Different Degrees Of Tolerance Research Articles

Effect of short-term cadmium stress on Populus nigra L. detached leaves

Pollution by toxic metals, accumulating into soils as result of human activities, is a worldwide major concern in industrial countries. Plants exhibit different degrees of tolerance to heavy metals, as a consequence of their ability to exclude or accumulate them in particular tissues, organs or sub-cellular compartments. Molecular information about cellular processes affected by heavy metals is still largely incomplete. As a fast-growing, highly tolerant perennial plant species, poplar has become a model for environmental stress response investigations. To study the short-term effects of cadmium accumulation in leaves, we analyzed photosystem II (PSII) quantum yield, hydrogen peroxide (H2O2) generation, hormone levels variation, as well as proteome profile alteration of 50μM CdSO4 vacuum-infiltrated poplar (Populus nigra L.) detached leaves. Cadmium management brought about an early and sustained production of hydrogen peroxide, an increase of abscisic acid, ethylene and gibberellins content, as well as a decrease in cytokinins and auxin levels, whereas photosynthetic electron transport was unaffected. Proteomic analysis revealed that twenty-one proteins were differentially induced in cadmium-treated leaves. Identification of fifteen polypeptides allowed to ascertain that most of them were involved in stress response while the remaining ones were involved in photosynthetic carbon metabolism and energy production.

Transport infrastructure shapes foraging habitat in a raptor community.

Transport infrastructure elements are widespread and increasing in size and length in many countries, with the subsequent alteration of landscapes and wildlife communities. Nonetheless, their effects on habitat selection by raptors are still poorly understood. In this paper, we analyzed raptors’ foraging habitat selection in response to conventional roads and high capacity motorways at the landscape scale, and compared their effects with those of other variables, such as habitat structure, food availability, and presence of potential interspecific competitors. We also analyzed whether the raptors’ response towards infrastructure depends on the spatial scale of observation, comparing the attraction or avoidance behavior of the species at the landscape scale with the response of individuals observed in the proximity of the infrastructure. Based on ecological hypotheses for foraging habitat selection, we built generalized linear mixed models, selected the best models according to Akaike Information Criterion and assessed variable importance by Akaike weights. At the community level, the traffic volume was the most relevant variable in the landscape for foraging habitat selection. Abundance, richness, and diversity values reached their maximum at medium traffic volumes and decreased at highest traffic volumes. Individual species showed different degrees of tolerance toward traffic, from higher abundance in areas with high traffic values to avoidance of it. Medium-sized opportunistic raptors increased their abundance near the traffic infrastructures, large scavenger raptors avoided areas with higher traffic values, and other species showed no direct response to traffic but to the presence of prey. Finally, our cross-scale analysis revealed that the effect of transport infrastructures on the behavior of some species might be detectable only at a broad scale. Also, food availability may attract raptor species to risky areas such as motorways.

Different Strategies Used by Domesticated Tomato and Wild-related Species to Confront Salt Stress

Salinity is responsible for important yield losses in crops, among them tomato (Solanum lycopersicum), a horticultural crop of the highest agro-economic importance. Comparing the responses to salinity of domesticated tomato and wild-relative species, displaying different degrees of tolerance, could give key insights in the strategies used by the latter ones to successfully confront salt stress, as well as to identify key genes involved in such tolerance mechanisms in wild tomato species. The behaviour in salt stress condition of a tomato cultivar (cv Moneymaker) and two wild genotypes of the S. cheesmaniae and S. pennellii species, presenting an intermediate and high level of tolerance, was compared. The objective is to dissect the differential responses to the osmotic effect as well as to the ionic stress due to salinity, applying a stress level which allows maintaining long-term plant growth. From the first hours of salt stress, the two wild species are able to respond to osmotic stress avoiding dehydration, contrarily to domesticated tomato, which suggests the importance of the osmotic tolerance under salt stress. Moreover, the strategies of both wild species seem to be different as reflected by leaf temperature (LT) results, measured by non-invasive infrared thermography, which is closely linked to water loss due to transpiration. Interestingly, the uptake and solutes transport also differed among species as well as the gene expression involved in ion homeostasis. These results may allow to identifying key physiological mechanisms and genes conferring salinity tolerance in wild tomatoes, which could be further introduced in domesticated tomato.Acknowledgements. This work was financed by the MINECO, Spain (Ref. AGL2012-40150-03) and Fundación Séneca, Región de Murcia, Spain (Ref. 18973/JLI/13).

Physiological and morphological responses of Prunus species with different degree of tolerance to long-term root hypoxia

Prunus species are considered as hypoxia-sensitive, although differences exist in the degree of tolerance among different genotypes. Our aim was to evaluate the responses and adaptations of different Prunus rootstocks species under root hypoxia. Prunus rootstocks, ‘Mariana 2624′ (Prunus cerasifera×Prunus munsoniana W. Wight & Hedrick), ‘Cab6P’ (Prunus cerasus L.), ‘Colt’ (Prunus avium (L.) L.×Prunus pseudocerasus Lindl.), ‘Maxma 14′ (Prunus mahaleb L.×Prunus avium), ‘Maxma 60′ (Prunus mahaleb×Prunus avium), ‘Garnem’ (G×N15) (Prunus dulcis (Mill.) Rchb.×(Prunus persica (L.) Batsch×Prunus davidiana (Carrière) N.E.Br.)) and ‘Mazzard F12/1′ (Prunus avium) were subjected to waterlogging for 14 days and physiological and morphological responses were assessed. Severe leaf damage, early plant mortality, decreases in photosynthesis rate (A) and stomatal conductance (gs) and higher concentration of malondialdehyde (MDA) were detected in sensitive genotypes when in waterlogged soil. However, in tolerant ones, gas exchange parameters and MDA concentration were unaffected in such condition. In addition, development of hypertrophied lenticels on the stem, adventitious roots and aerenchyma were observed in tolerant genotypes under waterlogged plants, being these morpho-anatomical adaptations reported here for the first time in these Prunus rootstocks. A comparative study of the most contrasting genotypes; i.e., ‘Mariana 2624′ (tolerant) and ‘Mazzard F12/1′ (sensitive), revealed that these morpho-anatomical changes would be playing a key role in survival of the tolerant Prunus genotype during O2 deprivation caused by waterlogging.

Molecular characterization of cyclophilin A-like protein from Piriformospora indica for its potential role to abiotic stress tolerance in E. coli

BackgroundCyclophilins (CyP), conserved in all genera, are known to have regulatory responses of various cellular processes including stress tolerance. Interestingly, CyP has a crucial role as peptidyl-prolyl cis–trans isomerases (PPIases). Our earlier in silico based approach resulted into the identification of cyclophilin family from rice, Arabidopsis and yeast. In our recent report, we discovered a new OsCYP-25 from rice. Here, we identified a novel cyclophylin A-like protein (PiCyP) from Piriformospora indica which is responsible for abiotic stress tolerance in E. coli.ResultsCyclophylin A-like protein (CyPA) (accession number GQ214003) was selected from cDNA library. The genomic organization CyPA revealed a 1304 bp of CyPA in P. indica genome, showing 10 exons and 9 introns. Further, CyPA was evident in PCR with gDNA and cDNA and Southern blot analysis. The phylogenetic examination of CyPA of P. indica showed that it is closed to human cyclophilin. The uniqueness of PiCyPA protein was apparent in western blot study. Kinetics of purified PiCyPA protein for its PPIas activity was determined via first order rate constant (0.104 s-1) in the presence of 1 μg of PiCyPA, with increasing PiCyPA concentration, in the presence of cyclosporin A (CsA) and the inhibition constant (4.435 nM) of CsA for inhibition of PiCyPA. The differential response of E. coli harbouring pET28a-PiCypA was observed for their different degree of tolerance to different abiotic stresses as compared to empty pET28a vector.ConclusionsOverexpression of PiCyPA protein E. coli cells confer enhanced tolerance to wide range of abiotic stresses. Thus, this study provides the significance of PiCypA as a molecular chaperone which advanced cellular stress responses of E. coli cells under adverse conditions, and it, furthermore, confirms the mounting the sustainability of E. coli for exploitation in recombinant proteins production. Additionally, the PiCyPA gene cooperates substantial functions in cellular network of stress tolerance mechanism, essentially required for various developmental stages, and might be a potential paramount candidate for crop improvement and its sustainable production under adverse conditions.

Within‐population variation in resistance of Digitaria sanguinalis to Ustilago syntherismae resulting from different modes of seed germination and environment

In annual plants affected by inflorescence‐invading smut pathogens, avoidance of infection is crucial, while in the event of infection, the existence of different degrees of tolerance could also affect the interaction dynamics. Two experiments were performed with Digitaria sanguinalis spikelets vacuum inoculated with ustilospores of Ustilago syntherismae. In the first experiment, they were sown in pots and mature plants were checked to detect internal hyphae. Observations revealed the presence of symptomless mycelium in a few plants. In the second experiment the spikelets, from two different lots, were grown in a chamber. The objective was to explore the importance of two factors in the degree of seedling infection, one genotypic – type of germination (TG; radicular or coleoptilar) and one environmental – 48 h dark treatment (DT) applied just after germination. Analysis of the infection frequency showed that all the main effects (seed lot origin, TG and DT) were significant, while interactions were not. For TG, the estimated least square mean infection percentages were 66% for radicular germination and 46% for coleoptilar germination. Darkness increased seedling infection by 25%. Differences between TG, DT and their relationship with mesocotyl length exposed to the germinating spores are discussed.

Class 1 non-symbiotic and class 3 truncated hemoglobin-like genes are differentially expressed in stone fruit rootstocks (Prunus L.) with different degrees of tolerance to root hypoxia

Root hypoxia produced by flooding or over-irrigation limits stone fruit tree development, particularly in orchards established on soils with restricted drainage. To overcome this problem, stone fruit trees are usually grafted on rootstocks (species or hybrid of the Prunus L. genus) with different degrees of tolerance to root hypoxia. However, the molecular base of such variability is largely unknown. In Arabidopsis thaliana (Heynh.), as well as in a number of crops and tree species, hemoglobin (Hb)-like genes stand out among hypoxia-related genes, but no such studies have been done with the Prunus species used as rootstocks. In this study, we analyzed the expression pattern of class 1 non-symbiotic Hb-like (nsHb) and class 3 truncated Hb-like (trHb) genes in Prunus rootstock roots with different responses to this stress. We observed that the putative Prunus nsHb and trHb genes were induced by root hypoxia in all analyzed Prunus genotypes, independently of their tolerance to hypoxia. However, Prunus nsHb and trHb genes had higher expression levels in roots of tolerant rootstocks. Prunus nsHb and trHb genes were also regulated by other abiotic stresses, such as salt stress and low temperatures. Our results suggest that changes in nsHb and trHb expressions could be part of the adaptive mechanisms that have evolved in the Prunus species to survive under hypoxia or other types of environmental stress that commonly challenge stone fruit tree orchards.

Use of Intravenous Fentanyl Against Morphine Tolerance in Breakthrough Cancer Pain

Palliative care physicians are accustomed to using transdermal fentanyl patch for cancer pain control but not so familiar with its intravenous administration. Historically, fentanyl has been used to treat breakthrough pain because it is a very potent analgesic with a rapid onset and short duration of action. Although several formulations of fentanyl have been recently developed for breakthrough cancer pain, these are unavailable or too expensive in some countries. Also, all opioids can induce tolerance potentially and different opioids cause significantly different degrees of tolerance. Therefore, sequential opioid trials may be a reasonable approach in patients with poor analgesic effect after dose escalation. Here, we present 2 morphine-tolerant patients with cancer in whom the intravenous fentanyl was effectively used for their refractory breakthrough pain.

Alterations in Phosphorylated CREB Expression in Different Brain Regions following Short- and Long-Term Morphine Exposure: Relationship to Food Intake

Background. Activation of the cyclic adenosine monophosphate (cAMP)/phosphorylated CREB (P-CREB) system in different brain regions has been implicated in mediating opioid tolerance and dependence, while alteration of this system in the lateral hypothalamus (LH) has been suggested to have a role in food intake and body weight. Methods. Given that opioids regulate food intake, we measured P-CREB in different brain regions in mice exposed to morphine treatments designed to induce different degrees of tolerance and dependence. Results. We found that a single morphine injection or daily morphine injections for 8 days did not influence P-CREB levels, while the escalating dose of morphine regimen raised P-CREB levels only in the ventral tegmental area (VTA). Chronic morphine pellet implantation for 7 days raised P-CREB levels in the LH, VTA, and dorsomedial nucleus of the hypothalamus (DM) but not in the nucleus accumbens and amygdala. Increased P-CREB levels in LH, VTA, and DM following 7-day treatment with morphine pellets and increased P-CREB levels in the VTA following escalating doses of morphine were associated with decreased food intake and body weight. Conclusion. The morphine regulation of P-CREB may explain some of the physiological sequelae of opioid exposure including altered food intake and body weight.

Alternative oxidase 1 (Aox1) gene expression in roots of Medicago truncatula is a genotype-specific component of salt stress tolerance

Alternative oxidase (AOX) is the central component of the non-phosphorylating alternative respiratory pathway in plants and may be important for mitochondrial function during environmental stresses. Recently it has been proposed that Aox can be used as a functional marker for breeding stress tolerant plant varieties. This requires characterization of Aox alleles in plants with different degree of tolerance in a certain stress, affecting plant phenotype in a recognizable way. In this study we examined Aox1 gene expression levels in Medicago truncatula genotypes differing in salt stress tolerance, in order to uncover any correlation between Aox expression and tolerance to salt stress. Results demonstrated a specific induction of Aox1 gene expression in roots of the tolerant genotype that presented the lowest modulation in phenotypic and biochemical stress indices such as morphologic changes, protein level, lipid peroxidation and ROS generation. Similarly, in a previous study we reported that induction of antioxidant gene expression in the tolerant genotype contributed to the support of the antioxidant cellular machinery and stress tolerance. Correlation between expression patterns of the two groups of genes was revealed mainly in 48h treated roots. Taken together, results from both experiments suggest that M. truncatula tolerance to salt stress may in part due to an efficient control of oxidative balance thanks to (i) induction of antioxidant systems and (ii) involvement of the AOX pathway. This reinforces the conclusion that differences in antioxidant mechanisms can be essential for salt stress tolerance in M. truncatula and possibly the corresponding genes, especially Aox, could be utilized as functional marker.

Do effects of landscape factors on coastal pond macrophyte communities depend on species traits?

We investigated the richness and composition of aquatic macrophyte communities of non-fragmented ponds in a matrix of coastal dunes in Southern Brazil. We tested three hypotheses on natural wetlands: (1) area, diversity of habitats and hydroperiod increase the total macrophyte richness; (2) isolation among ponds decreases the total macrophyte richness; and (3) the influence of environmental factors on macrophyte richness and composition change among macrophyte groups with different degrees of tolerance to hydrological variation. Our results showed that area was not a determining factor for macrophyte richness in coastal dune ponds. Diversity of habitats positively influenced total macrophyte richness, both hydrophyte and emergent species. Total richness of macrophytes declined with the increase in distance from source areas. However, this pattern varied among the study macrophyte groups with different degree of tolerance to hydrological variations. Whereas richness of hydrophyte and emergent species richness were related with isolation, the richness of amphibious species was not. Species composition was determined by the combination of the following environmental factors: isolation, diversity of habitats and hydroperiod. The current process of fragmentation taking place in Southern Brazil will increase the isolation among wetlands, and will influence the aquatic macrophyte species. The isolation effects may be most severe for hydrophytes.

Differential Sensitivity of Letters, Numbers, and Symbols to Character Transpositions

This study was designed to explore whether the human visual system has different degrees of tolerance to character position changes for letter strings, digit strings, and symbol strings. An explicit perceptual matching task was used (same-different judgment), and participants' electrophysiological activity was recorded. Materials included trials in which the referent stimulus and the target stimulus were identical or differed either by two character replacements or by transposing two characters. Behavioral results showed clear differences in the magnitude of the transposed-character effect for letters as compared with digit and symbol strings. Electrophysiological data confirmed this observation, showing an N2 character transposition effect that was only present for letter strings. An earlier N1 transposition effect was also found for letters but was absent for symbols and digits, whereas a later P3 effect was found for all types of string. These results provide evidence for a position coding mechanism that is specific to letter strings, that was most prominent in an epoch between 200 and 325 msec, and that operates in addition to more general-purpose position coding mechanisms.

Are corruption levels accurately identified? The case of U.S. states

This paper applies a novel methodology to measure corruption levels in U.S. states, leading to insights which could be useful to policymakers in their effort to reduce unethical behavior. The level of public corruption is difficult to quantify because much of it goes undetected and because different cultures and jurisdictions have different definitions and different degrees of tolerance for corruption. When comparing corruption across countries, in the absence of another solution, this difficulty has been addressed by using survey-based methods. Within countries, because of the greater homogeneity in culture, institutions, and legal frameworks, other measures have been used, such as public official convictions per capita. This paper suggests that even these more objective measures of corruption may lead to distortions, describes an alternative methodology based on the analysis of public official non-compliance as compared to general population non-compliance, and illustrates its use. The method is based on modeling an institution as a system (and corruption as a failure in that system) and using time-tested statistical quality control techniques to examine its incidence. When applied to states of the U.S. Union, the methodology flags some states as more corrupt than estimated through other methods and, conversely, identifies other states as less corrupt than anticipated. The paper thus offers a tool and suggestions to support policy-makers in their efforts to evaluate the prevalence of unethical practices and to reduce corruption levels.

Living with the Other, Street Sex Work

There is substantial literature on how fears of Other populations are prompting the increased surveillance and regulation of public spaces at the heart of Western cities. Yet, in contrast to the consumer-oriented spaces of the city centre, there has been relatively little attention devoted to the quality of the street spaces in residential neighborhoods beyond the central city. In this article, we explore how media representations of sex workers as an abject and criminalized Other inform the reactions of residents to street sex work in such communities. Drawing on our work in a number of British cities we highlight the different degrees of tolerance which residents express towards street sex work. In light of the Home Office strategy document, A Coordinated Prostitution Strategy, this article concludes by advocating participatory action research and community conferencing as a means of resolving conflicts and assuaging fears of difference.

Neotropical woodlice (isopoda) colonizing leaf-litter of pioneer plants in a coal residue disposal environment

The irregular disposal of coal combustion residues has adverse impacts on terrestrial ecosystems. Pioneer plants and soil invertebrates play an important role in the recovery of these areas. The goal of this study was to investigate the colonization patterns of terrestrial isopods (Oniscidea) in leaf litter of three spontaneous pioneer plants (grass - Poaceae, shrub - Euphorbiaceae, tree - Anarcadiaceae) at sites used for fly ash or boiler slag disposal. The experiment consisted of eight blocks (four per disposal site) of 12 litter bags each (four per plant species) that were randomly removed after 6, 35, 70 or 140 days of field exposure. Three isopod species were found in the litter bags: Atlantoscia floridana (van Name, 1940) (Philosciidae; n = 116), Benthana taeniata Araujo & Buckup, 1994 (Philosciidae; n = 817) and Balloniscus sellowii (Brandt, 1833) (Balloniscidae; n = 48). The isopods colonized the three leaf-litter species equally during the exposure period. However, the pattern of leaf-litter colonization by these species suggests a conflict of objectives between high quality food and shelter availability. The occurrence of A. floridana and the abundance and fecundity of B. taeniata were influenced by the residue type, indicating that the isopods have different degrees of tolerance to the characteristics of the studied sites. Considering that terrestrial isopods are abundant detritivores and stimulate the humus-forming processes, it is suggested that they could have an indirect influence on the soil restoration of this area.

Warming will affect phytoplankton differently: evidence through a mechanistic approach

Although the consequences of global warming in aquatic ecosystems are only beginning to be revealed, a key to forecasting the impact on aquatic communities is an understanding of individual species' vulnerability to increased temperature. Despite their microscopic size, phytoplankton support about half of the global primary production, drive essential biogeochemical cycles and represent the basis of the aquatic food web. At present, it is known that phytoplankton are important targets and, consequently, harbingers of climate change in aquatic systems. Therefore, investigating the capacity of phytoplankton to adapt to the predicted warming has become a relevant issue. However, considering the polyphyletic complexity of the phytoplankton community, different responses to increased temperature are expected. We experimentally tested the effects of warming on 12 species of phytoplankton isolated from a variety of environments by using a mechanistic approach able to assess evolutionary adaptation (the so-called ratchet technique). We found different degrees of tolerance to temperature rises and an interspecific capacity for genetic adaptation. The thermal resistance level reached by each species is discussed in relation to their respective original habitats. Our study additionally provides evidence on the most resistant phytoplankton groups in a future warming scenario.

Tolerance and Economic Performance in American Metropolitan Areas: An Empirical Investigation1

This article exploits differences in the Gay Index representing diversity and tolerance to estimate the effect of talent on economic performance in U.S. metropolitan areas, and proposes a theory of mechanism of talent distribution and its economic consequences. The index shows there were different degrees of tolerance in early years in different metropolitan areas, with different associated talent. Areas that had high tolerance in early years are more likely tolerant and diverse currently, and can attract more talent. Exploiting differences in the Gay Index as an instrument for current talent, this study estimates a large effect of talent on income per capita. Findings also suggest that other factors, such as high technology and amenities, do not affect regional development directly but do so indirectly by attracting talent.

Intra-specific variation in pea responses to ammonium nutrition leads to different degrees of tolerance

The form of nitrogen nutrition affects many biochemical and physiological processes in plants, leading to markedly different growth responses. Many plant species have been characterized as ammonium tolerant or sensitive. The objective of this work was to assess the range of physiological adaptative responses involved in tolerance of ammonium nutrition at the intra-specific level. Pisum sativum L. was selected as a model of tolerance for the study, and four varieties of agricultural importance (Snap-pea, Rondo, Tristar and Eclipse) were grown hydroponically with ammonium or nitrate (0.5, 2.5, 5.0 and 10.0 mM) as the sole nitrogen source. Physiological parameters including photosynthesis, respiration and ammonium contents were analyzed. Activities/expression of key enzymes of the nitrogen metabolism was also determined, for which novel antibodies against glutamate dehydrogenase and glutamine synthetase were obtained. Snap-pea was considered a reference plant for ammonium tolerance, since its biomass accumulation was not affected by nitrogen source. It avoided the physiological effects of ammonium through low growth potential, high respiratory rates and activity of the alternative pathway. A multivariate analysis of the results showed that each of the four varieties had distinct adaptative responses to ammonium nutrition, highlighting the flexibility of response to ammonium nutrition at the species level. A general activation of glutamate dehydrogenase (GDH) was observed, regardless of the degree of tolerance to ammonium, which may be due to GDH being part of a common stress response to carbon deficit rather than an ammonium tolerance mechanism.

Selection and phenotype characterization of potassium antimony tartrate-resistant populations of four New World Leishmania species

In the present study, we selected in vitro populations of Leishmania Viannia guyanensis, L.V. braziliensis, L. Leishmania amazonensis and L.L. infantum chagasi that were resistant to potassium antimony tartrate (SbIII). The resistance index of these populations varied from 4- to 20-fold higher than that of their wild-type counterparts. To evaluate the stability of the resistance phenotype, these four resistant populations were passaged 37 to 47 times in a culture medium without SbIII. No change was observed in the resistance indexes of L.V. guyanensis (19-fold) and L.L. infantum chagasi (4-fold). In contrast, a decrease in the resistance index was observed for L.V. braziliensis (from 20- to 10-fold) and L.L. amazonensis (from 6- to 3-fold). None of the antimony-resistant populations exhibited cross-resistance to amphotericin B and miltefosine. However, the resistant populations of L.V. braziliensis, L.L. amazonensis and L.L. infantum chagasi were also resistant to paromomycin. A drastic reduction was observed in the infectivity in mice for the resistant L.V. guyanensis, L.L. amazonensis and L.V. braziliensis populations. The SbIII-resistant phenotype of L.V. braziliensis was stable after one passage in mice. Although the protocol of induction was the same, the SbIII-resistant populations showed different degrees of tolerance, stability, infectivity in mice and cross-resistance to antileishmanial drugs, depending on the Leishmania species.

Seleção varietal de Phaseolus vulgaris quanto à tolerância ao estresse salino com base em variáveis de crescimento

Neste estudo objetivou-se avaliar e selecionar variedades de feijoeiro (Phaseolus vulgaris L.) quanto à tolerância ao estresse salino e identificar, usando variedades de feijoeiro com diferentes graus de tolerância, variáveis que auxiliem na discriminagão de variedades de feijoeiro quanto à tolerância a esse tipo de estresse, independentemente do mecanismo apresentado pela planta. Os experimentos foram realizados em casa de vegetagão. Inicialmente foram avaliadas 48 variedades de P. vulgaris (alocadas nas subparcelas) em dois níveis de salinidade (distribuídos nas parcelas): solução nutritiva normal (SNN) a 0,81 dS m-1 e a teste (SNT) a 5,6 dS m-1, obtida pela adigão de NaCl no delineamento experimental em blocos casualizados, com quatro repetigões. A partir da massa seca da parte aérea calculou-se a relagão percentual de crescimento alcançada na SNT relativo à SNN das variedades, que variou de 138,7 a 54,1 %, discriminando-as de acordo com o critério de Scott-Knott em duas populagões: uma com 14 variedades mais "tolerantes" e outra com 34 variedades, onde ficaram agrupadas variedades "moderadamente tolerantes" e "sensíveis". Para identificar variáveis de crescimento que permitam selecionar feijoeiros quanto à tolerância ao estresse salino duas variedades tolerantes (Vermelho e CNF 5574), uma medianamente tolerante (FT 83-86) e uma sensível (LM 30074), classificadas no experimento anterior, foram cultivadas em solução nutritiva com cinco níveis de salinidade (0,81; 2,7; 4,6; 6,5; e 8,4 dS m-1). Analisando-se a massa seca da raiz, do caule, do pecíolo, das folhas e da parte aérea, a área foliar e a área foliar específica, concluiu-se que a área foliar específica foi o índice que efetivamente mais contribuiu para a discriminação das variedades de feijoeiro quanto à tolerância à salinidade.