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Gravel for Soilless Tomato Culture in theMediterranean RegionDamianos Neocleous a & Polycarpos Polycarpou aa Agricultural Research Institute, Ministry of Agriculture, NaturalResources and Environment , Nicosia, CyprusPublished online: 24 Mar 2010.

To cite this article: Damianos Neocleous & Polycarpos Polycarpou (2010) Gravel for Soilless TomatoCulture in the Mediterranean Region, International Journal of Vegetable Science, 16:2, 148-159, DOI:10.1080/19315260903357812

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International Journal of Vegetable Science, 16:148–159, 2010Copyright © Taylor & Francis Group, LLCISSN: 1931-5260 print / 1931-5279 onlineDOI: 10.1080/19315260903357812

WIJV1931-52601931-5279International Journal of Vegetable Science, Vol. 16, No. 2, Feb 2009: pp. 0–0International Journal of Vegetable ScienceGravel for Soilless Tomato Culture in the Mediterranean RegionSoilless Tomato CultureD. Neocleous and P. Polycarpou

Damianos Neocleous and Polycarpos Polycarpou

Agricultural Research Institute, Ministry of Agriculture, Natural Resources andEnvironment, Nicosia, Cyprus

In most Mediterranean countries the current knowledge of soilless culture is still insuf-ficient. Experiments were carried out to determine responses of tomato (Lycopersiconesculentum Mill.) to production using locally available gravel, an alternative, lesscostly, growth medium than imported perlite. Local gravel is a diabase volcanic rockproduced in several Cyprus regions for building purposes. Local gravel and importedperlite were agronomically tested in a hydroponic, recirculated production system in agreenhouse. Use of local gravel for the hydroponic cultivation of tomato producedresults similar to those with imported perlite. There does not appear to be a compellingreason not to use the gravel for soilless tomato production.

Keywords Lycopersicon esculentum, Cyprus, Gravel, Hydroponics, Nutrient content,Perlite, Yield.

INTRODUCTION

The interest in soilless culture in Mediterranean countries is increasing due toexhausted soils, soil disinfection, and water quality and availability (Magnaniet al., 2003; Maloupa et al., 1993; Martinez and Abad, 1993). More efficient,and less polluting, controlled-environment recycling production systems inglasshouses are being planned and used (Magnani et al., 2003). Alternativeartificial substrates can be employed for hydroponic systems (Lenzi et al.,2001). Alternative growing materials must be easily available, cheaper,renewable, and recyclable, compared to traditional other substrates includingperlite and rockwool. In Cyprus, a material in the building industry is locallyquarried gravel (Panagides, 2002). This material is a diabase volcanic rock(∼60% diabase-basalt and microdiorite). The original rocks are subjected to

Address correspondence to Damianos Neocleous, Agricultural Research Institute,Ministry of Agriculture, Natural Resources and Environment, P.O. Box 22016, 1516Nicosia, Cyprus. E-mail: d.neocleous@arinet.ari.gov.cy

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Soilless Tomato Culture 149

low-grade degradation of the greenschist-actinolite facies and associated sodametasomatism. The rocks are composed of 3 or more of the following minerals:albite, quartz, diopside, diopsidic augite, actinolite, chlorite, epidote, andcalcite (Louca, 2007). Local gravel could be used as a substrate in soilless culture.The possibility of using locally available materials that are less costly thanimported materials is necessary for successful cultivation. It is estimated thatsoilless culture in Cyprus represents 18.7 ha (6.5% of the total greenhousecultivation area). This is relatively low and likely due to growers havingknowledge of greenhouse production and the use of substrates (Chimonidou,2000). The project was undertaken to assess locally available gravel as amedium for greenhouse tomato (Lycopersicon esculentum Mill.) production.

MATERIALS AND METHODS

The experiment was conducted at the Agricultural Research Institute ofCyprus (long. 32 °E, lat. 35 °N) from 16 Nov. 2005 to 13 June 2006; harvestingwas from 2 Jan. 2006 to 13 June 2006. Tomato, cv. FA 179 Brillante, plantswere grown in a polyethylene-coated, multispan, temperature-controlledgreenhouse, 4 m high, 21 m wide, and 27 m long, with side and roof openings.Tomato seedlings were germinated in a soilless germinating mix and trans-planted at the third true-leaf stage in local gravel or perlite in polygal soillessplant beds (Ramat-Hashofet, Israel) in double 20-m channel rows in a recircu-lating hydroponic system. Local gravel, or imported perlite, was used once,twice, or three times for the same crop under the same conditions. Substrateswere disinfected between crops using sodium hypochlorite (NaOCl).

Rows were oriented north–south with 0.3 m between plants and 1.2 mbetween channels with a density of 2.5 plants per m2. Temperature did notexceed 28°C or drop below 12°C (average temperature ∼22°C). Relativehumidity ranged from 60% to 75% throughout the growing period.

Substrate particle size for local gravel was 3–7 mm and for imported perlite3–5 mm. Local gravel is a silicate-based material used in the building industrywith a chemical composition shown in Table 1 (Gass, 1960). Perlite is a grey-white mineral of volcanic origin comprised of potassium sodium aluminiumsilicate mined from lava flows (Olympios, 1992). One hundred thirty-eightplants, distributed in 4 replications for each treatment, were arranged in arandomized complete block design. There were 8 rows per treatment with acapacity of 700 L of substrate per row.

IrrigationIrrigation was begun automatically daily at 6:00 AM and continued to 6:00 PM.

The program was operated for up to 10 time intervals. Capillary tubes withindividual drip emitters and a flow rate of 2 L·h−1 were installed for each

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150 D. Neocleous and P. Polycarpou

plant. Plants were supplied with a known amount of nutrient solution A andthe drainage B was measured. The difference between A and B was theamount of solution taken up by plants during the day. To this amount another30% to 40% was added in order to avoid excess accumulation of nutrients inthe substrate and the new amount of (A − B) + 30% = C nutrient solution wasgiven to meet plant requirements; surplus of nutrient solution rangingbetween 20% and 50% of the total supply is needed to generate leachate andreduce buildup of salts (Böhme, 1995a, 1995b; Uronen, 1995). The amount Cwas divided by the capacity of the drippers to determine the time needed forfertigation during the day (Schröder and Lieth, 2002). The drainage solutionfrom the substrates was filtered (150 μm) and disinfected with a UV lamp(Wohanka, 2002). The irrigation schedule was to keep the electrical conduc-tivity in the root system of the plants relatively constant. The water-holdingcapacity of the materials used was low, requiring frequent irrigation (up to10 times).

Nutrient SolutionAmounts of essential macro- and micronutrients needed by tomato for

maximum yield and good quality are known (Adams, 2002; Benton, 1997;Mavrogiannopoulos, 2006; Sonneveld, 2002). Concentrations of macroele-ments used are shown in Table 2. Concentrations of micronutrients in thesolution, as (mg·L−1), were Fe = 0.85, B = 0.25, Mn = 0.25, Zn = 0.125, Cu =0.01, Mo = 0.025. The corresponding EC (HI 8733, Hanna Instruments,Padova, Italy) value of the solution was 1.6 dS·m−1 and pH (HI 8314, HannaInstruments, Padova, Italy) was maintained at 6.2. To obtain a higher EC

Table 1: Chemical composition of local gravel.

Composition % of Weight

SiO2 49.10Al2O3 15.60Na2O 2.38K2O 1.65Fe2O3 2.08CaO 7.58MgO 10.42TiO2 0.30FeO 5.04P2O5 0.04MnO 0.18Na2O 2.38H2O 4.22H3O 1.64Total 100.23S.G. 2.76pH 7.7 (extr. 1:2.5 w/w)

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151

Tab

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.69

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152 D. Neocleous and P. Polycarpou

(2.0) during periods of low transpiration the concentration of macroelementswas changed proportionally to the increase of EC; the concentration of themicroelements remained unchanged.

YieldHarvested fruit were counted, weighed, and separated into marketable

and unmarketable categories. Numbers of fruit per plant and fruit weight weredetermined. All immature fruit at the last harvest were counted. Fruit wereunmarketable if they were split, had any defects, or weighed less than 150 g.

Nutrient StatusMature red fruit and leaves opposite and below the top flower cluster were

collected at different plant growth stages, dried, and finely ground. Values ofCa, Mg, Fe, Mn, Cu, and Zn in solution were quantified using an inductivelycoupled plasma spectrometry (model S12, Allied Analytical Systems, Andover,Mass.; Allan, 1971). The N and P contents were quantified in a continuous flowanalyzer (Chemlab Instruments Ltd, Essex, England) and K determined with aflame emission spectrophotometer (Charalampous and Papakonstantinou,1965). Analysis for Cl in leaves was with the Nelson (1960) method. Boron wasdetermined by the carmine method (Hatcher and Wilcox, 1950). Substratenutrient composition was determined using in situ extraction with a ceramiccup inserted into the substrate (Raviv et al., 2002). Elemental analysis was per-formed according to Charalampous and Papakonstantinou (1965) and micronu-trients were analyzed by the DTPA extraction method (Alt and Peters, 1993).

Leaf Water Potential and Chlorophyll FluorescenceWater potentials were measured on the youngest fully expanded leaves

using a plant moisture system (model SKPM 1400, Skye Instruments Ltd.,Wales, UK) according to Scholander et al. (1965). Leaf chlorophyll fluores-cence was determined using a chlorophyll fluorometer (model OS-30p, Opti-Sciences, Hudson, N.H.). The OS-30p measures chlorophyll fluorescenceparameters Fo and Fm, where Fo is the initial fluorescence, Fm is the maximumfluorescence, and the variable fluorescence Fv is calculated as Fv = Fm - Fo. Theparameter Fv/Fm is very useful to estimate extent of inhibition of photosynthe-sis, due to damage in photosystem II, by inoptimal electron transfer occurringunder stress.

Fruit QualityRandom fruit samples from clusters 3 and 5 were taken to determine some

quality attributes. Soluble solids concentration (SSC) was determined in thehomogenized sample using a refractometer and expressed as %Brix (model

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Soilless Tomato Culture 153

GPR 11-37, Index Instruments, Cambridgeshire, England). Titratable aciditywas measured by mixing 2 g of pulp and 50 mL of distilled water with a fewdrops of phenolphthalein indicator and titrating the mixture with 0.1 NNaOH. The titratable acidity was expressed as percentage citric acid equiva-lent to the quantity of NaOH used for the titration (Ryan and Dupant, 1973).The ratio of SSC to titratable acidity was calculated. Vitamin C content wasestimated by the Association of Analytical Chemists’ (AOAC, 1980) titrimetricmethod using 2,6-dichlorophenolindophenol solution. Fruit dry matter wasdetermined by drying to a constant weight at 70°C in a ventilated oven.

The data were subjected to analysis of variance (ANOVA) in SAS (SASInc., Cary, N.C.) for main effects and their interaction. If the interaction wassignificant, it was used to explain results. If the interaction was not signifi-cant, Duncan’s multiple range test was used to separate means.

RESULTS AND DISCUSSION

Irrigation and LeachingRunoff accounted for about 33% of the solution provided to the plants.

Because runoff varied from day to day, overwatering was used to ensure suffi-cient irrigation of plants and to stabilize nutrient content of the substrate.Due to recirculation there is limited economic loss or environmental hazardcaused by runoff as can occur in open systems. Water consumption for plantsat a density of 2.5 plants per m2 was between 275 and 320 L per plant duringthe growing season, about 688 to 800 L per m2.

Total water consumption by plants in an open system with inert mediaand a 20% runoff averaged 60 L per plant (Uronen, 1995) including a loss ofelements, because nutrient content of the substrate solution and the leachateare generally very close (Böhme, 1995a, 1995b; Uronen, 1995). There are fewreports on soilless production with emphasis on water use efficiency (Bradleyand Marulanda, 2000; Schwarz et al., 1998), and there is little informationavailable on hydroponics systems in arid climates. In the current experimentthe average productivity was 8.9 kg per plant, which corresponds to a value of29.9 kg.Mt−1 of water.

Nutrient StatusNutrient content of substrates (Table 3) was within recommendations

(Sonneveld, 2002), and there were no limitations on vegetative growth andreproductive development (Adams, 2002). No leaf discoloration or growthretardation was observed after 1, 2, or 3 years’ use for both materials.

Electrical conductivity (EC) in the gravel and around roots averaged 3.0,3.4, and 4.0 dS m−1 for the first, second, and third time use, respectively.

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154 D. Neocleous and P. Polycarpou

In perlite electrical conductivity was 3.2 dS m−1 for the first-time use and 3.5and 3.7 dS.m−1 for the second- and third-time uses, respectively. The pH valuearound roots for both substrates, and the 3 years, ranged between 6.5 and 7.0.

Substrate affected levels of Na, Zn, Cu, and Fe; time of use affected levelsof N and Mn in tomato leaves, and the interaction was not significant (Table 4).In the substrate levels of N, P, K, Ca, Mg, B, and Mn averaged 3.94, 0.93, 4.81,1.34, 0.78, 45, and 47, respectively. Level of Na was significantly higher ingravel (0.21% DW) than in perlite (0.19% DW). Levels of Zn (39 mg·L−1), Cu(16 mg·L−1), and Fe (112 mg·L−1) were higher in gravel than in perlite, whichwere Zn (34 mg·L−1), Cu (14 mg·L−1), and Fe (92 mg·L−1). Regarding number oftimes used, P, K, Ca, Mg, Na, and B, Zn, Cu, and Fe averaged 0.93%, 4.81%,1.35%, 0.78%, 0.21%, and 46, 36, 15, and 102 mg·L−1, respectively. The level of Nwas highest in the first-time use substrates (4.08% DW) and in the second- and

Table 3: Nutrient content around roots for two different substrates used once, twice, or 3 times (one-time measurements).

Gravel Perlite

Variablea 1st 2nd 3rd 1st 2nd 3rd

EC 3.04 3.41 3.96 3.22 3.54 3.74pH 6.79 6.83 6.95 6.51 6.53 6.73NH4-N 13.2 23.3 23.6 12.2 14.3 15.3NO3-N 208 234 228 228 232 250K 290 310 330 272 284 300P 15.2 16.6 15.7 16.9 15.8 22.3Ca 200 264 280 140 180 180Mg 51 43.7 80 65.7 63.2 70.5Na 48 69 124 78 74 78Cl 35.5 44.4 80 88.7 88.7 97.5Fe 2.13 2.93 2.93 0.74 0.89 0.80Cu 0.09 0.09 0.16 0.03 0.05 0.03Mn traces 0.20 0.40 0.07 0.50 0.38Zn 0.05 0.24 0.31 0.04 0.24 0.40B 0.20 0.25 0.31 0.79 0.81 0.84

aAll values in mg·L−1 except EC (mS·cm−1) and pH (−log[H+]).

Table 4: ANOVA results of substrate and times of use on tomato leaf nutrient composition.

Source

(% of Dry wt.) (mg·L-1)

N P K Ca Mg Na B Zn Mn Cu Fe

Substrate ns ns ns ns ns * ns * ns * *Time of use * ns ns ns ns ns ns ns * ns nsTime × Substr ns ns ns ns ns ns ns ns ns ns *

ns, *Nonsignificant or significant or at P ≤ 0.05, ANOVA.

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Soilless Tomato Culture 155

third-time use substrates, 3.85% and 3.9% DW, respectively. Amounts of Mnin the second-time use media (53 mg·L−1) were higher than in the third-time usemedia (42 mg·L−1) and the amount in the first-time use media (47 mg·L−1) wassimilar to both.

Reduction in nitrogen content may be attributed to increases of microorgan-ism activity (nitrogen needs) in the root environment due to organic residuesdeposited in the substrate after the first time of use (Abou-El-Hassan et al.,1992; Ibrahim, 1992). Nutrient content in tomato leaves is most probablyrelated to the nutrient availability in the substrate solution (Raviv et al.,2002). Furthermore, excess watering in the closed system may result indecreased N in fruit (Christou et al., 1994; Dumas et al., 1994).

YieldSubstrate did not affect marketable or unmarketable yield; time of use

affected marketable and unmarketable yield per plant and the interaction wasnot significant (Table 5). Marketable yield per plant averaged 8.11 kg; mar-ketable fruit weight averaged 174 g, unmarketable yield per plant averaged0.77 kg, and unmarketable fruit weight averaged 79.6 g. The marketable yieldper plant for plants grown in the second and third use media were similar(average 8.38 kg) and higher than in plants grown in the first used media(7.17 kg). The unmarketable yield per plant was highest for plants in the first-time used media (0.92 kg), which was higher than from plants in the second-and third-time used media, which were similar (average 0.73 kg).

That mean fruit weight remained constant in both cases indicates thatreuse of substrates likely did not affect flowering and fruit setting (Fakhriet al., 1995; Manios et al., 1995). Available water and nutrients were likelyadequate in the substrate (Fakhri et al., 1995). These findings are supportedby the fact that unmarketable yield per plant was reduced with times ofthe substrate use, but the unmarketable mean fruit weight remainedunchanged.

Table 5: ANOVA results of substrate and time of use on marketable and nonmarketable yield and mean fruit weight.

Marketable yield Nonmarketable yield

Source Per plant (kg) Mean fruit wt. (g)a Per plant (kg) Mean fruit wt. (g)a

Substrate ns ns ns nsTime of use * ns * nsTime × Substr ns ns ns ns

aMean fruit weight was calculated by dividing the marketable yield by the number of fruit.ns, *Nonsignificant or significant at P ≤ 0.05, ANOVA.

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Leaf Water Potential and Chlorophyll FluorescenceSubstrate did not affect leaf water potential (−0.67 Mpa) and chlorophyll

fluorescence (0.75 Fv/Fm); time of use did, and the interaction was not signifi-cant (Table 6). The leaf water potential in media used for the first and secondtimes were similar (−0.7 Mpa) and were higher than in media used for thethird time (−0.64 Mpa).

Increases in water potential indicate better availability in roots (Böhme,1995a, 1995b). Leaf water potential remained higher than −1.0 MPa, indi-cating that plants can grow in both substrates, used up to 3 times, withoutwater limitations (Raviv and Blom, 2001). Chlorophyll fluorescence valueswere close to 0.8, indicating that leaves were healthy, with no photochemicalinhibition due to stress (Bounfour et al., 2002; Feierabend, 1992; Lu andVonshak, 1999).

Fruit QualitySubstrate affected percentage of N and P but not K; time of use had no

effect and the interaction was not significant (Table 7). Gravel had higher N(1.74%) than did perlite (1.62%); perlite had higher P (0.7%) than did gravel(0.62%). Over times of use N, P, and K averaged 1.68%, 0.65%, and 4.5%,respectively. Substrate did not affect pH or concentration of vitamin C, SSC,titratable acidity (TA), or the SSC/TA ratio; time affected only SSC and TAconcentration; the interaction for vitamin C concentration and pH was

Table 6: ANOVA results of substrate and time of use on leaf water potential and chlorophyll fluorescence.

Source WP (Mpa) Fv/Fma

Substrate ns nsTime of use * nsTime × Substr ns ns

aFv/Fm is the variable fluorescence over the maximumfluorescence.ns, *Nonsignificant or significant at P ≤ 0.01, ANOVA.

Table 7: ANOVA results of substrate and time of use on tomato fruit N, P, K concentration as affected by substrate and time of use.

Source N (% dry wt.) P (% dry wt.) K (% dry wt.)

Substrate * * nsTime of use ns ns nsTime × Substr ns ns ns

ns, *Nonsignificant or significant at P ≤ 0.05, ANOVA.

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significant (Table 8). Media used for the third time had higher %Brix (4.4)than for media used once or twice, which were similar (4.08). Taste qualitydepends on the ratio of soluble solids to TA (D’Amico et al., 2003). A smallincrease in this ratio probably did not indicate meaningful differencesbetween substrates.

These results indicate that locally available gravel could be used as analternative growth medium for soilless tomato production in the Mediterra-nean region.

REFERENCES

Abou-El-Hassan, E.A., A.H. Khereba, M.S. Youssef, M.H. Zaki, and H. Khalifa. 1992.Studies on using some local media for two successive years without sterilization onplant growth, yield and nutrient uptake of cucumber grown under unheated green-house in Egypt. Acta Hort. 323:451–460.

Adams, P. 2002. Nutritional control in hydroponics, p. 211–262. In: D. Savvas and H.Passam (eds.). Hydroponic production of vegetables and ornamentals. PublicationsEmbryo, Athens.

Allan, J.E. 1971. The preparation of agricultural samples for analysis by atomicabsorption spectroscopy. Ruakura Soil Research Station, Hamilton, New Zealand.

Alt, D. and I. Peters. 1993. Analysis of macro- and trace elements in horticulturesubstrates by means of the CaCl2/DTPA method. Acta Hort. 342:287–292.

Association of Analytical Chemists. 1980. Official methods of association of analyticalchemist. Association of Analytical Chemists, Washington, D.C.

Benton, J. 1997. Hydroponics practical guide for soilless culture. St. Lucie Press, BocaRaton, Fla.

Böhme, M. 1995a. Effects of closed systems in substrate culture for vegetable productionin greenhouses. Acta Hort. 396:45–54.

Böhme, M. 1995b. Evaluation of organic, synthetic and mineral substrates for hydro-ponically grown cucumber. Acta Hort. 401:209–217.

Bounfour, M., K.L. Tanigoshi, C. Chen, J.S. Cameron, and S. Klauer. 2002. Chlorophyllcontent and chlorophyll fluorescence in red raspberry leaves infested withTetranychus urticae and Eotetranychus carpini borealis (Acari: Tetranychidae).Environ. Entomol. 31:215–220.

Table 8: ANOVA results of substrate and time of use on vitamin C (vit. C), soluble solids concentration (SSC), titratable aciditity (TA), and pH.

SourceVit. C

(mg/100 g FW )SSC

(% Brix)TA

(% citric acid)pH

(-log[H+]) SSC/TA

Substrate ns ns ns ns nsTime of use ns * * ns nsTime × Substr ** ns ns * ns

ns, *, **Nonsignificant or significant at P ≤ 0.05 or 0.001, ANOVA.

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a] a

t 13:

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Bradley, P. and C. Marulanda. 2000. Simplified hydroponics to reduce global hunger.Acta Hort. 554:289–295.

Charalambous, J. and J. Papakonstantinou. 1965. Methods of analysis for agriculturalresearch workers. A laboratory handbook. Agricultural Research Institute, Nicosia,Cyprus.

Chimonidou, D. 2000. Protected cultivation and soilless culture in Cyprus. FAO Proc.Soilless Culture, Halkidiki, Greece, 31 Aug.–6 Sept. 1999.

Christou, M., S. Leoni, P. Cornillon, A. Gainza, Y. Dumas, A. Rodriguez, and A.Dimirkou. 1994. Influence of water and nitrogen availability on elemental compo-sition of processing tomato fruit in EU countries. Acta Hort. 376:279–284.

D’Amico, M.L., R. Izzo, F. Navari-Izzo, F. Tognoni, and A. Pardosi. 2003. Sea waterirrigation: antioxidants and quality of tomato berries (Lycopersicon esculentum).Acta Hort. 609:59–65.

Dumas, Y., C. Leoni, C.A.M. Portas, and B. Bieche. 1994. Influence of water and nitrogenavailability on elemental composition of processing tomato fruit in the EuropeanUnion countries. Acta Hort. 376:185–192.

Fakhri, M.N., E. Maloupa, and G. Gerasopoulos. 1995. Effects of substrates andfrequency of irrigation on yield and quality of three Gerbera jamesonii cultivars.Acta Hort. 408:41–45.

Feierabend, J., C. Schaan, and B. Hertwig. 1992. Photoinactivation of catalase occursunder both high- and low-temperature stress conditions and accompanies photoin-hibition of photosystem II. Plant Physiol. 22:1554–1561.

Gass, I.G. 1960. The geology and mineral resources of the Dhali area. Memoir No. 4.Geological Survey Department, Nicosia, Cyprus.

Hatcher, J.T. and L.V. Wilcox. 1950. Colorimetric determination of boron using carmine.Anal. Chem. 22:567–569.

Ibrahim, A. 1992. Response of plants to irrigation with CO2-enriched water. Acta Hort.323:205–214.

Lenzi, A., N. Oggiano, M. Maletta, A. Bolaffi, and R. Tesi. 2001. Caratteristiche fisichee chimiche dei substrati a base di perlite, pomice e torba. Italus Hortus 8(2):23–31.

Louca, K. 2007. Petrography of representative rock samples from the Sha quarry.Eleftherios Panayi & Sons LTD., Sha, Nicosia, Cyprus.

Lu, C.M. and A. Vonshak. 1999. Characterization of PS II photochemistry in salt-adapted cells of cyanobacterium Spirulina platensis. New Phytol. 141:231–239.

Magnani, G., A. Grassotti, and B. Nessi. 2003. Lapillus growing medium for cutbulbous flowers in soilless culture. Acta Hort. 609:389–393.

Maloupa, E., I. Mitsios, P.F. Martinez, and S. Bladenopoulou. 1993. Study of substrateuse in gerbera soilless culture grown in plastic greenhouses. Acta Hort. 323:139–144.

Manios, V., M.D. Papadimitriou, and M.D. Kefakis. 1995. Hydroponic culture of tomatoand gerbera at different substrates. Acta Hort. 408:11–15.

Martinez, P.F. and A. Abad. 1993. Soilless culture of tomato in different mineralsubstrates. Acta Hort. 323:251–259.

Mavrogiannopoulos, G.N. 2006. Hydroponics installations. Stamouli A.E. Press,Athens. (in Greek)

Nelson, R.A. 1960. Potentiometric determination of the chloride content of tobacco.Anal. Chem. 43:518.

Dow

nloa

ded

by [

Kun

glig

a T

ekni

ska

Hog

skol

a] a

t 13:

53 1

1 O

ctob

er 2

014

Soilless Tomato Culture 159

Olympios, C.M. 1992. Soilless media under protected cultivation rockwool, peat, perliteand other substrates. Acta Hort. 323:215–234.

Panagides, I. 2002. Mineral resources. The geology of Cyprus. Geological SurveyDepartment Bul. 10. (in Greek)

Raviv, M. and T.I. Blom. 2001. The effect of water availability and quality on photosyn-thesis and productivity of soilless grown cut roses. Sci. Hort. 88:257–276.

Raviv, M., R. Wallach, A. Silber, and A. Bar-Tal. 2002. Substrates and their analysis,p. 225–101. In: D. Savvas and H. Passam (eds.). Hydroponic production of vegetablesand ornamentals. Publications Embryo, Athens.

Ryan, J.J. and J.A. Dupant. 1973. Identification and analysis of the major acids fromfruit juices and wines. J. Agric. Food Chem. 21:45–49.

Scholander, P.F., H.T. Hammel, E.D. Bradstreet, and E.A. Hemmingsen. 1965. Sappressure in vascular plants. Science 148:339–346.

Schröder, F.-G. and J.H. Lieth. 2002. Irrigation control in hydroponics, p. 265–298. In:D. Savvas and H. Passam (eds.). Hydroponic production of vegetables and orna-mentals. Publications Embryo, Athens.

Schwarz, D., R. Kuchenburch, and R. Munoz-Carpena. 1998. Water uptake by tomatoplants grown in closed hydroponic system depended on the EC-level. Acta Hort.458:323–328.

Sonneveld, C. 2002. Composition of nutrient solutions, p. 179–210. In: D. Savvas andH. Passam (eds.). Hydroponic production of vegetables and ornamentals. PublicationsEmbryo, Athens.

Uronen, K.R. 1995. Leaching of nutrients and yield of tomato in peat and rockwoolwith open and closed system. Acta Hort. 401:443–449.

Wohanka, W. 2002. Nutrient solution disinfection, p. 345–372. In: D. Savvas andH. Passam (eds.). Hydroponic production of vegetables and ornamentals. PublicationsEmbryo, Athens.

Dow

nloa

ded

by [

Kun

glig

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ekni

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a] a

t 13:

53 1

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