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Abstract Background Salt tolerance in plants is defined as their ability to grow and complete their life cycle under saline conditions. Staple crops have limited salt tolerance, but forage grass can survive in large unexploited saline areas of costal or desert land. However, due to the restriction of self-incompatible fertilization in many grass species, vegetative propagation via stem cuttings is the dominant practice; this is incompatible with current methodologies of salt-tolerance phenotyping, which have been developed for germination-based seedling growth. Therefore, the performance of seedlings from cuttings under salt stress is still fuzzy. Moreover, the morphological traits involved in salt tolerance are still mostly unknown, especially under experimental conditions with varying levels of stress. Results To estimate the salt tolerance of cutting propagation-dependent grasses, a reliable and low-cost workflow was established with multiple saline treatments, using Paspalum vaginatum as the material and substrate as medium, where cold stratification and selection of stem segments were the two variables used to control for experimental errors. Average leaf number (ALN) was designated as the best criterion for evaluating ion-accumulated salt tolerance. The reliability of ALN was revealed by the consistent results among four P. vaginatum genotypes, and three warm-season (pearl millet, sweet sorghum, and wild maize) and four cold-season (barley, oat, rye, and ryegrass) forage cultivars. Dynamic curves simulated by sigmoidal mathematical models were well-depicted for the calculation of the key parameter, Salt50. The reliability of the integrated platform was further validated by screening 48 additional recombinants, which were previously generated from a self-fertile mutant of P. vaginatum. The genotypes displaying extreme ALN-based Salt50 also exhibited variations in biomass and ion content, which not only confirmed the reliability of our phenotyping platform but also the representativeness of the aerial ALN trait for salt tolerance. Conclusions Our phenotyping platform is proved to be compatible with estimations in both germination-based and cutting propagation-dependent seedling tolerance under salt stresses. ALN and its derived parameters are prone to overcome the species barriers when comparing salt tolerance of different species together. The accuracy and reliability of the developed phenotyping platform is expected to benefit breeding programs in saline agriculture.

Background: Salt tolerance in plants is defined as their ability to grow and complete their life cycle under saline conditions. Staple crops have limited salt tolerance, but forage grass can survive in large unexploited saline areas of costal or desert land. However, due to the restriction of self-incompatible fertilization in many grass species, vegetative propagation via stem cuttings is the dominant practice; this is incompatible with current methodologies of salt-tolerance phenotyping, which have been developed for germination-based seedling growth. Therefore, the performance of seedlings from cuttings under salt stress is still fuzzy. Moreover, the morphological traits involved in salt tolerance are still mostly unknown, especially under experimental conditions with varying levels of stress. Results: To estimate the salt tolerance of cutting propagation-dependent grasses, a reliable and low-cost workflow was established with multiple saline treatments, using Paspalum vaginatum as the material and substrate as medium, where cold stratification and selection of stem segments were the two variables used to control for experimental errors. Average leaf number (ALN) was designated as the best criterion for evaluating ion-accumulated salt tolerance. The reliability of ALN was revealed by the consistent results among four P. vaginatum genotypes, and three warm-season (pearl millet, sweet sorghum, and wild maize) and four cold-season (barley, oat, rye, and ryegrass) forage cultivars. Dynamic curves simulated by sigmoidal mathematical models were well-depicted for the calculation of the key parameter, Salt50. The reliability of the integrated platform was further validated by screening 48 additional recombinants, which were previously generated from a self-fertile mutant of P. vaginatum. The genotypes displaying extreme ALN-based Salt50 also exhibited variations in biomass and ion content, which not only confirmed the reliability of our phenotyping platform but also the representativeness of the aerial ALN trait for salt tolerance. Conclusions: Our phenotyping platform is proved to be compatible with estimations in both germination-based and cutting propagation-dependent seedling tolerance under salt stresses. ALN and its derived parameters are prone to overcome the species barriers when comparing salt tolerance of different species together. The accuracy and reliability of the developed phenotyping platform is expected to benefit breeding programs in saline agriculture. Key message: A novel phenotyping system was developed to screen for salt tolerance of erect stems of Paspalum vaginatum. [ABSTRACT FROM AUTHOR]

The calmodulin-like (CML) family is an important calcium (Ca2+) sensor in plants and plays a pivotal role in the response to abiotic and biotic stresses. As one of the most salt-tolerant grass species, Paspalums vaginatum is resistant to multiple abiotic stresses, such as salt, cold, and drought. However, investigations of PvCML proteins in P. vaginatum have been limited. Based on the recently published P. vaginatum genome, we identified forty-nine PvCMLs and performed a comprehensive bioinformatics analysis of PvCMLs. The main results showed that the PvCMLs were unevenly distributed on all chromosomes and that the expansion of PvCMLs was shaped by tandem and segmental duplications. In addition, cis-acting element analysis, expression profiles, and qRT–PCR analysis revealed that PvCMLs were involved in the response to salt and cold stress. Most interestingly, we found evidence of a tandem gene cluster that independently evolved in P. vaginatum and may participate in cold resistance. In summary, our work provides important insight into how grass species are resistant to abiotic stresses such as salt and cold and could be the basis of further gene function research on CMLs in P. vaginatum.

To evaluate the nitrogen and phosphorus requirements of Salicornia neei, Apium graveolens and Paspalum vaginatum for use in saline aquaponics, plants were hydroponically cultivated with distinct concentrations of sole and mixed nitrogen forms, under low and high phosphorus concentrations. The low nitrogen concentration (0.2 mg L− 1) caused inhibition of many growth parameters. All species can take up both nitrogen forms, but S. neei and A. graveolens prefer nitrate. The high ammonium concentration as the sole nitrogen form (10 mg L− 1) negatively affected S. neei and A. graveolens, and the toxicity may be explained by rhizosphere acidification, since the negative effect was relieved by increasing the nutrient solution pH. Paspalum vaginatum was not sensitive to the high ammonium concentration. Mixed nitrogen forms resulted in plentiful growth of all species, which increased markedly towards the nitrate rich treatment. High ammonium might be applied once the nitrate concentration is ≥ 10 mg L− 1. Phosphorus was not an issue but may limit S. neei and A. graveolens production under a highly nitrifying condition in the water, a common feature of intensive aquaculture systems. [ABSTRACT FROM AUTHOR]

Turfgrasses are considered an important part of the landscape and ecological system of golf courses, sports fields, parks, and home lawns. Turfgrass species are affected by many abiotic stresses (e.g., drought, salinity, cold, heat, waterlogging, and heavy metals) and biotic stresses (mainly diseases and pests). In the current study, seashore paspalum (Paspalum vaginatum Sw.) and Tifway bermudagrass (Cynodon transvaalensis Burtt Davy × C. Dactylon) were selected because they are popular turfgrasses frequently used for outdoor lawns and sport fields. The effect of the combined stress from both soil salinity and cold on these warm season grasses was investigated. Some selected organic and inorganic amendments (i.e., humic acid, ferrous sulphate, and silicon) were applied as foliar sprays five times during the winter season from late October to March. This was repeated over two years in field trials involving salt-affected soils. The physiological and chemical parameters of the plants, including plant height; fresh and dry weight per plot; total chlorophyll content; and nitrogen, phosphorus, iron, and potassium content, were measured. The results showed that all the studied amendments improved the growth of seashore paspalum and Tifway bermudagrass during this period compared to the control, with a greater improvement observed when using ferrous sulphate and humic acid compared to silicon. For seashore paspalum, the highest chlorophyll content in April was recorded after the application of ferrous sulphate at a level of 1000 ppm. The current research indicates that when grown on salt-affected soils, these amendments can be used in warm-season grasses to maintain turf quality during cold periods of the year. Further research is needed to examine any negative long-term effects of these amendments and to explain their mechanisms. [ABSTRACT FROM AUTHOR]

Cadmium (Cd) is a non-essential heavy metal and high concentrations in plants causes toxicity of their edible parts and acts as a carcinogen to humans and animals. Paspalum vaginatum is widely cultivating as turfgrass due to its higher abiotic stress tolerance ability. However, there is no clear evidence to elucidate the mechanism for heavy metal tolerance, including Cd. In this study, an RNA sequencing technique was employed to investigate the key genes associated with Cd stress tolerance and accumulation in P. vaginatum. The results revealed that antioxidant enzyme activities catalase (CAT), peroxidase (POD), superoxide dismutase (SOD), and glutathione S-transferase GST) were significantly higher at 24 h than in other treatments. A total of 6820 (4457/2363, up-/down-regulated), 14,038 (9894/4144, up-/down-regulated) and 17,327 (7956/9371, up-/down-regulated) differentially expressed genes (DEGs) between the Cd1 vs. Cd0, Cd4 vs. Cd0, and Cd24 vs. Cd0, respectively, were identified. The GO analysis and the KEGG pathway enrichment analysis showed that DEGs participated in many significant pathways in response to Cd stress. The response to abiotic stimulus, the metal transport mechanism, glutathione metabolism, and the consistency of transcription factor activity were among the most enriched pathways. The validation of gene expression by qRT-PCR results showed that heavy metal transporters and signaling response genes were significantly enriched with increasing sampling intervals, presenting consistency to the transcriptome data. Furthermore, over-expression of PvSnRK2.7 can positively regulate Cd-tolerance in Arabidopsis. In conclusion, our results provided a novel molecular mechanism of the Cd stress tolerance of P. vaginatum and will lay the foundation for target breeding of Cd tolerance in turfgrass. [ABSTRACT FROM AUTHOR]

Seashore paspalum (Paspalum vaginatum) is an important warm-season turfgrass distributed in tropical and coastal areas. It has excellent resistance to abiotic stresses, such as salinity, drought, and low temperature. However, the research on genetic diversity of local P. vaginatum collections from China is limited. In this study, the genetic diversity among 58 P. vaginatum accessions from four different provinces in China and four cultivars were assessed using simple sequence repeat (SSR) markers. The results indicated that a total of 45 alleles were detected by 19 polymorphic markers, with a range of 2 to 4 and an average of 2.4 alleles per marker. The genetic similarity coefficients between each pair of the 58 P. vaginatum accessions and four cultivars ranged from 0.51 to 1.00, with an average of 0.77. The range of variation of Shannon diversity index of each SSR marker was 0.047 to 1.075, with an average of 0.486. The polymorphic information content of each SSR marker varies from 0.016 to 0.577, with an average of 0.249. The results of cluster analysis and principal component analysis (PCA) showed that 58 P. vaginatum accessions and four cultivars were divided into four groups. These results provide the theoretical basis for the genetic diversity assessments and molecular marker–assisted breeding of P. vaginatum species.

Abstract Background Seashore paspalum (Paspalum vaginatum), a halophytic warm-seasoned perennial grass, is tolerant of many environmental stresses, especially salt stress. To investigate molecular mechanisms underlying salinity tolerance in seashore paspalum, physiological characteristics and global transcription profiles of highly (Supreme) and moderately (Parish) salinity-tolerant cultivars under normal and salt stressed conditions were analyzed. Results Physiological characterization comparing highly (Supreme) and moderately (Parish) salinity-tolerant cultivars revealed that Supreme’s higher salinity tolerance is associated with higher Na+ and Ca2+ accumulation under normal conditions and further increase of Na+ under salt-treated conditions (400 mM NaCl), possibly by vacuolar sequestration. Moreover, K+ retention under salt treatment occurs in both cultivars, suggesting that it may be a conserved mechanism for prevention of Na+ toxicity. We sequenced the transcriptome of the two cultivars under both normal and salt-treated conditions (400 mM NaCl) using RNA-seq. De novo assembly of about 153 million high-quality reads and identification of Open Reading Frames (ORFs) uncovered a total of 82,608 non-redundant unigenes, of which 3250 genes were identified as transcription factors (TFs). Gene Ontology (GO) annotation revealed the presence of genes involved in diverse cellular processes in seashore paspalum’s transcriptome. Differential expression analysis identified a total of 828 and 2222 genes that are responsive to high salinity for Supreme and Parish, respectively. “Oxidation-reduction process” and “nucleic acid binding” are significantly enriched GOs among differentially expressed genes in both cultivars under salt treatment. Interestingly, compared to Parish, a number of salt stress induced transcription factors are enriched and show higher abundance in Supreme under normal conditions, possibly due to enhanced Ca2+ signaling transduction out of Na+ accumulation, which may be another contributor to Supreme’s higher salinity tolerance. Conclusion Physiological and transcriptome analyses of seashore paspalum reveal major molecular underpinnings contributing to plant response to salt stress in this halophytic warm-seasoned perennial grass. The data obtained provide valuable molecular resources for functional studies and developing strategies to engineer plant salinity tolerance.

Turfgrasses are considered an important part of the landscape and ecological system of golf courses, sports fields, parks, and home lawns. Turfgrass species are affected by many abiotic stresses (e.g., drought, salinity, cold, heat, waterlogging, and heavy metals) and biotic stresses (mainly diseases and pests). In the current study, seashore paspalum (Paspalum vaginatum Sw.) and Tifway bermudagrass (Cynodon transvaalensis Burtt Davy × C. Dactylon) were selected because they are popular turfgrasses frequently used for outdoor lawns and sport fields. The effect of the combined stress from both soil salinity and cold on these warm season grasses was investigated. Some selected organic and inorganic amendments (i.e., humic acid, ferrous sulphate, and silicon) were applied as foliar sprays five times during the winter season from late October to March. This was repeated over two years in field trials involving salt-affected soils. The physiological and chemical parameters of the plants, including plant height; fresh and dry weight per plot; total chlorophyll content; and nitrogen, phosphorus, iron, and potassium content, were measured. The results showed that all the studied amendments improved the growth of seashore paspalum and Tifway bermudagrass during this period compared to the control, with a greater improvement observed when using ferrous sulphate and humic acid compared to silicon. For seashore paspalum, the highest chlorophyll content in April was recorded after the application of ferrous sulphate at a level of 1000 ppm. The current research indicates that when grown on salt-affected soils, these amendments can be used in warm-season grasses to maintain turf quality during cold periods of the year. Further research is needed to examine any negative long-term effects of these amendments and to explain their mechanisms.

Most plant species, including most crops, perform poorly in salt-affected soils because high sodium levels are cytotoxic and can disrupt the uptake of water and important nutrients. Halophytes are species that have evolved adaptations to overcome these challenges and may be a useful source of knowledge for salt tolerance mechanisms and genes that may be transferable to crop species. The salt content of saline habitats can vary dramatically by location, providing ample opportunity for different populations of halophytic species to adapt to their local salt concentrations; however, the extent of this variation, and the physiology and polymorphisms that drive it, remain poorly understood. Differential accumulation of inorganic elements between genotypes or populations may play an important role in local salinity adaptation. To test this, we investigated the relationships between population structure, tissue ion concentrations, and salt tolerance in 17 "finetextured" genotypes of the halophytic turfgrass seashore paspalum (Paspalum vaginatum Swartz). A high-throughput ionomics pipeline was used to quantify the shoot concentration of 18 inorganic elements across three salinity treatments. We found a significant relationship between population structure and ion accumulation, with strong correlations between principal components derived from genetic and ionomic data. Additionally, genotypes with higher salt tolerance accumulated more K and Fe and less Ca than less tolerant genotypes. Together these results indicate that differences in ion accumulation between P. vaginatum populations may reflect locally adapted salt stress responses. [ABSTRACT FROM AUTHOR]

Cadmium (Cd) is a non-essential heavy metal and high concentrations in plants causes toxicity of their edible parts and acts as a carcinogen to humans and animals. Paspalum vaginatum is widely cultivating as turfgrass due to its higher abiotic stress tolerance ability. However, there is no clear evidence to elucidate the mechanism for heavy metal tolerance, including Cd. In this study, an RNA sequencing technique was employed to investigate the key genes associated with Cd stress tolerance and accumulation in P. vaginatum. The results revealed that antioxidant enzyme activities catalase (CAT), peroxidase (POD), superoxide dismutase (SOD), and glutathione S-transferase GST) were significantly higher at 24 h than in other treatments. A total of 6820 (4457/2363, up-/down-regulated), 14,038 (9894/4144, up-/down-regulated) and 17,327 (7956/9371, up-/down-regulated) differentially expressed genes (DEGs) between the Cd1 vs. Cd0, Cd4 vs. Cd0, and Cd24 vs. Cd0, respectively, were identified. The GO analysis and the KEGG pathway enrichment analysis showed that DEGs participated in many significant pathways in response to Cd stress. The response to abiotic stimulus, the metal transport mechanism, glutathione metabolism, and the consistency of transcription factor activity were among the most enriched pathways. The validation of gene expression by qRT-PCR results showed that heavy metal transporters and signaling response genes were significantly enriched with increasing sampling intervals, presenting consistency to the transcriptome data. Furthermore, over-expression of PvSnRK2.7 can positively regulate Cd-tolerance in Arabidopsis. In conclusion, our results provided a novel molecular mechanism of the Cd stress tolerance of P. vaginatum and will lay the foundation for target breeding of Cd tolerance in turfgrass.

[Objectives] Protein arginine methyltransferases (PRMT) family genes performed important roles in regulating plant growth, development and stress tolerance. However, the expression patterns and stress tolerance functions of PRMT members in turf grass were still unclear. The purpose of this study was to explore the expression patterns of Paspalum vaginatum PvPRMT gene family under abiotic stress and the stress tolerance functions of PPRMT10. [Methods] With warm-season turfgrass seashore paspalum as the plant material, and by referring to the transcriptome database information, sequence analysis and PCR were used to clone the full length sequences of 8 members of seashore paspalum PRMT family, and then the proteins were analyzed by phylogenetic trees and MEME online tool. Quantitative real-time PCR (RT-qPCR) was used to analyze the relative expression levels of PvPRMTs under different stress conditions (NaCl, drought, Cd and ABA treatment). Arabidopsis PvPRMT10 over expressed lines were obtained by transgenic technology, and phenotypic identification was performed under stress conditions. [Results] The analysis found that seashore paspalum and rice were both monocotyledon and their 8 genes of PRMT family evolutionary relationship were closer than Arabidopsis, and could be divided into three categories (I, II and III type). The more closely related genes had similar expression patterns under different stresses. In addition to PvPRMT4, other genes were up or down-regulated to different expression levels in response to different stresses. The expression level of PPRMT10 in leaves under NaCl treatment increased by nearly 10 times at 6 and 12 h, and the expression level under CdCl2 treatment increased by nearly 15 times at 6 h. PRMT genes responses in leaves were stronger than those in root under different stress conditions. Further, we also found that over-expression of the type I gene PPRMT10 enhanced cadmium (Cd) and salt stress tolerance of Arabidopsis. The seed survival rate of over-expressed lines under CdCl2 treatment was about 15% higher than that of wide type, and the seed survival rate of over-expressed lines under NaCl treatment was about 45% higher than that of wide type, and the seedling root appearance was about twice longer than that of wild type. [Conclusions] In this study, PRMT family genes were cloned and their expression patterns under abiotic stress were analyzed, and PvPRMT10 was found to be resistant to Cd and NaCl. [ABSTRACT FROM AUTHOR]

The use of nonpotable water for irrigation on various sport venues has led to an increased use of seashore paspalum (Paspalum vaginatum) turf in Hawaii. An ongoing challenge many seashore paspalum turf managers struggle with is bermudagrass (Cynodon dactylon) infestations. Herbicide efficacy studies were conducted at the Hoakalei Country Club [‘SeaDwarf’ seashore paspalum (fairway cut)] and the Magoon Research Station [‘SeaStar’ seashore paspalum (grown in container)] on the island of Oahu in Hawaii. Spray applications of the herbicides mesotrione, topramezone, metribuzin, and ethofumesate were evaluated alone and in tank mixtures for bermudagrass suppression and seashore paspalum injury. At the Hoakalei Country Club, maximum bermudagrass injury with minimal seashore paspalum discoloration was obtained with tank mixes of mesotrione (0.06 lb/acre) + metribuzin (0.19 lb/acre) + ethofumesate (1.00 lb/acre) and topramezone (0.02 lb/acre) + metribuzin (0.19 lb/acre) + ethofumesate (1.00 lb/acre). Unacceptable seashore paspalum turf injury was obtained in all treatments that did not include metribuzin. At the Magoon Research Station, maximum selective bermudagrass suppression was achieved with tank mixes of topramezone (0.01 lb/acre) + ethofumesate (1.00 lb/acre) and topramezone (0.01 lb/acre) + metribuzin (0.09 lb/acre) + ethofumesate (1.00 lb/acre). The addition of metribuzin and/or ethofumesate to the tank mix safened (reduced turf discoloration) seashore paspalum to topramezone or mesotrione foliar bleaching. Tank mixes of mesotrione, topramezone, metribuzin, and ethofumesate have the potential for bermudagrass suppression and control of other grassy weeds in seashore paspalum turf.

Background: Seashore paspalum (Paspalum vaginatum), a halophytic warm-seasoned perennial grass, is tolerant of many environmental stresses, especially salt stress. To investigate molecular mechanisms underlying salinity tolerance in seashore paspalum, physiological characteristics and global transcription profiles of highly (Supreme) and moderately (Parish) salinity-tolerant cultivars under normal and salt stressed conditions were analyzed. Results: Physiological characterization comparing highly (Supreme) and moderately (Parish) salinity-tolerant cultivars revealed that Supreme's higher salinity tolerance is associated with higher Na+ and Ca2+ accumulation under normal conditions and further increase of Na+ under salt-treated conditions (400 mM NaCl), possibly by vacuolar sequestration. Moreover, K+ retention under salt treatment occurs in both cultivars, suggesting that it may be a conserved mechanism for prevention of Na+ toxicity. We sequenced the transcriptome of the two cultivars under both normal and salt-treated conditions (400 mM NaCl) using RNA-seq. De novo assembly of about 153 million high-quality reads and identification of Open Reading Frames (ORFs) uncovered a total of 82,608 non-redundant unigenes, of which 3250 genes were identified as transcription factors (TFs). Gene Ontology (GO) annotation revealed the presence of genes involved in diverse cellular processes in seashore paspalum's transcriptome. Differential expression analysis identified a total of 828 and 2222 genes that are responsive to high salinity for Supreme and Parish, respectively. "Oxidation-reduction process" and "nucleic acid binding" are significantly enriched GOs among differentially expressed genes in both cultivars under salt treatment. Interestingly, compared to Parish, a number of salt stress induced transcription factors are enriched and show higher abundance in Supreme under normal conditions, possibly due to enhanced Ca2+ signaling transduction out of Na+ accumulation, which may be another contributor to Supreme's higher salinity tolerance. Conclusion: Physiological and transcriptome analyses of seashore paspalum reveal major molecular underpinnings contributing to plant response to salt stress in this halophytic warm-seasoned perennial grass. The data obtained provide valuable molecular resources for functional studies and developing strategies to engineer plant salinity tolerance. [ABSTRACT FROM AUTHOR]

The golf courses present major areas of grass that need high volumes of water for maintenance. In regions with arid climate, elevated water losses by evapotranspiration contrast with low rainfall. In the urban-touristic area of Los Cabos, 13 golf courses have been built in a distance of 40 km along the coast. This benefits private developers but golf courses provoke various environmental and social problems, including habitat loss, pollution of soils and aquifers, among others. Because the golf courses do not report their water demand, the annual water consumption was analyzed by indirect methods, using satellite imagery and geographic information systems. The obtained annual water demand of the 13 golf fields is 7.09 million m3, which is more than the whole water volume used for agriculture in this area. The findings suggest that the water consumption should be taken into account as an important environmental impact before the realization of new golf courses in Mexico. [ABSTRACT FROM AUTHOR]

This investigation was carried out at a Privet Farm, El-Ibrahimia District, Sharkia Governorate, Egypt during the two consecutive seasons of 2016/2017 and 2017/2018 to study the effect of different saline irrigation water levels (0.0, 10000, 15000 and 20000 ppm NaCl), amino acids type (0.0, proline at 200 ppm, putrescine at 200 ppm and proline + putrescence each one at 200 ppm) and their combinations on plant growth, root system, salt resistance index and leaf pigments content of seashore paspalum (Paspalum vaginatum, Swartz) turfgrass. Plastic pots in 35 cm diameter filled with 5.5 kg of sand and clay mixture (1:2, V/V) were used in this experiment. The obtained results showed that plant growth (plant height , covering density percentage and herb fresh and dry weights), root system (root fresh and dry weights and root length), salt resistance index and leaf pigments (chlorophyll a, chlorophyll b and carotenoids contents) were descendingly decreased with increasing salinity level of irrigation water comparing with the control in both seasons, but they were progressively increased as the concentration of amino acids (proline and putrescine) was used. From these results, it can be recommended to irrigate seashore paspalum turfgrass with saline water up to 10000 ppm NaCl and sprayed with proline + putrescine each at 200 ppm to obtain the best growth, colour and higher covering density. [ABSTRACT FROM AUTHOR]

As population growth places greater pressures on potable water supplies, nonpotable recycled irrigation water is becoming widely used on turfgrass areas including golf courses, sports fields, parks, and lawns. Nonpotable recycled waters often have elevated salinity levels, and therefore turfgrasses must, increasingly, have good salinity tolerance to persist in these environments. This greenhouse study evaluated 10 commonly used cultivars representing warm-season turfgrass species of bermudagrass (Cynodon spp.), zoysiagrass (Zoysia spp.), st. augustinegrass [Stenotaphrum secundatum (Walt.) Kuntze], and seashore paspalum (Paspalum vaginatum Swartz) for their comparative salinity tolerance at electrical conductivity (EC) levels of 2.5 (control), 15, 30, and 45 dS·m-1. Salinity treatments were imposed on the grasses for 10 weeks via subirrigation, followed by a 4-week freshwater recovery period. Attributes, including turf quality, the normalized difference vegetation index (NDVI), canopy firing, and shoot biomass reductions were evaluated before and after salinity stress, as well as after the 4-week freshwater recovery period. Results showed considerable differences in salinity tolerance among the cultivars and species used, with the greatest tolerance to elevated salinity noted within seashore paspalum cultivars and Celebration® bermudagrass. In comparison with growth in 2.5-dS·m-1 control conditions, increased shoot growth and turf quality were noted for many bermudagrass and seashore paspalum cultivars at 15 dS·m-1. However, st. augustinegrass and some zoysiagrass cultivars responded to elevated salinity with decreased growth and turf quality. No cultivars that had been exposed to 30- or 45-dS·m-1 salinity recovered to acceptable levels, although bermudagrass and seashore paspalum recovered to acceptable levels after exposure to 15-dS·m-1 salinity. More severe salinity stress was noted during year 2, which coincided with greater greenhouse temperatures relative to year 1. [ABSTRACT FROM AUTHOR]

Climate change has become a real threat, and its impacts are being felt throughout the world. Temperature is considered one of the significant elements by the recent consequences of climate change and global warming, specially the salinity which is increased at higher temperature. Turfgrasses are adversely affected due to an increasing trend in salinity. The main aim of this investigation was to find out salt-tolerant ecotypes from native species of UAE to mitigate the salinity problem. Performance of a native grass, Aeluropus lagopoides, was investigated under high saline conditions during the year 2014 under the UAE climatic conditions. The experiment was planned under randomised complete block design (RCBD) with two factors and four replications. During the experiment, 50 ecotypes of Aeluropus lagopoides, alongside Paspalum vaginatum (as control), were tested at different salt levels, i.e. 0, 15, 30, 45, 60 and 75 dSm−1. Significant differences were found among various ecotypes as well as salinity levels for different agronomic traits including green cover, canopy stiffness, leaf colour and salinity of leaf rinseates. Most of the ecotypes tolerated salinity up to 30 dSm−1, maintaining the quality, but beyond this level the quality declined. However, some of the ecotypes survived under high salinity, even beyond sea level (75 dSm−1). All the ecotypes, except RUA2, RUA3 and RUA1, showed better performance than P. vaginatum, the prevailing commercial turfgrass in the UAE. Based on their performance, the ecotypes RUDA7, FA5, RA3, RUDA2 and RA2 could be used for turf purposes under saline conditions. [ABSTRACT FROM AUTHOR]

Morphological and physiological responses to freezing were evaluated in two ecotypes of the perennial turfgrass Paspalum vaginatum. Leaf extension rate, number of active meristems, leaf water potential and net photosynthesis were measured on plants of both a commercial cultivar, 'Sea Isle 2000', and a wild ecotype from the Flooding Pampa grasslands of Argentina. Plants were propagated by cloning, cultivated in pots, and examined during 18 consecutive days under two treatments: a non-frozen control treatment (15.5±7 ºC) and a frozen treatment with two stages: Stage 1 with four hours of freezing stress for 10 nights (-5ºC), and Stage 2 with 12 hours of freezing stress for eight nights (five nights at -5ºC and three nights at -8ºC). After these treatments, plants were returned to the outside environment to evaluate shoot injury and post-freezing recovery. Leaf water potential, net photosynthesis and leaf extension rate were significantly higher in the wild ecotype than in the commercial cultivar. Meristem density was reduced after freezing in both ecotypes, but was more pronounced in the commercial cultivar (98.5%) than in the wild ecotype (80%). Thus, the two ecotypes coming from different environments, exhibited different morphological and physiological responses to exposure to freezing temperatures.

A limiting factor for prodution of turf grasses in temperate regions is their low level of cold tolerance. In order to elucidate the cold tolerance, physiological and biochemical responses of two turf species, this study was conducted at a controlled environment greenhouse of Faculty of Agriculture in Shiraz University, Shiraz, Iran by a factorial experiment in completely randomized design with three replicates. Factors consisted of two turf species including Kentucky bluegrass (Poa pratensis) and seashore paspalum (Paspalum vaginatum) and four temperatures: 25, 15, 5 and -5 °C. Data analysis revealed that decreased temperature resulted in significant increases in proline, soluble sugars contents and activity of peroxidase, ascorbate peroxidase, catalase and superoxide dismutase enzymes, although seashore paspalum indicated a significant drop in antioxidant enzymes activity at cold stress of -5 °C. Furthermore, decreased temperature brought about a significant decline in visual quality, chlorophyll, starch and relative water content. Seashore paspalum exhibited a greater deterioration in visual quality, chlorophyll and relative water content at -5 °C compared to Kentucky bluegrass. The results showed that Kentucky bluegrass withstood cold stress with a better and more efficient defensive mechanism in comparison with seashore paspalum, thus it is considered more tolerant to cold stress and could, potentially, be used in temperate regions.

This investigation was conducted under open field conditions at the Experimental Farm of Hort. Res. Inst., ARC, Giza, Egypt during 2013 and 2014 seasons to find out the response of seashore paspalum (Paspalum vaginatum Swartz) grown in 40-cmdiameter plastic pots filled with about 6 kg of an equal mixture of sand and clay (1:1, v/v) to some natural activators, viz. super blue green (SBG) at 3 ml/l, Ascobien at 1 g/l, BioHorm at 1 ml/l and to some combinations of them when applied as a foliar spray, five times with one month interval. The verdure of control plants was sprayed with the tap water. The results of such investigation have shown that all vegetative growth traits were significantly improved over control in response to either sole or combined treatments applied in this study. Among the individual treatments, BioHorm at 1 ml/l was the best treatment, followed by SBG at 3 ml/l and then 1 ml/l of Ascobien treatment. An excessive improvement was obtained when combining the single treatments, especially combining between the three used activators (SBG at 3 ml/l + Ascobien at 1 g/l + BioHorm at 1 ml/l), as such combination gave the utmost high means of vegetative growth parameters at all in the two seasons. A similar trend to that of vegetative growth was also observed as well regarding the content of chlorophyll a, b, carotenoids, N, P, K, total soluble sugars and total indoles in the leaves, but the opposite was the right concerning total phenols content which was decreased by the various used treatments to reach the minimum values by the combination of 3 ml/l SBG + 1 g/l Ascobien + 1 ml/l BioHorm in the two seasons. Hence, it is recommended to spray the verdure of seashore paspalum turf with a combination of SBG (3 ml/l) + Ascobien (1 g/l) + BioHorm (1 ml/l), five times with 1 month interval during the growth stage to score the best growth performance and highest quality.

Seashore paspalum (Paspalum vaginatum O. Swartz) is an important warm-season turfgrass with great salinity tolerance. Based on establishment of embryogenic callus induction and regeneration from different mature seeds of ‘Sea Spray’, an Agrobacterium tumefaciens-mediated transformation was established and optimized in this study. Three clones of callus were selected for examining transformation conditions using Agrobacterium tumefaciens strain AGL1 carrying the binary vector pCAMBIA1305.2, containing β-glucuronidase (GUS) as a reporter gene and hygromycin phosphotransferase (HPT) as a selective marker gene. The results showed that a high transient transformation efficiency was observed by using Agrobacterium concentration of OD600 = 0.6, 5 min of sonication treatment during Agrobacterium infection, and 2 d of co-cultivation. By using the optimized transformation conditions, transgenic seashore paspalum plants were obtained. PCR and Southern blot analysis showed that T-DNA was integrated into the genomes of seashore paspalum. GUS staining experiments showed that the GUS gene was expressed in transgenic plants. Our results suggested that the transformation protocol will provide an effective tool for breeding of seashore paspalum in the future. [ABSTRACT FROM AUTHOR]

The increasing demand on potable water has resulted in a greater reliance on poorer quality water, including saline sources, for maintaining forage and turfgrasses in agricultural and urban landscapes. Consequently, it will be crucial to identify grasses that can tolerate saline irrigation water. This study aimed to determine salinity tolerance among a large range of bermudagrasses relative to other perennial C 4 grasses and test the relationship between salt tolerance and drought resistance. We report the salinity tolerance of 70 genotypes of mostly Australian bermudagrass ecotypes that were compared to halophytic cultivars of seashore paspalum ( Paspalum vaginatum Swartz) and a non-halophytic cultivar of Queensland blue couch ( Digitaria didactyla Willd) using a flood and drain sand culture system with salt treatments 1–40 dS m −1 . For the first time for C 4 grasses, salt tolerance was determined by comparing total biomass of the grasses with and without salt treatment. Large genetic variation in salinity tolerance was identified and six bermudagrasses collected from saline habitats had salinity tolerance equal to that of seashore paspalum under the salinity treatments used in this study. There was no correlation between salt tolerance and drought resistance phenotypes determined from our previous research. Canopy temperature differential during salt stress was negatively correlated (r = −0.71 to −0.91, P < 0.001) to salt tolerance and has potential to be used for screening bermudagrasses for salt tolerance using flood and drain sand culture. Salinity levels above 20 dS m −1 for 8 weeks appeared to be effective for detecting large variation for salt tolerance in bermudagrass. [ABSTRACT FROM AUTHOR]

The negative effects of the ongoing climate change include unusual prolonged droughts and increased salinity pressures on the agricultural lands. Consequently, crops are facing unprecedented environmental pressure, and this calls for more research toward controlling such major stresses. The current study investigates the effects of seaweed extract sprays of Ascophyllum nodosum (5 and 7 mL·L−1; 6 day intervals) on Paspalum vaginatum Salam' during prolonged irrigation intervals (2 and 6 day) and saline growing conditions (1 and 49.7 dS·m−1) for 6 weeks in containers under greenhouse conditions. Control plants showed reduced turf quality, photochemical efficiency, root length and dry weight, total non-structural carbohydrates, and K and Ca compositions. Seaweed extracts increased turf quality, leaf photochemical efficiency, root length and dry weight, total non-structural carbohydrates, K, Ca, and proline in treated plants during prolonged irrigation intervals as well as saline shock conditions. There were also increases in the antioxidant defensive mechanisms such as catalase (CAT), superoxide dismutase (SOD) and ascorbate peroxidase (APX) activities and non-enzymatic antioxidants as well as reduced lipid peroxidation. The application of SWE at 7 mL·L−1 showed higher performance in treated plants during prolonged irrigation intervals as well as saline conditions. Our findings imply that several mechanisms including drought tolerance, osmotic adjustment and antioxidant defense system may interact to enhance the performance of plants in the face of environmental stress following SWE treatments.

Centipedegrass [Eremochloa ophiuroides (Munro) Hack.] and seashore paspalum (Paspalum vaginatum Sw.) can be weedy species with other turfgrasses. Monosodium methylarsenate (MSMA) selectively controls these grasses in polyculture with tolerant species such as bermudagrass [Cynodon dactylon (L.) Pers.], but the mechanisms of selectivity are not well understood. The objectives of this research were to investigate the efficacy and behavior of MSMA in bermudagrass, centipedegrass, and seashore paspalum. In greenhouse experiments, the hierarchical rank of injury ranges for species from high to low was centipedegrass > seashore paspalum > bermudagrass. Monosodium methylarsenate reduced dry shoot biomass of centipedegrass and seashore paspalum six and three times greater than bermudagrass after 4 wk, respectively. The hierarchical rank of lipid peroxidation after MSMA treatments, as measured by malondialdehyde (MDA) content, from high to low was centipedegrass > seashore paspalum > bermudagrass. Grasses reached peak foliar absorption of 14C-MSMA at 1 d after treatment (DAT), but differences among species were not detected. There was no metabolism of 14C-MSMA in any species at 1, 3, or 7 DAT, suggesting MSMA could remain bioavailable in clippings of tolerant and susceptible grasses. Overall, the selectivity of MSMA in warm-season turfgrasses is associated with differential levels of lipid peroxidation. [ABSTRACT FROM AUTHOR]

Management of conventional crops must adapt to the particularities of urban greening techniques, such as green roofing. The aim of the study was to determine seashore paspalum (Paspalum vaginatum Swartz 'Platinum TE') response when grown in shallow green roof substrates and under moisture deficit conditions during two summer periods. Treatments included: (i) six different green roof substrates formulated from locally available materials by mixing combinations of sandy loam soil, pumice, perlite, clinoptilolite zeolite, peat, and compost; (ii) two substrate depths (7.5 or 15 cm); and (iii) two irrigation regimes (60 or 100% crop evapotranspiration). Measurements included the determination of substrate moisture content (SMC) and turfgrass normalized difference vegetation index (NDVI). It was found that, during moisture deficit periods, NDVI was mostly affected by irrigation regime and substrate depth but not by substrate type. Turfgrass retained higher NDVI values for longer time intervals when the high irrigation regime of 100% crop evapotranspiration was combined with the deeper substrates of 15 cm. Regression between SMC and NDVI revealed that SMC should be retained from 23.7 to 28.5% (v/v) to keep seashore paspalum within acceptable NDVI values when grown under shallow green roof conditions. [ABSTRACT FROM AUTHOR]

The negative effects of the ongoing climate change include unusual prolonged droughts and increased salinity pressures on the agricultural lands. Consequently, crops are facing unprecedented environmental pressure, and this calls for more research toward controlling such major stresses. The current study investigates the effects of seaweed extract sprays of Ascophyllum nodosum (5 and 7 mL·L-1; 6 day intervals) on Paspalum vaginatum Salam' during prolonged irrigation intervals (2 and 6 day) and saline growing conditions (1 and 49.7 dS·m-1) for 6 weeks in containers under greenhouse conditions. Control plants showed reduced turf quality, photochemical efficiency, root length and dry weight, total non-structural carbohydrates, and K and Ca compositions. Seaweed extracts increased turf quality, leaf photochemical efficiency, root length and dry weight, total non-structural carbohydrates, K, Ca, and proline in treated plants during prolonged irrigation intervals as well as saline shock conditions. There were also increases in the antioxidant defensive mechanisms such as catalase (CAT), superoxide dismutase (SOD) and ascorbate peroxidase (APX) activities and non-enzymatic antioxidants as well as reduced lipid peroxidation. The application of SWE at 7 mL·L-1 showed higher performance in treated plants during prolonged irrigation intervals as well as saline conditions. Our findings imply that several mechanisms including drought tolerance, osmotic adjustment and antioxidant defense system may interact to enhance the performance of plants in the face of environmental stress following SWE treatments. [ABSTRACT FROM AUTHOR]

Seashore paspalum (Paspalum vaginatum) is among the most salt- and cadmium-tolerant warm-season perennial grass species widely used as turf or forage. The objective of this study was to select stable reference genes for quantitative real-time polymerase chain reaction (qRT-PCR) analysis of seashore paspalum in response to four abiotic stresses. The stability of 12 potential reference genes was evaluated by four programs (geNorm, NormFinder, BestKeeper, and RefFinder). U2AF combined with glyceraldehyde-3-phosphate dehydrogenase (GAPDH) showed stable expression in Cd-treated leaves and cold-treated roots. U2AF and FBOX were the most stable reference genes in Cd-treated roots and cold-treated leaves. In Polyethylene Glycol (PEG)- or salt-treated roots, the reference gene U2AF paired with either ACT or CYP were stable. SAND and CACS exhibited the most stability in salt-treated leaves, and combining UPL, PP2A, and EF1a was most suitable for PEG-treated leaves. The stability of U2AF and instability of UPL and TUB was validated by analyzing the expression levels of four target genes (MT2a, VP1, PIP1, and Cor413), and were shown to be capable of detecting subtle changes in expression levels of the target genes in seashore paspalum. This study demonstrated that FBOX, U2AF, and PP2A could be used in future molecular studies that aim to understand the mechanisms of abiotic stress tolerance in seashore paspalum. [ABSTRACT FROM AUTHOR]

This study investigated the influence of nitrogen-fixing hydrocarbon-degrading bacteria from the rhizosphere of plants in the biodegradation of crude oil in the polluted soil. Several nitrogen-fixing and crude oil utilizing bacteria were isolated from the rhizosphere of the turf grass Paspalum vaginatum Sw. using crude oil as carbon and energy source. The isolates showed between 98% - 99% 16S rRNA gene similarity with species of Alcaligenes, Brevundimonas and Klebsiella. Three of the isolates, Brevundimonas diminuta C4B, Alcaligenes faecalis B5 and Alcaligenes faecalis D4A with the ability to grow well in crude oil as carbon and energy source were selected for further studies. Alcaligenes faecalis B5 had the highest growth rate constant of 0.038 µ-1 with a mean generation time of 18.46 h. Analysis of culture extracts by gas chromatography with flame ionization detector showed that Alcaligenes faecalis B5 degraded 90.5% of crude oil in 24 days, while Alcaligenes faecalis D4A and Brevundimonas diminuta C4B biodegraded 84.6% and 82.1% of the oil respectively. Only Alcaligenes faecalis C1B, Klebsiella varicola C3B and Klebsiella varicola C3BB had the nifH gene; and the genes responsible for nitrogenfixing abilities of all the isolates were not plasmid-borne. Confirmation of nitrogenfixing ability was determined by the acetylene reduction assay (ARA). Alcaligenes faecalis B5 produced the highest amount of ethylene (15.18 nmol) after 24 h of incubation, while Alcaligenes faecalis D4A and Brevundimonas diminuta C4B produced 12.10 nmol and 9.60 nmol of ethylene respectively. Nitrogen-fixing hydrocarbon utilizers are therefore potential seeds in the bioaugmentation of nitrogen-limited hydrocarbon-polluted environments. [ABSTRACT FROM AUTHOR]

Four halophytic perennial forage grass species, Distichlis spicata, Paspalum vaginatum, Sporobolus virginicus and S. arabicus, were planted in three salt-degraded and abandoned farms at Mezaira'a, Madinat Zayed and Ghayathi in the United Arab Emirates. The salinity of the irrigation water in the three farms at the time of establishment of the grasses ranged between 14.1 and 17.4 dSm-1. The productivity of the grasses was assessed over 3 years (2012-14) by harvesting three times per year. Averaged over locations and species, dry biomass yields of the four grasses ranged between 32.64 and 40.68 t ha-1 year-1. Sporobolus virginicus produced highest biomass yields, followed by D. spicata, P. vaginatum and S. arabicus, although differences among the four grasses were marginal. In Madinat Zayed and Ghayathi, the average respective forage yields in terms of water productivity were estimated to be 1.68 and 2.42 kg dry matterm-3 water, better than the reported yield of the traditionally cultivated Rhodes grass (Chloris gayana) from less saline conditions. The study showed that the four halophytic grasses have the potential to contribute to rationalised use of scarce water resources for forage production, besides providing options for enhancing domestic forage production through rehabilitating the salt-affected farms that are unproductive for conventional crops. [ABSTRACT FROM AUTHOR]

In many arid and semiarid regions worldwide, high levels of soil salinity is a key driver of land degradation, as well as a key impediment to re-establishing plant cover. Combating land degradation and erosion associated with soil salinity requires experimental determination of plant species that can grow in soils with high levels of salinity and can be used to re-establish plant cover. Herein, we evaluated the responses of untested candidate cultivars of two halophytic grass species to high soil salinity: alkali sacaton (Sporobolus airoidesTorr.) and seashore paspalum (Paspalum vaginatumSwartz). We evaluated the growth responses of both species in a greenhouse under control (no-salt) and various levels of NaCl salinity (EC 8, 16, 24, 32, 40, and 48 dSm−1) using Hoagland solution in a hydroponics system in a randomized complete block design trial. At all salinity levels, sacaton grass had a greater shoot height, shorter root length, lower shoot fresh and dry weights, and poorer color and general quality compared to seashore paspalum. The shoot fresh and dry weights of both grasses were greatest at the low to medium levels of salinity, with the greatest response observed at EC 16 dSm−1. At the highest level, salinity significantly reduced shoot fresh and dry weights of both grasses. Because growth of both halophytic species exhibited high tolerance to salinity stress and were stimulated under low to medium levels of salinity, both species could be considered suitable candidates for re-establishing plant cover in drylands to combat desertification and land degradation associated with high levels of soil salinity. [ABSTRACT FROM PUBLISHER]

The use of warm-season turfgrasses is consolidated in the transitional areas of Mediterranean countries and some field trials have provided information on the adaptability of seashore paspalum to Mediterranean environment. Nonetheless, little is known on the performance of the different commercial cultivars of Paspalum vaginatum in this climatic zone. Furthermore, considering the high degree of variability of this species, ecotypes have the potential to supply new plant material with desired turf characteristics. The research aimed at comparing growth characteristics and morphological traits of eight commercial cultivars of seashore paspalum (Platinum, Salam, SeaDwarf, Sea Isle 1, Sea Isle 2000, Velvetene, Marina and Sea Spray) and four ecotypes (CeRTES 101, CeRTES 102, CeRTES 103, CeRTES 104), during establishment and on mature turf grown in two Italian locations (Pisa and Palermo). Probably due to higher mean minimum temperatures a clear effect of location was recorded during the establishment year with fastest stolon growth rate and higher ground cover at 133 days after planting being registered in Palermo. Internode length and diameter, node density, horizontal stem density, turf quality and colour gave instead higher values in Pisa. On mature turf best colour ratings were of SeaDwarf and the ecotype CeRTES 104. The finest leaves were found in Sea Isle 2000 (1.5 mm) while the denser cultivars, and potentially the most wear resistant were Sea Isle 1, CeRTES 104, and Platinum. Top quality was scored for Sea Isle 1, Sea Isle 2000 and Platinum. Best performances for fall colour retention and spring green up were frequently associated with commercial cultivars. The relative ranking of the commercial cultivars for aesthetic and functional performance can be a tool for the decisions of turf managers while data of ecotype CeRTES 104 as to colour, shoot density and quality stimulate further research for the identifications of ecotypes with superior traits of visual quality and wear resistance. [ABSTRACT FROM AUTHOR]

Malaysia's climate is struggling with unusually hot and dry weather from February to May 2016. Temperatures soared to the limits of a new record. One of the solutions is by having green roof to reduce the heat transfer in urban microclimate and buildings. Thus, the evaluation of potential plants in this study is to understand their performance in surface temperature reduction. In this study, the field measurements was carried out with ten types of groundcover and one exposed soil and one selected concrete flooring on three clear days. The measurement is taken from 8 AM to 6 PM and recorded at one-hour interval using an infrared thermometer. This study was done to compare the surface temperature of green roof and exposed bare roof within the same outdoor ambient environment. The result from this study indicates that Eremochloa ophiuroides and Rhoeo spathacea are suitable for planting in extensive rooftop system. Eremochloa ophiuroides and Rhoeo spathacea significantly provide the value of the average percentage of surface temperature reduction which was 18.9% and 18.8% respectively. Thus, it is recommended that both species are suitable for extensive roof planting. This knowledge can be applied by professionals in landscape architecture, horticulture, urban planning and design to provide better rooftop planting material in tropical urban environments. [ABSTRACT FROM AUTHOR]

To investigate the effects of different super absorbent polymers (SAP) with different application amount on photosynthesis and physiological characteristics of Paspalum vaginatum under drought stress, the plants were managed for 28 days under natural drought condition after applying three different kinds SAP with 0, 10, 20 and 30 g/m2, the plants under normal management condition were set as the control group. The results showed that SAP increased soil water content, root biomass and mot activity, improved turfgrass quality, alleviated the loss of leaf relative water content and chlorophyll content, reduced the increase of electrolyte leakage and malonaldehyde content, when compared with single drought stress. Moreover, SAP also enhanced net photosynthetic rate, transpiration rate and stornatal conductance. Therefore, the drought resistance of Paspalum vaginatum could be improved by SAP, and the drought resistance was increased with the increase of SAP application amount. The differences of SAP effects were found among different kinds SAP with the same application amount, and the rank of anti-drought and water-retention effects in three kinds SAP was S1 > S2 > S3. [ABSTRACT FROM AUTHOR]

Seashore paspalum ( Paspalum vaginatum Swartz) is an important warm-season turfgrass indigenous to tropical and coastal areas worldwide. The objectives of this study were to investigate the growth response and ion regulation of Chinese seashore paspalum germplasm under salinity stress. Twenty-seven seashore paspalum accessions and one check cultivar “Sea Isle 2000” were grown in solution culture in a glasshouse, with NaCl added to achieve salinities of 0 (control), 340 and 510 mmol/L. Compared with the nonsaline controls, the salinity stressed accessions showed significantly increased leaf firing, decreased shoot growth, and an increase or decrease in root growth. Significant genetic variations in the leaf firing (LF), relative shoot weight (RSW) and relative root weight (RRW) were found among the different accessions, with coefficients of variation ranging from 19.54% to 37.84%. The P40 accession had the best salinity tolerance with little leaf firing under salinity stress, followed by Sea Isle 2000, P29 and P14. For the control, the average K + concentration was 1161.69 mmol/kg in the shoots and 383.73 mmol/kg in the roots. Compared to the control, the salinity treatment showed that the K + concentration treatment decreased in both the shoots and roots; however, the percentage of the reduction in the shoots was significantly lower (26.20%) than that in the roots (69.68%). The Na + concentration was very low in both the shoots and roots of the seashore paspalum, with an average of 65.90 mmol/kg and 39.50 mmol/kg, respectively, under the treatment of nonsalinity. Compared to the nonsalinity control, the Na + concentration greatly increased in both the shoots and roots; however, the percentage of the increase in the shoots was lower (15-fold) than in the roots (25-fold). The results indicate that taking up more of the K + , maintaining a high K + concentration in the shoots and reducing the Na + being transferred from the roots to the shoots could be the mechanisms for Na + and K + regulation for salinity tolerance in seashore paspalum. [ABSTRACT FROM AUTHOR]