Journal of Plant Nutrition Ameliorative Effects of

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Ameliorative Effects of Potassium Phosphate on Salt‐Stressed Pepper and Cucumber a

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Cengiz Kaya , David Higgs , Faruk Ince , Bernado Murillo Amador , Atilla Cakir & Ebru Sakar a

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Soil Science Department, Agriculture Faculty , University of Harran , Sanliurfa, Turkey

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Environmental Sciences , University of Hertfordshire , College Lane Hatfield, Herts, AL10 9AB, UK c

Centro de Investigaciones Biológicas del Noroeste , Col. Playa Palo de Santa Rita , La Paz, Baja California Sur, Mexico d

Horticulture Department, Agriculture Faculty , University of Harran , Sanliurfa, Turkey Published online: 24 Jun 2011.

To cite this article: Cengiz Kaya , David Higgs , Faruk Ince , Bernado Murillo Amador , Atilla Cakir & Ebru Sakar (2003) Ameliorative Effects of Potassium Phosphate on Salt‐Stressed Pepper and Cucumber, Journal of Plant Nutrition, 26:4, 807-820, DOI: 10.1081/PLN-120018566 To link to this article: http://dx.doi.org/10.1081/PLN-120018566

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JOURNAL OF PLANT NUTRITION Vol. 26, No. 4, pp. 807–820, 2003

Ameliorative Effects of Potassium Phosphate on Salt-Stressed Pepper and Cucumber Cengiz Kaya,1 David Higgs,2,* Faruk Ince,1 Bernado Murillo Amador,3 Atilla Cakir,4 and Ebru Sakar4 1

Soil Science Department, Agriculture Faculty, University of Harran, Sanliurfa, Turkey 2 Environmental Sciences, University of Hertfordshire, College Lane, Hatfield, Herts, UK 3 Centro de Investigaciones Biolo´gicas del Noroeste, Col. Playa Palo de Santa Rita, La Paz, Baja California Sur, Mexico 4 Horticulture Department, Agriculture Faculty, University of Harran, Sanliurfa, Turkey

ABSTRACT Bell pepper (Capsicum annuum cv. Urfa Isoto) and cucumber (Cucumis sativus cv. Beith Alpha F1) were grown in pots containing field soil to investigate the effects of supplementary potassium phosphate applied to the root zone of salt-stressed plants. Treatments were (1) control: soil alone (C); (2) salt treatment: C plus 3.5 g NaCl kg1 soil (C þ S); and (3) supplementary potassium phosphate: C þ S plus supplementary 136 or 272 mg KH2PO4 kg1 soil (C þ S þ KP). Plants grown in saline treatment

*Correspondence: David Higgs, Environmental Sciences, University of Hertfordshire, College Lane Hatfield, Herts AL10 9AB, UK; E-mail: [email protected]. 807 DOI: 10.1081=PLN-120018566 Copyright # 2003 by Marcel Dekker, Inc.

0190-4167 (Print); 1532-4087 (Online) www.dekker.com


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Kaya et al. produced less dry matter, fruit yield, and chlorophyll than those in the control. Supplementary 136 or 272 mg KH2PO4 kg1 soil resulted in increases in dry matter, fruit yield, and chlorophyll concentrations compared to salt-stressed (C þ S) treatment. Membrane permeability in leaf cells (as assessed by electrolyte leakage from leaves) was impaired by NaCl application. Supplementary KH2PO4 reduced electrolyte leakage especially at the higher rate. Sodium (Na) concentration in plant tissues increased in leaves and roots in the NaCl treatment. Concentrations of potassium (K) and Phosphorus (P) in leaves were lowered in salt treatment and almost fully restored by supplementary KH2PO4 at 272 mg kg1 soil. These results clearly show that supplementary KH2PO4 can partly mitigate the adverse effects of high salinity on both fruit yield and whole plant biomass in pepper and cucumber plants. Key Words: Salinity; Bell pepper; Cucumber; Potassium phosphate; Fruit yield.

INTRODUCTION Salinity affects crops during vegetative and reproductive stages and can cause reductions in both dry matter and grain yield.[1] One important deleterious effect of elevated salt is leaf senescence and this varies with the growth stage; young seedlings and plants at the flowering stage seem to be more sensitive than mature stages.[2] One of the major factors inducing leaf senescence is the decrease of chlorophyll content under saline conditions.[3] Leaf senescence is also correlated with increased membrane permeability at high salt concentration.[4] Excess NaCl in the soil may also depress nutrient ion activities. As a result, the plant becomes susceptible to osmotic and specific-ion injury as well as to nutritional disorders that may result in reduced yield or quality.[5] The effects of salt stress on plant growth and physiology have been well documented in cereals, for example, rice[6] and barley.[7] However, the effects of salt stress on vegetable crop growth and physiology are still not well understood. In some cases, salinity decreases P concentration in plant tissue,[8] but in some other studies, it is indicated that salinity either increased or had no effect on P uptake. Plant growth medium, plant type, and cultivar also play a large role in P accumulation.[9] Salinity stress may increase the P requirement of certain crops. For example, Awad et al.[10] found that when NaCl was increased in the substrate from 10 to 50 to 100 mM, the P concentrations in the youngest mature tomato leaf necessary to obtain 50% yield increased from 58 to 77 to 97 mmol kg1 dry weight, respectively.


Salt-Stressed Pepper and Cucumber

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It is also well established that high salt concentrations induce K deficiency in tomato,[11,12] cucumber,[13] spinach,[14] and maize.[15] Breeding for tolerance to salinity in crops has usually been limited by a lack of reliable traits for selection.[16,17] Investigations on tolerance to saline environments frequently point to restricted ion accumulation and organic solute synthesis as major adaptations leading to salt resistance in glycophytes.[18] Moreover, there are multiple genes that seem to act in concert to increase salinity tolerance, and certain proteins involved in salinity stress protection have also been recognized.[19] An alternative approach for overcoming the negative effect of salinity could be to add supplemental P and=or K where the growth medium is saline at some time during the crop growth cycle. In this investigation we report an experiment with bell pepper and cucumber plants. The experiment was conducted to investigate the effects of root zone salinity on P and K nutrition and other parameters and also to study the effects of supplementary potassium phosphate on salt stressed bell pepper and cucumber.

MATERIALS AND METHODS Plant Culture and Treatments Experiment was conducted out doors at the University of Harran (Turkey) Agriculture Faculty Research Station from April to July 2001 with bell pepper (Capsicum annuum cv. Urfa Isotu) and cucumber (Cucumis sativus cv. Beith Alpha F1). Average daily maximum and minimum temperatures were 39 C and 19 C, respectively. Three seeds of each cultivar were sown directly in plastic pots each containing 5 kg of air-dried field soil and 1 kg of washed sand to improve drainage. After germination, plants were thinned to one plant per pot and then plants were grown for a further 12 weeks. Containers were covered with black plastic to excluded light from the roots and to minimize evaporation water loss. Treatments were (1) control: soil alone (C); (2) high salt treatment: C plus 3.5 g NaCl kg1 soil (C þ S); and (3) supplementary potassium phosphate: C þ S plus supplementary 136 (KP1) or 272 (KP2) mg KH2PO4 kg1 soil. Supplementary P and K were supplied as KH2PO4 in three equal split dressings and banded into the soil prior to planting, at flowering and fruit set. Adding 3.5 g kg1 NaCl to the soil increased Electrical Conductivity (EC) value from 1.18 dS m1 to 7.2 dS m1. This level of NaCl was added to the soil because, in our previous work[20] with cucumber it was found that this level of NaCl could create salinity in the growth medium. This increased EC


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value was checked at intervals and found to be maintained throughout the experiment. Soil texture was loamy clay, pH (1 : 2.5 water) 7.1, EC 1.18 dS m1. Nitrogen (N), P, and K were applied at the rates of 300, 100, and 250 mg kg1, respectively, to the soil for all treatments. Nitrogen as ammonium sulphate and P and K as mono potassium phosphate were applied in three equal split dressings prior to planting, at flowering and fruit set. Nitrogen was surface applied and P and K were banded into the soil. Each treatment was replicated four times in a randomized completeblock design and each replicate included six plants (i.e., 24 plants per treatment). The volume of water applied to the root zone of plants ranged from 50 mL to 1000 mL per container each day depending on intensity and amount of solar radiation and plant size. Excess water drained through holes in the container bases. Fruits were harvested twice a week for four weeks from the middle of June to middle of July. The values for the fruit yields are the means of the fruit yield of six plants per replicate and given in grams per plant. Leaf relative water content (LRWC) was calculated based on the methods from Yamasaki and Dillenburg.[21] Two leaves were always collected from the mid section of two plants per replicate in order to minimize age effects. Individual leaves were first removed from stem and then weighed to obtain fresh mass (FM). In order to determine the turgid mass (TM), leaves were floated in distilled water inside a closed petri dish. During the imbibition period, leaf samples were weighed periodically, after gently wiping the water from the leaf surface with tissue paper until a steady state was achieved. At the end of the imbibition period, leaf samples were placed in a pre-heated oven at 80 C for 48 h, in order to obtain dry mass (DM). All mass measurements were made using an analytical scale, with a precision of 0.0001 g. Values of FM, TM, and DM were used to calculate LRWC using the equation below: LRWCð%Þ ¼

FM DM 100 TM DM

Chlorophyll Concentration Two plants per replicate were used for chlorophyll determination. Fresh leaf samples taken from the youngest fully expanded leaf (1 g) were extracted with 90% acetone and read using a UV=Visible Spectrophotometer (Bausch and Lomb, Belgium) at 663, 645, and 750 nm wavelengths. Absorbance at


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750 nm was subtracted from absorbance at the other two wavelengths to correct for any turbidity in solution before chlorophyll concentrations were calculated using the formulae below from Strain and Svec.[22] Chl: aðmg mL1 ¼ 11:64 ðA663Þ 2:16 ðA645Þ


Chl: bðmg mL1 Þ ¼ 20:97 ðA645Þ 3:94 ðA663Þ (A663) and (A645) represent absorbance values read at 663 and 645 nm wavelengths, respectively. Electrolyte Leakage Electrolyte leakage was used to assess membrane permeability. Electrolyte leakage was measured using an electrical conductivity meter. The procedure used was based on Lutts et al.[2] Two randomly chosen plants per replicate were used and two leaf samples per plant were taken from the second leaf below the shoot apex and the second leaf above the base to represent developing and mature leaves, respectively, and cut into 1 cm segments. Leaf samples were then placed in individual stoppered vials containing 10 mL of distilled water after three washes with distilled water to remove surface contamination. These samples were incubated at room temperature (ca. 25 C) on a shaker (100 rpm) for 24 h. Electrical conductivity of bathing solution (EC1) was read after incubation. Samples were then placed in an autoclave at 120 C for 20 min and the second reading (EC2) was determined after cooling the bathing solutions to room temperature. Electrolyte leakage was calculated as EC1=EC2 and expressed as percent. Chemical Analysis and Dry Weight Determinations Three randomly chosen plants per replicate were divided into leaves, stems, and roots, and dried in an oven at 70 C for two days to determine dry weights and elemental concentrations. Chemical analyses were carried out on ground leaf and root samples dry-ashed at 550 C for six hours, mixed with 2 M hot HCl, filtered, and then brought to a final volume of 50 mL with distilled water. Sodium, K, and P were determined in these sample solutions. Phosphorus was analyzed by a vanadate-molybdate method using a UV=Visible spectrophotometer (Bausch and Lomb, Belgium) and Na and K in the sample solution were analyzed using a Corning 401 (UK) flame photometer.[23] A Statview ANOVA program was used to analyze all data. Means were separated by LSD test (P < 0.05).

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RESULTS AND DISCUSSION


Plant Growth Dry matter production and chlorophyll concentration were used to assess the effects of both high salinity and supplementary P and K on plant growth. Dry matter and chlorophyll content decreased in the 60 mM NaCl (C þ S) compared to the Control (C) treatment for both species (Tables 1 and 2). Similar results have been shown by Bar-Tal et al.[24] for corn, Adams,[25] and Satti and Al-Yahyai[26] for tomato, and Leidi and Saiz[27] for cotton. The adverse affect of high NaCl on chlorophyll concentration has previously been shown for rice[28] and barley.[29] Supplementing soil with P and K increased both DM and chlorophyll contents with higher (C þ S þ KP2) treatment restoring both parameters to control levels in most cases. These findings are in partial agreement with work of Mohammad et al.[30] who applied supplementary phosphorus only to salt stressed tomato plants.

Electrolyte Leakage and Leaf Relative Water Content The C þ S treatment induced significant increases in electrolyte leakage compared to the control (C) as shown in Table 3 for both species. Similar results were obtained by Lutts et al.[6] for NaCl-sensitive rice varieties; they reported that high salt concentration increased membrane leakage.

Table 1. Dry weights (g plant1)a of cucumber and pepper cultivars grown in salinized soil with or without addition of two levels of supplementary KH2PO4. Cucumber

Pepper

Treatments

Shoot

Root

Total plant

Shoot

Root

Total plant

C CþS C þ S þ KP1 C þ S þ KP2

76.8 48.4 56.4 73.3

8.5 3.9 5.9 7.3

85.3 52.2 62.3 75.6

68.7 35.3 51.2 62.6

6.9 3.1 4.6 5.8

75.6 38.4 55.8 68.4

a c b a

a b b a

a b b a

a d c b

a b b a

a b b a

Note: Within each column, same letter indicates no significant difference among treatments (P < 0.05). C, Control: soil alone; S, 3.5 g kg1 sodium chloride added to soil; KP1, 136 mg kg1 KH2PO4; KP2, 272 mg kg1 KH2PO4 supplemented in soil. a Means of four replicates of three plants.


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Table 2. Chlorophyll contents (mg kg1 F.W.)a of cucumber and pepper cultivars grown in salinised soil with or without addition of two levels of supplementary KH2PO4. Cucumber


Treatments C CþS C þ S þ KP1 C þ S þ KP2

Pepper

Chl. a

Chl. b

Chl, aþb

Chl. a

Chl. b

Chl, aþb

1,157 a 964 c 1,025 b 1,098 a

768 a 396 c 615 b 745 a

1,925 a 1,360 c 1,650 b 1,843 a

1,169 a 876 c 1,037 b 1,112 a

778 a 367 c 589 b 755 a

1,947 a 1,234 c 1,626 b 1,867 a

Note: Within each column, same letter indicates no significant difference between treatments (P < 0.05). C, Control: soil alone; S, 3.5 g kg1 sodium chloride added to soil; KP1, 136 mg kg1 KH2PO4; KP2, 272 mg kg1 KH2PO4 supplemented in soil. a Means of four replicates and each replicate includes three plants.

Table 3. Electrolyte leakagea of developing (DL) and mature leaves (ML) and leaf relative water contenta of cucumber and pepper cultivars grown in salinized soil with or without addition of two levels of supplementary KH2PO4. Leaf relative water content (%)

Electrolyte leakage (%)b Cucumber Treatments C CþS C þ S þ KP1 C þ S þ KP2

DL 7.9 39.7 18.4 10.3

Pepper

ML c a b c

9.4 43.2 19.7 11.4

DL d a b c

8.6c 43.2 a 20.2 b 12.4 c

ML 9.7 47.6 22.4 14.1

c a b c

Cucumber ML

Pepper ML

92 a 80 c 84 b 90 a

93 a 76 d 82 c 89 b

Note: Within each column, same letter indicates no significant difference among treatments (P < 0.05). C, Control: soil alone; S, 3.5 g kg1 sodium chloride added to soil; KP1, 136 mg kg1 KH2PO4; KP2, 272 mg kg1 KH2PO4 supplemented in soil. a Means of four replicates of two plants. b EC1=EC2 (full explanation in materials and methods section).

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Supplementary P and K restored control of membrane permeability; to levels similar to the control in the higher (KP2) treatment. In our previous work with tomato, membrane permeability was shown to be maintained by supplementary P and K applied via the leaves.[31] Leaf relative water content was lower in plants grown at high salinity compared to control treatment and was increased by supplementary P and K (Table 3). This clearly shows mitigation of salinity-induced water stress in the plant by supplemental P and K. Fruit Yield Marketable fruit yield was reduced in the salt only (C þ S) treatment compared to unstressed control (C) plants (Table 4). A number of other workers have reported similar effects of salinity in reducing both fruit yield and=or biomass for a range of other agricultural and horticultural crops, i.e., Bar-Tal et al.[24] for corn, Adams[25] Satti and Al Yahyai[26] for tomato, and Leidi and Saiz[27] for cotton. Unmarketable fruit yield was increased by salinity treatment and was reduced with supplementary P and K (Table 4). The high supplementary P and K treatment was most effective in mitigating the detrimental effect of salinity on all aspects of fruit yield and restoring values equal to controls in all cases (Table 4). Nutrient Concentrations Concentration of Na increased in leaves and roots of plants in the presence of NaCl stress (Table 5). Sodium concentration was also significantly higher in both the supplemental P and K treatments compared to the control, but the P and K additions did significantly lower Na concentrations in all parts of the plants tested (Table 5). These results are in agreement with findings obtained by others (Satti and Al-Yahyai[26] for tomato and Asch et al.[32] for rice). High concentrations of Na accumulated in roots in the presence of NaCl stress and highest levels were in roots rather than leaves (Table 5). Developing leaves contained slightly higher Na than mature leaves. The relatively small reductions in plant sodium concentrations in even the high supplementary P and K treatment nevertheless appear to be sufficient to almost normalize both growth physiology and fruit yield. Concentrations of P and K decreased in both developing and mature leaves in the presence of NaCl stress, but increased in the roots (Tables 6 and 7). It has previously been reported that leaf K concentration is decreased by increasing NaCl concentration in nutrient solution or in the soil, e.g., in

5.87 3.58 4.23 5.43

C CþS C þ S þ KP1 C þ S þ KP2

0.43 1.20 0.90 0.69

b a a b

6.30 4.78 5.13 6.12

a c b a

1.97 1.05 1.35 1.83

a c b a

MFY (kg plant1) 0.25 0.45 0.39 0.32

b a a b

UM FY (kg plant1)

TFY (kg plant1)

UM FY (kg plant1)

2.22 1.50 1.74 2.15

a c b a

TFY (kg plant1)

Note: Within each column, same letter indicates no significant difference among treatments (P < 0.05). C, Control: soil alone; S, 3.5 g kg1 sodium chloride added to soil; KP1, 136 mg kg1 KH2PO4; KP2, 272 mg kg1 KH2PO4 supplemented in soil. a Means of four replicates of six plants.

a c b a

MFY (kg plant1)

Treatments

Pepper

Cucumber

Table 4. Marketable (M),a unmarketable (UM),a and total fruit yield (TFY)a of cucumber and pepper cultivars grown in salinized soil with or without addition of two levels of supplementary KH2PO4.


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Table 5. Sodium concentration (% dry wt.)a of developing (DL), mature leaves (ML), and roots of cucumber and pepper cultivars grown in salinized soil with or without addition of two levels of supplementary KH2PO4. Cucumber



DL 0.25 1.59 1.29 1.05

ML d a b c

0.20 1.45 1.19 0.98

Pepper Root

d a b c

0.34 2.07 1.89 1.67

c a b b

DL 0.26 1.69 1.40 1.20

ML d a b c

0.22 1.53 1.32 1.12

Root d a b c

0.36 2.16 1.78 1.74

c a b b


cucumber,[13] in tomato,[33] in maize and barley.[34] Adams[25,33] also noted that leaf P concentration decreased in tomato plants with increasing NaCl concentration in nutrient solution. Supplemental P and K corrected the deficiencies of both P and K in the leaves, although values generally remained somewhat lower than in the controls. This finding is in agreement with Satti and Al-Yahyai[26] who showed that additional P and K in nutrient solution corrected P and K deficiencies in tomato grown in a saline medium. In our previous work with strawberry, foliar application of potassium phosphate spray increased the plant Table 6. Potassium concentration (% dry wt.)a of developing (DL), mature leaves (ML), and roots of cucumber and pepper cultivars grown in salinized soil with or without addition of two levels of supplementary KH2PO4. Cucumber Treatments C CþS C þ S þ KP1 C þ S þ KP2

DL 2.68 1.36 1.97 2.23

ML a d c b

2.43 1.24 1.79 2.02

Pepper Root

a d c b

3.43 4.67 5.02 5.45

d c b a

DL 2.67 1.22 1.67 1.98

ML a d c b

2.46 1.13 1.56 1.75

Root a c b b

3.65 4.97 5.23 5.89

d c b a

Note: Within each column, same letter indicates no significant difference among treatments (P < 0.05). C, Control: soil alone; S, 3.5 g kg1 sodium chloride added to soil; KP1, 136 mg kg1 KH2PO4 KP2, 272 mg kg1 KH2PO4 supplemented in soil. a Means of four replicates of three plants.


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Table 7. Phosphorus concentration (% dry wt.)a of developing (DL), mature leaves (ML), and roots of cucumber and pepper cultivars grown in salinized soil with or without addition of two levels of supplementary KH2PO4. Cucumber



DL 0.68 0.25 0.37 0.57

ML a d c b

0.56 0.20 0.32 0.50

Pepper Root

a c b a

1.43 2.67 2.89 3.02

d c b a

DL 0.63 0.22 0.32 0.43

ML a d c b

0.45 0.16 0.26 0.40

Root a c b a

1.52 2.89 3.12 3.29

d c b a


concentrations of both P and K[35] so it may well be that the demonstrated mitigation effects of KH2PO4 under saline growth conditions have a wider application both in terms of species and mode of application.

CONCLUSIONS From the results of this experiment, it can be concluded that:

High NaCl in soil significantly decreases leaf chlorophyll concentrations, plant growth, fruit yield, membrane permeability, and significantly reduces fruit quality. High NaCl can induce P and K deficiencies in the leaves. Supplementing soil with P and K significantly improved the parameters affected by high salinity (e.g., plant growth, fruit yield, and membrane permeability) and also generally corrected both P and K deficiencies in the leaves.

ACKNOWLEDGMENTS Authors wish to thank University of Harran (Turkey), University of Hertfordshire (UK), and Biological Research Centre (Mexico) for supporting this work.

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REFERENCES 1. Aslam, M.; Qureshi, R.H.; Ahmad, N. A rapid screening technique for salt tolerance in rice (Oryza sativa L.). Plant Soil 1993, 150, 99–107. 2. Lutts, S.; Kinet, J.M.; Bouharmont, J. NaCl-induced senescence in leaves of rice (Oryza sativa L.) cultivars differing in salinity resistance. Ann. Bot. 1996, 78, 389–398. 3. Chen, C.T.; Li, C.C.; Kao, C.H. Senescence of rice leaves. XXXI. Changes of chlorophyll, protein and polyamine contents and ethylene production during senescence of a chlorophyll-deficient mutant. J. Plant Growth Reg. 1991, 10, 201–205. 4. Dhindsa, R.S.; Plumb-Dhindsa, P.; Thorpe, T.A. Leaf senescence correlated with increased levels of membrane permeability and lipid peroxidation, and decreased levels of superoxide dismutase and catalase. J. Exp. Bot. 1981, 32, 93–101. 5. Grattan, S.R.; Grieve, C.M. Salinity-mineral nutrient relations in horticultural crops. Sci. Hort. 1999, 78 (1–4), 127–157. 6. Lutts, S.; Kinet, J.M.; Bouharmont, J. NaCl-induced senescence in leaves of rice (Oryza sativa L.) cultivars differing in salinity resistance. Ann. Bot. 1996, 78, 389–398. 7. Morales, F.; Abadia, A.; Go¨ mez-Aparisi, J.; Abadia, J. Effects of combined NaCl and CaCl2 salinity on photosynthetic parameters of barley grown in nutrient solution. Physiol. Plant. 1992, 86, 419–426. 8. Sharpley, A.N.; Meisinger, J.J.; Power, J.F.; Suarez, D.L. Root extraction of nutrients associated with long term soil management. In Advances in Soil Science; Stewart, B., Ed.; Springer-Verlag: Berlin, 1992; Vol. 19, 151–217. 9. Grattan, S.R.; Grieve, C.M. Mineral nutrient acquisition and response by plants grown in saline environments. In Handbook of Plant and Crop Stress; Pessarakli, M., Ed.; Marcel Dekker, Inc.: New York, 1994; 203–226. 10. Awad, A.S.; Edwards, D.G.; Campell, L.C. Phosphorus enhancement of salt tolerance of tomato. Crop Sci. 1990, 30, 123–128. 11. Song, J.Q.; Fujiyama, H. Difference in response of rice and tomato subjected to sodium salinization to the addition of calcium. Soil Sci. Plant Nutr. 1996, 42, 503–510. 12. Lopez, M.V.; Satti, S.M.E. Calcium and potassium-enhanced growth and yield of tomato under sodium chloride stress. Plant Sci. 1996, 114, 19–27. 13. Sonneveld, C.; de Kreij, C. Response of cucumber (Cucumis sativus L.) to an unequal distribution of salt in the root environment. Plant Soil 1999, 209, 47–56.



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14. Chow, W.S.; Bal, M.C.; Anderson, J.M. Growth and photosynthetic responses of spinach to salinity: Implication of K nutrition for salt tolerance. Aust. J. Plant Physiol. 1990, 17, 563–578. 15. Botella, M.A.; Martinez, V.; Pardines, J.; Cerda, A. Salinity induced potassium deficiency in maize plants. J. Plant Physiol. 1997, 150, 200–205. 16. Shannon, M.C. Principles and strategies in breeding for higher salt tolerance. Plant Soil 1985, 89, 227–241. 17. Noble, C.L.; Rogers, M.E. Arguments for the use of physiological criteria for improving the salt tolerance in crops. Plant Soil 1992, 146, 99–107. 18. Greenway, H.; Munns, R. Mechanisms of salt tolerance in nonhalophytes. Annu. Rev. Plant Physiol. 1980, 31, 149–190. 19. Bohnert, H.J.; Jensen, R.G. Metabolic engineering for increased salt tolerance: The next step. Aust. J. Plant Physiol. 1996, 23, 661–667. 20. Kaya, C.; Higgs, D. Calcium nitrate as a remedy for salt stressed cucumber plants. J. Plant Nutr. 2002, 25 (4), 861–871. 21. Yamasaki, S.; Dillenburg, L.C. Measurements of leaf relative water content in Araucaria angustifolia. R. Bras. Fisiol. Veg. 1999, 11 (2), 69–75. 22. Strain, H.H.; Svec, W.A. Extraction, separation, estimation and isolation of chlorophylls. In The Chlorophylls; Vernon, L.P., Seeley, G.R., Eds.; Academic Press: New York, 1966; 21–66. 23. Chapman, H.D.; Pratt, P.F. Methods of Analysis for Soils, Plants and Water; Chapman Publisher: Riverside, CA, 1982. 24. Bar-Tal, A.; Fergenbaun, S.; Sparks, D.L. Potassium-salinity interaction in irrigated corn. Irrig. Sci. 1991, 12, 27–35. 25. Adams, P. Some responses of tomatoes grown in NFT to sodium chloride. In Proceedings of the 7th International Congress on Soilless Culture; ISOSC: Wageningen, 1988; 59–70. 26. Satti, S.M.E.; Al-Yahyai, R.A. Salinity tolerance in tomato: Implications of potassium, calcium and phosphorus. Commun. Soil Sci. Plant Anal. 1995, 26 (17–18), 2749–2760. 27. Leidi, E.O.; Saiz, J.F. Is salinity tolerance related to Na accumulation in upland cotton seedlings? Plant Soil 1997, 190, 67–75. 28. Yeo, A.R.; Yeo, M.E.; Flowers, S.A.; Flowers, T.J. Screening of rice (Oryza sativa L.) genotypes for physiological characters contributing to salinity resistance, and their relationship to overall performance. Theoret. Appl. Genet. 1990, 79, 377–384. 29. Belkhodja, R.; Morales, F.; Abadia, A.; Gomez-Aparisi, J.; Abadia, J. Chlorophyll fluorescence as a possible tool for salinity tolerance screening in barley (Hordeum vulgare L.) Plant Physiol. 1994, 104, 667–673.


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Kaya et al.

30. Mohammad, M.; Shibli, R.; Ajlouni, M.; Nimri, L. Tomato root and shoot responses to salt stress under different levels of phosphorus nutrition. J. Plant Nutr. 1998, 21 (8), 1667–1680. 31. Kaya, C.; Kirnak, H.; Higgs, D. Enhancement of growth and normal growth parameters by foliar application of potassium and phosphorus in tomato cultivars grown at high (NaCl) salinity. J. Plant Nutr. 2001, 24 (2), 357–367. 32. Asch, F.; Dingkuhn, M.; Wittstock, C.; Doerffling, K. Sodium and potassium uptake of rice panicles as affected by salinity and season in relation to yield and yield components. Plant Soil 1999, 207, 133–145. 33. Adams, P. Effect of increasing the salinity of the nutrient solution with major nutrients or sodium chloride on the yield quality and composition of tomato grown in rockwool. J. Hort. Sci. 1991, 66 (2), 201–207. 34. Benes, S.E.; Aragues, R.; Grattan, S.R.; Austin, R.B. Foliar and root absorbtion of Na and Cl in maize and barley: Implications for salt tolerance screening and the use of saline sprinkler irrigation. Plant Soil 1996, 180, 75–86. 35. Kaya, C.; Kirnak, H.; Higgs, D. An experiment to investigate the ameliorative effects of foliar potassium phosphate sprays on salt stressed strawberry plants. Aust. J. Agric. Res. 2001, 52 (10), 995–1000.