their combination while applied Si lowered these parameters. Lowering SOD and CAT but increasing APX, Si treatment significantly affected the enzyme activities of both rootstocks. Based on the present work, it can be concluded that Si alleviates the adverse effects of salinity, B toxicity and combined salinity-B toxicity on grapevine rootstocks by preventing both oxidative membrane damage and translocation of Na and B from root to shoots and/or soil to plant, and also lowering the phytotoxic effects of Na and B within plant tissues. When considering the antioxidative response and membrane systems, it was concluded that the rootstock 1103P was responsive to Si under stress conditions. To our knowledge, this is the first report that Si improves the combined salt and B tolerance of grapevine grown under saline, B toxic, and B toxic and saline conditions which describes membrane related parameters and antioxidant responses.     

Response of Vitis vinifera L. plants inoculated with Phaeoacremonium angustius and Phaeomoniella chlamydospora to thiabendazole,resveratrol and sodium arsenite

The effect of some pesticides (sodium arsenite, thiabendazole and ziram) and the natural phytoalexin (resveratrol) on mycelial growth of Phaeomoniella chlamydospora and Phaeoacremonium angustius was studied. Several strains of these species were grown on malt extract agar (MEA) plates containing different concentrations of inhibitory compounds and colony diameters were measured. While sodium arsenite and ziram had little effect on the growth of both species, thiabendazole inhibited colony growth, at minimum concentrations of 6 μM for Ph. chlamydospora and 15 μM for P. angustius. Resveratrol at concentrations equal to or grater than 867 μM also inhibited colony growth of both species. To assay the effect of these substances on plant response to infection, in vitro grapevines were inoculated with Ph. chlamydospora or P. angustius spores and were grown in the presence of sodium arsenite (0–30 μM), thiabendazole (0–30 μM) or resveratrol (0–876 μM). Infected untreated plants and sodium arsenite-treated plants developed symptoms of senescence (reduced growth, increased membrane lipid peroxidation, and decreased chlorophyll content and fluorescence). In contrast, infected plants treated with thiabendazole (30 μM) or with resveratrol (876 μM) showed similar characteristics of fresh weight, malondialdehyde accumulation and chlorophyll fluorescence to those of uninfected plants. These results are promising with respect to the use of thiabendazole-containing pesticides as alternatives to currently used pesticides for control of esca in vines. Results also suggest that the presence of resveratrol in grapevines may be useful to induce resistance to these fungi.     

Effects of dietary polyunsaturated fatty acid/vitamin E (PUFA/tocopherol ratio on antioxidant defence mechanisms of juvenile gilthead sea bream (Sparus aurata L., Osteichthyes, Sparidae)

Lipid peroxidation, specifically polyunsaturated fatty acid (PUFA) oxidation is highly deleterious, resulting in damage to cellular biomembranes, and may be a principal cause of several diseases in fish including jaundice and nutritional muscular dystrophy. Tissue lipid PUFA content and composition are critical factors in lipid peroxidation, as is the level of endogenous antioxidant molecules such as vitamin E. The primary objective of the present study was the characterization of antioxidant systems in a cultured juvenile marine fish, gilthead sea bream (Sparus aurata) with the underlying aim to understand how to avoid oxidation problems that may cause pathologies and disease and so to enhance growth and quality of early ongrowing stages. Juvenile sea bream were fed diets having either high or low levels of fish oil and supplemented or basal levels of vitamin E with PUFA/vitamin E ratios ranging from 117±12 in the diet with low PUFA supplemented with vitamin E to 745±48 in the diet with high PUFA with no additional vitamin E. None of the diets had serious deleterious effects on growth or survival of the fish, but the different dietary regimes were effective in significantly altering the PUFA/vitamin E ratios in the fish livers with values ranging from 5.7±0.4 in fish fed the diet with low PUFA supplemented with vitamin E to 91.1±13.2 in fish fed the diet with high PUFA with no additional vitamin E. This had effects on the peroxidation status of the fish as indicated by the significantly altered levels of in vivo lipid peroxidation products measured in liver, with fish fed the diet rich in PUFA and low in vitamin E showing significantly higher values of thiobarbituric acid reactive substances (TBARS) and isoprostanes. The isoprostane levels generally followed the same pattern as the TBARS levels supporting its value as an indicator of in vivo oxidative stress in fish, as it is in mammals. However, few significant effects on antioxidant enzyme activities were observed suggesting that more severe conditions may be required to affect these activities such as increasing the PUFA/vitamin E ratio or by increasing peroxidative stress through the feeding of oxidized oils.     

铈对盐胁迫下小麦种子萌发过程中生理指标的影响

以小麦为材料,在实验室模拟条件下,研究一定浓度的Ce（NH4）2（NO3）6对盐胁迫下小麦种子萌发的影响。发现当用浓度为0．8％NaCl溶液对小麦种子进行盐胁迫时,溶液中含10mg／L的Ce（NH4）2（NO3）6能够降低盐胁迫下的小麦种子可溶性糖和丙二醛含量,说明稀土元素铈在一定程度上能降低盐胁迫对小麦种子的危害。     

铜胁迫和间作对玉米抗氧化酶活性及丙二醛含量的影响

为探讨红壤地玉米-豌豆间作种植模式对铜污染的响应机制,通过盆栽试验,研究了不同铜浓度(0、100、200、400、600 mg·kg-1)对玉米单作和玉米间作豌豆条件下植株生物量、铜含量、玉米抗氧化酶活性[超氧化物歧化酶(SOD)、过氧化氢酶(CAT)和过氧化物酶(POD)]及丙二醛含量(MDA)的影响。结果表明:在高Cu2+浓度(600mg·kg-1)胁迫下,间作玉米地上部和地下部干重较单作分别提高了20%和36.6%,与单作相比,随着Cu2+浓度升高(100、200、400、600 mg·kg-1),间作模式下玉米地上部铜含量分别降低了86.81%、44.57%、22.01%、11.11%,而地下部铜含量则分别提高了78.89%、24.79%、35.29%、13.31%,且差异均达到显著水平。在不同Cu2+浓度胁迫下,玉米叶和根中的SOD、POD、CAT活性和MDA含量均随着Cu2+浓度的增加而提高,仅Cu2+浓度达到600mg·kg-1时玉米体内的CAT活性有所下降。间作条件下玉米根的SOD活性较单作提高了48.07%~117.27%,间作玉米叶的SOD活性较单作提高了11.30%~46.90%。不同种植模式对Cu2+胁迫条件下的玉米POD活性均没有显著影响。在Cu2+(0~400mg·kg-1)胁迫下,间作玉米叶的CAT活性较单作均显著提高,分别提高了71.37%、140.40%、229.80%和161.75%,间作玉米根的CAT活性与单作无显著差异。间作玉米根的MDA含量较单作降低了26.13%~64.53%;在100、200 mg·kg-1Cu2+胁迫下,间作玉米叶的MDA含量较单作降低了0.30%和26.24%,但在400、600 mg·kg-1Cu2+胁迫下,间作玉米叶的MDA含量较单作提高了32.62%和93.51%。综上所述,在一定范围的Cu2+胁迫条件下,玉米根和叶中的抗氧化酶活性及MDA含量均有所提高来维持正常生长,间作模式在Cu2+胁迫下对玉米根和叶的抗氧化酶系统能起到一定的保护作用。