等渗的盐分和水分胁迫对芦荟幼苗生长和离子分布的效应

 研究了等渗透势（-0.44、-0.88 MPa）NaCl和PEG 6000处理对六叶龄芦荟(Aloe vera)幼苗叶片生长速率、干物质积累、电解质渗漏和离子吸收、分配的效应。结果表明: -0.44、-0.88 MPa NaCl和PEG处理10 d均明显抑制芦荟幼苗叶片伸长生长,植株干物质积累速率显著降低, 叶片含水量降低,叶片细胞电解质渗漏率上升。NaCl对芦荟幼苗生长的抑制作用显著大于PEG处理的。不同器官离子含量、根系和叶片横切面X-射线微区分析结果表明, NaCl胁迫导致芦荟体内Na+、Cl－含量显著上升,根中增幅明显高于叶片,其中Cl－尤为显著。NaCl胁迫严重抑制芦荟对K+ 和Ca2+ 的吸收及其向叶片的运输,根、叶K+/Na+、Ca2+/Na+ 比率显著下降,而PEG胁迫对离子平衡的干扰较轻,是芦荟对水分胁迫的适应能力高于盐胁迫的主要原因之一。但芦荟对 -0.44～-0.88 MPa NaCl胁迫仍有一定的适应能力,主要原因是：1) 根系对离子的选择性吸收和运输较强,并随着盐胁迫强度增加其选择性增强; 2) 芦荟叶片中的盐分在贮水组织中显著积累,明显高于其它组织细胞。同时,芦荟是CAM（景天酸代谢）途径植物,蒸腾极小,盐分随蒸腾流进入地上部的机会小。     

等渗的盐分和水分胁迫对杠柳种子萌发的影响

通过等渗的NaCl和PEG溶液模拟盐分和水分胁迫,设置渗透梯度,在控制条件下对杠柳种子的萌发过程中总萌发率、幼苗鲜重、胚根生长、种子活力、发芽值等指标系统研究,对种子萌发率与渗透势之间关系进行回归分析,主要结果包括：（1）杠柳种子萌发过程中总萌发率、幼苗鲜重、活力指数和发芽值四项指标均随NaCl和PEG溶液的渗透势降低逐渐下降,综合研究活力指数和发芽值表明渗透势≥-0.5 MPa和≤-1.4 MPa时,PEG对种子萌发抑制作用大于NaCl,其他情况相反;（2）杠柳种子逐日萌发率和胚根日变化研究表明,与NaCl相比,PEG推迟杠柳种子萌发,并且对胚根增长抑制作用较大;（3）建立盐分和水分胁迫条件下种子萌发率与渗透势回归方程,发现杠柳种子在PEG胁迫下的萌发临界值和极限值为-1.0和-1.4 MPa,在NaCl胁迫下是-0.9和-1.3 MPa,解除胁迫条件,不同处理的杠柳种子复水萌发率均达到100%。说明杠柳具有良好的耐盐抗旱的特性。     

温度对干旱、盐胁迫下两种黄芪属种子萌发和幼苗生长的影响

为探讨温度对干旱、盐胁迫下黄芪属种子萌发和幼苗生长特性的影响,以黄芪属蒙古黄芪和扁茎黄芪2种种子为研究对象,纯净水处理为对照组,NaCl、PEG处理为实验组,设置4个渗透势水平(0、-0.1、-0.3、-0.5 MPa),置于5种不同的温度(10、15、20、25、30 ℃)下,每日观察并记录两种种子萌发和幼苗生长情况。结果表明：旱盐胁迫下蒙古黄芪和扁茎黄芪种子萌发最适宜的温度分别为25和20 ℃左右;蒙古黄芪耐高温不耐低温,而扁茎黄芪恰恰相反;但25和20 ℃均适宜两种幼苗生长,包括胚根、胚轴和子叶的生长。蒙古黄芪各处理组(除未发芽的种子)的平均发芽时间都比扁茎黄芪长;NaCl胁迫程度的增加使得两种种子的最终发芽率降低,但蒙古黄芪的耐盐性高于扁茎黄芪;随着PEG胁迫程度的增加,二者的发芽均受到抑制,甚至会出现完全不萌发,但扁茎黄芪的耐旱性高于蒙古黄芪;在相同的渗透势时,尤其是-0.5 MPa,PEG比NaCl对两种种子的影响大;交互胁迫作用下,随着渗透势的增加两种幼苗的鲜重、干重以及胚根、胚轴、子叶的长和宽变化较大;利用Design Expert软件预测发现：温度25 ℃、NaCl渗透势为-0.1 MPa,温度24 ℃、PEG渗透势为-0.04 MPa的处理是蒙古黄芪种子萌发和幼苗生长达到最优化的组合;而扁茎黄芪最优化的组合则为23 ℃下NaCl渗透势为-0.07 MPa的处理,20 ℃下PEG渗透势为-0.13 MPa的处理。     

盐分和水分胁迫对菊芋幼苗离子吸收及叶片酶活性的影响

采用砂培试验,用不同浓度的NaCl和等渗PEG6000(聚乙二醇6000,渗透势约为-0．44MPa)处理生长20d的菊芋幼苗,3d后分别测定其根、茎、叶中的Na^ 、K^ 、Cl^-含量以及叶片SOD、POD活性。结果表明,在NaCl和PEG胁迫下,根、茎、叶的Na^ 、Cl^-含量不断升高,而K^ 含量保持稳定。其中,茎中Na^ 含量高于根和叶。NaCl胁迫下,根、茎、叶的SX、Na值随胁迫强度的增加而递增,茎中SK、Na值小于根和叶。随着NaCl胁迫强度的增加,菊芋幼苗叶片的SOD和POD活性先上升后下降;PEG处理下,SOD活性分别高于对照和等渗NaCl处理31．1％和27．1％;而POD活性却分别低于对照和等渗NaCl处理26．0％和36．1％。     

温度对干旱、盐胁迫下两种黄芪属种子萌发和幼苗生长的影响

为探讨温度对干旱、盐胁迫下黄芪属种子萌发和幼苗生长特性的影响,以黄芪属蒙古黄芪和扁茎黄芪2种种子为研究对象,纯净水处理为对照组,NaCl、PEG处理为实验组,设置4个渗透势水平(0、-0.1、-0.3、-0.5 MPa),置于5种不同的温度(10、15、20、25、30℃)下,每日观察并记录两种种子萌发和幼苗生长情况。结果表明:旱盐胁迫下蒙古黄芪和扁茎黄芪种子萌发最适宜的温度分别为25和20℃左右;蒙古黄芪耐高温不耐低温,而扁茎黄芪恰恰相反;但25和20℃均适宜两种幼苗生长,包括胚根、胚轴和子叶的生长。蒙古黄芪各处理组(除未发芽的种子)的平均发芽时间都比扁茎黄芪长; NaCl胁迫程度的增加使得两种种子的最终发芽率降低,但蒙古黄芪的耐盐性高于扁茎黄芪;随着PEG胁迫程度的增加,二者的发芽均受到抑制,甚至会出现完全不萌发,但扁茎黄芪的耐旱性高于蒙古黄芪;在相同的渗透势时,尤其是-0.5 MPa,PEG比NaCl对两种种子的影响大;交互胁迫作用下,随着渗透势的增加两种幼苗的鲜重、干重以及胚根、胚轴、子叶的长和宽变化较大;利用Design Expert软件预测发现:温度25℃、NaCl渗透势为-0.1 MPa,温度24℃、PEG渗透势为-0.04 MPa的处理是蒙古黄芪种子萌发和幼苗生长达到最优化的组合;而扁茎黄芪最优化的组合则为23℃下NaCl渗透势为-0.07 MPa的处理,20℃下PEG渗透势为-0.13 MPa的处理。     

NaCl对渗透胁迫下三角叶滨藜光合作用和水分状况的调节

以溶液培养的三角叶滨藜(Atriplex triangularis)为材料, 测定分析了在PEG诱导的渗透胁迫条件下, 适量的NaCl对其光合作用和水分吸收的影响, 以探讨环境溶液中NaCl对植物适应干旱的影响。结果表明, PEG诱导的渗透胁迫导致三角叶滨藜植株吸水困难、叶绿素含量降低、光合系统受损、生长受抑制、生物量减少; 而在PEG渗透胁迫的处理液中添加10–40 mmol·L^–1NaCl可以明显降低植株水势和叶片渗透势, 维持较高的细胞膨压, 减缓PEG渗透胁迫对光合系统的破坏作用, 保证相对较高的光合速率和生长速度, 从而有效增强了三角叶滨藜对渗透胁迫的适应能力。     

Na2CO3胁迫对芦荟幼苗叶片叶绿体保护酶和渗透调节物质的影响

以盆栽耐盐碱芦荟'不夜城'幼苗为材料,采用不同浓度Na2CO3溶液(不同渗透势)处理芦荟幼苗7 d后,测定其叶片叶绿体保护酶超氧化物歧化酶(SOD)、过氧化氢酶(CAT)、抗坏血酸氧化酶(APX)、谷胱甘肽转移酶(GST)活性以及叶绿素、丙二醛(MDA)、渗透调节物质含量和电解质外渗率等的变化,以探讨芦荟抵抗盐碱胁迫伤害的机制.结果显示:当溶液渗透势较高时(大于-7.19×105 Pa),Na2CO3胁迫下的芦荟幼苗叶片叶绿体保护酶活性都呈显著上升趋势,而叶绿素含量、可溶性蛋白、MDA含量以及电解质外渗率却无明显变化;在溶液渗透势较低时(小于-7.19×105 Pa),Na2CO3胁迫下芦荟幼苗的渗透调节物质含量显著增高,叶绿体保护酶活性特别是叶绿素含量显著下降,而MDA含量和电解质外渗率却呈上升的趋势.研究表明:一定浓度的Na2CO3胁迫下,芦荟幼苗可以通过提高自身叶绿体保护酶的活性来降低活性氧的积累量,同时提高渗透调节能力来增强其抗逆性;但在过高浓度的盐碱胁迫下,过高的Na+浓度和pH也会对芦荟幼苗叶片造成一定的氧化伤害.     

等渗Ca(NO3)2和NaCl胁迫对黄瓜幼苗生长及渗透调节物质含量的影响

采用营养液培养方法,以耐盐性较弱的‘津春2号’黄瓜品种为试材,研究了等渗Ca(NO3)2和NaCl胁迫对黄瓜幼苗生长、根系电解质渗透率、根系活力、Na+和K+含量及渗透调节物质含量的影响。结果显示:(1)在84mmol.L-1 NaCl和56mmol.L-1 Ca(NO3)2等渗胁迫下,黄瓜幼苗鲜重和干重均显著下降,且NaCl处理下降的幅度大于等渗Ca(NO3)2处理。(2)NaCl主要通过对黄瓜根系的伤害来抑制植株生长,表现为根系活力下降、根系质膜透性增大、Na+大量积累、K+含量显著下降、Na+/K+明显上升,最终导致根冠比下降;而Ca(NO3)2处理对根系质膜透性、K+含量、Na+/K+的影响均小于NaCl胁迫,且根系活力和根冠比上升,但Ca(NO3)2胁迫后叶片含水量和渗透调节能力均小于NaCl胁迫。(3)NaCl胁迫条件下,黄瓜幼苗内渗透调节物质以可溶性糖为主,而Ca(NO3)2胁迫以可溶性蛋白为主。研究表明,NaCl胁迫对黄瓜幼苗的伤害大于等渗Ca(NO3)2,NaCl主要通过破坏根系质膜结构影响植株生长,而Ca(NO3)2主要通过引起地上部生理干旱来影响植株生长。     

等渗Ca（NO3）2和NaCl胁迫对黄瓜砧用南瓜幼苗生长和活性氧代谢的影响

以黄瓜砧用黑籽南瓜和白籽南瓜幼苗为材料,通过营养液栽培研究了等渗Ca(NO3)2和NaCl胁迫对南瓜幼苗生长和活性氧代谢的影响。结果表明,不同盐胁迫下两砧木幼苗生长和抗氧化系统活性均受到不同程度抑制;与黑籽南瓜相比,白籽南瓜‘青砧1号’植株的生物量和SOD、POD和CAT活性均较高,而盐害指数、膜相对透性、MDA含量及O2.-产生速率则明显降低。等渗Ca(NO3)2和NaCl对两砧木南瓜幼苗的盐胁迫效应不同,Ca(NO3)2胁迫对砧木生长的抑制作用及盐害指数、膜相对透性、MDA含量、O2.-产生速率均小于等渗的NaCl处理,而其SOD、POD、CAT活性高于NaCl处理。可见,白籽南瓜‘青砧1号’具有较强的生长势和有效清除体内活性氧能力,有效降低膜质过氧化伤害程度,这是其耐盐性高于黑籽南瓜的重要原因;Ca(NO3)2处理使两砧木幼苗细胞受氧化损伤程度较轻,对植株生长的抑制程度明显低于等渗的NaCl。     

燕麦幼苗活性氧代谢和渗透调节物质积累对NaCl胁迫的响应

采用营养液砂培方法,研究了不同浓度NaCl胁迫(0、50、100、150、200和250mmol·L-1)对“定莜6号”燕麦幼苗生长、活性氧代谢和渗透调节物质含量的影响.结果表明:NaCl胁迫显著抑制燕麦幼苗的生长,抑制程度随NaCl浓度提高而增强,燕麦可耐受的最高NaCl浓度约为150 mmol·L-1;随着NaCl浓度的增加,叶片O2-产生速率、H2O2和丙二醛含量明显增加,超氧化物歧化酶、过氧化物酶和抗坏血酸过氧化物酶活性先升后降,过氧化氢酶活性迅速下降后逐渐升高,NaCl胁迫明显降低了谷胱甘肽含量,而抗坏血酸含量变化不大;NaCl胁迫显著提高了叶片脯氨酸含量,Na+含量随着NaCl浓度增加不断提高,K+含量和K+/Na+逐渐下降,质膜H+-ATP酶活性、总可溶性蛋白、热稳定蛋白和热不稳定蛋白含量先升后降,游离氨基酸含量先降后升,可溶性糖含量呈降-升-降趋势变化;盐胁迫下活性氧代谢失调和Na+、K+平衡破坏及积累有机溶质进行渗透调节时更多能量的消耗可能是燕麦生长受抑的重要因素.     

Iso-osmotic effect of NaCl and PEG on growth, cations and free proline accumulation in callus tissue of two indica rice (Oryza sativa L.) genotypes

One-month old calli of two indica rice genotypes, i.e., Basmati-370 and Basmati-Kashmir were subjected to two iso-osmotic concentrations (−0.57 MPa and −0.74 MPa) created with 50 and 100 mol m⁻³ NaCl or 10 and 18% solutions of PEG-8000. Both genotypes tolerated only low levels of stress and showed severe growth suppression at −0.74 MPa. The degree of stress tolerance of both genotypes was greater for PEG induced stress than for NaCl induced stress. The relative growth rate of callus was reduced under both stresses, however, the reverse was true for callus dry weight. Sodium (Na⁺) content of the callus tissue was increased only under NaCl induced stress. Salt induced stress reduced K⁺ and Ca²⁺ contents, but the PEG induced stress increased them. Higher levels of stress increased the proline content many folds with more increase being under PEG stress than that under NaCl. Water and osmotic potentials of the callus tissue decreased, whereas turgor potential increased under both abiotic stresses. Overall, Basmati-370 was more tolerant to both NaCl and PEG induced stresses than Basmati-Kashmir, because of less reduction in growth and more dry weight. Moreover, Basmati-370 accumulated higher amounts of cations, free proline, and maintained maximum turgor as compared to Basmati-Kashmir. In conclusion, at cellular level, mechanism of NaCl induced osmotic stress tolerance was found to be associated with more ionic accumulation of inorganic solutes and that of PEG induced osmotic stress tolerance with the accumulation of free proline, as an important osmolyte in the cytosol.     

Effect of Salinity on Germination and Seedling Growth of twoAtriplexspecies (Chenopodiaceae)

Salinity is one of the environmental factors that has a criticalinfluence on the germination of halophyte seeds and plant establishment.Salinity affects imbibition, germination and root elongation.However, the way in which NaCl exerts its influence on thesevital processes, whether it is through an osmotic effect ora specific ion toxicity, is still not resolved. Dimorphic seedsof the halophytesAtriplex prostrataandA. patulawere treatedwith various iso-osmotic solutions of NaCl and polyethyleneglycol (PEG). For each treatment, imbibition, germination rate,percent germination, germination recovery and nuclear area ofroot tip cells were compared. Higher concentrations of NaCl(-1.0 MPa) were more inhibitory to imbibition, germination andseedling root elongation than iso-osmotic PEG solutions. Allseeds recovered from a pre-treatment with -2.0 MPa NaCl andPEG solutions, except large seeds ofA. prostratawhich failedto germinate following transfer from -2.0 MPa NaCl. NaCl causeda greater increase in nuclear volume than iso-osmotic PEG solutions.These data suggest that the influence of NaCl is a combinationof an osmotic effect and a specific ion effect.Copyright 1998Annals of Botany Company Atriplex patula,Atriplex prostrata,cytophotometry, osmotic potential, salinity, seed germination.     

Effect of water and salt stresses on growth, chlorophyll, mineral ions and organic solutes contents, and enzymes activity in mung bean seedlings

The experiment was made by using different concentrations of polyethylene glycol (PEG) or salt solutions to decrease the osmotic potential of the growth medium to reveal the response of mung bean (Vigna radiata) to water and salt stresses. No germination (emergence of the seedling) occurred at medium osmotic potential lower than -1.0 MPa in all treatments. It was found that the activity of α-amylase and protease, and contents of proline, saccharides and the soluble proteins decreased in the germinating seeds during 3-d stress. However, after 10-d stress, the contents of organic solutes and the activity of the hydrolytic enzymes increased. Growth, chlorophyll content and mineral uptake were also significantly reduced under stress. The seedlings under water stress induced by PEG were affected much more than under salinity. This may be due to the maintenance of a higher succulence under salt stress than under PEG-induced water stress. This revised version was published online in August 2006 with corrections to the Cover Date.     

Osmotic adjustment in Lycopersicon esculentum and L. Pennellii under NaCl and polyethylene glycol 6000 iso–osmotic stresses

Changes in leaf solute contents in response to saline (NaCl) and osmotic (polyethylene glycol, PEG, 6000) stresses were measured in three different salt tolerant cultivars of Lycopersicon esculentum (L.) Mill. (Pera, P-73 and Volgogradskij), and its wild relative L. pennellii (Correll) D'Arcy accession PE-47. Iso-osmotic stresses (–0. 5 MPa) of NaCl (140 mM) and PEG 6000 (150 g l^-1) were applied to one-month old plants for 3 weeks. Decreasing leaf dry weight was similar in L. pennellii or L. esculentum cv. P-73 and Volgogradskij under both stresses, while leaf dry weight of L. esculentum cv. Pera decreased more under PEG stress than under NaCl stress. Water contents decreased in all the PEG treated populations, while their calculated solute potential (Ψ_s increased. Under osmotic stress, the total ion contents decreased in relation to control, whereas organic solutes (sugars, amino acids and organic acids) markedly increased in both tomato species, specially in the tomato cultivars, where these solutes represented 50% of the Ψ₅ calculated. Soluble sugar increase was three times higher in leaves of L. esculentum than in the leaves of L. pennellii. Free proline increased under both stresses and its content was highest in L. esculentum and in L. pennellii, respectively, under NaCl and PEG stresses. Nevertheless, the contribution of this metabolite to Ψ_s did not exceed 5%, irrespective of treatment and species. The greater organic solute accumulation in L. esculentum than in L. pennellii– which was not reflected in their Ψ₅ values – was not correlated with the tolerances of the two species to osmotic stress. Therefore, osmotic adjustment may not be the only process influencing salt and drought tolerances in tomato; the ability of plants to regulate their metabolic and physiological functions could also play an important role under these harmful conditions. The possible roles of inorganic solutes and metabolites in osmotic adjustment, energetic metabolism and redox regulation are discussed     

栽培和野生大豆及其杂交后代幼苗的耐氯性与多胺积累的关系

对经逐代耐盐性筛选的栽培和野生大豆杂交组合(‘Jackson’בBB52’)F4代‘JB185’株系及其亲本幼苗以不同浓度NaCl和等渗(-0.53 MPa)PEG-6000、NaCl、钠盐(无Cl-)和氯盐(无Na )溶液处理6d。结果表明:(1)随NaCl浓度的提高,3种遗传材料幼苗叶片相对电解质渗漏率和MDA含量均呈上升趋势,叶绿素含量除‘BB52’和‘JB185’在NaCl 50mmol/L处理时显著上升外,其余处理呈下降趋势,‘JB185’变化介于两亲本之间。(2)不同离子胁迫下,它们叶片相对电解质渗漏率和MDA含量较对照多表现增加趋势,其中‘BB52’和‘JB185’在钠盐(无Cl-)处理下的变化明显大于氯盐(无Na )处理。叶片中游离态和束缚态Put、Spd和Spm含量都较对照明显提高,但‘BB52’和‘JB185’在钠盐(无Cl-)处理下游离态(Spd Spm)/Put比值和束缚态多胺总量为3种盐处理中最低。表明‘JB185’与野生大豆‘BB52’种群一样对Na 敏感而对Cl-表现较强的耐性。     

Drought tolerance in faster- and slower-growing black spruce (Picea mariana) progenies: II. Osmotic adjustment and changes of soluble carbohydrates and amino acids under osmotic stress

The possibility was considered that osmotic adjustment, the ability to accumulate solutes in response to water stress, may contribute to growth rate differences among closely-related genotypes of trees. Progeny variation in osmotic adjustment and turgor regulation was investigated by comparing changes in osmotic and pressure potentials, soluble carbohydrates, and amino acids in osmotically stressed seedlings in 4 full-sib progenies of black spruce [ Picea mariana (Mill.) B. S. P.] that differed in growth rate under drought. Osmotic stress was induced by a stepwise increase in the concentration of polyethylene glycol (PEG)-3350 from 10 (w/v) to 18 and 25%, which provided osmotic potentials in solution culture of -0.4, -1.0 and -2.0 MPa each for 3 days. All 4 progenies maintained a positive cell turgor even at 25% PEG, due to a significant decline in osmotic potential. Although total amino acids, principally proline, increased, ca 60% of the decrease in osmotic potential was attributable to soluble carbohydrates and glucose was the major osmoregulating solute. There was little progeny variation in any of measured parameters in unstressed seedlings. Compared to two slower-growing progenies, the two progenies capable of more vigorous growth under drought in the field accumulated more soluble carbohydrates (mainly glucose and fructose), developed lower osmotic potential and maintained higher turgor pressure when osmotically-stressed in solution culture. The ability to adjust osmotically and maintain turgor under drought stress could thus be a useful criterion for the early selection of faster-growing, drought-tolerant genotypes.