Further Increase In Salinity Research Articles

Effect of salinity and nitrogen on growth, sodium, potassium accumulation, and osmotic adjustment of halophyte Suaeda aegyptiaca (Hasselq.) Zoh

Suaeda aegyptiaca is an important native annual halophyte in salt-affected soils around coastal areas of the Persian Gulf. In order to study the effects of different levels of saturation paste soil salinity (10, 20, 40, 60, and 80 dS m−1) and nitrogen supply (25, 50, and 75 mg kg−1 N as urea) on growth and physiological characteristic of S. aegyptiaca, a greenhouse factorial experiment in completely randomized design was conducted with three replications. Salinity treatments were established after early growth of plants and nitrogen was applied in two steps. Results showed that increasing salinity up to 20 dS m−1 led to increase in dry weight (DW) of plants and this decreased by increasing salinity. Also, DW of plants was significantly increased by application of 75 mg kg−1 nitrogen. Increasing salinity significantly decreased plant height, chlorophyll index, and total nitrogen content; while proline content and total soluble solids (TSS) were significantly increased. The electrolyte leakage (EL) and sodium concentration were increased under salinity stress. However, further increase in salinity decreased these two parameters. By increasing the nitrogen levels, relative water content (RWC), chlorophyll index, proline, and total nitrogen contents were increased, whereas EL was decreased.

Ecophysiological responses of the salt marsh grass Spartina maritima to salinity

The effects of salinity on growth and productivity of Spartina maritima (Curtis) Fernald were investigated in glasshouse and field experiments in 2008. In the glasshouse study, plants were subjected to 2%, 10%, 20%, 40% and 80% sea water, with tidal simulation, for 10 months. Increase in salinity from 2% to 20% sea water increased biomass accumulation, CO2 exchange, quantum yield of Photosystem II (PSII), electron transport rate (ETR) through PSII, and intrinsic photochemical efficiency of PSII, while further increases in salinity to 80% resulted in significant decreases in these parameters. Concentrations of proline increased significantly with increase in salinity up to 80% sea water. In the field study, soil physicochemical conditions between streamside and inland sites were compared, and the constraints imposed by any differences on plant ecophysiological responses determined. At the inland site, soil water potential (ψ), electrical conductivity of the soil, total cations, and the concentrations of Na+, Ca2 +, Mg2 + and P, were significantly higher than those of the streamside site, while CO2 exchange, quantum yield of PSII, ETR through PSII, and intrinsic photochemical efficiency of PSII were significantly lower. The results suggest that S. maritima grows optimally at a salinity of about 20% sea water, and that higher salinity decreases growth and photosynthetic performance.

Effects of salinity on the germination, growth, and nitrate contents of purslane (Portulaca oleracea L.) cultivated under different climatic conditions

SummaryInterest in cultivating purslane (Portulaca oleracea L.) as a food crop has increased since its identification as an excellent source of some biologically-active compounds that are considered to be essential for the promotion of human health and the prevention of disease. The aim of this research was to determine the effects of salinity, by means of exposure to different concentrations of NaCl in the nutrient solution, on the germination, growth, yield, and nitrate contents of purslane cultivated in a hydroponic system under two different light intensities. The results indicated that higher germination percentages (approx. 50%) were obtained between saline levels with electrical conductivities (EC) of 0 – 12.5 dS m–1. Above 12.5 dS m–1, the germination percentage decreased significantly. Salinity reduced both shoot and root growth. This reduction was greater in plants grown under the lower light intensity. When the EC of the nutrient solution increased from 2.5 dS m–1 to 15.0 dS m–1, yields were reduced by 26% in plants grown in a greenhouse, and by 82.2% in plants grown under the lower light intensity in a growth chamber. In both cases, nitrate levels increased in plants grown at an EC of 5.0 dS m–1, but nitrate levels decreased with further increases in salinity. In all cases, nitrate levels were below the maximum levels established by European Regulations for lettuce.

Ecophysiological performance of an urban strain of the aeroterrestrial green alga Klebsormidium sp. (Klebsormidiales, Klebsormidiophyceae)

Aeroterrestrial green algae are among the most ubiquitous members of the microbial flora colonizing aerial surfaces. Filamentous green algae, in particular, produce large populations in several natural and artificial habitats. In recent years it has been shown that the bases of the walls of urban environments are frequently colonized by filamentous green algae. However, information concerning the physiology of these organisms and the factors that determine their distribution is extremely limited. We studied the physiological responses of a strain of Klebsormidium sp. (Klebsormidiales, Klebsormidiophyceae) collected in an urban area (Konstanz, Germany). Growth responses, photosynthetic performance, desiccation tolerance and accumulation of organic osmolytes were measured in several different combinations of environmental factors. Klebsormidium sp. exhibited optimal growth and highest photosynthetic efficiency under relatively low photon fluence rates, performing optimally between 15 and 30 µmol photons m−2 s−1 and showing increasing inhibition above 85 µmol photons m−2 s−1. Although it could survive at salinities up to 60 psu, this alga was relatively stenohaline; growth was optimal between 1.2 and 15 psu and declined considerably at higher salinities. Sucrose acted as the major organic osmolyte, and its concentration increased almost linearly between 1.2 and 30 psu from 29.7 to 171.2 µmol g−1 dry weight. Further increases in salinity, however, were accompanied by a strong reduction in sucrose content pointing to insufficient osmotic adjustment. Klebsormidium sp. was able to photosynthesize efficiently for up to 2 hours under complete desiccation. Afterwards, however, there was no measurable photosynthetic activity although complete photosynthetic efficiency (F v/F m) was recovered upon rehydration for 48 hours. Overall, the results correlate well with the ecology of Klebsormidium sp. in the field and its distribution in continental Europe.

Antioxidative Defense Potential to Salinity in the Euhalophyte Salicornia brachiata

The antioxidative defense mechanism to salinity was assessed by monitoring the activities of some antioxidative enzymes and levels of antioxidants in an obligate halophyte, Salicornia brachiata, subjected to varying levels of NaCl (0, 200, 400, and 600 mM) under hydroponic culture. In the shoots of S. brachiata, salt treatment preferentially enhanced the activities of ascorbate peroxidase (APX), guaiacol peroxidase (POX), glutathione reductase (GR), and superoxide dismutase (SOD), whereas it induced the decrease of catalase (CAT) activity. Similarly, salinity caused an increase in total glutathione content (GSH + GSSG) and a decrease in total ascorbate content. Growth of S. brachiata was optimum at 200 mM NaCl and decreased with further increase in salinity. Salinity caused an increase in Na+ content and a decrease in K+ content of shoots. Proline levels did not change at low (0-200 mM NaCl) or moderate (400 mM NaCl) salinities, whereas a significant increase in proline level was observed at high salinity (600 mM NaCl). Accumulation of Na+ may have a certain role in osmotic homeostasis under low and moderate salinities in S. brachiata. Parameters of oxidative stress such as malondialdehyde (MDA), a product of lipid peroxidation, and H2O2 concentrations decreased at low salinity (200 mM NaCl) and increased at moderate (400 mM NaCl) and high salinities (600 mM NaCl). As a whole, our results suggest that the capacity to limit ionic and oxidative damage by the elevated levels of certain antioxidative enzymes and antioxidant molecules is important for salt tolerance of S. brachiata.

Morphological and physiological responses of the halophyte, Odyssea paucinervis (Staph) (Poaceae), to salinity

In this study, salt tolerance was investigated in Odyssea paucinervis Staph, an ecologically important C 4 grass that is widely distributed in saline and arid areas of southern Africa. Plants were subjected to 0.2%, 10%, 20%, 40%, 60% and 80% sea water dilutions (or 0.076, 3.8, 7.6, 15.2, 22.8, and 30.4 parts per thousand) for 11 weeks. Increase in salinity from 0.2% to 20% sea water had no effect on total dry biomass accumulation, while further increase in salinity to 80% sea water significantly decreased biomass by over 50%. Morphological changes induced by salinity included reductions in the number of culms, leaves and internodes as well as decreases in internode length and leaf length:leaf width ratios. Carbon dioxide exchange, leaf conductance and transpiration decreased at salinities of 40% and higher, while quantum yield of photosystem II (PSII), electron transport rate (ETR) through PSII and intrinsic photosynthetic efficiency generally decreased at salinities of 60% and higher compared to 0.2% sea water. Concentrations of Na + and Cl − increased significantly with salinity increase in both roots and shoots. Na +/K + ratios in the roots and shoots ranged from 0.66 to 3.28 and increased with increase in substrate salinity. The maximal rate of secretion at 80% sea water was 415 nmol cm −2 d −1 for Na + and 763 nmol m −2 d −1 for Cl − with high selectivity for these two ions. Predawn and midday ψ decreased with increase in salinity and were more negative than those of the treatment solutions. The concentration of proline increased with increase in salinity in both roots and shoots. The data clearly indicated that O. paucinervis is a highly salt-tolerant species that is morphologically and physiologically adapted to a saline environment.

Germination of Dyckia encholirioides (Gaudichaud) Mez var. encholirioides under saline conditions

Summary Dyckia encholirioides (Gaudichaud) Mez var. encholirioides is an endangered endemic bromeliad occurring in the Brazilian Atlantic Forest running along of the Atlantic Ocean. We investigated its seed germination at different salt levels (0, 100, 200, 300, 400 and 500 mmol L -1 NaCl) under different temperature regimes(10-20, 15-25, 20-30 and 25-35°C). The highest seed germination rate was obtained at 0, 100 and 200 mmolL -1 NaCl at 20-30°C and a further increase in salinity resulted in a gradual decrease in germination. Less than 5% of seeds germinated at 500 mmol L -1 NaCl. Few seeds germinated at concentrations higher than 200 mmol L -1 NaCl. Germination rate was fastest at 20-30°C and slowest at 10-20°C. Low seed germination rate was obtained in the dark in comparison to seeds germinated in a 12 hours photoperiod under saline conditions. Recovery experiments showed that exposure of seeds to various salinity and temperature regimes had little effect on viability of seeds D. encholirioides

Responses of the saltmarsh rush Juncus kraussii to salinity and waterlogging

Juncus kraussii Hochst., an important saltmarsh macrophyte, is intensively harvested for many commercially orientated products and current populations are under threat of overexploitation. In saline, intertidal mud banks, this species occurs on higher ground, suggesting that it is adapted to lower salinities and less frequent inundation. The objectives of this study were to determine biomass accumulation, as well as morphological and physiological adaptations of J. kraussii to salinity and waterlogging stresses. Plants collected from the field were subjected to 0.2, 10, 30, 50 and 70% seawater under drained or flooded conditions for three months. Measurements were made of biomass accumulation, CO 2 exchange, chlorophyll fluorescence, ion and water relations. Furthermore, seed germination responses to a range of salinities were investigated. Total dry biomass accumulation, as well as the number and height of culms, decreased with increase in salinity under both flooded and drained conditions. Generally, CO 2 exchange, stomatal conductance, Photosystem II (PSII) quantum yield and electron transport rate (ETR) through PSII declined with increase in salinity in both the flooded and drained treatments. Predawn and midday ψ in culms decreased with increase in salinity, being lower under drained than flooded conditions. Inorganic solute concentrations in culms increased with increase in salinity, with Na + and Cl − being the predominant ions. Na +/K + ratios in culms increased significantly with increase in salinity. Proline concentrations in roots and culms, which increased with salinity, were considerably higher under drained than flooded conditions. Germination was best at salinities less than 20% seawater and decreased significantly with further increase in salinity to 110% seawater. Transfer of ungerminated salt-treated seeds to distilled water stimulated germination. This study has demonstrated that J. kraussii is a highly salt and flood tolerant species, being able to grow and survive in salinities up to 70% seawater, under both drained and flooded conditions. Maximal growth occurred at low salinities (<10% seawater) under flooded condition.

Leaf H +-ATPase activity and photosynthetic capacity of Cakile maritima under increasing salinity

The present study focuses on the sodium regulation mechanisms and the photosynthetic activity of the halophyte Cakile maritima, in response to 6 week-exposure to increasing salinity (0–500 mM NaCl). Relative growth rate (RGR) was transiently enhanced by the application of 100 mM NaCl and a further increase in salinity either had no effect or decreased RGR. Concomitant increase in shoot Na + accumulation and leaf succulence in salt-treated plants suggested that this halophyte may use the inclusive strategy when dealing with salinity. This assumption was supported by the increase of the leaf vacuolar V H +-ATPase activity up to 300 mM NaCl and the absence of salt excretion structures at the leaf surface. Plasma membrane PM H +-ATPase activity was stimulated at the intense salinities, whereas that of mitochondrial/chloroplast F H +-ATPase declined progressively at supra-optimal salinites. Photosynthesis parameters (CO 2 assimilation rate, stomatal conductance, sub-stomatal CO 2 concentration, transpiration rate and Rubisco specific activity) were significantly increased at the optimal salinity (100 mM NaCl), as compared to the control. Higher salt levels impaired photosynthetic capacity of C. maritima mainly via a stomatal limitation, as stomatal conductance was the most reduced factor. Irrespective of salt treatment, PEPC specific activity was lower than that of Rubisco. Both nitrogen-use efficiency (NUE) and photosynthetic nitrogen-use efficiency (PNUE) were significantly high at 100 mM NaCl. Further increase in salinity led to a substantial reduction of PNUE, which might have been mainly due to salt-induced leaf succulence.

A look behind the salt curve: the link between rheology, structure, and salt content in shampoo formulations

The salt curve is well documented in the literature, whereby the viscosity of a solution initially increases with the addition of salt but then decreases with further increases in salinity. This paper examines the rheological behavior of eight common shampoo bases made with sodium lauryl ether sulfate or a mixture of ammonium lauryl ether sulfate and ammonium lauryl sulfate. Dynamic rheological measurements reveal that in all eight cases the salt effect is due to a variation in micellar relaxation time. The profile of the relaxation time vs. salt concentration was found to mirror the variation with salinity in measured entanglements per micelle. The roles of increased micellar branching, decreased micelle length, and increased micellar flexibility at higher salinity are outlined here.

Effect of light, salinity, and temperature on seed germination of Limonium stocksii

Limonium stocksii (Boiss.) Kuntze (Plumbaginaceae) is a perennial, woody shrub distributed at Hawks Bay, Karachi, Pakistan. Experiments were carried out to investigate seed germination responses of L. stocksii at different salinities (0, 100, 200, 300, 400, and 500 mmol/L NaCl) and under different temperature regimes (10:20, 15:25, 20:30, and 25:35 °C), both in a 12 h dark : 12 h light photoperiod and in complete darkness. The highest percentage of germination (about 100%) was obtained at 0, 100, and 200 mmol/L NaCl at 20:30 °C, and a further increase in salinity resulted in a gradual decrease in germination. Less than 5% of seeds germinated at 500 mmol/L NaCl. Germination under salinity treatment at 15:25 °C was slightly more inhibitory than the optimal temperature regime, whereas under both 10:20 and 25:35 °C temperature regimes, seed germination was substantially reduced and few seeds germinated at concentrations higher than 200 mmol/L NaCl. Germination rate was fastest at 20:30 °C and slowest at 10:20 °C. Relatively low seed germination was obtained in the dark in comparison to seeds germinated in a 12-h photoperiod under saline conditions. Recovery experiments showed that exposure of seeds to various salinity and temperature regimes had little effect on viability of seeds.Key words: germination, light, Limonium stocksii, NaCl, recovery, temperature.

Effect of salinity on the growth and ion content of Salicornia rubra

Salicornia rubra is a stem succulent annual halophyte, which is widely distributed in the saltpans of Northern Utah playas. This study reports the effect of salinity (0, 200, 400, 600, 800, and 1000 mM NaCl) on the growth, succulence, osmotic and water relations of the species under greenhouse conditions. Fresh and dry weight of plants increased with an increase in salinity. Optimal growth of S. rubra plants were recorded at 200 mM NaCl and the growth declined with a further increase in salinity. Both sodium (Na) and chloride (Cl) contents of plants increased with an increase in salinity, while Ca2+, Mg2+, and K+ content decreased. Succulence of shoots increased at low salinity and decreased at high salinity. Water potential of plants become more negative with an increase in salinity. The Fv/Fm ratio was more affected by higher salinity and irradiation stress during growth.

Effect of Seawater on the Growth, Ion Content and Water Potential of Rhizophora mucronata Lam.

Growth and physiological responses at seedling (six months old) and sapling (12 months old) stages were studied under various seawater concentrations. The optimum growth of plants was obtained at 50% seawater and declined with further increases in salinity. Leaf water and osmotic potentials and xylem tension increased with an increase in media salinity both in seedlings and saplings, whereas stomatal conductance was decreased. Concentrations of sodium and chloride ions increased, while those of potassium and calcium decreased with an increase in salinity.

Effects of salinity and nitrogen on growth, ion relations and proline accumulation in Triglochin bulbosa

The effects of salinity and nitrogen on growth, ion relations and prolineaccumulation in the monocotyledonous halophyte, Triglochin bulbosa,was investigated in hydroponic culture over 5 months. The experimentaldesign was a 3 × 3 factorial with three salinity treatments (0, 150 and 300 mol m-3 NaCl) and three levels of N (5, 10 and 20 μgml-1 N as NaNO3). Total and root dry biomass accumulationwere significantly affected by salinity, but not by N or N × salinityinteraction. Increase in NaCl from 0 to 150 mol m-3 had no effecton total or root dry biomass, while further increase in salinity to 300mol m-3 significantly reduced biomass by 21% and 25%respectively. Shoot dry biomass, which was significantly affected by N andnot by salinity, increased with increase in N from 5 to 10 μgml-1. Ion concentrations in roots and shoots were significantlyaffected by salinity, but not by N or N × salinity interaction. Theconcentration of Na+ and Cl- in roots and shoots increasedprogressively with an increase in salinity, while that of K+ decreased. Under non-saline conditions, Na+/K+ ratios were low (0.41to 0.44) and increased significantly with an increase in salinity in both rootsand shoots. Shoot sap osmotic potentials decreased progressively with anincrease in salinity. Increase in N in the hydroponic solution from 5 to20 μg ml-1 significantly increased root and shoot N by 66%and 41% respectively. Tissue concentrations of proline were significantlyaffected by salinity and substrate N but not by N × salinity interaction. Theconcentration of proline in roots and shoots increased significantly by334% and 48%, respectively, with an increase in salinity from 0 to 300mol m-3 NaCl. Increase in substrate N from 5 to 20 μg ml-1 significantly increased proline in roots and shoots by 66% and41% respectively. The significance of substrate N on the accumulationof proline is discussed in relation to salt tolerance.

The effect of salinity on the growth, water status, and ion content of a leaf succulent perennial halophyte, Suaeda fruticosa (L.) Forssk

Suaeda fruticosa (L.) Forssk plants grown in saline conditions (200 to 400 mol m−3NaCl) had greater fresh and dry weights than those grown in non-saline controls, and 600 to 1000 mol m−3NaCl inhibited growth. Gibberellic acid and kinetin both alleviated some of the inhibitory effects of salinity at 800 mol m−3NaCl on shoot growth of S. fruticosa while root growth was promoted by kinetin. Tissue water content increased in up to 200 mol m−3NaCl but decreased with a further increase in salinity. Water potential and osmotic potential of plants became more negative with an increase in salinity. Leaf Ca2+, Mg2+, and K+concentration decreased with increasing salinity, while both Na+and Cl−increased and reached 1391 and 1673 mmol kg−1dry weight, respectively. Total glycinebetaine content of shoots was highest at 600 to 1000 mol m−3NaCl.

Effects of salinity on growth, ion content, and osmotic relations in Halopyrum mucronatum (L.) Stapf.

Halopyrum mucronatum (L.) Stapf. is a perennial grass found on the coastal dunes of Karachi, Pakistan. Halopyrum mucronatum plants were grown in 0, 90,180, and 360 mol m‐3 NaCl in a sand culture using a sub‐irrigation method. Fresh and dry weight of roots and shoots peaked at 90 mol m‐3 NaCl. A further increase in salinity inhibited plant growth, ultimately resulting in plant death at 360 mol m‐3 NaCl. The relative growth rate of plants was highest between 60 and 90 days after final salinity concentrations were reached. Maximum succulence was noted in 90 mol m‐3 NaCl. Water potential and osmotic potential of plants became more negative with an increase in salinity, while plants lost turgor with increasing salinity. Time of harvest did not have any significant effect on the water relations of plants. Sodium (Na) and chloride (Cl) content of plants increased with an increase in salinity, while calcium (Ca), magnesium (Mg), and potassium (K) content decreased. Glycinebetaine content of shoots increased significantly only at the highest salinity (360 mol m‐3 NaCl).

Growth and water use of eucalypt trees irrigated with saline drainage water

Leaf chemical composition, growth and water use of Eucalyptus camaldulensis (Lake Albacutya provenance) were measured in the 4th year of a split-plot salinity by nutrition trial. The main plot consisted of irrigating with five different water salinities: 0.5 dS/m (S0.5), 2 dS/m (S2), 5 dS/m (S5), 7.5 dS/m (S7.5) and 10 dS/m (S10). The subplot treatments consisted either of annual additions of 200 kg N and 100 kg P per hectare (+ N + P) or no addition of nutrients (– N – P). Irrigation with water from a drainage system (treatments S2, S5, S7.5 and S10) added about a further 100 kg N/ha annually. Leaf concentrations of N and P were higher in the + N + P treatments. In S0.5, nutrient addition stimulated growth. In + N + P treatments, raising the irrigation salinity from 0.5 to 2.0 dS/m increased leaf Na and decreased the growth rate, however, further increases in salinity affected neither leaf Na nor growth. In – N – P, growth rate depression due to inadequate nutrition was overcome in S2 and S5 by the 100 kg/ha of N in the drainage water. At higher salinities, the N added by drainage water did not overcome the effect of inadequate nutrition. On days when the reference crop evapotranspiration (ETo) was less than 3 mm/day, the correlations between water use of trees in litres per day and ETo and between water use of trees in litres per day and the basal area of the tree butt were highly significant. On days when the ETo was 3 mm/day or greater, the correlation between tree water use and basal area was highly significant, but that between tree water use and ETo was not significant.

Flocculation of sediment from the Tanshui River estuary

Experiments on the flocculation of fine-grained sediments from the Tanshui River estuary, Taiwan, were carried out. The effects of fluid shear, sediment concentration and salinity on floc growth were investigated. The ranges of these parameters were 12.5 to 400 s-1 for the shear, 50 to 600 mg L-1 for the sediments concentration and 0% to 100% sea water for the salinity. The results showed the following. (1) The time required to reach a steady state ranges from 2 to 44 h and median floc sizes range from 100 to 520 μm. (2) The steady-state median floc size decreases with the increase in sediment concentration. (3) The floc size increases as the shear increases. (4) Increasing the proportion of sea water from 0% to 50% decreases the floc size to one-fourth of that of freshwater flocs, and a further increase in salinity does not decrease floc size significantly. (5) The time required to reach a steady state decreases with the decrease in shear, the increase in sediment concentration and the increase in salinity. (6) The larger the steady-state flocs, the longer they take to form. Comparison of these results with those obtained in similar studies of Lake Erie sediments shows that the flocculation properties of Tanshui sediments are substantially different from those of Lake Erie sediments. Tanshui sediments are much more difficult to aggregate, but once flocs are formed they are larger. The reasons why different types of sediment behave differently should be studied further.

Seed germination in the coastal halophytes Triglochin bulbosa and Triglochin striata

Triglochin bulbosa L. and Triglochin striata Ruiz and Pavon, herbaceous perennials in the family Juncaginaceae, are widely distributed along the coastal areas of Southern Africa and form an important component of the vegetation of salt marshes, lagoons and mangrove swamps. We measured and compared the germination responses of these two species to light, temperature and salinity. Both species exhibited a light requirement for germination and germinated better at an alternating day/night thermoperiod of 30/20°C (12 h photoperiod) than at 25/15°C or 20/10°C. Germination was best in distilled water and at salinities less than 250 mol m −3 NaCl, and decreased significantly with further increases in salinity up to 500 mol m −3, especially in T. striata. Transfer of ungerminated, salt-treated seeds to distilled water stimulated germination more in T. striata than in T. bulbosa. There was a significant relationship between salinity level and the time requirement for 50% germination in both species. Comparison of germination responses in solutions of low osmotic potential, induced by NaCl or polyethylene glycol (PEG-6000), suggested that the effects of salinity were primarily osmotic. The study indicated that a vast majority of the seeds are viable and are capable of germination under a range of alternating thermoperiods (10–30°C) and salinities (0–500 mol m −3 NaCl). Triglochin bulbosa germinated at a wider salinity range than T. striata. Remaining dormant at high salinities and germinating rapidly during periods of reduced salt stress in T. striata may be a more efficient adaptive strategy in seedling establishment in saline areas.

Effect of nitrogen fertilizer on yield of perennial pastures irrigated with saline water

This study examines the interaction between salinity and nitrogen (N) fertiliser in perennial pastures growing in the Shepparton Irrigation Area of northern Victoria. In a greenhouse experiment, perennial ryegrass was irrigated with 5 concentrations of sodium chloride (100-6000 mg NaCl/L) and fertilised with 5 concentrations of N (25-800 mg/L). Nitrogen at 200 mg/L was optimum for dry matter yield; at N concentrations &gt;200 mg/L, yield declined. Dry matter yield was greater at 750 mg NaCl/L than at 100 mg NaCl/L but was reduced with further increases in salinity. Significant interactions between salinity and N were recorded for dry matter, and for chloride, Na, potassium, and magnesium concentrations in perennial ryegrass. In a field experiment, the growth of mixed perennial ryegrass-white clover pastures irrigated with saline water [53000 mg/L of total dissolved solids (TDS)] also responded to N applications. With no added N, yield (2-year average) decreased from 16 630 to 11 277 kg DM/ha (32% decrease) with an increase in salinity from 100 to 3000 mg TDS/L. With 150 kg N/ha, the average yield was 17681 kg DM/ha at 100 mg TDSL and 14 123 kg DM/ha at 3000 mg TDS/L (20% decrease). Form of N (calcium nitrate, ammonium nitrate, or urea) had no significant effect on yield at 150 kg N/ha. Application of urea at 150 kg N/ha to pastures irrigated with water of salinity up to 3000 mg TDS/L would be economically justifiable.