The Effect of Short Warm Breaks during Chilling on Water Status, Intensity of Photosynthesis of Maize Seedlings and Final Grain Yield

The effects of short-term exposure of seedlings to suboptimal temperature (14 °C for 1 or 4 h in 24 h cycles) during chilling (5 °C for 12 days) on the water status and intensity of photosynthesis of tolerant (TG) and chilling-sensitive (SG) maize genotypes were studied. Daily warming for 1 or 4 h resulted in a decrease in the hydration of the seedlings to 31.1 % and 61.5 % (SG) and 14.8 % (TG) and 39.1 % (SG), respectively, in comparison with the continuously chilled control. During warming for 4 h, both genotypes absorbed water from soil in amounts that partly compensated for its loss through transpiration, after the plants had been moved to the lower temperature. A protective effect of shorter warming (1 h) on the hydration of the seedlings was a result of a strong, stomatal limitation of transpiration during the initial days of chilling. Warming for 1 or 4 h also increased the ability of TG stomata to close in reaction to water deficit in chilling conditions. The effect of increased temperature delayed the decrease of P_N in leaves and limited RGR inhibition of the seedling mass caused by chilling. Daily warming of plants at the seedling phase (14 and 20 °C for 1 or 4 h) reduced the unfavourable effect of chilling (5 °C for a period of 8 days) on the final yield, the filling of caryopses and their number in a cob after growth in natural conditions.     

菘蓝试管苗玻璃化过程中抗氧化物酶活性的变化

为明确植物体内抗氧化酶活性变化与组培玻璃苗发生的关系,以菘蓝(Isatis indigotica Fort.)正常试管苗和玻璃苗为研究材料,对其抗氧化物酶活性和膜脂质过氧化水平进行了比较分析.结果表明:正常苗和玻璃苗中过氧化物酶(POD)活性随培养时间的延长先降低后升高,过氧化氢酶(CAT)活性先升高后降低,过氧化物歧化酶(SoD)活性和丙二醛(MDA)含量始终呈上升趋势.同一培养时期,玻璃苗中CAT、SOD活性均低于正常苗,而MDA水平远远高于正常苗.表明组培过程中有氧自由基的胁迫,而玻璃苗细胞内保护酶的调节功能紊乱,从而发生了更严重的脂质过氧化.此外,与正常苗相比,玻璃苗中POD同工酶电泳谱带出现增加、缺失等异常现象,表明玻璃苗中酶的表达失常,遗传稳定性改变.     

镉胁迫对莴苣种子萌发及抗氧化酶系统的影响

以笋王一号莴苣为试验材料,研究了不同浓度Cd胁迫对莴苣种子萌发、胚根胚芽生长、丙二醛(MDA)及抗氧化酶系统的影响.结果表明:随着Cd浓度的增加,莴苣种子的发芽率逐渐降低,而Cd对种子的发芽势、发芽指数和活力指数以及胚根的伸长则表现出低促高抑的效应.Cd对胚根生长的抑制程度较胚芽明显.随着Cd浓度的增加.胚根中MDA含量、SOD、G-POD活性明显增加,APX和CAT活性则明显降低,而胚芽中只在高浓度Cd胁迫下(100μmol/L)才发生明显变化.     

Activation of Antioxidant System by KCl Improves the Chilling Tolerance in Hybrid Maize

As maize is a chilling-sensitive crop, low temperatures during the early stages of development can be injurious to crop growth and development. Prime mechanism behind chilling-induced damage is oxidative stress. This study was undertaken to improve the chilling tolerance in hybrid maize by seed priming with KCl. For priming, seeds of the maize hybrid Hycorn 8288 were soaked in 50, 100 and 150 mg l⁻¹ aerated solution of KCl for 24 h and then re-dried close to original weight. Primed and untreated seeds were sown at 27 °C (optimal temperature) and at 15 °C (chilling stress) under controlled conditions. Seed priming improved the performance of maize under both normal and stress conditions. It was found that the chilling tolerance in maize is well associated with the enhanced capacity of the anti-oxidative system. Priming with KCl significantly improved the chilling tolerance mainly by the activation of antioxidants including catalase, superoxide dismutase and ascorbate peroxidase enzymes. KCl treatments also improved the germination rate and time, root and shoot length, and fresh and dry weights of seedlings compared with control. Soluble sugars and α-amylase activity determined as general metabolic indicators of stress were also improved by seed priming with KCl. Other possible bases of chilling tolerance in maize included maintenance of high tissue water contents, reduced electrolyte leakage and carbohydrate metabolism. Seed treatment with 100 mg l⁻¹ KCl was the best treatment to improve the performance of hybrid maize both under normal and chilling stress conditions.     

镉对小麦种子萌发、幼苗生长及抗氧化酶活性的影响

为了防止重金属毒害的发生和在环境监测中对重金属的评价,以小麦为试验对象,采用室内培养方法,研究了不同浓度镉胁迫对小麦种子萌发和幼苗生长、丙二醛及抗氧化酶系统的影响,结果表明,较低浓度镉胁迫对种子发芽率、发芽势、芽生长的抑制效应较小.随着镉胁迫浓度的提高,发芽指数、活力指数及根生长明显受抑制,且镉胁迫浓度越大,抑制作用越大.随着镉浓度的增加,幼苗根、芽中的MDA含量、G-POD明显增加,SOD活性呈现先增加后降低的趋势,其中根的SOD活性在1 000 μmol/L Cd胁迫下略低于对照,而CAT、APX活性总体呈下降趋势,且浓度越高下降幅度越大,表明遭受了氧化胁迫和膜脂过氧化损伤,这可能是镉胁迫下小麦幼苗根生长受阻的重要原因.     

Effects of Exposure to Short Periods of Suboptimal Temperature during Chill (5 °C) on Gas Exchange and Chlorophyll Fluorescence in Maize Seedlings (Zea Mays L.)

The effect of various periods of exposure to suboptimal temperature ('warm breaks'– WB: 14 °C for 4 h, 1 h and 0 h – control in 24 h cycles) during chilling (5 °C) of maize seedlings on the photosynthesis, the photochemical efficiency of photosystem II (Fv/Fm) and on the injuries of the cell membranes of leaves and water content in plants was compared. The measurements were conducted after 1, 3, 7 and 12 chill cycles. It was found that WB of either length distinctly diminished the chill-induced inhibition of net photosynthesis and the decrease of photochemical efficiency of PSII. The protective effect on WB on these parameters was observed shortly after completion of chilling of the plant as well as an after-effect. Daily warming up of the plants also reduced the leakage of electrolytes and diminished the water deficit of the chilled seedlings. The protective effect of WB on the measured parameters of the plants was greater in the chill-sensitive genotype than in the chill-tolerant one, especially when plants were warmed up for 4 h. The results obtained are an indication that short periods of warm weather during cold spring may diminish the injuries of the photosynthetic apparatus, as well as reduce the disturbance of water status of seedlings, contributing in this way to better condition of maize crops.     

外源硅对盐胁迫下黄果厚壳桂幼苗的光合荧光及抗氧化特性的影响

为探讨外源硅对盐胁迫下黄果厚壳硅的缓解作用。以一年生黄果厚壳桂(Cryptocarya concinna)幼苗为材料,在100 mg/L NaCl胁迫下,添加不同浓度(0、0.5、1、2 mmol/L)外源硅对幼苗进行处理,测定和分析不同处理下幼苗叶片的叶绿素含量、光合、叶绿素荧光特性参数和抗氧化酶含量。结果表明,外源硅能不同程度提高Pn、Tr、Gs、Fv/Fm,降低Ci;提高叶绿素a、叶绿素b和类胡萝卜素含量;提高SOD、PPO和APX活性,降低MDA含量。其中PPO在1.0 mmol/L硅处理下效果最佳,其他指标均在 2.0 mmol/L硅处理效果最佳。可见,添加适度浓度硅可以缓解盐胁迫对黄果厚壳桂幼苗的伤害,提高其耐盐能力,该研究为黄果厚壳桂引种栽培提供参考。     

热处理对青椒冷害的影响及作用机理的研究

以新鲜青椒为试验材料,研究热处理抑制贮藏期间青椒冷害的发生和机理.采用37℃热处理24 h,对照为20℃,然后在0℃条件下贮藏;对贮藏过程中冷害发生及与冷害的发生相关的细胞膜渗透率、丙二醛含量、叶绿素含量以及自由基清除剂超氧化物歧化酶(SOD)、过氧化物酶(POD)、过氧化氢酶(CAT)活性的变化趋势进行了研究.结果表明,37℃热处理可以减轻青椒低温贮藏冷害发生,延缓细胞膜渗透率的上升和丙二醛(MDA)的积累,延缓叶绿素含量的下降,提高膜脂过氧化保护酶POD、SOD、CAT活性,保护膜的稳定性.     

两种生态型黄瓜幼苗光系统I抗氧化酶对弱光的响应

以2种生态型黄瓜品种为材料,在人工气候室内,研究了弱光对光系统I(PSI)水-水循环电子传递过程中一系列酶活性的影响,以期了解黄瓜苗期弱光响应的生理机制。结果表明,在弱光胁迫的早期,超氧化物歧化酶(SOD)、抗坏血酸过氧化氢酶(APX)和脱氢抗坏血酸还原酶(DHAR)活性比对照有所增加,但随着黄瓜幼苗对弱光的不断适应,3种酶活性逐渐降低。此时,耐弱光型品种(S1)叶片中的SOD、APX和DHAR活性增幅要明显高于S404,而单脱氢抗坏血酸还原酶(MDHAR)和谷胱甘肽还原酶(GR)活性在两供试材料中与对照相比均有所减弱。弱光下,S1叶片中MDHAR活性高于S404,而GR活性却低于S404。因此,耐弱光型黄瓜品种具有较高地清除活性氧和自由基的能力,可能通过调节NADPH在PS I水-水循环电子传递链中的分配来更好地适应弱光逆境。     

DMTU对香石竹切花花瓣水分胁迫的抗氧化效应

以香石竹切花马斯特品种为试材,以0、5 mmol/L、10 mmol/L三种浓度的二甲基硫脲(DMTU)作为瓶插液,对不同瓶插时期的香石竹切花花瓣细胞保护酶活性进行测定,以期从细胞膜保护酶水平上明确H2O2外源抑制剂DMTU改善香石竹切花应对水分胁迫能力的机理。实验结果显示:在瓶插前期用DMTU处理的超氧化物歧化酶(SOD)活性变化平稳,过氧化物酶(POD)活性显著高于对照,瓶插后期用DMTU处理的SOD活性、过氧化氢酶(CAT)活性均显著高于对照,POD活性低于对照,说明DMTU在瓶插早期主要对POD起到了保护作用,而瓶插后期主要对SOD和CAT起到了保护作用。对不同DMTU的浓度而言,浓度为10 mmol/L清除活性氧、维持保护酶活性的作用更强,但是10 mmol/L处理的瓶插寿命短于5 mmol/L处理,5 mmol/L处理的瓶插寿命长于对照,因此DMTU的处理浓度以5 mmol/L为宜。由此可见DMTU在香石竹切花衰老时可清除活性氧,提高保护酶活性,从而缓解水分胁迫带来的膜脂过氧化,延缓花瓣衰老进程,延长其瓶插寿命。     

Effects of Exogenous Abscisic Acid on Antioxidant System in Weedy and Cultivated Rice with Different Chilling Sensitivity under Chilling Stress

Two chilling‐tolerant genotypes, that is, weedy rice WR03‐45 and cultivated rice Lijiangxintuanheigu and two chilling‐sensitive genotypes, that is, weedy rice WR03‐26 and cultivated rice Xiuzinuo were used in this study to investigate the effects of exogenous abscisic acid (ABA) on protection against chilling damage as well as on changes in physiological features. The results showed that under chilling stress the increased levels of superoxide radical (), hydrogen peroxide (H₂O₂) and malondialdehyde (MDA) in WR03‐45 and Lijiangxintuanheigu were lower than those in WR03‐26 and Xiuzinuo. Activities of antioxidant enzymes (superoxide dismutase (SOD), catalase (CAT), ascorbate peroxidase (APX), glutathione reductase (GR)) and non‐enzymatic antioxidants (ascorbate acid (AsA) and reduced glutathione (GSH)) were enhanced in WR03‐45 and Lijiangxintuanheigu, whereas they were decreased significantly in WR03‐26 and Xiuzinuo. Application of exogenous ABA reduced the chilling damage in the four genotypes. The pre‐treatment with ABA decreased the levels of , H₂O₂ and MDA caused by chilling stress in the four genotypes through increasing the activities of SOD, CAT, APX, GR and the contents of AsA and GSH in the four genotypes under chilling stress. Moreover, pre‐treatment with Fluridone, the ABA biosynthesis inhibitor, prohibited the effects of ABA through enhancing the oxidative damages and suppressing the antioxidant defence systems under chilling stress. The results indicate the mechanism for rice with chilling tolerance is to enhance the capacity of antioxidant defence systems under chilling stress. Furthermore, ABA plays important roles in the tolerance of rice against chilling stress for it could induce the capacity of whole antioxidant defence systems including enzymatic and non‐enzymatic constitutions under chilling stress.     

硒对生菜抗氧化酶活性及光合作用的影响

以盆栽试验研究了叶面喷施不同浓度硒对生菜SOD、POD、MDA、光合特性及生长的影响。结果表明：低浓度硒提高了SOD、POD活性,净光合速率、蒸腾速率和气孔导度,促进了生菜生长,而高浓度硒则起抑制作用;MDA随着喷施硒浓度的增大呈升高趋势,胞间CO2浓度随喷施硒浓度的增加而增加。总之,适量的硒处理能增强生菜的抗氧化能力和光合作用,提高产量。     

Exploring the Role of Calcium to Improve Chilling Tolerance in Hybrid Maize

Abiotic stresses, including chilling, impede the plant growth and development mainly by oxidative damage. In this study, seed priming with CaCl₂ was employed to reduce the damage caused by chilling stress in hybrid maize. Maize hybrid (Hycorn 8288) seeds were soaked in 50, 100 and 150 mg l⁻¹ (ppm) aerated solution of CaCl₂ for 24 h and dried. Treated and untreated seeds were sown at 27 °C (optimal temperature) and 15 °C (chilling stress) under controlled conditions. Seed priming with CaCl₂ significantly reduced the chilling damage and improved the germination rate, root and shoot length, and seedling fresh and dry weights. Activities of antioxidants, including catalase, superoxide dismutase and ascorbate peroxidase, were also improved. Soluble sugars and α-amylase concentrations determined as general metabolic indicators of stress were also increased by seed priming with CaCl₂. Priming also improved the performance of maize at optimal temperature. Maintenance of tissue water contents, reduction in membrane leakage and increase in antioxidant activities, and carbohydrate metabolism seemed to induce chilling tolerance by CaCl₂. Seed priming with 100 mg l⁻¹ CaCl₂ was the optimal concentration in improving the performance of hybrid maize both under optimal and stress conditions.     

玉米抗感种质资源苗期耐盐性的光合作用机制研究

土壤盐渍化程度日趋严重,成为影响作物生长发育、制约产量的一个主要环境因子,明确玉米苗期耐盐的光合作用机制尤为重要.本研究采用水培法,对已耐盐性鉴定筛选的强耐盐型自交系(B46)和盐高度敏感型自交系(NC236)为材料,分析二者在盐胁迫条件下光合作用的变化.低浓度盐(55 mmol/L NaCl)胁迫条件可促进玉米自交系...     

Chilling Tolerance of Maize Seedlings in the Field during Cold Periods in Spring is Related to Chilling-Induced Increase in Abscisic Acid Level

Recent studies on chilling tolerance mechanisms in maize revealed a significant positive correlation between genotypic chilling tolerance and chilling‐induced accumulation of the stress hormone abscisic acid (ABA) under controlled growth chamber conditions. Based on this and other results, the hypothesis was developed that chilling tolerance in maize is related to the ability to accumulate large amounts of ABA rapidly, as a protection against chilling injury. The objective of the present study was to test this hypothesis under field conditions during natural cold weather periods in spring, which often cause severe chilling injury in maize fields. In two experiments at two locations in Europe with contrasting climates, eight maize genotypes with different genotypic chilling tolerance were cultivated in spring in the field according to agronomic practice for maize. Before and at the end of cold weather periods, ABA levels and water contents were determined in the third leaves. It was found that chilling‐tolerant genotypes accumulated higher amounts of ABA during the chilling period than chilling‐sensitive genotypes. A significant positive correlation between chilling tolerance and the levels of ABA in the leaves was found. These results support the above‐mentioned hypothesis. In contrast to earlier studies performed under growth chamber conditions, the water content in chilled leaves was mostly higher than in non‐chilled leaves. The increase in ABA is therefore not attributable to chilling‐induced water deficit, but probably to the low temperature itself.     

NaCl胁迫对甜高粱幼苗抗性酶活性的影响

【研究目的】研究了不同浓度盐胁迫下甜高粱幼苗的抗性酶的活性及MDA和可溶性蛋白的含量。【方法】甜高粱幼苗采用水培的方法,设了3个盐梯度,1个对照。【结果】随着NaCl胁迫的加剧（当NaCl浓度大于50 mmol•L-1时）甜高粱幼苗膜脂过氧化程度不断加大,膜系统受到破坏;膜保护酶（POD,SOD,CAT,APX）活性降低,200 mmol•L-1 NaCl处理的酶活下降最大,100 mmol•L-1 NaCl处理次之,使体内酶促和非酶促防御系统均遭到破坏,活性氧含量增加对幼苗产生毒害。其中,100 mmol•L-1 NaCl处理后膜脂过氧化程度较轻,膜系统受害程度也轻于200 mmol•L-1 NaCl处理。【结论】轻度盐胁迫（当NaCl浓度是50 mmol•L-1）时,由于抗性酶的作用,活性氧对膜系统没有产生破坏作用。随着盐浓度的增加,抗性酶的活性降低,活性氧的含量不断增加,膜系统受破坏程度也不断加大。     

NaCl胁迫对胡卢巴幼苗抗氧化酶活性和丙二醛含量的影响

以胡卢巴幼苗为试验材料,研究NaCl胁迫下胡卢巴幼苗叶和根中抗氧化酶SOD、POD、CAT活性及丙二醛(MDA)含量的变化。结果表明:随着NaCl处理浓度的升高,SOD、POD、CAT活性总体呈现先上升后下降的趋势,MDA含量则呈上升趋势。叶片中抗氧化酶活性在NaCl浓度为1.0%时达到峰值,根中抗氧化酶活性在NaCl浓度为0.5%时达到峰值。在0.5%的NaCl浓度处理下,随着处理时间的延长,3种抗氧化酶协同作用,使MDA含量减少并控制在较稳定的阶段。可见,盐胁迫下胡卢幼苗可通过提高抗氧化酶活性,降低膜质过氧化水平,减缓盐胁迫对植株的伤害,从而增强其耐盐性。     

盐胁迫下LaCl3和CPZ对稻苗抗氧化酶类活性的影响

以质膜Ca2+通道阻断剂LaCl3和钙调素(CaM)拮抗剂氯丙嗪(CPZ)对水稻幼苗预处理以阻碍Ca2+*CaM信使传导后, 览研究了盐胁迫下, 稻苗保护酶活性的变化. 结果表明: 0.15 mol/L NaCl胁迫下, LaCl3和CPZ预处理显著加剧稻苗过氧化氢酶 (CAT)活性和抗坏血酸过氧化物酶(APX)活性下降; 对谷胱甘肽还原酶(GR)活性则无明显影响; 而超氧化     

再生水灌溉对冬小麦不同生育期抗氧化酶系的影响

通过对冬小麦再生水灌溉与清水灌溉的比较研究,从作物生理角度确定再生水灌溉的可行性。试验采用不同预处理的城市再生水;同时进行大田和盆栽两种培育方式;以冬小麦叶片为检测样品;以可溶性蛋白、丙二醛（MDA）含量、过氧化氢酶（CAT）、超氧化物歧化酶（SOD）、超氧化物酶（POD）为测定生物学指标作为评价。分别在不同生育期测试了再生水灌溉和清水灌溉冬小麦下,上述指标的差异。结果表明：再生水灌溉与清水灌溉对冬小麦抗氧化酶系的影响没有显著差异,从而说明以再生水灌溉冬小麦是可行的。     

自毒物质对番茄幼苗光合作用及保护酶活性的影响及碳化玉米芯的缓解作用

探讨缓解根系腐解液自毒物质抑制番茄幼苗生育的方法。试验以珍珠岩基质进行盆栽试验,研究了珍珠岩基质中添加碳化玉米芯对番茄根系腐解液抑制番茄幼苗生长、光合作用及番茄叶片保护酶活性变化的缓解效果。结果表明:与对照相比,施用番茄根系腐解液对幼苗的生物量、叶绿素含量、光合作用指标均具有显著的抑制作用,番茄叶片的保护性酶活性在处理初期提高,随着处理时间的延长,POD和CAT活性明显下降,同时显著增加了番茄叶片内MDA的含量。在添加碳化玉米芯或活性炭可显著缓解番茄根系腐解液对番茄幼苗的毒害作用。与活性炭相似,碳化玉米芯具有显著缓解番茄根系腐解液自毒物质抑制番茄幼苗生长的作用。因此,番茄生产中施用碳化玉米芯可作为防止番茄连作障碍的措施之一。