Relative Salt Tolerance of Four Herbaceous Perennial Ornamentals

Salt tolerant ornamental plants can be irrigated with alternative water sources that are typically saline as a sustainable practice for urban landscaping, especially in arid and semi-arid regions. However, the salt tolerance of many ornamentals is not known. An eight-week greenhouse experiment was conducted to assess the relative salt tolerance of four perennial ornamentals, ‘Angelina’ (Sedum rupestre), ‘Autumn Joy’ (S. telephium), ‘Blue Spruce’ (S. reflexum), and ‘Blue Daze’ (Evolvulus glomeratus). The plants were grown in pots with potting mix substrate and irrigated with control or saline solutions. The electrical conductivities (EC) of the saline solutions were 5.0 and 10.0 mS/cm. Data collected included relative shoot, root, and total dry weight (DW), visual score, shoot tissue concentrations of Na+, Cl−, K+, and Ca2+, and the K+/Na+ ratio. There were significant differences in treatment and varieties for all response variables, and some interactions were also significant, indicating different responses to salinity for the four varieties. Shoot, root, and total DW decreased with increasing salinity for all varieties. Visual score was highest in Autumn Joy and Blue Spruce when treated with EC5 and EC10 and lowest in Angelina and Blue Daze, the latter of which showed symptoms of moderate foliar damage including leaf necrosis, or “burn”, due to salt stress. The concentrations of Na+ and Cl− in the shoot tissue increased with increasing salinity while K+ and Ca2+ and the K+/Na+ ratio tended to decrease. Of the four varieties of herbaceous perennial ornamentals evaluated in this study, Autumn Joy and Blue Spruce were considered the most relatively salt tolerant while Angelina and Blue Daze were least tolerant.

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Salt-Tolerance in Castor Bean (Ricinus communis L.) Is Associated with Thicker Roots and Better Tissue K+/Na+ Distribution

Agriculture ◽

10.3390/agriculture11090821 ◽

2021 ◽

Vol 11 (9) ◽

pp. 821

Author(s):

Junlin Zheng ◽

Gilang B. F. Suhono ◽

Yinghao Li ◽

Maggie Ying Jiang ◽

Yinglong Chen ◽

...

Keyword(s):

Salt Stress ◽

Salt Tolerance ◽

Castor Bean ◽

Ricinus Communis ◽

Dry Weight ◽

Root Diameter ◽

Oilseed Crop ◽

Salt Tolerant ◽

Ricinus Communis L ◽

Young Leaves

Soil salinity is a serious threat to agriculture worldwide. Castor bean (Ricinus communis L.) is an in-demand oilseed crop containing 40–60% highly valued oil in its seeds. It is moderately sensitive to salinity. Two glasshouse experiments were conducted to assess plant growth and ion tissue distribution in different castor bean genotypes under various salt stress conditions to explore their potential for cultivation on saline land. Experiment 1 evaluated the response of five castor bean genotypes to four salt treatments (0, 50, 100, or 150 mM NaCl) up to 91 days after sowing (DAS). Experiment 2 further evaluated two genotypes selected from Experiment 1 in 1 m deep PVC tubes exposed to 0, 100, or 200 mM NaCl treatment for 112 DAS (Experiment 2). Experiment 1 showed that salt addition (particularly 150 mM NaCl) reduced plant height, stem diameter, shoot and root dry weights, photosynthetic traits, and leaf K+/Na+ ratio while increasing the leaf Na+ concentration of castor bean plants. Two genotypes, Zibo (Chinese variety) and Freo (Australian wild type), were more salt-tolerant than the other tested genotypes. In Experiment 2, salt-stressed Zibo flowered earlier than the control, while flowering time of Freo was not influenced by salt stress. The 200 mM NaCl treatment reduced the total root length and increased the average root diameter of both Zibo and Freo compared to the control. In addition, the 200 mM NaCl treatment significantly decreased total leaf area, chlorophyll content, and shoot and root dry weight of both castor bean genotypes by 50%, 10.6%, 53.1%, and 59.4%, respectively, relative to the control. In contrast, the 100 mM NaCl treatment did not significantly affect these traits, indicating that both genotypes tolerated salt stress up to 100 mM NaCl. In general, Freo had greater salt tolerance than Zibo, due to its higher average root diameter, lower Na+ concentration, and higher K+/Na+ ratio in young leaves under salt conditions. In conclusion, genotype Freo is recommended for cultivation in saline soils and could be used to breed high-yielding and salt-tolerant castor bean genotypes.

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Characterization of Maize Hybrids (Zea mays L.) for Detecting Salt Tolerance Based on Morpho-Physiological Characteristics, Ion Accumulation and Genetic Variability at Early Vegetative Stage

Plants ◽

10.3390/plants10112549 ◽

2021 ◽

Vol 10 (11) ◽

pp. 2549

Author(s):

Md Al Samsul Huqe ◽

Md Sabibul Haque ◽

Ashaduzzaman Sagar ◽

Md Nesar Uddin ◽

Md Alamgir Hossain ◽

...

Keyword(s):

Multivariate Analysis ◽

Salt Stress ◽

Salt Tolerance ◽

Dry Weight ◽

Ion Accumulation ◽

Growth And Yield ◽

Tolerance Index ◽

Salt Tolerant ◽

Maize Cultivars ◽

Root Shoot Ratio

Increasing soil salinity due to global warming severely restricts crop growth and yield. To select and recommend salt-tolerant cultivars, extensive genotypic screening and examination of plants’ morpho-physiological responses to salt stress are required. In this study, 18 prescreened maize hybrid cultivars were examined at the early growth stage under a hydroponic system using multivariate analysis to demonstrate the genotypic and phenotypic variations of the selected cultivars under salt stress. The seedlings of all maize cultivars were evaluated with two salt levels: control (without NaCl) and salt stress (12 dS m−1 simulated with NaCl) for 28 d. A total of 18 morpho-physiological and ion accumulation traits were dissected using multivariate analysis, and salt tolerance index (STI) values of the examined traits were evaluated for grouping of cultivars into salt-tolerant and -sensitive groups. Salt stress significantly declined all measured traits except root–shoot ratio (RSR), while the cultivars responded differently. The cultivars were grouped into three clusters and the cultivars in Cluster-1 such as Prabhat, UniGreen NK41, Bisco 51, UniGreen UB100, Bharati 981 and Star Beej 7Star exhibited salt tolerance to a greater extent, accounting for higher STI in comparison to other cultivars grouped in Cluster-2 and Cluster-3. The high heritability (h2bs, >60%) and genetic advance (GAM, >20%) were recorded in 13 measured traits, indicating considerable genetic variations present in these traits. Therefore, using multivariate analysis based on the measured traits, six hybrid maize cultivars were selected as salt-tolerant and some traits such as Total Fresh Weight (TFW), Total Dry Weight (TDW), Total Na+, Total K+ contents and K+–Na+ Ratio could be effectively used for the selection criteria evaluating salt-tolerant maize genotypes at the early seedling stage.

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Detecting Salt Tolerance in Doubled Haploid Wheat Lines

Agronomy ◽

10.3390/agronomy9040211 ◽

2019 ◽

Vol 9 (4) ◽

pp. 211 ◽

Cited By ~ 7

Author(s):

Al-Ashkar ◽

Alderfasi ◽

El-Hendawy ◽

Al-Suhaibani ◽

El-Kafafi ◽

...

Keyword(s):

Genetic Variation ◽

Salt Tolerance ◽

Salinity Tolerance ◽

Doubled Haploid ◽

Dry Weight ◽

Shoot Length ◽

Salt Tolerant ◽

Breeding Programs ◽

Shoot Dry Weight ◽

Wheat Lines

Improving salt tolerance of genotypes requires a source of genetic variation and multiple accurate selection criteria for discriminating their salt tolerance. A combination of morpho-physiological and biochemical parameters and multivariate analysis was used to detect salt tolerance variation in 15 wheat lines developed by doubled haploid (DHL) technique. They were then compared with the salt-tolerant check cultivar Sakha 93. Salinity stress was investigated at three salinity levels (0, 100, and 200 mM NaCl) for 25 days. Considerable genetic variation was observed for all traits, as was high heritability (>60%) and genetic gain (>20%). Principal component analysis indicated the ability of nine traits (root number, root length, root dry weight, shoot length, shoot dry weight, specific root length, relative water content, membrane stability index, and catalase) to identify differences in salinity tolerance among lines. Three traits (shoot length, shoot dry weight, and catalase) were indicative of salt-tolerance, indicating their importance in improving and evaluating salt tolerant genotypes for breeding programs. The salinity tolerance membership index based on these three traits classified one new line (DHL21) and the check cultivar (Sakha 93) as highly salt-tolerant, DHL25, DHL26, DHL2, DHL11, and DHL5 as tolerant, and DHL23 and DHL12 as intermediate. Discriminant function analysis and MANOVA suggested differences among the five groups of tolerance. Among the donor genotypes, Sakha 93 remained the donor of choice for improving salinity tolerance during the seedling stage. The tolerated lines (DHL21, DHL25, DHL26, DHL2, DHL11, and DHL5) could be also recommended as useful and novel genetic resources for improving salinity tolerance of wheat in breeding programs.

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Assessment of salt tolerance and analysis of the salt tolerance gene Ncl in Indonesian soybean germplasm

Plant Genetic Resources ◽

10.1017/s1479262118000618 ◽

2019 ◽

Vol 17 (03) ◽

pp. 265-271

Author(s):

D. Cao ◽

Y. L. Yan ◽

D. H. Xu

Keyword(s):

Salt Tolerance ◽

Dry Weight ◽

Salt Tolerant ◽

Soil Medium ◽

Spad Value ◽

Shoot Dry Weight ◽

Leaf Chlorophyll ◽

Tolerance Gene ◽

Salt Tolerance Gene ◽

Hydroponic Conditions

AbstractSoybean [Glycine max (L.) Merr.] is one of the most important legume crops in the world. However, soybean grain yield is extensively affected by environmental stresses such as soil salinity. In this study, we evaluated the germplasm of 51 Indonesian soybean accessions for salt tolerance to identify salt-tolerant germplasms for possible use in breeding for soybean salt tolerance. Based on experiments under hydroponic conditions, adding 100 mM of NaCl to a 1/2 concentration of Hoagland and Arnon solution, several Indonesian soybean germplasms, such as Java 7, Seputih Raman, Tambora, Ringgit (JP 30217), Sinyonya (early) and Sinyonya (late) were identified as salt-tolerant in terms of salt tolerance rate (STR) and leaf chlorophyll content (SPAD value) taken with the Konica Minolta SPAD-502 chlorophyll meter. The selected salt-tolerant germplasms were further evaluated under soil medium cultivation in pots irrigated with 100 mM NaCl for around 5 weeks. The six selected soybean germplasms again showed higher salt tolerance in terms of SPAD, STR and shoot dry weight. Expression analysis of the salt tolerance gene Ncl revealed a significant positive correlation between Ncl expression and salt tolerance, suggesting that Ncl is essential for salt tolerance in the Indonesian soybean germplasms we tested. The salt-tolerant Indonesian soybean germplasms identified in this study could be used in local soybean breeding practices for the improvement of salt tolerance.

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Identification and Characterization of Wheat Germplasm for Salt Tolerance

Plants ◽

10.3390/plants10020268 ◽

2021 ◽

Vol 10 (2) ◽

pp. 268

Author(s):

Xiaoyan Quan ◽

Xiaoli Liang ◽

Hongmei Li ◽

Chunjuan Xie ◽

Wenxing He ◽

...

Keyword(s):

Salt Stress ◽

Salt Tolerance ◽

Redox Homeostasis ◽

Soluble Sugars ◽

Dry Weight ◽

Limiting Factors ◽

Salt Tolerant ◽

Fresh Weight ◽

Shoot Height ◽

Wheat Genotypes

Salinity is one of the limiting factors of wheat production worldwide. A total of 334 internationally derived wheat genotypes were employed to identify new germplasm resources for salt tolerance breeding. Salt stress caused 39, 49, 58, 55, 21 and 39% reductions in shoot dry weight (SDW), root dry weight (RDW), shoot fresh weight (SFW), root fresh weight (RFW), shoot height (SH) and root length (RL) of wheat, respectively, compared with the control condition at the seedling stage. The wheat genotypes showed a wide genetic and tissue diversity for the determined characteristics in response to salt stress. Finally, 12 wheat genotypes were identified as salt-tolerant through a combination of one-factor (more emphasis on the biomass yield) and multifactor analysis. In general, greater accumulation of osmotic substances, efficient use of soluble sugars, lower Na+/K+ and a higher-efficiency antioxidative system contribute to better growth in the tolerant genotypes under salt stress. In other words, the tolerant genotypes are capable of maintaining stable osmotic potential and ion and redox homeostasis and providing more energy and materials for root growth. The identified genotypes with higher salt tolerance could be useful for developing new salt-tolerant wheat cultivars as well as in further studies to underline the genetic mechanisms of salt tolerance in wheat.

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Relative Salt Tolerance of Seven Japanese Spirea Cultivars

HortTechnology ◽

10.21273/horttech04280-19 ◽

2019 ◽

Vol 29 (3) ◽

pp. 367-373

Author(s):

Yuxiang Wang ◽

Liqin Li ◽

Youping Sun ◽

Xin Dai

Keyword(s):

Salt Tolerance ◽

Irrigation Water ◽

Saline Solution ◽

Visual Quality ◽

Dry Weight ◽

Saline Irrigation ◽

Salt Damage ◽

Shoot Dry Weight ◽

Salinity Levels ◽

Saline Solutions

Spirea (Spiraea sp.) plants are commonly used in landscapes in Utah and the intermountain western United States. The relative salt tolerance of seven japanese spirea (Spiraea japonica) cultivars (Galen, Minspi, NCSX1, NCSX2, SMNSJMFP, Tracy, and Yan) were evaluated in a greenhouse. Plants were irrigated with a nutrient solution with an electrical conductivity (EC) of 1.2 dS·m−1 (control) or saline solutions with an EC of 3.0 or 6.0 dS·m−1 once per week for 8 weeks. At 8 weeks after the initiation of treatment, all japanese spirea cultivars irrigated with saline solution with an EC of 3.0 dS·m−1 still exhibited good or excellent visual quality, with all plants having visual scores of 4 or 5 (0 = dead, 1 = severe foliar salt damage, 2 = moderate foliar salt damage, 3 = slight foliar salt damage, 4 = minimal foliar salt damage, 5 = excellent), except for Tracy and Yan, with only 29% and 64%, respectively, of plants with visual scores less than 3. When irrigated with saline solution with an EC of 6.0 dS·m−1, both ‘Tracy’ and ‘Yan’ plants died, and 75% of ‘NCSX2’ plants died. ‘Minspi’ showed severe foliar salt damage, with 32% of plants having a visual score of 1; 25% of plants died. ‘Galen’ and ‘NCSX1’ had slight-to-moderate foliar salt damage, with 25% and 21%, respectively, of plants with visual scores of 2 or less. However, 64% of ‘SMNSJMFP’ plants had good or excellent visual quality, with visual scores more than 4. Saline irrigation water with an EC of 3.0 dS·m−1 decreased the shoot dry weight of ‘Galen’, ‘Minspi’, ‘SMNSJMFP’, and ‘Yan’ by 27%, 22%, 28%, and 35%, respectively, compared with that of the control. All japanese spirea cultivars had 35% to 56% lower shoot dry weight than the control when they were irrigated with saline irrigation water with an EC of 6.0 dS·m−1. The japanese spirea were moderately sensitive to the salinity levels in this experiment. ‘Galen’ and ‘SMNSJMFP’ japanese spirea exhibited less foliar salt damage and reductions in shoot dry weight and were relatively more tolerant to the increased salinity levels tested in this study than the remaining five cultivars (Minspi, NCSX1, NCSX2, Tracy, and Yan).

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Using Principal Component Analysis and RNA-Seq to Identify Candidate Genes That Control Salt Tolerance in Garlic (Allium sativum L.)

Agronomy ◽

10.3390/agronomy11040691 ◽

2021 ◽

Vol 11 (4) ◽

pp. 691

Author(s):

Xiangjun Zhou ◽

Yanxia Dou ◽

Xiaoxia Huang ◽

Gang Li ◽

Hongrui Zhang ◽

...

Keyword(s):

Principal Component Analysis ◽

Salt Tolerance ◽

Candidate Genes ◽

Principal Component ◽

Dry Weight ◽

Component Analysis ◽

Salt Tolerant ◽

Fresh Weight ◽

Shoot Dry Weight ◽

Leaves And Roots

To examine physiological responses of garlic to salinity, 17-day-old seedlings of eight soft-neck accessions were treated with 200 mM NaCl for seven days in a hydroponic system. Several morphological and physiological traits were measured at the end of the treatment, including shoot height, shoot fresh weight, shoot dry weight, root length, root fresh weight, root dry weight, photosynthesis rate, and concentrations of Na+ and K+ in leaves. The principal component analysis showed that shoot dry weight and K+/Na+ ratio contribute the most to salt tolerance among the garlic accessions. As a result, salt-tolerant and sensitive accessions were grouped based on these two parameters. Furthermore, to investigate the molecular mechanisms in garlic in response to salinity, the transcriptomes of leaves and roots between salt-tolerant and salt-sensitive garlic accessions were compared. Approximately 1.5 billion read pairs were obtained from 24 libraries generated from the leaves and roots of the salt-tolerant and salt-sensitive garlic accessions. A total of 47,509 genes were identified by mapping the cleaned reads to the garlic reference genome. Statistical analysis indicated that 1282 and 1068 genes were upregulated solely in the tolerant leaves and roots, whereas 1505 and 1203 genes were downregulated exclusively in the tolerant leaves and roots after NaCl treatment, respectively. Functional categorization of these genes revealed their involvement in a variety of biological processes. Several genes important for carotenoid biosynthesis, auxin signaling, and K+ transport were strongly altered in roots by NaCl treatment and could be candidate genes for garlic salt tolerance improvement.

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Relative Salt Tolerance of Eight Japanese Barberry Cultivars

HortScience ◽

10.21273/hortsci12358-17 ◽

2017 ◽

Vol 52 (12) ◽

pp. 1810-1815 ◽

Cited By ~ 1

Author(s):

Lifei Chen ◽

Youping Sun ◽

Genhua Niu ◽

Qiang Liu ◽

James Altland

Keyword(s):

Salt Tolerance ◽

Leaf Tissue ◽

Dry Weight ◽

Salt Damage ◽

Shoot Dry Weight ◽

Japanese Barberry ◽

Visual Score ◽

Control Growth ◽

Foliar Damage ◽

And Performance

Relative salt tolerance of eight Berberis thunbergii (japanese barberry) cultivars (B. thunbergii ‘Celeste’, ‘Kasia’, ‘Maria’, ‘Mini’, and ‘Talago’; B. thunbergii var. atropurpurea ‘Concorde’, ‘Helmond Pillar’, and ‘Rose Glow’) was evaluated in a greenhouse experiment. Plants were irrigated with nutrient solution at an electrical conductivity (EC) of 1.2 dS·m−1 (control) or saline solutions at an EC of 5.0 or 10.0 dS·m−1 (EC 5 or EC 10) once a week for 8 weeks. At 4 weeks after treatment, all barberry cultivars in EC 5 had minimal foliar damage with visual scores of 4 or greater (visual score 0: dead, 5: excellent). At 8 weeks after treatment, in EC 5, ‘Helmond Pillar’, ‘Maria’, ‘Mini’, and ‘Rose Glow’ plants exhibited slight foliar salt damage with an average visual score of 3.5, whereas ‘Celeste’, ‘Concorde’, ‘Kasia’, and ‘Talago’ had minimal foliar salt damage with an averaged visual score of 4.4. However, most barberry plants in EC 10 exhibited severe foliar salt damage 4 weeks after treatment with the exception of ‘Concorde’ and were dead 8 weeks after treatment. Compared with control, at the end of the experiment (8 weeks of treatments), shoot dry weight (DW) of ‘Celeste’, ‘Helmond Pillar’, ‘Maria’, and ‘Rose Glow’ in EC 5 was reduced by 47%, 47%, 50%, and 42%, respectively, whereas shoot DW of ‘Concorde’, ‘Kasia’, ‘Mini’, and ‘Talago’ in EC 5 did not change. In EC 10, shoot DW of ‘Celeste’, ‘Concorde’, ‘Kasia’, and ‘Talago’ was reduced by 75%, 35%, 55%, and 46%, respectively. The averaged sodium (Na) concentration of all barberry cultivars in EC 5 and EC 10 was 34 and 87 times, respectively, higher than the control, whereas leaf chloride (Cl) concentration of all barberry cultivars in EC 5 and EC 10 was 14–60 and 29–106 times, respectively, higher than the control. Growth, visual quality, and performance index (PI) were all negatively correlated with leaf Na and Cl content in all cultivars, suggesting that excessive Na and Cl accumulation in the leaf tissue led to growth reduction, salt damage, and death. In summary, ‘Concorde’, ‘Kasia’, and ‘Talago’ were relatively salt tolerant; ‘Helmond Pillar’, ‘Maria’, ‘Mini’, and ‘Rose Glow’ were relatively salt sensitive; and ‘Celeste’ was in between the two groups. Generally, barberry plants had moderate salt tolerance and can be irrigated with marginal water at an EC of 5 dS·m−1 or lower with slight foliar damage.

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Reliability of ion accumulation and growth components for selecting salt tolerant lines in large populations of rice

Functional Plant Biology ◽

10.1071/fp13158 ◽

2014 ◽

Vol 41 (4) ◽

pp. 379 ◽

Cited By ~ 11

Author(s):

Tanveer Ul Haq ◽

Javaid Akhtar ◽

Katherine A. Steele ◽

Rana Munns ◽

John Gorham

Keyword(s):

Salt Tolerance ◽

Mapping Population ◽

Recombinant Inbred Lines ◽

Dry Weight ◽

Inbred Lines ◽

Tiller Number ◽

Ion Accumulation ◽

Salt Tolerant ◽

Leaf Injury ◽

Large Populations

Ion accumulation and growth under salt stress was studied in two experiments in a rice mapping population derived from parents CO39 and Moroberekan with 4-fold differences in shoot Na+ accumulation. The 120 recombinant inbred lines (RILs) had differences up to 100-fold in Na+. Measurement of ‘salt tolerance’ (biomass production of the RILs in 100 mM NaCl relative to controls) after 42 days showed a 2-fold variation in ‘salt tolerance’ between parents, with five RILs being more tolerant than the more tolerant parent CO39. The reliability of various traits for selecting salt tolerance in large populations was explored by measuring Na+, K+ and K+/Na+ ratios in leaf blades and sheaths after 7 or 21 days of exposure to 100 mM NaCl, and their correlation with various growth components and with leaf injury. The highest correlations were found for Na+ in the leaf blade on day 21 with injury at day 42 in both experiments (r = 0.7). Earlier measurements of Na+ or of injury had lower correlations. The most sensitive growth components were tiller number plant–1 and shoot water content (g water g–1 dry weight), and these were correlated significantly with Na+ and, to a lesser extent, with K+/Na+. These studies showed that exposure for at least 42 days may be needed to clearly demonstrate the beneficial effect of the trait for Na+ exclusion on growth under salinity.

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Salt Tolerance of Hydrangea Plants Varied among Species and Cultivar within a Species

Horticulturae ◽

10.3390/horticulturae6030054 ◽

2020 ◽

Vol 6 (3) ◽

pp. 54 ◽

Cited By ~ 1

Author(s):

Genhua Niu ◽

Youping Sun ◽

Triston Hooks ◽

James Altland ◽

Haijie Dou ◽

...

Keyword(s):

Salt Tolerance ◽

Leaf Area ◽

Nutrient Solution ◽

High Mortality ◽

Dry Weight ◽

Salt Damage ◽

Shoot Dry Weight ◽

Greenhouse Study ◽

Hydrangea Macrophylla ◽

Saline Solutions

A greenhouse study was conducted to assess the relative salt tolerance of 11 cultivars of hydrangea: Hydrangea macrophylla ‘Ayesha’, ‘Emotion’, ‘Mathilda Gutges’, ‘Merritt’s Supreme’ and ‘Passion’; H. paniculata ‘Interhydia’ and ‘Bulk’; H. quercifolia ‘Snowflake’; H. serrata ‘Preciosa’; and H. serrata × macrophylla ‘Sabrina’ and ‘Selina’. Plants were treated with a nutrient solution at an electrical conductivity (EC) of 1.0 dS·m−1, and nutrient solution-based saline solutions at an EC of 5.0 dS·m−1 (EC 5) or 10 dS·m−1 (EC 10). The study was repeated in time (Experiments 1 and 2). In both experiments, by the fourth week after treatment, ‘Bulk’ plants in EC 10 exhibited severe salt damage with most of them dead. ‘Interhydia’ was also sensitive, showing severe salt damage in EC 10 with a high mortality rate by the end of the experiment. The leaf area and total shoot dry weight (DW) of all cultivars in EC 5 and EC 10 treatments were significantly reduced compared to the control. Leaf sodium (Na+) and chloride (Cl−) concentrations were negatively correlated with visual quality, leaf area and shoot DW. The salt-sensitive cultivars ‘Bulk’, ‘Interhydia’ and ‘Snowflake’ had inherently low leaf Na+ and Cl− concentrations in both control and salt-treated plants compared to other cultivars. Salt tolerance varied among species and cultivars within H. macrophylla. Among the 11 cultivars, H. macrophylla ‘Ayesha’ and two hybrids, ‘Sabrina’ and ‘Selina’, were relatively salt-tolerant. H. macrophylla ‘Merritt’s Supreme’ and ‘Mathilda’ were moderately tolerant. H. paniculata ‘Bulk’ was the most sensitive, followed by H. paniculata ‘Interhydia’, and then by H. serrata ‘Preciosa’ and H. macrophylla ‘Passion’, as evidenced by high mortality and severe salt damage symptoms. H. quercifolia ‘Snowflake’ and H. macrophylla ‘Emotion’ were moderately salt-sensitive.

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