Influence of Salt Stress on the Nutritional State of Cordyline fruticosa var. Red Edge, 2: Sodium,Potassium, Calcium,and Magnesium

The aim of this trial was to study the nutritional behavior generated by modifications in the salt concentration in the nutrient solution used for the fertigation of Cordyline fruticosa var. Red Edge plants. Four treatments were tested: T₁ [control, 1.5 dS m^?1, 14.3 mmol L^?1 sodium chloride (NaCl)]; T₂ (2.5 dS m^?1, 22.2 mmol L^?1 NaCl); T₃ (3.5 dS m^?1, 32.7 mmol L^?1 NaCl); and T₄ (4.5 dS m^?1, 38.2 mmol L^?1 NaCl). There is an accumulation of sodium (Na⁺) in roots, stem, and petiole when salinity increases, which avoid leaf damages. Potassium (K) concentration increases with the intermediate saline treatments in stems and leaves but decreases when plants are fertigated with T₄. Calcium (Ca) accumulates in roots with T₃ and T₄, in stems with T₄, and in petioles and leaves with T₃. Magnesium (Mg) concentration is greater in stems, petioles, and leaves of T₄, but is greater in roots of T₃. Plants fertigated with the three saline treatments extract 1.4 times more Na⁺ than T₁ plants. The greatest K⁺ extraction is observed in T₂, followed by T₃, and T₄. T₂, T₃, and T₄ plants extracted more Ca²⁺ than T₁ plants. Finally, Mg²⁺ extractions in T₃ are twice as much as they are in T₁, while in T₄ and T₂ are much greater.     

IMPACT OF SALT STRESS ON MICRONUTRIENTS IN CORDYLINE FRUTICOSA VAR. ‘RED EDGE'

This trial was carried out to study the influence of the nutrient solution on the microelements concentration and distribution in C. fruticosa var. ‘Red Edge' plants. Four treatments were tested: T₁ [control, 1.5 dS m^?1, 14.3 mmol L^?1 sodium chloride (NaCl)], T₂ (2.5 dS m^?1, 22.2 mmol L^?1 NaCl), T₃ (3.5 dS m^?1, 32.7 mmol L^?1 NaCl) and T₄ (4.5 dS m^?1, 38.2 mmol L^?1 NaCl). In roots and stems, iron (Fe) concentrations were lower in the no saline treatment. Stems accumulated more Fe with treatments T₃ and T₄. Copper concentration and extraction were not affected by salinity. The highest manganese (Mn) concentration in roots was observed in T₂, while in petioles was higher in T₃ and T₄. Manganese extraction reached higher levels in the saline treatments in roots and stems, while in petioles it was lower in T₁, T₂ and T₃. In roots, zinc (Zn) concentration was lower with the extreme treatments. Micronutrients concentration in leaves was unaffected by salinity, because an exclusion mechanism that consists on accumulation in roots and stems was developed.     

Influence of the Modification of Nutritional Parameters in Aglaonema commutatum: K+, Ca2+, Mg2+ and Na+

Abstract

This trial was carried out to establish an appropriate nutrient solution for Aglaonema commutatum and to investigate the nutritional effects generated by modifications in the solution. Six treatments were tested: control (T₀; pH 6.5, E.C. 1.5 dS m^?1, 6 mmol L^?1 NO₃ ^?‐N, and 6 mmol L^?1 K⁺); high nitrogen (N) level (T₁; 9 mmol L^?1 6:3 NO₃ ^?–NH₄ ⁺); N form (T₂; 6 mmol L^?1 N‐NH₄ ⁺); high K⁺ level (T₃; 12 mmol L^?1 K⁺); high electrical conductivity (T₄; E.C. 4 dS m^?1, 25 mmol L^?1 NaCl), and basic pH (T₅; pH 8). At the end of the cultivation, leaf, shoot, and root dry weights and elemental concentrations were determined. Nutrient contents and total plant uptake were calculated from the dry weights and nutrient concentrations. Plant K⁺ uptake increased with application of K⁺ or basic nutrient solution. The uptake and transport of calcium (Ca) were enhanced by the use of NO₃ ^?‐N and inhibited by the presence of other cations in the medium (NH₄ ⁺, K⁺, Na⁺) and by basic pH. Magnesium (Mg) uptake increased with NO₃ ^?‐N application and with pH. Sodium (Na) uptake was the highest in the saline treatment (T₄), followed by the basic pH treatment. Sodium accumulation was detected in the roots (natrophobic plant), where the plant generated a physiological barrier to avoid damage. Dry weight did not differ significantly (p<0.05) among treatments except in the NaCl treatment. These results may help in the formulation of nutrient solutions that take into account the ionic composition of irrigation water and the physiological requirements of plants.     

局部根系盐胁迫对冬小麦生长和光合特征的影响

通过分根装置设置无盐胁迫(0|0)、局部根系150 mmol-L-1NaCl胁迫(0|150)、全部根系75 mmol-L-1NaCl胁迫(75|75)、全部根系150 mmol-L-1NaCl胁迫(150|150)4种处理,研究根系局部盐胁迫对冬小麦生长及光合特征的影响。结果表明:盐胁迫显著抑制了小麦幼苗的生长,并且随着盐胁迫浓度的增加,小麦受抑制程度加重;根系盐胁迫方式对小麦幼苗生长影响显著,局部根系胁迫处理(0|150)小麦幼苗地上部干重比等浓度150 mmol-L-1NaCl全部盐胁迫处理(150|150)增加23.5%,比等浓度75 mmol-L-1NaCl全部盐胁迫处理(75|75)增加17.2%。在局部根系盐胁迫下,非盐胁迫一侧根系(0|150-0)补偿生长,其根长、侧根数、侧根长比盐胁迫一侧根系(0|150-150)分别增加195.2%、206.2%和237.8%,盐胁迫一侧根系吸收的Na+部分向非盐胁迫一侧根系运输,盐胁迫一侧根系(0|150-150)的Na+含量比全部胁迫处理(150|150)减少12.1%。与全部根系盐胁迫相比,局部根系盐胁迫减少了Na+在叶片中的积累,降低了钠/钾值。局部根系盐胁迫叶片净光合速率、气孔导度、胞间CO2浓度和叶绿素荧光参数(Fv/Fm)均高于同浓度完全盐胁迫处理的小麦幼苗,进而增加地上部和根系的生物量。因此,局部根系胁迫显著缓解了全部盐胁迫对小麦地上部和根系生长的抑制作用。     

PHYTOTOXICITY OF SALTS IN COMPOSTED SEWAGE SLUDGE AND CORRELATION WITH SODIUM CHLORIDE,CALCIUM NITRATE,AND MAGNESIUM NITRATE

The phytotoxicity of salts in composted sewage sludge (CSS) was evaluated. Concentrations of sodium (Na⁺), chloride (Cl^?1), calcium (Ca²⁺), and magnesium (Mg²⁺) were present at levels that would induce salt stress in plants. Nutrient imbalances were also found that would adversely affect the use of CSS as a growth medium. To further understand the phytotoxic nature of these salts, sodium chloride (NaCl), calcium nitrate [Ca(NO₃)₂] and magnesium nitrate [Mg(NO₃)₂] solutions were used to simulate the composition of salts found in CSS in an investigation of radish (Raphanus sativus L.) seed germination. High concentrations of Ca²⁺ (92.1 mmol.L^?1) and Mg²⁺ (27.4 mmol.L^?1) inhibited seed germination to an equal extent as did Na⁺ (40.6 mmol.L^?1). The lower concentration of Ca²⁺ (10 mmol.L^?1), however, significantly relieved the stress caused by NaCl. These results indicated that the composition and total amount of Na⁺, Cl^?1, Ca²⁺, and Mg²⁺ in CSS should be carefully monitored before it is used as a soil amendment or growth medium.     

TREATED EFFLUENT AND SALINE WATER IRRIGATION INFLUENCES SOIL PROPERTIES,YIELD, WATER PRODUCTIVITY AND SODIUM CONTENT OF SNOW PEAS AND CELERY

To determine the effects of irrigation water quality, plants were irrigated with normal potable water [0.25 dS m^?1 electrical conductivity (EC), 25 mg L^?1 sodium (Na), 55 mg L^?1 chloride (Cl)], treated effluent (0.94 dS m^?1 EC, 122 mg L^?1 Na, 143 mg L^?1 Cl) and saline water with low salinity (1.24 dS m^?1 EC, 144 mg L^?1 Na and 358 mg L^?1 Cl) and high salinity (2.19 dS m^?1 EC, 264 mg L ^?1Na and 662 mg L^?1 Cl) for snow peas, and high salinity (3.07 dS m^?1 EC, 383 mg L^?1 Na and 965 mg L^?1 Cl) and very high salinity (5.83 dS m^?1 EC, 741 mg L^?1 Na and 1876 mg L^?1 Cl) for celery. The greater salts build up in the soil and ion toxicity (Cl and Na) with saline water irrigation contributed to significantly greater reduction in root and shoot biomass, water use, yield and water productivity (yield kg kL^?1 of water used) of snow peas and celery compared with treated effluent and potable water irrigation. There was 8%, 56% and 74% reduction in celery yield respectively with treated effluent, high salinity and very high salinity saline water irrigation compared with potable water irrigation. The Na concentration in snow peas shoots increased by 54%, 234% and 501% with treated effluent, low and high salinity saline water irrigation. Similarly, the increases in Na concentration in celery shoots were 19%, 35% and 82%. The treated effluent irrigation also resulted in a significant increase in soil EC, nitrogen (N) and phosphorus (P) content compared with potable water irrigation. The heavy metals besides salts build up appears to have contributed to yield reductions with treated effluent irrigation. The study reveals strong implications for the use of saline water and treated effluent for irrigation of snow peas and celery. The salt build up within the root zone and soil environment would be critical in the long-run with the use of saline water and treated effluent for irrigation of crops. To minimize the salinity level in rhizosphere, an alternate irrigation of potable water with treated effluent or low salinity level water may be better option.     

Differential responses of three chamomile genotypes to salinity stress with respect to physiological,morphological, and phytochemical characteristics

Effect of water salinity was studied in different Matricaria recutita L. genotypes (Isfahan, Ahvaz, and Shiraz) to understand their protective mechanisms and agronomic performance. Based on a split-plot design arranged in a randomized complete-block consisted of four salinity levels as the main plot and three genotypes as the subplots with three replications this field experiment was conducted in 36 plots with 3 m² space in the Isfahan Center for Research of Agricultural Science and Natural Resources during 2014–2015. The findings showed that the three genotypes differed in resistance to salinity and tolerance mechanisms. They have evolved different physiological, morphological, and biochemical adaptations to salt stress. The Ahvaz genotype in the absence of salt, the Isfahan genotype at 6, and the Shiraz genotype at 9 and 12 dS m^?1 sodium chloride (NaCl) were desirable, taking both quantity and quality into consideration. While preserving shoot growth, the Isfahan genotype was more tolerant to 6 dS m^?1 NaCl most likely due to peroxidase activity. The resistance of the Shiraz genotype is associated with root growth stimulation at 9 and Na compartmentation in root at 12 dS m^?1 NaCl. The Isfahan genotype had the highest oil and chamazulene content, which was not affected by salinity. The Shiraz genotype in the control treatment, the Isfahan genotype at 6 and 9 and the Ahavaz genotype at 12 dS m^?1 NaCl synthesized higher flavonoid compounds.     

Effects of Nutrient and NaCl Salinity on Growth,Yield, Quality and Composition of Pepper Grown in Soilless Closed System

The effects of nutrient or sodium chloride (NaCl) salinity on pepper grown in closed soilless culture systems were studied. A control (2 dS m^?1) and two saline nutrient solutions (4 dS m^?1) differing in the salt sources (fertilizers or NaCl) were studied. Shoot biomass production as well as total and marketable yield were more affected by NaCl than nutrient salinity. Fruit dry matter and total soluble solids increased in both salinity treatments compared to the control. Total phenol content rose slightly (10%) with NaCl salinity, while the concentration of carotenoids was enhanced by 40% with NaCl compared to the control and nutrient salinity. The results showed that the response of pepper to salinity is both osmotic and ion specific, but a more negative effect was recorded under NaCl stress. Moreover, the highest content of antioxidant compounds in NaCl treated fruits may indicate that NaCl caused more stressful conditions than nutrient salinity.     

Gas exchange,water relations,and Ion concentrations of salt‐stressed tomato and melon plants

Abstract

Tomato and melon plants were grown in a greenhouse and irrigated with nutrient solution having an EC of 2 dS m^?1 (control treatment) and 4, 6, and 8 dS m^?1, produced by adding NaCl to the control nutrient solution. After 84 days, leaf water relations, gas exchange parameters, and ion concentrations, as well as plant growth, were measured. Melon plants showed a greater reduction in shoot weight and leaf area than tomato at the two highest salinity levels used (6 and 8 dS m^?1). Net photosynthesis (Pn) in melon plants tended to be lower than in tomato, for all saline treatments tested. Pn was reduced by 32% in melon plants grown in nutrient solution having an EC of 4 dS m^?1, relative to control plants, and no further decline occurred at higher EC levels. In tomato plants, the Pn decline occurred at EC of 6 dS m^?1, and no further reduction was detected at EC of 8 dS m^?1. The significant reductions in Pn corresponded to similar leaf Cl^? concentrations (around 409 mmol kg^?1 dry weight) in both plant species. Net Pn and stomatal conductance were linearly correlated in both tomato and melon plants, Pn being more sensitive to changes in stomatal conductance (g_s) in melon than in tomato leaves. The decline in the growth parameters caused by salinity in melon and tomato plants was influenced by other factors in addition to reduction in Pn rates. Melon leaves accumulated larger amounts of Cl^? than tomato, which caused a greater reduction in growth and a reduction in Pn at lower salinity levels than in tomato plants. These facts indicate that tomato is more salt‐tolerant than melon.     

Effect of Enhanced Nickel Levels on Wheat Plant Growth and Physiology under Salt Stress

A pot experiment was conducted to study the response of wheat to concurrent stresses of salinity and nickel (Ni)-toxicity. Soil was spiked with Ni (0, 20 and 40 mg kg^?1) combined with two levels of salinity (control and 10 dS m^?1) using Ni(ii) nitrate hexahydrate (Ni(NO₃)₂.6H₂O) and sodium chloride (NaCl), respectively, in a completely randomized design with four replicates. Plants were harvested at the tailoring stage and the results showed that wheat growth was positively affected by Ni at 20 mg kg^?1, and negatively at 40 mg kg^?1 concentration both in control and at 10 dS m^?1. Ni (20 mg kg^?1) had a nonsignificant positive effect on tissue potassium (K⁺) and a significant negative effect on Na⁺ concentration. Moreover, Ni translocation from root to shoot and accumulation decreased by increasing the levels of Ni in both control and salinity treatments. It can be concluded that Ni at 20 mg kg^?1 increased wheat growth by alleviating salinity stress; however, at 40 mg kg^?1 it aggravated the plant stress and decreased the plant growth.     

Growth,Root Characteristics,and Leaf Nutrients Accumulation of Four Faba Bean (Vicia faba L.) Cultivars Differing in Their Broomrape Tolerance and the Soil Properties in Relation to Salinity

The effects of salinity on four faba bean (Vicia faba L) cultivars [Giza 429, Giza 843, Misr 1 (Orobanche-tolerant), and Giza 3 (Orobanche-susceptible)] and soil properties were investigated in a pot experiment with addition of 0, 50, and 100 mM sodium chloride (NaCl) for 9 weeks. Salinity significantly decreased calcium (Ca²⁺), magnesium (Mg²⁺), potassium (K⁺), bicarbonate (HCO₃ ^?), and sulfate (SO₄ ^2?) while significantly increasing sodium (Na⁺), chloride (Cl^?), pH, and electrical conductivity (EC; dS m^?1). Root length density (cm cm^?3), root mass density (mg cm^?3), total dry weight, and salt-tolerance indexes were significantly reduced as a result of application of salinity. The results presented support evidence on the positive relationship between Orobance tolerance and salt tolerance in the three cultivars (Giza 429, Giza 843, and Misr 1). This adaptation was mainly due to a high degree of accumulation of inorganic nitrogen (N), phosphorus (P), K⁺, Ca²⁺, and Mg²⁺ and lesser quantities of Na⁺ and Cl^?, as well as greater K⁺/Na⁺ and Ca²⁺/Na⁺ ratios.     

Nitrogen Source and Concentration Affect Growth and Performance of Bedding-Plant Impatiens

ABSTRACT

Impatiens (Impatiens wallerana Hook. f.) is the most important annual bedding plant in the United States, based on wholesale dollar volume. Production of high-quality plants requires optimization of the nutrition regimen during growth, especially the total nitrogen (N) concentration and the ratio of N sources. The objective was to determine the N concentration and the nitrate (NO₃ ^??N):ammonium (NH₄ ⁺?N) ratio of N source that optimized bedding-plant impatiens growth and flower development. Four N concentrations (3.5, 7, 10.5, and 14 mmol N · L^?1) were used in factorial combination with four ratios of NO₃ ^??N:NH₄ ⁺?N (4:0, 3:1, 1:1, and 1:3). Application of treatments was made for 30 d. Then for 10 d only deionized water was applied to reduce salt buildup. Substrate pH was lowest (4.9) with the NH₄ ⁺?N source and electrical conductivity (EC) highest, but never > 2.4 dS m^?1. Nitrogen concentration and N source displayed an interaction for most growth parameters. Shoot fresh and dry weights and flower bud number were maximized at the 1:3 NO₃ ^??N:NH₄ ⁺?N ratio with a N concentration of 10.5 mmol L^?1. However, plant diameter, leaf number, and leaf chlorophyll content responded quadratically to N form ratio, with the 1:1 ratio optimum at a concentration of 10.5 mmol N· L^?1.     

COMPARATIVE STUDY OF DIFFERENT SALTS (SODIUM CHLORIDE,SODIUM SULFATE,POTASSIUM CHLORIDE,AND POTASSIUM SULFATE) ON GROWTH OF FORAGE SPECIES

Osmotic and specific ion effects are the most frequently mentioned mechanisms by which saline substance reduces plant growth. However, the relative importance of osmotic and specific ion effect on plant growth seems to vary depending on the salt tolerance of the plant under study. Tall wheatgrass (TW), perennial ryegrass (PR), African millet (AM) and Rhodesgrass (Rh) were grown in nutrient solution with sodium chloride (NaCl), sodium sulfate (Na₂SO₄), potassium chloride (KCl), and potassium sulfate (K₂SO₄) salinity up to electrical conductivity (EC) 27 dS m^?1. Growth of all plant species decreased significantly at high level (EC 27 dS m^?1) of NaCl and Na₂SO₄ salts. However, the growth of none of the plant species was affected significantly by KCl and K₂SO₄ at any level. Even leaf and shoot fresh weights were enhanced by K₂SO₄ in all plant species, except AM. Chlorine (Cl) was taken up in similar quantities from KCl and NaCl solutions and the content of the respective cations was similar to each other. Further sensitivity to sulfate and chloride was equal when sodium concentrations in shoots were equal, regardless of the anion composition of the media. The sodium (Na) concentration of the leaves of the plant species increased with increased NaCl and Na₂SO₄ levels in the nutrient solutions. The leaf Na concentration of TW was lower than that of the other plant species. However, the root Na concentration of TW was higher than that of the other plant species. Increased NaCl and Na₂SO₄ concentrations had a marked effect on leaf water potential of all plant species, and the TW showed higher leaf water potential at all levels of salts. Tall wheatgrass adjusted osmotically by accumulating electrolytes from the nutrient solution and by accumulation of glycinebetaine. Sodium was generally found more injurious than Chloride in all the four forage species. Salt tolerance could be ascribed as greater exclusion of Na ion.     

Effect of Magnesium Chloride–Induced Salinity on Carbon Dioxide Evolution and Nitrogen Mineralization in a Silty Clay Loam Soil

A laboratory incubation experiment was conducted to evaluate the effect of magnesium chloride–induced salinity on carbon dioxide (CO₂) evolution and nitrogen (N) mineralization in a silty loam nonsaline alkaline soil. Magnesium chloride (MgCl₂) salinity was induced at 0, 4, 8, 12, 16, 20, 30, and 40.0 dS m^?1 and measured CO₂ evolution and N mineralization during 30 days of incubation. Both CO₂ evolution and N mineralization decreased significantly with increasing salinity. The cumulative CO₂ evolution decreased from 235 mg kg^?1 soil at electrical conductivity (EC) 0.65 dS m^?1 to 11.9 mg kg^?1 soil at 40 dS m^?1 during 30 days of incubation. Similarly, N mineralization decreased from 185.4 mg kg^?1 at EC 0.65 dS m^?1 to 34.45 mg kg^?1 at EC 40.0 dS m^?1 during the same period. These results suggested that increasing magnesium chloride salinity from 4 dS m^?1 adversely affect microbial activity in terms of carbon dioxide evolution and N mineralization.     

Different Levels of Irrigation Water Salinity and Biochar Influence on Faba Bean Yield,Water Productivity,and Ions Uptake

Greenhouse experiment was conducted to investigate the effect of different levels of irrigation water salinity (0.5, 2.5, 5 and 7.5 dS m^?1) and wheat straw biochar (0%, 1.25%, 2.5%, and 3.75% w/w) on growth and yield of faba been using complete randomized design with three replications. Stomatal conductance (green canopy temperature) of faba bean increased (decreased) by application of biochar at each salinity level. The results showed increasing salinity to 2.5 dS m^?1 at zero biochar application increased the seed yield through osmotic adjustment, while by declining the osmotic potential, the nutritional values of biochar caused the seed yield to increase by increasing salinity to 5 dS m^?1. The root length density and root dry weight density in 0–8 cm soil layer declined under application of 3.75% w/w biochar in all salinity levels in comparison with that obtained in 2.5% w/w biochar, due to higher saline condition of the soil as result of higher biochar application. The results showed that addition of 2.5% w/w biochar can significantly mitigate salinity stress due to its high salt sorption capacity and by increasing potassium/sodium ratio in the soil. In general, since 2.5 % w/w biochar and salinity of 5 dS m^?1 increased dry seed yield and irrigation water productivity compared with that obtained in control (B₀S_0.5), these levels are recommended to improve faba bean growth and yield; however, these levels have to be evaluated under field conditions.     

Changes in Extractable Si,Fe, and Mn as Affected by Silicon,Salinity, and Waterlogging in a Sandy Loam Soil

Silicon (Si) is one of the most abundant elements in the earth's crust, although its availability may be affected by some edaphic and abiotic factors such as soil moisture and salinity. In a laboratory experiment, effects of silicon (Si), salinity, and soil moisture on changes of extractable Si, iron (Fe), and manganese (Mn) concentrations were investigated on a sandy loam calcareous soil. The experiment was arranged as a factorial completely randomized design with three replications. Two levels of Si (8 and 200 mg per kg of soil), three salinity levels [0.46 dS m^?1, 8 dS m^?1 as sodium chloride (NaCl), and 8 dS m^?1 as four-salt combination], two soil moisture regimes (–20 kPa and waterlogged), and four incubation times (0, 7, 30, and 45 days) were applied. Salt composition consisted of sodium chloride, sodium sulfate, calcium chloride, and magnesium sulfate at a molar ratio of 4:2:2:1. Acetic acid–extractable Si, Fe, and Mn were determined after 0, 7, 30, and 45 days of incubation. Waterlogging caused significant increase in the extractable Si, Fe, and Mn. Soil salinity of 8 dS m^?1, only in the form of sodium chloride, resulted in a marked decrease in extractable Si, Fe, and Mn. Silicon addition enhanced the soil Si concentration, with no effect on Fe and Mn. Equilibrium time for Si and Fe was 30 days, whereas Mn concentration reached to a constant level after 1 week of waterlogging. It was concluded that Si, Fe, and Mn fertilizers should be applied in sufficient amounts to the saline soils to prevent their deficiencies in plants. Meanwhile, overfertilization in waterlogged conditions must be avoided, because of the probability of nutrient imbalance or toxicity.     

GROWTH,YIELD, AND ION RELATIONS OF STRAWBERRY IN RESPONSE TO IRRIGATION WITH CHLORIDE-DOMINATED WATERS

Strawberry is listed as the most salt sensitive fruit crop in comprehensive salt tolerance data bases. Recently, concerns have arisen regarding declining quality of irrigation waters available to coastal strawberry growers in southern and central California. Over time, the waters have become more saline, with increasing sodium (Na⁺) and chloride (Cl^?). Due to the apparent extreme Cl^? sensitivity of strawberry, the rising Cl^? levels in the irrigation waters are of particular importance. In order to establish the specific ion causing yield reduction in strawberry, cultivars ‘Ventana’ and ‘Camarosa’ were grown in twenty-four outdoor sand tanks at the ARS-USDA U. S. Salinity Laboratory in Riverside, CA and irrigated with waters containing a complete nutrient solution plus Cl^? salts of calcium (Ca²⁺), magnesium (Mg²⁺), Na⁺, and potassium (K⁺). Six salinity treatments were imposed with electric conductivities (EC) = 0.835, 1.05, 1.28, 1.48, 1.71, and 2.24 dS m^?1, and were replicated four times. Fresh and dry weights of ‘Camarosa’ shoots and roots were significantly higher than those of ‘Ventana’ at all salinity levels. Marketable yield of ‘Camarosa’ fruit decreased from 770 to 360 g/plant as salinity increased and was lower at all salinity levels than the yield from the less vigorous ‘Ventana’ plants. ‘Ventana’ berry yield decreased from 925 to 705 g/plant as salinity increased from 0.835 to 2.24 dS m^?1. Relative yield of ‘Camarosa’ decreased 43% for each unit increase in salinity once irrigation water salinity exceeded 0.80 dS m^?1. Relative ‘Ventana’ yield was unaffected by irrigation water salinity up to 1.71 dS m^?1, and thereafter, for each additional unit increase in salinity, yield was reduced 61%. Both cultivars appeared to possess an exclusion mechanism whereby Na⁺ was sequestered in the roots, and Na⁺ transport to blade, petiole and fruit tissues was limited. Chloride content of the plant organs increased as salinity increased to 2.24 dS m^?1 and substrate Cl increased from 0.1 to13 mmol_cL^?1. Chloride was highest in the roots, followed by the leaves, petioles and fruit. Based on plant ion relations and relative fruit yield, we determined that, over the range of salinity levels studied, specific ion toxicity exists with respect to Cl^?, rather than to Na⁺ ions, and, further, that the salt tolerance threshold is lower for ‘Camarosa’ than for ‘Ventana’.     

Effect of nutrient solution salinity and ionic concentration on parsley (Petroselinum crispum Mill.) essential oil yield and content

The growth and essential oil (EO) production of parsley were evaluated in response to salinity and nutrient solution concentrations in a soilless culture. Parsley plants that were 60 days old were potted in a coconut fiber and peat moss medium and were treated with four different nutrient solutions, including T1, T2, T3 and T4. The T1 nutrient solution was the standard, the T2 and T3 solutions contained incremental macronutrient concentrations with an electrical conductivity (EC) of up to 2.2 and 3.2 dS m^?1, respectively, and the T4 solution was the same as T2 but with sodium chloride (NaCl) and an incremental macronutrient concentration with an EC of 3.2 dS m^?1. Next, these plants were grown for 90 days in a greenhouse with natural daylight in Nador, Morocco. Shoot and root growth significant decreased with increasing EC. However, the salinity that resulted from the addition of NaCl did not affect plant growth in the nutrient solutions. The optimum obtained growth and EO production were 1.2 and 2.2 dS m^?1, respectively. Consequently, the optimum EC value (based on the EO production) of parsley in the soilless culture was 1.2–2.2 dS m^?1.     

Mitigation of ammonium toxicity by silicon in tomato depends on the ammonium concentration

Ammonium toxicity in hydroponically grown crops can affect tomato development. However, it has been shown that the silicon (Si) attenuates ammonium toxicity in plants depending on the plant species, the stage of development and the ammonium concentration in the nutrient solution. Thus, in order to investigate how Si attenuates stress caused by ammonium in tomato, a study was carried out involving plants cultivated up to 40 days after seed germination using nutrient solutions containing ammonium concentrations (1, 2, 4, 6 and 8?mmol?L^?1), in the absence or presence of Si (1?mmol?L^?1). The accumulation and efficiency of nitrogen and Si use, as well as the concentrations of chlorophyll, carotenoids, malondialdehyde, hydrogen peroxide and growth parameters was assessed. At a concentration of 1?mmol?L^?1 ammonium, Si increases the accumulation of nitrogen and Si, the nitrogen use efficiency, the root area and dry biomass of the shoot. At concentrations of 1 and 2?mmol?L^?1 ammonium, Si increases the leaf area and root dry biomass, and in higher concentrations, there was no effect of Si after the supply of ammonium. It was observed that the addition of Si mitigates ammonium toxicity by 1?mmol?L^?1 ammonium, and we can recommend its use in the nutrient solution (Si?=?1?mmol?L^?1) to grow tomato cropsthat employs ammonium concentration of 1?mmol?L^?1.     

Interactive Effect of Soil Salinity and Water Stress on Growth and Chemical Compositions of Pistachio Nut Tree

ABSTRACT

The effects of three sodium chloride (NaCl) levels (0, 1200, and 2400 mg kg^{? 1} soil) and three irrigation intervals (3, 7, and 14 d) on the growth and chemical composition of two Pistacia vera rootstocks (‘Sarakhs’ and ‘Qazvini’) were investigated under greenhouse conditions. Eight-week-old pistachio seedlings were gradually exposed to salt stress which afterward, water stress was initiated. At any irrigation interval, plant height and shoot and root dry weights of both rootstocks were reduced with increasing salinity. However, increasing irrigation intervals alleviated the adverse effects of soil salinity. A negative relationship observed between relative shoot growth and electrical conductivity of soil saturation extract (EC_e) confirmed the above findings. Under 3-d irrigation interval, the EC_e required to cause a 50% growth reduction was lower than those under 7- and/or 14-d irrigation intervals. Shoot and root chemical analyses indicated that the salinity as well as irrigation regime affected the concentration and distribution of sodium (Na⁺), potassium (K⁺), and chloride (Cl^?) in pistachio. The concentration of Na⁺, K⁺ and C1^? ions increased with a rise in NaCl level, and was generally declined with increasing irrigation interval. Based on plant height, shoot and root dry weights and the concentrations of Na⁺, K⁺, and C1^? in the plant tissues, at lowest irrigation intervals ‘Sarakhs’ shows a higher sensitivity to soil salinity than ‘Qazvini’, but with increasing irrigation interval, ‘Sarakhs’ and ‘Qazvini’ can be classified as resistant and sensitive to salinity, respectively.