干旱胁迫下苎麻的生理生化变化与抗旱性的关系

 在干旱胁迫下 ,抗旱性强的品种叶片相对含水量、细胞膜的稳定性高 ,随着干旱胁迫加强 ,抗旱性强的品种过氧化物酶活性提高 ,复水后下降快 ;而抗旱性弱的品种在一定限度胁迫下过氧化物酶活性增加 ,严重胁迫下则大幅度下降 ,然后复水后呈缓慢下降趋势 ;在干旱胁迫较轻时 ,抗旱性弱的品种积累游离脯氨酸多于抗旱性强的品种 ,而随着胁迫加强 ,抗旱性强品种游离脯氨酸积累强度大于抗旱性弱的品种 ;复水后抗旱性强的品种游离脯氨酸下降快 ,而抗旱性弱的品种则下降缓。干旱胁迫下苎麻叶片丙二醛 (MDA)含量增加 ,随着胁迫加强 ,抗旱性弱的品种增加的速度快 ,抗旱性强的品种增加的速度慢     

烤烟和白肋烟及香料烟抗旱能力的比较研究

为了在生产中选择抗旱性较强的品种提供理论依据,在研究了水分胁迫下烤烟、自肋烟、香料烟抗旱能力的同时,还对干旱胁迫下烟草不同部位叶片的伸展速度、茎高、茎围、叶片萎蔫状况、复水后叶姿恢复能力等抗旱生物学指标和烟叶含水量、叶绿素含量、根系活力、细胞膜透性等生理指标进行了系统研究．结果表明：香料烟(沙姆逊种)的抗旱性最强,烤烟(NC89)次之,白肋烟(白肋21)的抗旱性较差．对有关抗旱指标比较表明：生物学指标以第3叶伸长速率对干旱较敏感,用于抗旱鉴定效果较好,而用萎蔫状况来判断烟草抗旱性则需要长时间的观察．生理指标中以叶片含水量变化较为敏感,叶绿素含量和细胞膜透性也是判断烟草抗旱性的敏感指标,对下部烟叶进行抗旱生理指标鉴定更为有效．     

水分胁迫对水稻结实期活性氧产生和保护系统的影响

 【目的】探索不同抗旱品种在结实期水分胁迫条件下叶片活性氧对水稻膜脂的伤害和清除机制。【方法】选用抗旱性不同的3个杂交水稻品种，在干旱棚内分别在正常供水和水分胁迫条件下，研究水稻结实期超氧阴离子自由基（O2-）、双氧水（H2O2）、丙二醛（MDA）、还原型谷胱甘肽（GSH）、抗坏血酸（AsA）及保护性酶活性等生理性状变化。【结果】结实期随土壤水分胁迫加剧和时间延长，细胞膜脂过氧化加重，抗旱性弱的品种膜脂过氧化更为严重；O2- 和H2O2积累迅速，抗旱性弱的品种比抗旱性强的品种积累速度快、幅度大；GSH、AsA、叶绿素含量和叶片相对含水量下降，且表现为，抗旱性弱的品种降速快、幅度大。抽穗后0～14 d随胁迫时间的延长叶片内超氧化物歧化酶（SOD）、过氧化氢酶（CAT）和过氧化物酶（POD）3种酶活性升高，随后下降。【结论】抗旱性强的品种具有较强的抗氧化能力；O2-积累速率、H2O2含量、叶片MDA含量、GSH含量、AsA含量及保护性酶活性的变化幅度与品种的抗旱性密切相关。     

玉米苗期抗旱性鉴定指标的研究

采用盆栽鉴定试验,以7个不同基因型玉米品种为材料,研究了正常灌水和干旱胁迫下玉米苗期抗旱生理生化和物质生产表现,结果表明:干旱胁迫下,丙二醛(MDA)含量增加,渗透调节物质脯氨酸、可溶性糖含量升高,保护酶SOD、POD活性升高,叶绿素含量减少,光合作用能力及水分利用效率(WUE)下降,导致玉米品种干物质积累降低;通过相关分析、主成分分析和灰色关联分析,筛选出WUE、POD、脯氨酸、叶绿素含量等生理生化指标作为玉米品种苗期重要的抗旱性评价指标,在抗旱性鉴定中加以利用。     

干旱及复水对不同抗旱性玉米光合特性的影响

采用盆栽试验,以抗旱性不同的玉米品种郑单958和陕单902为试材,在水分胁迫0、3、6、9天和复水3、6、9天条件下,通过气体交换和叶绿素荧光技术,研究水分胁迫和复水后叶片的气体交换、叶绿素荧光参数、叶绿素的变化特征。结果表明,随着水分胁迫天数的增加,陕单902的Pn、Ci、Gs、Fv/Fm、Yield、qP、Chl等指标的下降幅度均大于郑单958;NPQ上升的幅度大于郑单958。郑单958的光系统在水分胁迫时受到的伤害程度要小于陕单902。复水后郑单958的光合参数、叶绿素荧光参数、叶绿素等迅速恢复,陕单902光合参数及其他参数恢复缓慢。在水分胁迫条件下,耐旱玉米品种郑单958能保持良好的光合特性,在复水后,具有良好的生理补偿效应,是适应干旱环境的重要生理因素。     

干旱及复水处理对抗旱性不同小麦品种/系苗期生理生化指标的影响

为明确干旱胁迫及复水处理对抗旱性不同小麦材料生理指标的影响,以抗旱型品种‘靖麦12号’与干旱敏感型品系‘皮麦’为材料,以正常水分管理作为对照,待小麦长至三叶期,采用干旱胁迫-复水法,取幼苗叶片测量过氧化氢酶、过氧化物酶、超氧化物歧化酶、丙二醛、脯氨酸、脱落酸、总抗氧化能力、可溶性蛋白、可溶性糖以及叶绿素等生理指标的变化情况。结果表明：抗旱型品种‘靖麦12号’与干旱敏感型品系‘皮麦’的保护酶活性、总抗氧化能力、可溶性糖及叶绿素含量均存在显著差异及极显著差异;干旱胁迫下,保护酶活性、脯氨酸、丙二醛、脱落酸、总抗氧化能力均呈上升趋势,可溶性糖、可溶性蛋白及叶绿素含量却明显降低;复水以后,保护酶活性、脯氨酸、总抗氧化能力、可溶性蛋白、可溶性糖含量明显降低,叶绿素、脱落酸、丙二醛含量明显上升;两品种/系的处理与对照间脱落酸、丙二醛含量不存在明显差异。在干旱胁迫和复水情况下,‘靖麦12号’表现出较高的酶活性和较高渗透调节物质且叶绿素含量下降缓慢,因此‘靖麦12号’具有较高的抵御干旱胁迫以及复水后的恢复能力,可作为云南地区重要的抗旱种质资源。     

哈密瓜苗期抗旱相关指标及主成分分析

[目的]在于旱胁迫条件下,研究哈密瓜幼苗与抗旱性有关的生理指标并进行主成分分析,为哈密瓜的抗旱育种提供理论基础.[方法]利用抗旱性不同的9份哈密瓜品种,采取盆栽控水技术进行水分干旱胁迫处理,测定与植物抗旱性有关的游离脯氨酸、甜菜碱、叶绿素、丙二醛(MDA)和保护性酶活性的变化等生理生化指标并对各指标进行主成分分析.[结果]苗期干旱胁迫增加了游离脯氨酸、甜菜碱、MDA、可溶性糖含量、超氧化物歧化酶(SOD)、过氧化物酶(POD)的活性,同时减少了叶绿素含量.[结论]通过主成分分析,干旱胁迫下游离脯氨酸、MDA、可溶性糖、SOD、POD、叶绿素均可作为哈密瓜苗期抗旱性的鉴定指标,在9份参试品种中,西州密24号抗旱性最强,红心脆抗旱性最弱.     

宁南山区旱地冬小麦品种和自育高代品系资源抗旱性鉴定研究

干旱是影响宁夏春小麦产量的重要因素之一.为了研究小麦品种的抗旱性与形态或生理指标的关系,本试验通过室内模拟干旱条件,在生育期对不同抗旱性小麦品种和自育高代品系资源分别对抗旱系数、株高、离体叶片失水速率、叶片含水量等形态和生理指标进行了研究分析.结果发现,在干旱胁迫条件下,抗旱强的品种(系)抽穗期叶绿素含量、离体叶片失水速率与抗旱性中等和抗旱性弱的有一定差别.本研究将为小麦抗旱育种提供理论依据.     

干旱胁迫对油菜蕾薹期生理特性及农艺性状的影响

【目的】针对长江流域特别是长江上游近几年春季降水偏少易导致干旱的特点,研究水分胁迫对油菜蕾薹期生理特性及农艺性状的影响,为揭示油菜蕾薹期抗旱机制及抗旱品种选育提供理论依据。【方法】采用盆栽的方式,在遮雨网室对两种抗旱性不同的油菜品种中双10号（抗旱性弱）和94005（抗旱性强）蕾薹期进行干旱胁迫,以各性状的抗旱系数研究油菜相关生理指标及农艺性状的变化,在此基础上筛选出适用于该区域油菜蕾薹期抗旱性鉴定的指标。【结果】随着干旱时间的延长,两种油菜的叶片净光合速率、气孔导度、蒸腾速率、胞间二氧化碳浓度、RWC、叶绿素含量、RuBP羧化酶活性、株高、茎粗、一次分枝数以及单株产量抗旱系数均呈下降趋势,下降幅度与胁迫时间成正相关。其中,气孔导度、蒸腾速率抗旱系数下降幅度与材料抗旱性成正相关,其余指标则与材料抗旱性成负相关。抗旱性弱的材料气孔限制值、水分利用率抗旱系数分别呈现出上升-下降与一直下降的趋势,抗旱性强的材料则均为上升趋势。POD、SOD、CAT活性、可溶性糖以及可溶性蛋白相对值随着干旱胁迫时间的延长先升高后下降,抗旱性强的材料增加幅度高于抗旱性弱的材料;细胞膜透性、丙二醛（MDA）含量和脯氨酸相对值随干旱胁迫时间的延长呈上升趋势。对干旱胁迫下的油菜蕾薹期和复水后的成熟期相关指标之间的关系进行分析表明,干旱胁迫下,产量与净光合速率、RWC、叶绿素含量和一次分枝数抗旱系数呈极显著正相关,与细胞膜透性、MDA含量抗旱系数呈显著负相关。主成分分析将单株产量、净光合速率、胞间二氧化碳浓度、气孔限制值、水分利用率、RWC、叶绿素、RuBP羧化酶、SOD、POD、CAT、细胞膜透性、MDA、可溶性糖、株高、茎粗及一次分枝数划分为第一主成分;将叶片气孔导度、蒸腾速率、脯氨酸、可溶性蛋白划分为第二主成分。【结论】第一主成分的各指标（单株产量、净光合速率、胞间二氧化碳浓度、气孔限制值、水分利用率、RWC、叶绿素、RuBP羧化酶、SOD、POD、CAT、细胞膜透性、MDA、可溶性糖、株高、茎粗及一次分枝数）变化与品种抗旱性密切相关,在油菜抗旱品种选育时可作为油菜蕾薹期抗旱性鉴定的主要指标,第二主成分的各指标（叶片气孔导度、蒸腾速率、脯氨酸、可溶性蛋白）则是次要鉴选指标。     

抽雄期干旱胁迫与复水对不同玉米品种生长及产量的影响

[目的]探讨广西不同玉米品种在抽雄期对干旱胁迫及旱后复水的响应,为玉米抗旱机理研究、抗旱品种选育及广西玉米秋播用种选择提供理论依据.[方法]在大棚内采用桶栽法对桂单0810、迪卡008、正大619、琛玉969和桂单901等5个玉米品种在抽雄期进行4、8、12、16和20d的干旱胁迫处理及相应胁迫时间后的复水处理试验,每个品种均以正常浇水为对照.[结果]干旱胁迫下各玉米品种的冠干重、根干重、次生根数、最长根长和绿叶数均比对照下降,且各指标与对照比值随胁迫时间的延长而下降.复水后,各指标的恢复生长量随胁迫时问的增加而减少;除最长根长在干旱胁迫4 d后复水出现超补偿生长外,其他指标均未产生超补偿效应.桂单0810、迪卡008和正大619在干旱胁迫下各指标的降幅均小于琛玉969和桂单901;复水后,前者的恢复能力又高于后者桂单0810、迪卡008和正大619的抗旱系数和抗旱指数均高于琛玉969和桂单901,通过抗旱系数的聚类分析,可将5个玉米品种分为两大类,桂单0810、迪卡008和正大619归为抗旱性较强的品种,桂单901和琛玉969归为抗旱性较弱的品种.[结论]桂单0810、迪卡008和正大619在抽雄期受干旱胁迫时根、冠生长所受影响较小,且在复水后能够有效地恢复生长,从而保证较高的生物量及产量,可作为广两秋播玉米抗旱品种推广应用.     

Evaluation of Chlorophyll Content and Fluorescence Parameters as Indicators of Drought Tolerance in Barley

Drought is a major abiotic stress that severely affects food production worldwide. Agronomic and physiological traits associated with drought tolerance are suitable indicators for selection of drought tolerance genotypes to reduce the impact of water deficit on crop yield in breeding program. The objective of this study was to identify indicators related to drought tolerance through analysis of photosynthetic traits in barley （Hordeum vulgare L.）. These traits included chlorophyll content, initial fluorescence （Fo）, maximum primary yield of photochemistry of photosystem Ⅱ （Fv /Fo） and maximum quantum yield of photosystem Ⅱ （Fv/Fm）. Four genotypes （Tadmor, Arta, Morocco9-75 and WI2291） variable in drought tolerance were used to investigate the correlation between these traits and drought tolerance. The results reflected that all of these traits were affected negatively in the four genotypes at different levels of post-anthesis drought stress, but the decrease in drought tolerant genotypes was much less than that of drought sensitive genotypes. The results further revealed that the components of the photosynthetic apparatus could be damaged significantly in drought sensitive genotypes, while drought tolerant genotypes were relatively less affected. On the other hand, the values of chlorophyll content, Fo, Fv/Fo and Fv/Fm in drought tolerance genotypes were significantly higher than those in drought sensitive genotypes under drought stress. It was concluded that chlorophyll content, Fo, Fv/Fo and Fv/Fm could be considered as reliable indicators in screening barley germplasm for drought tolerance.     

Screening of drought resistance indices and evaluation of drought resistance in cotton (Gossypium hirsutum L.)

Sixteen cotton cultivars widely planted in China were sowed under five different drought concentrations (0, 2.5, 5, 7.5, and 10%) using PEG₆₀₀₀ to screen the indices of drought resistance identification and explore the drought resistance of different cotton cultivars. Eighteen physiological indices including root, stem, and leaf water contents (RWC, SWC, and LWC), net photosynthetic rate (P_n), the maximum photochemical quantum yield (F_v/F_m), the actual photochemical quantum yield (ϕPSII), non-photochemical quenching coefficient (NPQ), leaf water potential (LWP), osmotic potential (ψs), leaf relative conductivity (REC), leaf proline content (Pro), leaf and root soluble protein contents (LSPC and RSPC), leaf and root malondialdehyde (MDA) contents (LMDA and RMDA), root superoxide dismutase, peroxidase, and catalase activities (RSOD, RPOD, and RCAT) were measured. Results indicated the 18 physiological indices can be converted into five or six independent comprehensive indices by principal component analysis, and nine typical indices (F_v/F_m, SWC, LWP, Pro, LMDA, RSPC, RMDA, RSOD, and RCAT) screened out by a stepwise regression method could be utilized to evaluate the drought resistance. Moreover, the 16 cotton cultivars were divided into four types: drought sensitive, drought weak sensitive, moderate drought resistant, and drought resistant types. The resistance ability of two selected cotton cultivars (drought resistant cultivar, Dexiamian 1; drought sensitive cultivar, Yuzaomian 9110) with contrasting drought sensitivities were further verified by pot experiment. Results showed that the responses of final cotton biomass, yield, and yield composition to drought were significantly different between the two cultivars. In conclusion, drought resistant cultivar Dexiamian 1 and drought sensitive cultivar Yuzaomian 9110 were screened through hydroponics experiment, which can be used as ideal experimental materials to study the mechanism of different cotton cultivars with contrasting drought sensitivities in response to drought stress.     

Effect of low-nitrogen stress on photosynthesis and chlorophyll fluorescence characteristics of maize cultivars with different low-nitrogen tolerances

Nitrogen(N) is a critical element for plant growth and productivity that influences photosynthesis and chlorophyll fluorescence. We investigated the effect of low-N stress on leaf photosynthesis and chlorophyll fluorescence characteristics of maize cultivars with difference in tolerance to low N levels. The low-N tolerant cultivar ZH311 and low-N sensitive cultivar XY508 were used as the test materials. A field experiment(with three N levels: N0, 0 kg ha–1; N1, 150 kg ha–1; N2, 300 kg ha–1) in Jiyanyang, Sichuan Province, China, and a hydroponic experiment(with two N levels: CK, 4 mmol L–1; LN, 0.04 mmol L–1) in Chengdu, Sichuan Province, China were conducted. Low-N stress significantly decreased chlorophyll content and rapid light response curves of the maximum fluorescence under light(Fm′), fluorescence instable state(Fs), non-photochemical quenching(qN), the maximum efficiency of PSII photochemistry under dark-adaption(Fv/Fm), potential activity of PSII(Fv/Fo), and actual photochemical efficiency of PSII(ΦPSII) of leaves. Further, it increased the chlorophyll(Chl) a/Chl b values and so on. The light compensation point of ZH311 decreased, while that of XY508 increased. The degree of variation of these indices in low-N tolerant cultivars was lower than that in low-N sensitive cultivars, especially at the seedling stage. Maize could increase Chl a/Chl b, apparent quantum yield and light saturation point to adapt to N stress. Compared to low-N sensitive cultivars, low-N tolerant cultivars maintained a higher net photosynthetic rate and electron transport rate to maintain stronger PSII activity, which further promoted the ability to harvest and transfer light. This might be a photosynthetic mechanism by which low-N tolerant cultivar adapt to low-N stress.     

干旱胁迫对辣椒生理机制的影响研究

以湘研1、5、10号为试材,研究干旱胁迫下辣椒相关生理指标的变化。干旱胁迫下辣椒组织的相对含水量和叶绿素含量呈下降趋势;脯氨酸含量急剧增加;质膜相对透性和丙二醛含量先降低后增加。不同品种间的差异显示:总体上抗旱性强的品种保持着相对较高的组织相对含水量、叶绿素含量和脯氨酸含量,相对较低的丙二醛含量和质膜相对透性,抗旱性弱的品种则相反。组织相对含水量、丙二醛含量和脯氨酸含量可作为辣椒抗旱性鉴定的直接指标,而叶绿素含量可作为辣椒抗旱性鉴定的间接指标。     

Responsibility of non-stomatal limitations for the reduction of photosynthesis—response of photosynthesis and antioxidant enzyme characteristics in alfalfa (Medicago sativa L.) seedlings to water stress and rehydration

Water stress by polyethylene glycol (PEG)-6000 solution (ψ _s = 0.2 MPa, stress time: 48 h, rehydration time: 48 h) was performed in leaves of two alfalfa cultivar (Long-Dong and Algonquin) seedlings. Gas exchange parameters, chlorophyll fluorescence parameters, activity of antioxidant enzyme and photosynthetic pigment concentrations were measured to investigate the available photosynthetic and antioxidant enzyme response to variable water conditions as well as stomatal and non-stomatal limitations to photosynthesis. The results showed that non-stomatal limitations were responsible for the reduction of photosynthesis during water stress. At the beginning of water stress (12 h), water was lost and then the stomata closed rapidly, which resulted in a decrease of transpiration, net photosynthesis and CO₂ diffusion. Therefore, when intercellular CO₂ concentration and carboxylation efficiency decrease, water use efficiency and value of stomatal limitation would increase. However, the decline of net photosynthetic rate was faster than transpiration rate. At the same time, the maximal photochemical efficiency, potential activity of PSII reaction center and photochemical quenching of chlorophyll fluorescence declined significantly, the activity of antioxidant enzyme increased rapidly and the photosynthetic pigment concentrations changed slightly. The results also indicated that, at the initial period of stress, neither oxidative stress nor membrane lipid peroxidation was induced, nor were photosynthetic structures damaged, but photosynthetic functions were partly inhibited. Therefore, the stomatal limitation and non-stomatal limitations had the same responsibility for the reduction of photosynthesis. At the mid-late stage of water stress, net photosynthetic rate, stomatal conductance, maximal photochemical efficiency, potential activity of PSII reaction center and photochemical quenching of chlorophyll fluorescence decreased linearly with the decline of the relative water content. And the relative electron transport rate, the effective quantum yield of PSII photochemistry and photosynthetic pigment concentrations declined continually. The activity of antioxidant enzymes maintained at a higher level but malondialdehyde accumulated gradually with prolonging of water stress. Simultaneously, the non-photochemical quenching of chlorophyll fluorescence increased obviously after water stress for 24 h. The remarkable decline of light saturated point of photosynthetic electron transport, that is, the initial point of photo-inhibition, was observed in advance. Therefore, non-stomatal limitations dominated the changes of a series of physiological and biochemical reactions during mid-late period of water stress. After 48 h rehydration, all the parameters except intercellular CO₂ concentration in Long-Dong recovered obviously but incompletely, which resulted from severe oxidative injury and photo-inhibition induced by water stress even though photo-protection was triggered during water stress in alfalfa leaves. Alfalfa seedlings were sensitive to water stress and there were certain differences between cultivars.     

干旱胁迫及复水对大豆抗坏血酸-谷胱甘肽循环的影响

为明确大豆耐旱机制,以黑农44(耐旱型品种)和黑农65(敏感型品种)为试验材料,采用盆栽方式,于大豆初花期作胁迫处理,而后复水。研究不同土壤含水率及复水后抗坏血酸-谷胱甘肽(ASA-GSH)循环中抗氧化物质含量及抗氧化酶活性变化。结果表明,土壤含水率降低改变ASA-GSH循环非酶和酶成分,诱导丙二醛(MDA)积累。ASA-GSH循环中,干旱胁迫处理下还原型抗坏血酸(ASA)、还原型谷胱甘肽(GSH)含量先升后降,脱氢抗坏血酸(DHA)、氧化型谷胱甘肽(GSSG)含量呈升高趋势,ASA/DHA呈先升后降趋势,GSH/GSSG呈高-低-高-低变化趋势,复水后ASA、DHA、GSH含量升高,GSSG含量下降。抗坏血酸过氧化物酶(APX)、单脱氢抗坏血酸还原酶(MDHAR)、脱氢抗坏血酸还原酶(DHAR)、谷胱甘肽还原酶(GR)活性呈先升后降趋势,复水后APX、GR、MDHAR、DHAR活性升高。黑农44抗氧化物质含量和抗氧化酶活性高于黑农65,MDA含量低于黑农65。研究为大豆抗旱筛选及抗氧化机制探究提供理论基础。     

Irrigation mitigates the heat impacts on photosynthesis during grain filling in maize

Elevating soil water content (SWC) through irrigation was one of the simple mitigation measures to improve crop resilience to heat stress. The response of leaf function, such as photosynthetic capacity based on chlorophyll fluorescence during the mitigation, has received limited attention, especially in field conditions. A two-year field experiment with three treatments (control treatment (CK), high-temperature treatment (H), and high-temperature together with elevating SWC treatment (HW)) was carried out during grain filling with two maize hybrids at a typical station in North China Plain. Averagely, the net photosynthetic rate (P_n) was improved by 20%, and the canopy temperature decreased by 1–3°C in HW compared with in H in both years. Furthermore, the higher SWC in HW significantly improved the actual photosynthetic rate (Phi2), linear electron flow (LEF), variable fluorescence (F_v), and the maximal potential quantum efficiency (F_v/F_m) for both hybrids. Meanwhile, different responses in chlorophyll fluorescence between hybrids were also observed. The higher SWC in HW significantly improved thylakoid proton conductivity (gH⁺) and the maximal fluorescence (F_m) for the hybrid ZD958. For the hybrid XY335, the proton conductivity of chloroplast ATP synthase (vH⁺) and the minimal fluorescence (F_o) was increased by the SWC. The structural equation model (SEM) further showed that SWC had significantly positive relationships with P_n, LEF, and F_v/F_m. The elevating SWC alleviated heat stress with the delayed leaf senescence to prolong the effective period of photosynthesis and enhanced leaf photosynthetic capacity by improving Phi2, LEF, F_v, and F_v/F_m. This research demonstrates that elevating SWC through enhancing leaf photosynthesis during grain filling would be an important mitigation strategy for adapting to the warming climate in maize production.     

壬基酚对四尾棚藻生长及群体形成的影响

选取水体中广泛存在的壬基酚为代表,研究其对四尾栅藻生理特性及群体形成的影响。实验设置6个暴露组(0.63、1.02、1.65、2.67、4.32和7.00 mg·L-1)和1个对照组(0 mg·L-1),测定了96 h内四尾栅藻细胞密度、叶绿素a含量、胞外多糖合成、最大光能转化效率(Fv/Fm)以及群体形态等变化。结果表明,四尾栅藻起始细胞密度6.64×105 cells·m L-1下,壬基酚对四尾栅藻细胞密度的EC50为2.05 mg·L-1;随着壬基酚质量浓度的提高,四尾栅藻的叶绿素a含量和Fv/Fm下降,四尾栅藻的生长受到抑制,但细胞胞外多糖含量增多,导致细胞间黏性增强,同时双细胞和多细胞(≥3个)群体占总细胞比例上升。     

Physiological response of four wolfberry (Lycium Linn.) species under drought stress

We studied gas-exchange, chlorophyll pigments, lipid peroxidation, antioxidant enzymes, and biomass partitioning responses in seedlings of four wolfberry species (Lycium chinense Mill. var. potaninii (Pojark.) A. M. Lu, Lycium chinense Mill., Lycium barbarum L., and Lycium yunnanense Kuang & A. M. Lu) under four water supply regimes. In all four species, drought affected seedlings in terms of chlorophyll content, net photosynthesis rate (P_n), transpiration rate (E), and lipid peroxidation. Drought also increased some antioxidant enzyme activities, such as peroxidase (POD), catalase (CAT), superoxide dismutase (SOD), and ascorbate peroxidase (APX). Significant changes in dry biomass partitioning also occurred in response to water stress. In particular, dry biomass of leaves and fruits decreased significantly. L. chinense Mill. and L. barbarum L. possessed greater drought tolerance and exhibited superior antioxidant processing ability and other related physiological traits compared to the other two species. L. chinense Mill. was the most tolerant to all levels of drought. In contrast, L. yunnanense Kuang & A. M. Lu was more affected by water supply and had the lowest resistance to drought stress. These findings would provide some important information regarding genetic resources for future forest tree improvement in relation to drought tolerance.     

芦苇对阿特拉津胁迫的生理响应及其与耐受性的关系

为揭示阿特拉津胁迫下芦苇的生理响应规律及其与芦苇耐受性的关系,通过水培实验研究了阿特拉津对芦苇叶绿素含量、抗氧化酶(SOD和POD)活性和叶绿素荧光参数的影响,并以植物相对生长率为耐受性指标,利用逐步回归法分析了各生理指标与耐受性的关系。结果表明:≤8 mg·L~(-1)阿特拉津胁迫1周,芦苇虽可正常存活,但相对生长率受到显著抑制;胁迫2周时,生长停止;叶绿素a(Chla)和叶绿素b(Chlb)随处理浓度的增加而降低。POD活性胁迫1周时显著增强,胁迫2周时最低和最高浓度处理(0.5、8 mg·L~(-1))较1周时有所下降,与对照无显著差异;而SOD活性随处理浓度增加无显著变化。随处理浓度的增加,F_v/F_m和F_v/F_0显著降低,qN显著增加,而胁迫2周较1周时qN显著下降。研究表明,芦苇对阿特拉津比较敏感,但在短期内(1周)表现一定的耐受性,主要是通过增强非光化学淬灭能力来保护叶绿体,从而保持一定浓度的叶绿素来维持光合作用的物质基础,抵抗来自阿特拉津的胁迫。