棉花萌发期和苗期耐盐性评价及耐盐指标筛选

于2010年在江苏南京农业大学人工气候室内进行砂培试验,采用不同浓度的NaCl水溶液模拟盐胁迫,以多项指标盐害系数隶属函数值和总隶属函数值为依据,比较了13个棉花品种萌发期和苗期的耐盐性,并进行聚类分析.结果表明:150mmol·L-1NaCl是进行棉花耐盐性鉴定的适宜盐浓度.棉花的耐盐性在生育期和品种间表现不同:中棉所44和中棉所177是在萌发期和苗期均表现稳定的耐盐品种,表现稳定但不耐盐品种有中棉所102、苏棉12号和泗棉3号,表现稳定且中等耐盐品种有中棉所103、德夏棉1号和美棉33B;发芽率、发芽势、发芽指数、活力指数和鲜质量的盐害系数可以作为棉花萌发期耐盐鉴定指标,株高、叶片伸展速率、地上部干质量、根系干质量、根系活力和净光合速率的盐害系数可以作为棉花苗期耐盐鉴定指标.     

Effect of soil salinity, soil drought, and their combined action on the biochemical characteristics of cotton roots

Stress caused by soil salinity and soil drought limits cotton productivity in China. To determine the tolerance levels of cotton, we assessed the effects of soil salinity and soil drought on the biochemical characteristics of the roots of two cotton cultivars (CCRI-44, salt-tolerant; Sumian 12, salt-sensitive). Specifically, we analyzed root biomass, fatty acid composition, antioxidative enzyme activity, lipid peroxidation, H⁺-ATPase and Ca²⁺-ATPase activities. The cotton root biomass of the two cultivars declined significantly under conditions of soil salinity, soil drought, and the two stressors combined. The antioxidant enzyme activity of the roots also decreased markedly, which caused lipid peroxidation to increase, and changed the composition of the fatty acid membrane. H⁺-ATPase, Ca²⁺-ATPase and antioxidant enzyme activity decreased more under the two stressors combined. However, H₂O₂ content and O₂ ^? generation increased under the two stressors combined, compared to each stressor separately. Overall, the combination of soil salinity and drought has a greater inhibitory effect and more harmful impact on root growth than each stressor separately. The higher tolerance of CCRI-44 to soil salinity and drought stress than Sumian 12 might be explained by differences in cotton root antioxidative enzyme activity. The lipid peroxidation levels of cotton roots might represent an important biochemical trait for stress tolerance.     

Morphological and Physiological Responses of Cotton (Gossypium hirsutum L.) Plants to Salinity

Salinization usually plays a primary role in soil degradation, which consequently reduces agricultural productivity. In this study, the effects of salinity on growth parameters, ion, chlorophyll, and proline content, photosynthesis, antioxidant enzyme activities, and lipid peroxidation of two cotton cultivars, [CCRI-79 (salt tolerant) and Simian 3 (salt sensitive)], were evaluated. Salinity was investigated at 0 mM, 80 mM, 160 mM, and 240 mM NaCl for 7 days. Salinity induced morphological and physiological changes, including a reduction in the dry weight of leaves and roots, root length, root volume, average root diameter, chlorophyll and proline contents, net photosynthesis and stomatal conductance. In addition, salinity caused ion imbalance in plants as shown by higher Na⁺ and Cl⁻ contents and lower K⁺, Ca²⁺, and Mg²⁺ concentrations. Ion imbalance was more pronounced in CCRI-79 than in Simian3. In the leaves and roots of the salt-tolerant cultivar CCRI-79, increasing levels of salinity increased the activities of superoxide dismutase (SOD), ascorbate peroxidase (APX), and glutathione reductase (GR), but reduced catalase (CAT) activity. The activities of SOD, CAT, APX, and GR in the leaves and roots of CCRI-79 were higher than those in Simian 3. CAT and APX showed the greatest H₂O₂ scavenging activity in both leaves and roots. Moreover, CAT and APX activities in conjunction with SOD seem to play an essential protective role in the scavenging process. These results indicate that CCRI-79 has a more effective protection mechanism and mitigated oxidative stress and lipid peroxidation by maintaining higher antioxidant activities than those in Simian 3. Overall, the chlorophyll a, chlorophyll b, and Chl (a+b) contents, net photosynthetic rate and stomatal conductance, SOD, CAT, APX, and GR activities showed the most significant variation between the two cotton cultivars.     

Antioxidant enzymes and physiological characteristics in two Jerusalem artichoke cultivars under salt stress

The effects of NaCl stress on the activity of antioxidant enzymes, lipid peroxidation, cell membrane stability, net photosynthetic rate, gas-exchange, and chlorophyll content were investigated in two Jerusalem artichoke cultivars, Dafeng (salt-tolerant) and Wuxi (salt-sensitive), grown under control (nutrient solution) or salt stress (nutrient solution containing 75, 150, and 225 mM NaCl) conditions for 7 days. In leaves of salt-tolerant cv. Dafeng, superoxide dismutase (EC 1.15.1.1), peroxidase (EC 1.11.1.7), and catalase (EC 1.11.1.6) activities significantly increased as compared to the controls, whereas no significant change was observed in cv. Wuxi. Lipid peroxidation and cell membrane injury were enhanced in both cultivars. Net photosynthesis and stomatal conductance decreased in response to salt stress, but cv. Dafeng showed a smaller reduction in photosynthesis than cv. Wuxi. The results indicated that stomatal aperture limited leaf photosynthetic capacity in the NaCl-treated plants of both cultivars. However, significant reduction in the leaf chlorophyll content due to NaCl stress was observed only in cv. Wuxi. These results suggested that salt-tolerant Jerusalem artichoke varieties may have a better protection against reactive oxygen species, at least in part, by increasing the activity of antioxidant enzymes under salt stress.     

蕾期土壤盐度降低后棉花叶片的生理功能恢复

试验于2011—2012年在江苏南京江苏省农业科学院经济作物研究所试验田进行,采用盆栽方法,以鲁棉研37号和苏棉22号为供试材料,设置土壤盐度降低试验(初始土壤含盐量为0.2%,棉花进入二叶期后每7d加入混合盐1次,每次增加0.1%,使土壤含盐量逐渐达到0.5%,蕾期进行盐度降低处理,使土壤含盐量降低到0.2%左右),研究蕾期土壤盐度降低后棉花叶片的生理代谢动态特征。结果表明:土壤盐度降低后,棉花叶片叶绿素(Chl)、类胡萝卜素(Car)含量和Chl/Car升高;净光合速率和气孔导度升高,且分别在土壤盐度降低后第14天和7天接近于低盐对照;土壤盐度降低后棉花叶片超氧化物歧化酶(SOD)和过氧化物酶(POD)活性升高,过氧化氢酶(CAT)活性和丙二醛(MDA)含量降低,MDA含量在土壤盐度降低后第14天接近于低盐对照;土壤盐度降低后棉花叶片中可溶性糖、游离氨基酸和脯氨酸含量降低,且接近于低盐对照。上述结果表明土壤盐度降低后,棉花叶片生理功能逐渐恢复,进而实现棉花生长发育的恢复补偿。棉花叶片生理功能在土壤盐度降低后的恢复能力存在品种间差异,鲁棉研37号较苏棉22号叶片生理功能表现出更强的恢复能力。     

Higher salinity tolerance cultivars of winter wheat relieved senescence at reproductive stage

In order to probe into the potential of relieving senescence in the new cultivars, we have compared gas exchanges and related physiological parameters of two cultivars of winter wheat (DK961, salt-tolerant; JN17, salt-sensitive) under a series of NaCl concentrations. Through out the whole reproductive period, it was noted that net photosynthetic rate, stomatal conductance, pigment contents, ions contents, leaf area index, leaf area duration, leaf relative water content and dry matter accumulation of spikes decreased in both cultivars with saline concentrations increasing. However, the salt-tolerant cultivars showed none significant reductions in those parameters compared with control under 0.3% and 0.5% salt concentrations, with only considerable decrease happening when soil salt concentration exceeded to 0.7%. Sharply contrast to salt-tolerant cultivars, the salt-sensitive cultivars appeared linear reductions in physiological parameters under a series of salt concentrations (0.3%, 0.5% and 0.7%), with the photosynthetic duration being evidently shorter. Significantly positive correlations among K⁺/Na⁺, reproductive growth period and total growth period were noted in salt-sensitive cultivars, however, none significant relations appeared among those parameters in salt-tolerant cultivars, indicating a strong tolerant behavior happened. Our result suggested that higher salinity tolerance cultivars of winter wheat could relieve senescence at the reproductive stage.     

Sugar accumulation,photosynthesis and growth of two indica rice varieties in response to salt stress

Sugar, a final product of photosynthesis, is reported to be involved in the defense mechanisms of plants against abiotic stresses such as salinity, water deficiency, extreme temperature and mineral toxicity. Elements involved in photosynthesis, sugar content, water oxidation, net photosynthetic rate, activity of enzyme and gene expression have therefore been studied in Homjan (HJ), salt-tolerant, and Pathumthani 1 (PT1), salt-sensitive, varieties of rice. Fructose-1,6-biphosphatase (FBP) and fructokinase (FK) genes were rapidly expressed in HJ rice when exposed to salt stress for 1–6 h and to a greater degree than in PT1 rice. An increase in FBP enzyme activity was found in both roots and leaves of the salt-tolerant variety after exposure to salt stress. A high level of sugar and a delay in chlorophyll degradation were found in salt-tolerant rice. The total sugar content in leaf and root tissues of salt-tolerant rice was 2.47 and 2.85 times higher, respectively, than in the salt-sensitive variety. Meanwhile, less chlorophyll degradation was detected. Salt stress may promote sugar accumulation, thus preventing the degradation of chlorophyll. Water oxidation by the light reaction of photosynthesis in the salt-tolerant variety was greater than that in the salt-sensitive variety, indicated by a high maximum quantum yield of PSII (F _v/F _m) and quantum efficiency of PSII (Φ_PSII) with low nonphotochemical quenching (NPQ), leading to a high net photosynthetic rate. In addition, the overall growth performances in the salt-tolerant variety were higher than those in the salt-sensitive variety. The FBP gene expression and enzyme activity, sugar accumulation, pigment stabilization, water oxidation and net photosynthetic rate parameters in HJ rice should be further investigated as multivariate salt-tolerant indices for the classification of salt tolerance in rice breeding programs.     

Photosynthetic limitations in olive cultivars with different sensitivity to salt stress

Olive (Olea europea L) is one of the most valuable and widespread fruit trees in the Mediterranean area. To breed olive for resistance to salinity, an environmental constraint typical of the Mediterranean, is an important goal. The photosynthetic limitations associated with salt stress caused by irrigation with saline (200 mm ) water were assessed with simultaneous gas‐exchange and fluorescence field measurements in six olive cultivars. Cultivars were found to possess inherently different photosynthesis when non‐stressed. When exposed to salt stress, cultivars with inherently high photosynthesis showed the highest photosynthetic reductions. There was no relationship between salt accumulation and photosynthesis reduction in either young or old leaves. Thus photosynthetic sensitivity to salt did not depend on salt exclusion or compartmentalization in the old leaves of the olive cultivars investigated. Salt reduced the photochemical efficiency, but this reduction was also not associated with photosynthesis reduction. Salt caused a reduction of stomatal and mesophyll conductance, especially in cultivars with inherently high photosynthesis. Mesophyll conductance was generally strongly associated with photosynthesis, but not in salt‐stressed leaves with a mesophyll conductance higher than 50 mmol m^?2 s^?1. The combined reduction of stomatal and mesophyll conductances in salt‐stressed leaves increased the CO₂ draw‐down between ambient air and the chloroplasts. The CO₂ draw‐down was strongly associated with photosynthesis reduction of salt‐stressed leaves but also with the variable photosynthesis of controls. The relationship between photosynthesis and CO₂ draw‐down remained unchanged in most of the cultivars, suggesting no or small changes in Rubisco activity of salt‐stressed leaves. The present results indicate that the low chloroplast CO₂ concentration set by both low stomatal and mesophyll conductances were the main limitations of photosynthesis in salt‐stressed olive as well as in cultivars with inherently low photosynthesis. It is consequently suggested that, independently of the apparent sensitivity of photosynthesis to salt, this effect may be relieved if conductances to CO₂ diffusion are restored.     

Evaluation and Exploration of Favorable QTL Alleles for Salt Stress Related Traits in Cotton Cultivars (G. hirsutum L.)

Soil salinization is one of the major problems in global agricultural production. Cotton is a pioneer crop with regard to salt stress tolerance, and can be used for saline-alkali land improvement. The large-scale detection of salt tolerance traits in cotton accessions, and the identification of elite quantitative trait loci (QTLs)/genes for salt-tolerance have been very important in salt tolerance breeding. Here, 43 advanced salt-tolerant and 31 highly salt-sensitive cultivars were detected by analyzing ten salt tolerance related traits in 304 upland cotton cultivars. Among them, 11 advanced salt-tolerance and eight highly salt-sensitive cultivars were consistent with previously reported results. Association analysis of ten salt-tolerance related traits and 145 SSRs was performed, and a total of 95 significant associations were detected; 17, 41, and 37 of which were associated with germinative index, seedling stage physiological index, and four seedling stage biochemical indexes, respectively. Of these associations, 20 SSR loci were simultaneously associated with two or more traits. Furthermore, we detected 117 elite alleles associated with salt-tolerance traits, 4 of which were reported previously. Among these loci, 44 (37.60%) were rare alleles with a frequency of less than 5%, 6 only existed in advanced salt-tolerant cultivars, and 2 only in highly salt-sensitive cultivars. As a result, 13 advanced salt-tolerant cultivars were selected to assemble the optimal cross combinations by computer simulation for the development of salt-tolerant accessions. This study lays solid foundations for further improvements in cotton salt-tolerance by referencing elite germplasms, alleles associated with salt-tolerance traits, and optimal crosses.     

基于棉花功能叶高光谱参数的土壤电导率监测模拟

通过2008-2009年在江苏南京农业大学牌楼试验站的盆栽试验,选择耐盐棉花品种中棉所44和盐敏感性品种苏棉12号为材料,模拟5种不同含盐水平的滨海盐土(0、0.35％、0.60％、0.85％和1.00％),分析了棉花生育期棉田土壤电导率与棉花功能叶光谱反射率和高光谱参数的关系,并建立了棉田土壤电导率(EC)的定量监测模型.结果表明:棉花功能叶光谱反射率在近红外和中红外区域均随土壤盐分水平的升高而升高;以敏感波段1350nm和2307 nm构建的归一化光谱指数NDSI(R1350,R2307)与土壤电导率的决定系数最高,基于此构建了基于NDSI(R1350,R2307)的棉田土壤EC监测模型:EC=-42.899NDSI(R1350,R2307)+27.338;在光谱微分参数中,以TM影像第5个波段的光谱反射率(TM5-SWIR)与棉田土壤EC的决定系数最高,构建了基于TM5-SWIR的棉田土壤EC监测模型:EC=0.0574 TM5-SWIR2-2.5928 TM5-SWIR+ 30.021.以NDSI(R1350,R2307)和TM5-SWIR为自变量的监测模型的预测精度均较高,分别为0.887和0.814,根均方差均较小,分别为1.09和1.29 dS·m-1.利用棉花功能叶NDSI(R1350,R2307)和TM5-SWIR均能较好地监测棉田土壤电导率.     

Relationship between salt tolerance and photosynthetic machinery performance in citrus

In citrus, salt stress has been related to the build up of chloride ions in plant tissues that affect photosynthesis, growth and yield. We investigated the effects of salt stress on the stability of the photosynthetic machinery with respect to the relative salt tolerance of different citrus genotypes including: Swingle Citrumelo, Carrizo citrange, C35 citrange, Cleopatra mandarin and Forner-Alcaide #5. Under identical salt-stress conditions, Forner-Alcaide #5 and Cleopatra mandarin accumulated less chloride ions in leaves than the other genotypes and showed a better plant performance. Chlorophyll fluorescence parameters indicated severe impairments of photosynthetic activity in salt-sensitive Citrumelo and citranges but Cleopatra and Forner-Alcaide #5 were less affected. In addition, differences in photosynthetic responses between these two moderately tolerant genotypes suggested different strategies to cope with salinity. The high tolerance to salinity shown by Forner-Alcaide #5 can be associated to the ability of keeping an active photosynthetic system at elevated saline conditions whereas the tolerance of Cleopatra was linked to rapid reductions of net photosynthetic rate, stomatal conductance, performance of PSII and photosynthetic efficiency.     

Effect of salt stress on photosynthesis and physiological parameters of three contrasting barley genotypes

In order to understand the physiological traits important in conferring salt tolerance in three barley genotypes, this study was performed under field conditions with three water salinity levels (2, 10, and 18 dS m–1). High salinity decreased net photosynthetic rate, transpiration rate, and stomatal conductance, K⁺ concentration, K⁺:Na⁺ ratio, and grain yield, but increased electrolyte leakage and Na⁺ content. Under 10 and 18 dS m–1 salinity, Khatam (salt-tolerant) had the maximum stomatal conductance, K⁺, K⁺:Na⁺ ratio, and the grain yield, and a minimum Na⁺ content and electrolyte leakage, whereas Morocco (salt-sensitive) had the lowest net photosynthetic rate, stomatal conductance, K⁺ content, K⁺:Na⁺ ratio, and grain yield, and the highest Na⁺ content and electrolyte leakage. This study showed that tolerant genotypes of barley may avoid Na⁺ accumulation in aboveground parts, facilitating a higher photosynthetic rate and higher grain yield.     

等渗盐胁迫下Na^＋和Cl^-对大豆幼苗光合作用的离子效应

研究和比较了等渗(-0.53MPa)的PEG-6000、NaCl、钠盐(无Cl-)和氯化物(无Na )溶液处理6d对栽培大豆品种‘Lee68’(耐盐性较强)和‘N23674’(耐盐性较弱)幼苗光合作用的离子效应。结果表明:PEG-6000处理使两品种叶片叶绿素含量和Rubisco活性较对照低,但降幅不如同样渗透压的NaCl、钠盐(无Cl-)和氯化物(无Na )溶液明显。PSII最大光化学效率(Fv/Fm)、电子传递速率(ETR)和PSII光化学的有效量子产额(Fv'/Fm')在PEG-6000处理2d和6d时显著下降,但在3种等渗盐处理下,多显著下降。两品种叶片气孔导度(Gs)和净光合速率(Pn)在4种胁迫处理下均显著下降,其中在3种盐处理下更明显,但胞间CO2浓度(Ci)仅在PEG-6000处理时下降,在盐处理下反而升高。两品种叶片叶绿素含量、Rubisco活性、Fv/Fm、ETR、Fv'/Fm'、Pn、Gs等在氯化物(无Na )溶液处理的下降幅度和叶绿体中Cl-含量及其与Na 总量的增加幅度均大于钠盐(无Cl-)处理的,在耐盐性弱的‘N23674’品种中更明显。可见,在NaCl胁迫对栽培大豆幼苗光合作用的毒害效应中,渗透胁迫较轻,离子毒害较重,其中Cl-的毒害大于Na 的。     

盐胁迫下水稻叶绿体中Na~ 、Cl~-积累导致叶片净光合速率下降

研究了 0～ 2 0 0mmol/L的NaCl胁迫下耐盐性不同的水稻品种Pokkali(耐盐 )和Peta(盐敏感 )根系、叶片和叶绿体中Na 、K 和Cl-含量的变化及其与叶片光合作用的关系。结果表明 :随着NaCl胁迫时间和浓度的增加 ,供试 2个品种在根、叶片和叶绿体中Na 、Cl-含量增加 ,K 含量下降。耐盐品种体内Na 、Cl-含量增加或K 含量减少的幅度小于盐敏感品种。在 2 0 0mmol/L的NaCl胁迫下盐敏感品种根、叶片和叶绿体中的Na /K 分别是耐盐品种的 2 0 8%、30 8%和 2 97%。与Na 相比 ,耐盐品种根系对K 的吸收和向叶片运输的选择性 (SK ,Na)较强。但在经过0、10 0和 2 0 0mmol/L的NaCl处理后 2个品种叶绿体中的Na /K 均高于叶片 (SK ,Na均小于 1)。盐胁迫下水稻叶绿体中Na 、Cl-含量和Na /K 与叶片净光合速率呈极显著负相关。     

盐胁迫下水稻叶绿体中Na+、Cl-积累导致叶片净光合速率下降

研究了0-200mmol/L的NaCl胁迫下耐盐性不同的水稻品种Pokkali(耐盐）和Peta(盐敏感）根系,叶片和叶绿体中Na^ ,K^ 和Cl^-含量的变化及其与叶片光合作用的关系。结果表明：随着NaCl胁迫时间和浓度的增加,供试2个品种在根,叶片和叶绿体中Na^ ,Cl^－含量增加,K^ 含量下降。耐盐品种体内Na^ ,Cl^－含量增加或K^ 含量减少的幅度小于盐敏感品种。在200mmol/L的NaCl胁迫下盐敏感品种根,叶片和叶绿体中的Na^ /K^ 分别是耐盐品种的208％,308％和297％。与Na^ 相比,耐盐品种根系对K^ 吸收和向叶片运输的选择性（SK,Na)较强。但在经过0,100和200mmol/L的NaCl处理后2个品种叶绿体中的Na^ /K^ 均高于叶片（SK,Na均小于1）。盐胁迫下水稻叶绿体中Na^ ,Cl^-含量和Na^ /K^ 与叶片净光合速度呈极显著负相关。     

Effects of Reddening of Cotton (Gossypium hirsutum L.) Leaves on Functional Activity of Photosynthetic Apparatus

Strong inhibition of rates of CO₂ assimilation and transpiration, stomatal conductance, and water use efficiency as well as photosystem 2 (PS2) photochemical activity were related to the severity of reddening. The inhibition of photosynthesis in red cotton leaves was due to both decreased photochemical activity and stomatal limitation. Lowered photosynthetic capacity could be one of the main factors of reduced yield in reddening cotton.     

Effects of salicylic acid and salinity on apoplastic antioxidant enzymes in two wheat cultivars differing in salt tolerance

The effects of salicylic acid (SA) and salinity on the activity of apoplastic antioxidant enzymes were studied in the leaves of two wheat (Triticum aestivam L.) cultivars: salt-tolerant (Gerek-79) and salt-sensitive (Bezostaya). The leaves of 10-d-old seedlings grown at nutrient solution with 0 (control), 250 or 500 mM NaCl were sprayed with 0.01 or 0.1 mM SA. Then, the activities of catalase (CAT), peroxidase (POX) and superoxide dismutase (SOD) were determined in the fresh leaves obtained from 15-d-old seedlings. The NaCl applications increased CAT and SOD activities in both cultivars, compared to those of untreated control plants. In addition, the NaCl increased POX activity in the salt-tolerant while decreased in the salt-sensitive cultivar. In control plants of the both cultivars, 0.1 mM SA increased CAT activity, while 0.01 mM SA slightly decreased it. SA treatments also stimulated SOD and POX activity in the salt-tolerant cultivar but significantly decreased POX activity and had no effect on SOD activity in the saltsensitive cultivar. Under salinity, the SA treatments significantly inhibited CAT activity, whereas increased POX activity. The increases in POX activity caused by SA were more pronounced in the salt-tolerant than in the salt-sensitive cultivar. SOD activity was increased by 0.01 mM SA in the salt-tolerant while increased by 0.1 mM SA treatment in the salt-sensitive cultivar.     

Differences in photosynthetic characterization of salt tolerance for two rice (<Emphasis Type="Italic">Oryza sativa</Emphasis>) cultivars

We photosynthetically characterized two rice cultivars - salt-sensitive ‘Annapurna’, and salt-tolerant ‘Dongjin’ - growing under NaCl stress. Both cultivars showed an increase in F_o/F_m (the ratio of initial to maximal chlorophyll fluorescence) and a decrease in F_v/F_m (an indicator of the photochemical efficiency of PS II). In particular, the F_v value for Annapurna significant declined while F_o/F_m was enhanced when plants were exposed to salt stress for 4 d. Annapurna also exhibited more rapid decreases in the coefficients for photochemical quenching (qQ) and non-photochemical quenching (qNP) than did Dongjin. In contrast, zeaxanthin formation was largely influenced by exposure to light rather than to high salinity, with Annapurna having a higher rate of production compared with Dongjin. When both cultivars were exposed to salt stress for 2 d, Annapurna had a much lower rate of photosynthetic oxygen evolution, corresponding to only 46% of the control; the rate for Dongjin was 90% of the control. Salt stress in both cultivars induced the accumulation of two osmoprotectants, glycinebetaine and proline, the rate being higher for the latter. These results indicate that Annapurna is more sensitive than Dongjin to salt stress, in terms of its deterioration in photosynthetic function.     

The response of Mo-hydroxylases and abscisic acid to salinity in wheat genotypes with differing salt tolerances

The differential responses of the wheat cultivars Shi4185 and Yumai47 to salinity were studied. The higher sensitivity of Yumai47 to salinity was linked to a greater growth reduction under salt stress, compared to more salt-tolerant Shi4185. Salinity increased the Na⁺, proline and superoxide anion radical (O₂ ^?) contents in both cultivars. Leaf Na⁺ content increased less in the more salt-tolerant cultivar Shi4185 than salt-sensitive Yumai47. The proline content increased more significantly in Shi4185 than Yumai47; on the contrary, superoxide anion radical content increased less in Shi4185 than Yumai47. This data indicated that wheat salinity tolerance can be increased by controlling Na⁺ transport from the root to shoot, associated with higher osmotic adjustment capability and antioxidant activity. Although salinity increased aldehyde oxidase (AO) activity and abscisic acid (ABA) content in the leaves and roots of both cultivars following the addition of NaCl to the growth medium, AO and ABA increased more in the salt-sensitive cultivar Yumai47 than the more salt-tolerant cultivar Shi4185. Xanthine dehydrogenase (XDH) activity in the leaves of both cultivars increased with increasing concentrations of NaCl; however, leaf XDH activity increased more significantly in Yumai47 than Shi4185. Root XDH activity in Shi4185 decreased with increasing NaCl concentrations, whereas salinity induced an increased root XDH activity in Yumai47. The involvement of AO and XDH enzymatic activities and altered ABA content in the response mechanisms of wheat to salinity are discussed herein.     

等渗NaCl、干旱胁迫对番茄幼苗光合特性及叶绿体超微结构的影响

为分析等渗盐分和水分胁迫对番茄叶片光合功能的影响,选用耐盐性不同的4种基因型番茄(小果型的辽园红玛瑙、野生醋栗番茄、大果型的金田粉冠、超402)进行等渗的140 mmol·L^-1NaCl和15%PEG6000模拟盐分和水分胁迫.结果表明: 在光合特性方面,处理12 d后,两种胁迫导致4种不同基因型番茄的叶绿素含量(叶绿素a、叶绿素b、叶绿素总量)、光合速率、气孔导度、胞间CO₂浓度、蒸腾效率降低,气孔限制值升高.两种胁迫导致的光合下降由气孔性因素所致.等渗的盐分胁迫对番茄的光合系统损伤大于水分胁迫,这是因为盐分胁迫除了渗透胁迫还会导致离子伤害.4种不同基因型番茄中,耐盐型的辽园红玛瑙具有高光合特性,金田粉冠光合效率最差.在叶绿体超微结构方面,两种胁迫会造成番茄叶片的气孔密度增加,气孔张开率降低,叶绿体长度增加,宽度变小,长宽比增大,叶绿体内基粒数减少,嗜锇颗粒数增多.盐分胁迫下两种番茄叶绿体结构的影响大于水分胁迫,耐盐种醋栗番茄气孔变化小于盐敏感品种金田粉冠.