Optimizing Levels of Water and Nitrogen Applied through Drip Irrigation for Yield, Quality, and Water Productivity of Processing Tomato (Lycopersicon esculentum Mill.) Hayrettin Kuscu 1* , Ahmet Turhan 1 , Nese Ozmen 2 , Pinar Aydinol 2 , and Ali Osman Demir 3 1 Department of Plant Production, Vocational School of Mustafakemalpasa, University of Uludağ, Bursa Street 16500, Bursa, Turkey 2 Department of Food Processing, Vocational School of Mustafakemalpasa, University of Uludağ, Bursa Street 16500, Bursa, Turkey 3 Department of Biosystems Engineering, Faculty of Agriculture, University of Uludağ, Gorukle, 16059, Bursa, Turkey *Corresponding author: [email protected]Received December 16, 2013 / Revised March 8, 2014 / Accepted March 9, 2014 Ⓒ Korean Society for Horticultural Science and Springer 2014 Abstract. The main goal of this study was to evaluate the effects of different levels of irrigation water and nitrogen on yield, quality, and water productivity of processing tomato grown in clay-loam soil. Three water levels of pan evaporation (Epan) replenishment applied via drip irrigation (1.00 × Epan, 0.75 × Epan, and 0.50 × Epan) and four N application rates with fertigation (0, 60, 120, and 180 kg N·ha -1 ) were tested in the sub-humid climate conditions of Turkey during the 2010 and 2011 growing seasons. The highest marketable yields were observed with full irrigation (1.00 × Epan) for each season. Decreasing irrigation rate generally improved dry matter, total soluble solids, total sugars, titratable acidity, lycopene and total carotene, and decreased fruit NO3-N content and fruit total protein content slightly. The highest water productivity was obtained with a moderate soil water deficit (0.75 × Epan). The 180 kg N·ha -1 fertilization rate produced the highest values for marketable yield, fruit size, total soluble solids yield, NO3-N, and total protein content. Increasing N rate also increased the values of fruit total sugars and titratable acidity. Increasing both irrigation and N levels increased the NO3-N and protein contents. The higher lycopene and total carotene values were obtained in the treatments of 60 and 120 kg N·ha -1 . Increasing N supply improved the water productivity with the 3 irrigation application ratios. Considering the quantity and quality for the processing and water productivity, the 0.75 × Epan irrigation regime and a 120 or 180 kg·ha -1 nitrogen supply can considered optimal. Additional key words: carotenoids, limited irrigation, N fertilization, total soluble solids, water-use efficiency Hort. Environ. Biotechnol. 55(2):103-114. 2014. DOI 10.1007/s13580-014-0180-9 ISSN (print) : 2211-3452 ISSN (online) : 2211-3460 Research Report Introduction Tomato ranks first among the most important vegetable crops of Turkey. The total area used for its cultivation in the country is 189,202 ha, and the total tomato production is approximately 11.35 million tons per year (TUIK, 2013). It is widely consumed as fresh and processed products, such as tomato paste, juice, and ketchup. The production of com- mercial tomato is influenced by both genetic and environmental factors, such as soil, climate, water quality, and crop manage- ment. Among the environmental factors, soil water and inorganic nutrition are the most limiting factors in the pro- duction and quality of tomatoes. Irrigation scheduling is a crucial factor in tomato cultivation when soil moisture is limited. Many irrigation experiments have revealed that tomato is sensitive to moisture stress (Locascio and Smasjstrla, 1996; Patanè and Cosentino, 2010).Tomato has a fairly deep root system (up to 1.5 m), and approximately 80% of the total water and nutrient uptake occurs in the first 0.5 to 0.7 m (Doorenbos and Kassam, 1979). Water and nutrient stress cause reduction of marketable yields by reducing crop biomass production. For high yields, the seasonal water requirements of tomato vary from 400 to 800 mm with a daily evapotran- spiration rate of 4 to 6 mm·d -1 , depending on the climate and the total length of the growing period (Hanson and May, 2006; Harmanto et al., 2005; Mukherjee et al., 2010). The maximum seasonal evapotranspiration of tomato crop was
Transcript
Optimizing Levels of Water and Nitrogen Applied through Drip Irrigation for Yield, Quality, and Water Productivity of Processing
Tomato (Lycopersicon esculentum Mill.)
Hayrettin Kuscu1*, Ahmet Turhan1, Nese Ozmen2, Pinar Aydinol2, and Ali Osman Demir3
1Department of Plant Production, Vocational School of Mustafakemalpasa, University of Uludağ, Bursa Street 16500, Bursa, Turkey
2Department of Food Processing, Vocational School of Mustafakemalpasa, University of Uludağ, Bursa Street 16500, Bursa, Turkey
3Department of Biosystems Engineering, Faculty of Agriculture, University of Uludağ, Gorukle, 16059, Bursa, Turkey
Received December 16, 2013 / Revised March 8, 2014 / Accepted March 9, 2014Ⓒ Korean Society for Horticultural Science and Springer 2014
Abstract. The main goal of this study was to evaluate the effects of different levels of irrigation water and nitrogen on yield, quality, and water productivity of processing tomato grown in clay-loam soil. Three water levels of pan evaporation (Epan) replenishment applied via drip irrigation (1.00 × Epan, 0.75 × Epan, and 0.50 × Epan) and four N application rates with fertigation (0, 60, 120, and 180 kg N·ha-1) were tested in the sub-humid climate conditions of Turkey during the 2010 and 2011 growing seasons. The highest marketable yields were observed with full irrigation (1.00 × Epan) for each season. Decreasing irrigation rate generally improved dry matter, total soluble solids, total sugars, titratable acidity, lycopene and total carotene, and decreased fruit NO3-N content and fruit total protein content slightly. The highest water productivity was obtained with a moderate soil water deficit (0.75 × Epan). The 180 kg N·ha-1 fertilization rate produced the highest values for marketable yield, fruit size, total soluble solids yield, NO3-N, and total protein content. Increasing N rate also increased the values of fruit total sugars and titratable acidity. Increasing both irrigation and N levels increased the NO3-N and protein contents. The higher lycopene and total carotene values were obtained in the treatments of 60 and 120 kg N·ha-1. Increasing N supply improved the water productivity with the 3 irrigation application ratios. Considering the quantity and quality for the processing and water productivity, the 0.75 × Epan irrigation regime and a 120 or 180 kg·ha-1 nitrogen supply can considered optimal.
Additional key words: carotenoids, limited irrigation, N fertilization, total soluble solids, water-use efficiency
Tomato ranks first among the most important vegetable crops of Turkey. The total area used for its cultivation in the country is 189,202 ha, and the total tomato production is approximately 11.35 million tons per year (TUIK, 2013). It is widely consumed as fresh and processed products, such as tomato paste, juice, and ketchup. The production of com-mercial tomato is influenced by both genetic and environmental factors, such as soil, climate, water quality, and crop manage-ment. Among the environmental factors, soil water and inorganic nutrition are the most limiting factors in the pro-duction and quality of tomatoes. Irrigation scheduling is a crucial factor in tomato cultivation when soil moisture is
limited.Many irrigation experiments have revealed that tomato is
sensitive to moisture stress (Locascio and Smasjstrla, 1996; Patanè and Cosentino, 2010).Tomato has a fairly deep root system (up to 1.5 m), and approximately 80% of the total water and nutrient uptake occurs in the first 0.5 to 0.7 m (Doorenbos and Kassam, 1979). Water and nutrient stress cause reduction of marketable yields by reducing crop biomass production. For high yields, the seasonal water requirements of tomato vary from 400 to 800 mm with a daily evapotran-spiration rate of 4 to 6 mm·d-1, depending on the climate and the total length of the growing period (Hanson and May, 2006; Harmanto et al., 2005; Mukherjee et al., 2010). The maximum seasonal evapotranspiration of tomato crop was
Hayrettin Kuscu, Ahmet Turhan, Nese Ozmen, Pinar Aydinol, and Ali Osman Demir104
Table 1. Some soil properties of the experimental field.
Property 2010 20110-30 cm soil depth
Total N (%) 0.20 0.15Available P (P2O5 - kg･ha-1) 81 85Exchangeable K (K2O - kg･ha-1) 1395 1280Organic matter (%) 1.9 2.0pH (saturation) 7.8 7.7EC (1:2.5 - dS･m-1) 0.48 0.45Infiltration rate (mm･h-1) 7.4 7.2
0-90 cm soil depthBulk density (g･cm-3) 1.41 1.41Field capacity (%) 38.3 38.3Permanent wilting point (%) 23.2 23.2
measured to be 864 mm in an open field experiment in the Mediterranean climate of Turkey (Erdal et al., 2006). Tomato is a heavy feeder of nutrients, and it responds well to the application of fertilizer (Hebbar et al., 2004); hence, fertigation is recommended for higher nutrient availability and use effi-ciency. The amount of fertilizer required, for a satisfactory yield and quality of tomatoes, is 100 to 150 kg·ha-1 of N, 65 to 110 kg·ha-1 of P, and 160 to 240 kg·ha-1 of K (Doorenbos and Kassam, 1979). The nutrient requirements of drip-irrigated tomato are relatively high (Hartz and Hochmuth, 1996; Pan et al., 1999).
Drip irrigation is widely used for irrigating vegetable crops in both developed and developing regions of the world. Over the past decade, use of drip irrigation has increased substantially in the Turkish tomato industry because the Turkish government has provided financial support to farmers in an effort to increase the water use efficiency. Subsequently, the use of combined irrigation and fertilization has gradually increased with the increasing use of drip irrigation in the country. Drip irrigation can help improve not only the water use efficiency, but also nutrient use efficiency. Drip irrigation in various agro-ecological conditions recorded one-third higher fruit yield per unit of water used in addition to 30 to 40% water saving, 15% increase in dry matter production, and 39% increase in leaf area index, thus increasing fertilizer use efficiency and improving the quality of tomato fruit in com-parison to the furrow irrigation method (Hanson and May, 2006; Hebbar et al., 2004; Malash et al., 2008; Yohannes and Tadesse, 1998). In the conditions of Turkey, drip irrigated tomato registered 87.5 t·ha-1 of marketable yield with a net return of $6,960/ha (Kuşçu et al., 2009).
It is obvious that a more efficient use of scarce water and costly fertilizer inputs is critical in achieving improved tomato yield and quality. To obtain high yields and maximum profits in commercial tomato production, optimal management of both fertilizer and water are required (Scholberg et al., 2000). Irrigation water scheduling enables an efficient use of water, fertilizer, and energy inputs. The goal of a fertilization program is to reduce the difference between crop demand and supply. Nitrogen is the most limiting nutrient for plant growth and potential biomass production during the entire growing season. However, excessive nitrogen application may cause NO3-N accumulation below the active root zone and create a risk of NO3-N leaching (Wang et al., 2012; Yang et al., 2006). However, current knowledge on the response of field-grown processing tomato yield and quality to drip irri-gation and nitrogen fertilization is very limited, especially regarding the effect of limited water allocations in sub-humid zones. Therefore, the present investigation was conducted to study the yield, quality, and water productivity response of processing tomato grown by drip irrigation in a sub-humid climatic region.
Materials and Methods
Field ExperimentField studies were conducted on a clay loam soil (23.6%
sand, 43.6% silt, and 32.8% clay) at the Agricultural Experiment Station, University of Uludağ, Turkey (40°02′ N, 28°23′ E; altitude 22 m above sea level) during the growing seasons of 2010 and 2011. The local climate is temperate, summers are hot and dry, and winters are mild and rainy. According to long-term meteorological data (1975-2010), the annual mean rainfall, temperature, and relative humidity are 681 mm, 14°C, and 68%, respectively. The climate of the study area is clas-sified as sub-humid according to the Thornthwaite climate classification system (Feddema, 2005). The total rainfall during the growing season (from mid-May to the last week in August) was 120.8 mm in 2010 and 52.2 mm in 2011. Soil properties of experimental area are summarized in Table 1. Total N was estimated using the Kjeldahl method, available P using the Olsen method, exchangeable K using the ammonium acetate method, and total organic matter using the Walckey-Black method (Page et al., 1982).
Treatments and Agricultural ApplicationsTreatments were arranged in field according to a split plot
experimental design with three replications in both seasons. The irrigation treatments were randomized in the main plots and N levels in the sub-plots. The treatments consisted of three irrigation levels of pan evaporation (Epan) replenishment [1.00 × Epan (I100), 0.75 × Epan (I75), and 0.50 × Epan (I50)] and four N application levels [0 (N0), 60 (N60), 120 (N120), and 180 (N180) kg･ha-1]. The United States Weather Bureau (USWB) Class A evaporation pan was used to determine the amount of irrigation water applied. Irrigation management was based on the common practice in the area for tomato, which consists
of irrigation at a 3-day interval. Seeds of a hybrid cultivar ‘Heinz-8004’ (H. J. Heinz Co., Pittsburgh, PA, USA) were supplied by the TAT Seed Company, Inc. (Mustafakemalpasa, Bursa, Turkey). Initially, seeds were germinated in organically- enriched peat in open plastic trays with a vermiculite cover to facilitate aeration. Thirty-five days after germination, seed-lings at the 3-4 true leaf stage were transplanted to the treatment plots during the third week of May. Each experimental plot was 5.1 m long by 5.6 m wide (28.56 m2), with 4 rows per plot. A buffer zone spacing of 2.0 m was provided between the plots. The row spacing and plant-plant spacing were 1.4 and 0.3 m, respectively. The seedlings were transplanted at a population density of 24,285 plants per ha in both seasons.
The plots were fertilized with 70 kg·ha-1 P2O5 as triple super phosphate (43-44% P2O5) in both years before planting. Because the soil test results indicated that there was a suf-ficient level of potassium in the soil (Table 1), no additional K fertilizer was applied on the experimental site. Nitrogen from ammonium sulfate (21% N and 24% S) was applied in nine equal rates for each treatment at a 9-day interval using a fertilizer tank connected to the drip irrigation system. The laterals were installed in each row (1.4 m apart) at a distance of 0.15 m from the stem. The thick-walled dripper lines (Dripnet PC-16390TM, Netafim Irrigation Inc., Tel Aviv, Israel) had inline compensating emitter pressure, and the discharge rate of the emitters was 3.0 L·h-1 at an operating pressure of 100 kPa. The emitter spacing was chosen as 0.40 m based on the soil characteristics. Irrigation water was pumped directly from the Mustafakemalpasa Aquifer to the drip irrigation system. The electrical conductivity of the water in the aquifer was 1.3 dS·m-1. The amount of first irrigation water for all of the plots was based on the moisture deficit that would be needed to bring the 0-90 cm layer of soil to field capacity (Çetin et al., 2002).
Standard cultural practices were adopted during the crop-growing season. Hoeing was performed twice during the growing season. The insecticides [Emamectin benzoate (Proclaim) and abamectin + chlorantraniliprole (Voliam Targo)] and fungicides [chlorothalonil (Bravo), azoxystrobin (Quadris), and mancozeb + mefenoxam (Ridomil)] were applied according to commercial recommendations.
MeasurementsThe soil water content was measured gravimetrically on
an oven dry basis in a 0.3 m-depth increment to 1.2 m through-out the growing season. Actual crop water consumption (ETc) was calculated using the soil water balance equation given below (Garrity et al., 1982).
ETc = I + P ± ΔS – D, (1)
where I is the irrigation water (mm), P is the precipitation (mm), ΔS is the change in the soil water content (mm), and D is the drainage below the root zone.
In the equation, I was measured using a water meter (VK-4P, volumetric type, Baylan Inc., Izmir, Turkey), P was observed at the meteorological station nearby the experimental area, and ΔS was obtained from gravimetric moisture ob-servations in the soil profile to a depth of 0.9 m. Whenever available water in the effective root zone (0-0.9 m) was above the field capacity, it was assumed to be the drainage below the root zone.
Ripe and disease-free fresh fruits from 34 plants in the two center rows from each plot were hand-harvested during the last week of August in both seasons, and marketable yields were calculated as ton of fresh weight (FW) per hectare.
Some qualitative characteristics of the fruits were investigated from 30 samples of red fruit collected at random from each plot. The collected samples were transported to the laboratory, and initially fresh weight of each fruit was measured. The fruits were washed once with tap water and twice with distilled water, sliced, and seeds were removed. Then they were analyzed for dry matter, total soluble solids, total sugar, titratable acidity, lycopene, total carotene, and NO3-N. Dry matter content (DM, % FW) was determined in homogenate samples dried in a forced-air oven at 80°C for 48 h according to the methods described by Tzortzakis and Economakis (2008). Total soluble solids (TSS, ºBrix) content was determined at 20°C using a hand refractometer (Abbe-type refractometer, model 60/DR, Bellingham and Stanley Ltd., Kent, UK) according to the methods described by Tigchelaar (1986). To analyze the total sugar content (TS, % FW), the Luff-Schoorl method was used (Gormley and Maher, 1990). A 10 mL sample was used for determination of acidity by titrating with 0.1 M NaOH. Titratable acidity (TA, g·100 g-1 FW) was calculated as the percentage of citric acid in the juice as described by Znidarcic and Pozrl (2006). The lycopene and total carotene contents (mg·100 g-1 FW) were determined by extraction using petroleum ether-acetone and spectrophotometric measurement using a spectrophotometer (UV-1208, Shimadzu, Kyoto, Japan) at 452 and 472 nm for lycopene and total carotene, respect-ively (Adsule and Dan, 1979; Tepic et al., 2006). The NO3-N content (mg·kg-1 FW) was measured using the spectrophoto-metric method at a wavelength of 410 nm (Fresenius et al., 1988). Fruit nitrogen was determined using the Kjeldahl method as described by AOAC (1980), and the percentage nitrogen was converted to crude protein (% FW) by multiplying the percentage by 6.25 (AOAC, 1980). The TSS yield (t·ha-1 FW) was also estimated by multiplying the TSS content with the marketable yield following Patanè et al. (2011).
Hayrettin Kuscu, Ahmet Turhan, Nese Ozmen, Pinar Aydinol, and Ali Osman Demir106
Table 2. Irrigation water applied (IWA) and seasonal evapotran-spiration (ETc) in two years of experiment.
zI, Irrigation; and N, Nitrogen. The treatments consisted of three irrigation levels of pan evaporation (Epan) replenishment [1.00 ×Epan (I100), 0.75 × Epan (I75) and 0.50 × Epan (I50)] and four N application levels [0 (N0), 60 (N60), 120 (N120), and 180 kg･ha-1 (N180)].
Fig. 1. Seasonal variation of average soil water content in 0-0.9 m depth for irrigation treatments across different nitrogen levels. I100, I75, and I50 are irrigation levels of pan evaporation (Epan) replenishment, [1.00 × Epan (I100), 0.75 × Epan (I75), and 0.50 ×Epan (I50), respectively.
Irrigation Water Use Efficiency and Water Use Efficiency
Irrigation water-use efficiency (IWUE, kg·m-3) was calculated as the marketable fruit yield (kg·ha-1) obtained per unit volume of seasonal irrigation water applied (m3·ha-1). Water-use effi-ciency (WUE, kg·m-3) was calculated as marketable fruit yield (kg·ha-1) obtained per unit volume of seasonal evapotranspiration (m3·ha-1) (Wang et al., 2007; Zotarelli et al., 2009).
Yield Response FactorThe yield response factor for total growing period was
determined by following approach described by Doorenbos and Kassam (1979).
(2)
where Ya and Ym are actual and maximum crop yields, cor-responding to ETa and ETm, at actual and maximum evapo-transpiration, respectively, and ky is crop yield response factor.
Data AnalysisThe data were subjected to analyses of variance using
statistical programs (IBM® SPSS® Statistics for Windows, Version 20.0, Copyright, 2011, IBM Corp., Armonk, NY). Duncan’s multiple range test was used to group the means of irrigation, nitrogen, and their interactions when the F-test was significant. A regression analysis was performed on the relationships between the fruit parameters and the irrigation and N rates.
Results
Analysis of VarianceResults of variance analysis (ANOVA) of data averaged
over individual years are given in Table 3. The results show that the effect of both irrigation and nitrogen rates on most of the parameters was significant (p ≤ 0.05). Additionally, the effect of the interactions between irrigation and nitrogen on all parameters observed, except total protein, was sig-nificant at the 0.05 level (Table 4).
Seasonal Irrigation Water Applied and Evapotranspiration
The seasonal irrigation water applied (IWA) and evapo-transpiration (ETc) values for the different treatments are shown in Table 2. The amount of IWA varied from 248 to 455 mm in 2010 and from 321 to 512 mm in 2011. The total water applied in the irrigation treatments was affected by the rate of rainfall during the experiment. In 2010, less water was distributed by irrigation, since more rainfall occurred, as the total rainfall during the growing season was 121 mm
in 2010 and 52 mm in 2011.Seasonal variation of average soil water content in 0-0.9
m depth for irrigation treatments across different nitrogen levels is presented Fig. 1. Soil water content fluctuated greatly
Table 3. Results of analysis of variance of marketable fruit yield, fruit size, dry matter (DM), total soluble solids (TSS), total sugar (TS), titratable acidity (TA), lycopene, total carotene, NO3-N, total N, and total protein for the irrigation and nitrogen treatments.
Irrigation and nitrogen level
Marketable fruit yield
(t FW･ha–1)Fruit size
(g FW)DM(%)
TSS(ºBrix)
TSSyield
(t･ha–1)TS
(% FW)TA
(g･100g-1 FW)Lycopene
(mg･100 g-1 FW )Total carotene(mg･100 g-1)
NO3-N(mg･kg–1 FW)
Totalprotein(% FW)
Year (Y) ** ** ** ** ** * ns ns ns ns *Irrigation level (I) ** ** ** ** ** ** ** ** ** ** **Nitrogen level (N) ** ** ** ** ** ** ** ** ** ** **I × N ** ** ** ** ** ** * ** ** ** nsY × I × N ** ** ** ** ** ** ns ** ** ns ns*,**,nsF-test significant at p ≤ 0.05, p ≤ 0.01, respectively, and not significant.
Fig. 2. Fertigated marketable fruit yield response to N level with pooled data from the two years and averaged of three replications and three irrigation treatments.
in response to the irrigation level. This increased with irrigation applications and decreased with evapotranspiration afterward, and showed fluctuations with rainfall during the vegetative growth period in 2010. Soil water content declined quickly from the vegetative stage to the fruit setting stage in this area of high evaporation and high crop water requirement.
The seasonal values of ETc per treatment ranged from 375 to 596 mm in 2010 and from 386 to 571 mm in 2011. As expected, the highest seasonal ETc was obtained in the I100 treatment as a result of favorable soil moisture, whereas the lowest ETc was recorded in the I50 treatment with a water deficit during the growing period. Seasonal ETc also increased with increasing N level for all irrigation treatments (Table 2).
Effect of Irrigation and Nitrogen Levels on Fruit Yield and Quality
Irrigation and nitrogen levels significantly affected marketable yield and fruit size in the individual experimental years. In general, there was a close relationship between irrigation and marketable yield or fruit size. Marketable yield and fruit size increased with the amount of irrigation water applied in both years (Table 4). The response of marketable fruit yield to the N level could be described with a second-degree polynomial curve, fitted to the pooled data of the two years and the three averaged irrigation treatments (Fig. 2). The irrigation × nitrogen interaction was significant in both years because with the rise of both water and nitrogen levels the marketable yield increased. Thus, the highest yield was obtained in the I100 × N180 due to favorable soil moisture and adequate N nutrition during the growing period (Table 4). The second highest marketable yield was obtained in the I75 × N180 for both years; however, in 2010, there was no significant difference in the yield between the I75 × N180 and I100 × N120. The heaviest fruits were also obtained in the I100 × N180 (Table 4). The results for two years can be summarized by stating that a producer would have obtained the highest marketable yield using full irrigation and a 180 kg N·ha-1 seasonal application.
The differences in DM and TSS were particularly notable
with variation in irrigation level. As expected, DM and TSS contents were higher in water-stressed plants. Conversely, differential DM and TSS responses of the plant to the nitrogen fertilization were observed. The irrigation × nitrogen interaction for DM was not significant in 2010. However, in 2011 the two factors significantly interacted and the greatest DM was recorded in the I50 × N120 combination. There were significant irrigation × nitrogen interactions for TSS in both years, with a trend similar to that of DM. The TSS content of the I50 × N120 combination was statistically greater than the other treatments in both years. Based on the irrigation × nitrogen combinations, the second highest DM and TSS values were obtained in the I75 × N120 for both years (Table 4).
Within irrigation treatments, TSS yield values differed significantly in both seasons. The highest TSS yield was obtained in the I100 × N180 combination in both years, whereas the lowest TSS yield was obtained in the I50 × N0 and I75 × N0 combinations, but with no significant difference. The TSS yield significantly increased with increasing levels of nitrogen fertilization in both years (Table 4).
Hayrettin Kuscu, Ahmet Turhan, Nese Ozmen, Pinar Aydinol, and Ali Osman Demir108
Table 4. Irrigation × nitrogen interactions for the fruit yield and quality parameters.
Marketable fruit yield (t･ha-1) Fruit size (g FW)Nitrogen Nitrogen
2010 yr 2010 yrI50 28.0 kz 48.7 h 65.7 e 68.2 d I50 48.7 k 56.6 h 62.3 f 61.8 fgI75 30.6 j 55.4 g 81.8 c 84.6 b I75 50.3 j 61.2 g 72.1 d 75.2 bI100 39.3 i 62.0 f 84.7 b 96.6 a I100 53.4 i 63.5 e 74.5 c 75.9 a
2011 yr 2011 yrI50 30.1 l 51.4 i 70.7 f 75.2 e I50 50.8 j 58.6 h 65.3 e 64.9 eI75 33.7 k 54.7 h 79.1 d 87.1 b I75 53.9 i 60.1 g 69.2 d 76.2 bI100 42.9 j 60.1 g 83.6 c 101.8 a I100 57.7 h 62.3 f 74.4 c 78.4 a
Dry matter (% FW) Total soluble solids (ºBrix)Nitrogen Nitrogen
2010 yr 2010 yrI50 6.44 6.53 6.85 6.46 I50 5.90 b 5.93 b 6.23 a 5.77 cI75 6.01 6.13 6.47 6.13 I75 5.47 e 5.50 e 5.93 b 5.67 dI100 5.45 5.48 5.75 5.48 I100 5.03 g 5.03 g 5.27 f 5.07 g
2011 yr 2011 yrI50 6.12 cd 6.17 c 7.09 a 6.08 cd I50 5.70 c 5.75 bc 6.33 a 5.53 dI75 5.75 f 5.90 e 6.32 b 6.02 d I75 5.28 e 5.47 d 5.83 b 5.53 dI100 5.49 gh 5.42 h 5.68 f 5.56 g I100 5.03 f 4.97 f 5.25 e 5.17 e
Total soluble solids yield (t･ha-1) Total sugar (% FW)Nitrogen Nitrogen
2010 yr 2010 yrI50 1.65 i 2.89 g 4.09 d 3.93 e I50 3.07 bc 3.11 b 3.12 b 3.25 aI75 1.67 i 3.05 f 4.86 ab 4.79 b I75 2.73 e 2.96 d 2.98 d 3.00 cdI100 1.98 h 3.12 f 4.46 c 4.90 a I100 2.09 i 2.38 h 2.51 g 2.65 f
2011 yr 2011 yrI50 1.71 i 2.95 g 4.48 d 4.16 f I50 2.94 cd 3.03 bc 3.12 b 3.42 aI75 1.78 i 2.99 g 4.62 c 4.82 b I75 2.79 ef 2.81 ef 2.88 de 2.89 deI100 2.16 h 2.99 g 4.39 e 5.26 a I100 2.37 h 2.57 g 2.59 g 2.75 f
Lycopene (mg･100 g-1) Total carotene (mg･100 g-1)Nitrogen Nitrogen
2010 yr 2010 yrI50 7.12 b 7.42 a 7.30 ab 6.47 d I50 8.90 a 8.83 a 8.89 a 7.79 cI75 6.50 d 7.19 b 6.88 c 5.43 f I75 7.93 c 8.98 a 8.49 b 6.47 eI100 5.35 f 5.78 e 5.92 e 5.78 e I100 6.52 e 7.23 d 7.31 d 7.23 d
2011 yr 2011 yrI50 6.78 d 7.48 b 8.35 a 6.43 e I50 8.48 c 9.22 b 10.18 a 7.74 dI75 6.13 f 7.27 bc 7.08 c 5.38 h I75 7.47 de 9.08 b 8.74 c 6.41 gI100 5.61 gh 5.83 g 5.83 g 4.25 i I100 6.85 f 7.29 e 7.20 e 5.32 h
2010-2011 yr 2010-2011 yrI50 0.29 g 0.30 f 0.37 c 0.43 a I50 6.4 j 15.8 g 19.8 e 22.8 cI75 0.23 j 0.28 h 0.33 d 0.38 b I75 7.8 i 16.0 g 20.3 de 30.5 bI100 0.22 k 0.24 i 0.28 h 0.31 e I100 13.0 h 17.70 f 21.2 d 34.0 a
zMeans followed by the same letter are not significantly different at the p = 0.05 level using Duncan’s multiple range test in each year.
The differences in the fruit TS contents among irrigation regimes were significant during the two years (Table 3). The TS increased with decreasing irrigation rate. Conversely, the TS content significantly increased with increasing N rate.
The highest TS content, 3.25 and 3.42% FW, was obtained in the I50 × N180 combination at in 2010 and 2011, respectively. Similar to TS, TA content was positively affected by water limitation. As shown in Table 4, TA values also significantly
Fig. 3. Relationships between seasonal irrigation water applied (IWA) or seasonal evapotranspiration (ETc) and marketable fruit yield (pooled data of the two years). Symbols represent the observed values. The values are means of three replicates and four levels of N.
Table 5. Irrigation water use efficiency (IWUE) and water use efficiency (WUE) in two years of experiment.
TreatmentIWUE**
(kg FW･m-3)WUE**
(kg FW･m-3)2010 2011 2010 2011
I50N0z 11.3 jy 9.4 j 7.5 i 7.8 j
I50N60 19.6 f 16.0 g 12.3 f 12.7 fI50N120 26.5 b 22.0 b 16.0 c 16.8 dI50N180 27.5 a 23.4 a 16.5 b 17.7 bI75N0 8.2 l 8.3 k 7.2 j 7.8 jI75N60 14.9 h 13.4 h 12.7 e 12.4 gI75N120 22.0 d 19.4 e 18.1 a 17.3 cI75N180 22.8 c 21.4 c 18.2 a 18.3 aI100N0 8.6 k 8.4 k 7.8 h 8.3 iI100N60 13.6 i 11.7 i 11.6 g 11.4 hI100N120 18.6 g 16.3 f 14.7 d 15.2 eI100N180 21.2 e 19.9 d 16.2 c 17.8 b
zI, Irrigation; and N, Nitrogen. The treatments consisted of three irrigation levels of pan evaporation (Epan) replenishment [1.00 ×Epan (I100), 0.75 × Epan (I75) and 0.50 × Epan (I50)] and four N application levels [0 (N0), 60 (N60), 120 (N120) and 180 kg·ha-1
(N180)].yMeans followed by the different letter are significantly different at the p = 0.05 level using Duncan’s multiple range test in each year.
increased with increasing N fertilization. According to the interaction of irrigation and nitrogen, the highest TA value, 0.43 g·100 g-1 FW, was obtained in the I50 × N180 combination in both years (Table 4).
Lycopene values in the fruit were negatively affected by increasing irrigation rate. In 2010, the I50 × N60 produced the highest DM, followed by I50 × N120. In 2011, however, I50 × N120 produced the highest DM, followed by I50 × N60. Higher total carotene values in the first year were found in the com-binations of I50 × N0, I50 × N60, I50 × N120, and I75 × N60. In the second year, the highest total carotene was obtained in the I50 × N120 combination.
The fruit NO3-N content was affected by irrigation level, N level, and irrigation × nitrogen interaction (Table 3). It ranged between 6.4 in the I50 × N0 to 34.0 mg·kg-1 in the I100 × N180, and significantly increased with increasing irrigation rate and N level (Table 4).
The total protein values were slightly affected by irrigation rate (Table 3). According to 2-year experimental data, the mean total protein values for the irrigation treatments of I50, I75 and I100 were 0.83, 0.90, and 1.02% FW, respectively. Nitrogen fertilization increased fruit content of total protein in both years. The mean total protein contents for the nitrogen applications of N0, N60, N120, and N180 were 0.73, 0.78, 0.97, and 1.20% FW, respectively.
Effect of Irrigation and Nitrogen Application on Water Productivity
The relationships between marketable fruit yield and seasonal irrigation water applied or seasonal ETc are shown in Fig. 3. The IWUE and WUE values varied in relation to ex-perimental treatment and year (Table 5). The WUE values show a more homogeneous distribution over the two years
and ranged between 7.2 and 18.3 kg FW·m-3 for both years. The highest WUE was obtained in the N180 sub-plots receiving I75 limited irrigation (I75N180) in both years. Conversely, higher IWUE values were found in the treatments of N120 and N180 with high water stress condition (I50). The IWUE values in the first year were higher than those in the second year because of more rainfall during the growing season in the first year. As shown in Table 5, both WUE and IWUE
Hayrettin Kuscu, Ahmet Turhan, Nese Ozmen, Pinar Aydinol, and Ali Osman Demir110
Fig. 4. Relationship between relative yield decrease (1-Ya･Ym-1) and
seasonal relative evapotranspiration deficit (1-ETa･ETm-1) for two
seasons’ experiment data combined.
significantly increased with increasing N fertilization.Yield Response Factor
Fig. 4 shows the relationship between relative fruit yield and seasonal relative evapotranspiration deficit, for the pooled data from the two seasons’ experiments, for water across N. The following regression equation was obtained:
(3)
Discussion
Data presented from the two experiments conducted in two years show that the marketable fruit yield significantly increased with increasing irrigation and N fertilization rates in sub-humid climate conditions with dry summer periods. The relationship between irrigation water applied and marketable fruit yield was positively linear (R2 = 0.75), implying that the yield increased with increasing applications of irrigation water. The seasonal ETc and marketable fruit yield on the average of investigated N levels exhibited a close quadratic relationship (R2 = 0.99). In a similar study, Çetin et al. (2002) reported a quadratic relationship between fruit yield and ETc. However, Mukherjee et al. (2010) found a linear rela-tionship between marketable yield and ETc. All of the agro- ecological factors that affect yield and crop water consumption may have caused this difference. Yield increases due to sufficient irrigation and optimal nitrogen fertigation resulted from significantly higher numbers of marketable fruits per plant and increased fruit size. This finding agrees with the results of Liu et al. (2011) and Al-Mohammadi and Al-Zu’bi (2011). In similar experiments in other studies (Candido et al., 2000; Kirda et al., 2004; Liu et al., 2011; Locascio and Smajstrla, 1996), marketable fruit yields were reported to be higher with full irrigation (100% ETc or Epan = 1) throughout the
crop growing season in agreement with our results. Conversely, limited irrigation during the growing season reduced the marketable fruit yield and fruit size. Limited irrigations (I50
and I75) consistently resulted in lower marketable fruit yields (25 and 12%, respectively) and fruit size (14 and 5%, respectively) over the 2-year period. The reason for these low percent, respectively weights is that the soil moisture is limited during the whole growing season. This soil water deficit decreases the accumulation of moisture in the fruit and, thus, contributes to the decrease in marketable fruit yield. These results are comparable with the recent findings of Patanè and Cosentino (2010) and Ozbahce and Tari (2010), who demonstrated that a negative trend in response to an increasing soil water deficit was observed for fruit yield.
The yield response factor (ky) for total growing season was 1.65. The ky value obtained in this study is higher than the value (ky=1.05) reported for tomato by Doorenbos and Kassam (1979). In a similar study, Ertek et al. (2012) reported the value of ky = 0.46 for water across different N fertilization applications. The ky value can vary depending upon location, species, variety, irrigation method and management, and growth stage when deficit evapotranspiration is imposed (Kaboosi and Kaveh, 2012; Kirda, 2002). The high ky value obtained in this study also implies that the rate of yield decrease was proportionally higher than the relative evapotranspiration deficit.
The N level applied and the marketable fruit yield exhibited a strong quadratic relationship (R2 = 0.99) with the average of the three irrigation levels. In a similar study, Kirda et al. (2003) reported a quadratic relationship between fruit yield and N concentration of the feeding solution. However, Warner et al. (2004) found a linear increase of fruit yield by the N fertilization rate up to the highest rates applied, 250 kg N·ha-1. At high rates of applied N, marketable fruit yields were reported to be higher with full irrigation (Erdal et al., 2006; Li et al., 2010; Singandhupe et al., 2003). In our study, the highest application rate of N (180 kg·ha-1) led to a significant yield increase as compared to the treatment without N ap-plication. In good agreement with our findings, Scholberg et al. (2000) also reported that severe N stress reduced tomato fruit yield by 60 to 70%. The rate of N required to produce maximum yield reported here is higher than rates reported by researchers in other areas. Ertek et al. (2012) reported that the application of 146 kg·ha-1 of N was sufficient to achieve maximum tomato yield in the Mediterranean climate conditions of Turkey. Campiglia et al. (2011) reported that marketable tomato yield increased to rates of N up to 150 kg·ha-1 in the Mediterranean environment of central Italy. However, Zotarelli et al. (2009) reported that there was no significant effect of N rate on tomato yield, but they found relatively high values for 330 kg·ha-1 of N as compared to 176 kg·ha-1 of N by fertigation through a surface drip irrigation
system under growing conditions in Florida, USA. These results reveal that it is difficult to obtain acceptable yield at low irrigation and N rates, suggesting that full irrigation and optimal nitrogen fertilization (150 to 180 kg·ha-1) are necessary.
However, frequently, the goal of producers is not to increase yields but to increase profits. The feasibility of increasing either the WUE or IWUE is a decision that needs to be based not only on the biophysical response of the crop, but also on economic factors (Payero et al., 2008). The IWUE and WUE are important indicators that reflect the effective use of water resources in crop production. If the water supply is limited, these indicators play a key role in determining appropriate irrigation management practices (Mukherjee et al., 2010). Patanè et al. (2011) stated that it is possible to save water by enhancing water productivity in growing processing tomato, but water should be applied to the crop during growing season, even at a low rate (50% ETc), to achieve adequate marketable fruit yield and to maintain high fruit quality levels. In another study near the research area, Bursa, Turkey, Kuşçu et al. (2009) reported that the 80% pan evaporation replenishment increased to the water productivity without a significant decrease in the marketable yield and net return for tomato ‘Heinz 9780’. Topcu et al. (2007) also reported that the partial root-zone drying practice and deficit irrigation increased the IWUE as compared to the full irrigation. Our results show that mod-erately limited irrigation (0.75 × Epan) and high nitrogen application (120 and 180 kg·ha-1) increased both IWUE and WUE. In addition to the common view that WUE increases with decreasing amount of irrigation water (Li et al., 2010; Mofoke et al., 2006; Ozbahce and Tari, 2010; Wang et al., 2007), our findings also indicate that N fertigation enhanced water productivity. However, Djidonou et al. (2013) reported the N rate above 112 kg·ha-1 did not lead to any significant increase of IWUE.
For processing tomato, it is desirable to have high values of both DM and TSS in the fruit. It is well known that TSS is the most important parameter affecting paste yield, and a high TSS content in fruits improves the efficiency of paste production during the industrial process because fruits with a higher total solids content may require a reduced amount of energy to evaporate water from fruit (DePascale et al., 2001; Favati et al., 2009; Johnstone et al., 2005; Patanè and Cosentino, 2010; Patanè et al., 2011). In recent years, processing tomato factories in Turkey have been considering a purchasing policy based not only on the weight of fresh fruits, but also on the TSS of fruit samples taken from the trailers that are brought to the factory. Therefore, these quality parameters of processing tomato have become the focus of attention of the processors as well as of farmers. In this study, increasing the seasonal irrigation water supply reduced both the DM and TSS of fresh tomato fruits.
Ozbahce and Tari (2010) found there was also a negative linear relationship between total soluble solids and irrigation water amount. Zegbe et al. (2006) reported that partial root zone drying at different phonological stages increased the TSS content of processing tomato. These results are also comparable with the recent findings of Favati et al. (2009) and Patanè and Cosentino (2010), who demonstrated that soil drying during the fruit ripening period could enhance soluble solids content. Maximum DM and TSS values were achieved with a fertilizer N rate of 120 kg·ha-1 and an irrigation rate of 0.5 × Epan. Results of several studies are in agreement with our findings that consistency is good for the irrigation regime (Liu et al., 2011; Patané et al., 2011; Zegbe-Dominguez et al., 2003) and N fertilization (May and Gonzales, 1994). Bénard et al. (2009) reported that the fruit dry matter content increased when nitrogen supply was reduced. However, some studies (Hartz and Bottoms, 2009; Warner et al., 2004) stated that nitrogen rate did not affect the fruit soluble solids.
Increasing irrigation rate negatively affected both TS and TA. The TS content and acidity are the most important characteristics of tomato taste (Rodica et al., 2008). The flavor quality of tomato fruits is largely determined by the sugar and acid composition of the fruit (Moretti et al., 1998). The results of the present study indicate that limited ir-rigations (I75 and I50) during the growing season significantly improved TS and TA as compared to full irrigation (I100) in both years. This result is supported by several researchers. For example, Patanè et al. (2011) found that deficit irrigation in various growing periods of processing tomato significantly enhanced titratable acidity as compared to full irrigation. These results are also supported by the recent research findings of Madrid et al. (2009), who showed that higher titratable acidity values occurred at lower irrigation levels for different fertilizer treatments. The present experiment showed that when the nitrogen level was increased, the TS and TA contents significantly increased. In agreement with our findings, Wang et al. (2007) reported that increasing the nitrogen supply increased the sugar and acid contents of cherry tomato fruits, thus improving fruit quality. Conversely, Simonne et al. (2007) reported that the TA content of yellow grape tomato grown decreased when the nitrogen supply was increased from 0 to 392 kg·ha-1. Bénard et al. (2009) reported an increased fruit sugar content with a reduced N supply and showed that the differences of the impact of reducing nitrogen supply most likely depend on the harvest date. Consequently, the present data implied that both the TS and TA of the fruit may respond in different ways to water and nitrogen levels based on genotype and other environmental factors such as the harvest date, temperature, and humidity.
Tomato fruit color is another important factor affecting
Hayrettin Kuscu, Ahmet Turhan, Nese Ozmen, Pinar Aydinol, and Ali Osman Demir112
paste quality in processing tomato. The color of a ripe tomato is mostly determined by the lycopene content (Lambelet et al., 2009; Marković et al., 2006). Thus, high lycopene and total carotene are desirable characteristics for the canned tomato industry because they improve the quality in terms of antioxidants of the processed product (DePascale et al., 2001). A total carotene concentration of more than 5.5 mg per 100 g FW is required for a satisfactory shade of red to develop, and lycopene accounts for 90% of the carotenoids (Dumas et al., 2003; Koskitalo and Ormrod, 1972). The present study showed that limited irrigation during the growing season enhanced both lycopene and total carotenoids. However, N supply up to 60 or 120 kg·ha-1 (not significant at the P < 0.05) increased both lycopene and total carotene, but a further increase of N rate to 180 kg·ha-1 led to a decrease of these values in both years. Consequently, the present data suggest that both lycopene and total carotene of processing tomato could be improved by an irrigation regime of 0.50 × Epan and by N application at either 60 or 120 kg·ha-1. This result agrees with the findings of Matsuzoe et al. (1998) who also reported in red cherry tomato cultivars that both total carotene of the fully ripe fruits and the amount of lycopene increased with soil water deficits. Liu et al. (2011) also reported that compared with no irrigation, water applications through a drip irrigation system decreased the lycopene content of processing tomato by 8%. However, in contrast to our study, Riggi et al. (2008) reported that the lycopene content was higher with full irrigation.
The fruit NO3-N content could be linked to different water and N levels with drip irrigation. We observed that high water and N rates supplied during the crop growing season increased with the NO3-N accumulation in fruits. Limited irrigations (I50 and I75) consistently resulted in a lower fruit NO3-N content, 25% in 2010 and 13% in 2011, than full irrigation (I100). Ayaz et al. (2007) reported 11.06 mg·kg-1 as the mean NO3-N content of fresh tomato fruits in Turkey. Our findings are higher than those cited above. However, Simion et al. (2008) reported that the nitrate level in tomatoes ranged between 82.24 and 116.75 mg·kg-1. The NO3-N content in vegetables could be influenced by factors including cultivar, light intensity, temperature, fertilization (Tosun and Ustun, 2004), and irrigation management.
Irrigation and nitrogen supply slightly positively affected the total protein content. In both years, the highest values were obtained from the combination of full irrigation and 180 kg N·ha-1. The result is similar to that of Erdal et al. (2007) who observed significant and positive impacts of irrigation level on processing tomato protein in response to N supply. They reported that the protein content of the fruit with the full irrigation and 160 kg N·ha-1supply were signi-ficantly greater than that with limited irrigation and N fertilization.
In conclusion, levels of irrigation water and nitrogen significantly affected the processing tomato yield and fruit quality. Applying water at 0.50 and 0.75 times the pan evaporation during the growing season as compared to applying 1.00 time significantly improved fruit quality, but decreased the marketable fruit yield. Compared to 0 and 60 kg·ha-1 N, application of 120 and 180 kg·ha-1 via fertigation for each irrigation treatment generally enhanced the marketable fruit yield, fruit quality, WUE, and IWUE. Considering the quality, quantity, IWUE and WUE, a 0.75 × Epan irrigation regime at a 3 day interval during the growing season in combination of 120 or 180 kg·ha-1 N application could give a better compromise of higher water productivity and fruit quality, and a relatively higher yield. This procedure could be recommended as the most suitable limited irrigation and optimal N fertilization schedule in the sub-humid areas for processing tomato cultivation. Using these conditions, an average of 15% yield loss should be expected as compared with application of 1.00 × Epan and 180 kg N·ha-1.
Acknowledgements: The authors are grateful to TAT Canned Company Inc. for providing laboratory facilities and grateful to TAT Seeding Company Inc. for providing tomato seeds. Authors are also grateful to American Journal Experts (AJE) and Project Management Centre of Uludağ University for editing the English of this manuscript.
Literature Cited
Adsule, P.G. and A. Dan. 1979. Simplified extraction procedure in the rapid spectrophotometric method for lycopene estimation in tomato. J. Food Sci. Technol. 16:216-218.
Al-Mohammadi, F. and Y. Al-Zu'bi. 2011. Soil chemical properties and yield of tomato as influenced by different levels of irrigation water and fertilizer. J. Agric. Sci. Technol. 13:289-299.
Association of Official Analytical Chemists (AOAC). 1980. Official methods of analysis. 12th edition. AOAC, Washington, D.C.
Ayaz, A., A. Topçu, and M. Yurttagul. 2007. Survey of nitrate and nitrite levels of fresh vegetables in Turkey. J. Food Technol. 5:177-179.
Bénard, C., H. Gautier, F. Bourgaud, D. Grasselly, B. Navez, C. Caris-Veyrat, M. Weiss, and M. Génard. 2009. Effects of low nitrogen supply on tomato (Solanum lycopersicum) fruit yield and quality with special emphasis on sugars, acids, ascorbate, carotenoids, and phenolic compounds. J. Agric. Food Chem. 57:4112-4123.
Campiglia, E., R. Mancinelli, and E. Radicetti. 2011. Influence of no-tillage and organic mulching on tomato (Solanum lycopersicum L.) production and nitrogen use in the Mediterranean environment of central Italy. Sci. Hort.130:588-598.
Candido, V., V. Miccolis, and M. Perniola. 2000. Effects of irrigation regime on yield of processing tomato (Lycopersicon esculentum Mill.) cultivars. Acta Hort. 537:779-788.
Çetin, Ö., O. Yıldırım, D. Uygan, and H. Boyacı. 2002. Irrigation scheduling of drip-irrigated tomatoes using class A pan evaporation. Turkish J. Agric. Forest. 26:171-178.
DePascale, S., A. Maggio, V. Fogliano, P. Ambrosino, and A. Retieni. 2001. Irrigation with saline water improves carotenoids content
and antioxidant activity of tomato. J. Hortic. Sci. Biotechnol. 76:447-453.
Doorenbos, J. and A.H. Kassam. 1979. Yield response to water. United Nations FAO Publication no. 33, Rome, Italy.
Djidonou, D., X. Zhao, E.H. Simonne, and K.E. Koch. 2013. Yield, water-, and nitrogen-use efficiency in field-grown, grafted tomatoes. HortScience 48:485-492.
Dumas, Y., M. Dadomo, G. Di Lucca, and P. Grolier. 2003. Review: Effects of environmental factors and agricultural techniques on antioxidant content of tomatoes. J. Sci. Food Agric. 83:369-382.
Erdal, I., A. Ertek, U. Senyigit, and H.I. Yilmaz. 2006. Effects of different irrigation programs and nitrogen levels on nitrogen concentration, uptake and utilisation in processing tomatoes (Lycopersicun esculentum). Austr. J. Exp. Agric. 46:1653-1660.
Erdal, I., A. Ertek, U. Senyigit, and M.A. Koyuncu. 2007. Combined effects of irrigation and nitrogen on some quality parameters of processing tomato. World J. Agric. Sci. 3:57-62.
Ertek, A., I. Erdal, H.I. Yilmaz, and U. Senyigit. 2012. Water and nitrogen application levels for the optimum tomato yield and water use efficiency. J. Agric. Sci. Technol. 14:889-902.
Favati, F., S. Lovelli, F. Galgano, V. Miccolis, T. Di Tomasso, and V. Candido. 2009. Processing tomato quality as affected by irrigation scheduling. Sci. Hort. 122:562-571.
Feddema, J.J. 2005. A revised Thornthwaite-type global climate classification. Phys. Geogr. 26:442-466.
Fresenius, W., K.E. Quentin, and W. Schneider. 1988. Water Analysis. A practical guide to physicochemical, chemical and microbiological water examination and quality assurance. Springer-Verlag, Berlin.
Garrity, P.D., D.G. Watts, C.Y. Sullivan, and J.R. Gilley. 1982. Moisture deficits and grain sorghum performance, evapotran-spiration yield relationships. Agron. J. 74:815-820.
Gormley, T.R. and M.J. Maher. 1990. Tomato fruit quality-an interdisciplinary. Profess. Hort. 4:7-12.
Hanson, B.R. and D.M. May. 2006. Crop evapotranspiration of processing tomato in the San Joaquin Valley of California, USA. Irrig. Sci. 24:211-221.
Harmanto, V., M. Salokhe, M.S. Babel, and H.J. Tantau. 2005. Water requirement of drip irrigated tomatoes grown in greenhouse in tropical environment. Agric. Water Manag. 71:225-242.
Hartz, T.K. and G.J. Hochmuth. 1996. Fertility management of drip- irrigated vegetables. HortTechnol. 6:168-172.
Hartz, T.K. and T.G. Bottoms. 2009. Nitrogen requirements of drip irrigated processing tomatoes. HortScience 44:1988-1993.
Hebbar, S.S., B.K. Ramachandrappa, H.V. Nanjappa, and M. Prabhakar. 2004. Studies on NPK drip fertigation in field grown tomato (Lycopersicon esculentum Mill.). Eur. J. Agron. 21:117-127.
Johnstone, P.R., T.K. Hartz, M. LeStrange, J.J. Nunez, and E.M. Miyao. 2005. Managing fruit soluble solids with late-season deficit irrigation in drip-irrigated processing tomato production. HortScience 40:1857-1861.
Kaboosi, K. and F. Kaveh. 2012. Sensitivity analysis of FAO 33 crop water production function. Irrig. Sci. 30:89-100.
Kirda, C. 2002. Deficit irrigation scheduling based on plant growth stages showing water stress tolerance, p. 3-10. In: FAO (ed.). Deficit irrigation practices. FAO water report no. 22. FAO, Rome, Italy.
Kirda, C., N. Baytorun, M.R. Derici, and H.Y. Dasgan. 2003. Nitrogen fertiliser recovery and yield response of greenhouse grown and fertigated tomato to root-zone soil water tension. Turk. J. Agric. Forest. 27:323-328.
Kirda, C., M. Cetin, Y. Dasgan, S. Topcu, H. Kaman, B. Ekici, M.R. Derici, and A.I. Ozguven. 2004. Yield response of greenhouse grown tomato to partial root drying and conventional deficit irrigation. Agric. Water Manag. 69:191-201.
Koskitalo, L.H. and D.P. Ormrod. 1972. Effects of sub-optimal ripening temperatures on the colour quality and pigment composition of
tomato fruit. J. Food Sci. 37:56-59.Kuşçu, H., B. Çetin, and A. Turhan. 2009. Yield and economic return
of drip-irrigated vegetable production in Turkey. New Zealand J. Crop Hort. Sci. 37:51-59.
Lambelet, P., M. Richelle, K. Bortlik, F. Franceschi, and M. Giori. 2009. Improving the stability of lycopene Z-isomers in isomerised tomato extracts. Food Chem. 112:156-161.
Li, X., F. Liu, G. Li, Q. Lin, and C.R. Jensen. 2010. Soil microbial response, water and nitrogen use by tomato under different irrigation regimes. Agric. Water Manag. 98:414-418.
Liu, K., T.Q. Zhang, C.S. Tan, and T. Astatkie. 2011. Responses of fruit yield and quality of processing tomatoto drip-irrigation and fertilizers phosphorus and potassium. Agron. J. 103:1339-1345.
Locascio, S.J. and A.G. Smajstrla. 1996. Water application scheduling by pan evaporation for drip irrigated tomatoes. J. Amer. Soc. Hort. Sci. 121:63-68.
Madrid, R., E.M. Barba, A. Sánchez, and A.L. García. 2009. Effects of organic fertilisers and irrigation level on physical and chemical quality of industrial tomato fruit (cv. Nautilus). J. Sci. Food Agric. 89:2608-2615.
Malash, N.M., T.J. Flowers, and R. Ragab. 2008. Effect of irrigation methods, management and salinity of irrigation water on tomato yield, soil moisture and salinity distribution. Irrig. Sci. 26:313-323.
Marković, K., M. Hruškar, and N. Vahčić. 2006. Lycopene content of tomato products and their contribution to the lycopene intake of Croatians. Nutr. Res. 26:556-560.
Matsuzoe, N., K. Zushi, and T. Johjima. 1998. Effect of soil water deficit on coloring and carotene formation in fruits of red, pink and yellow type cherry tomatoes. J. Japan. Soc. Hort. Sci. 67: 600-606.
May, D.M. and J. Gonzales. 1994. Irrigation and nitrogen management as they affect fruit quality and yield of processing tomatoes. Acta Hort. 376:227-234.
Mofoke, A.L.E., J.K. Adewumi, F.E. Babatunde, O.J. Mudiare, and A.A. Ramalan. 2006. Yield of tomato grown under continuous-flow drip irrigation in Bauchi state of Nigeria. Agric. Water Manag. 84:166-172.
Moretti, C.L., S.A. Sargent, D.J. Huber, A.G. Calbo, and R. Puschmann. 1998. Chemical composition and physical properties of pericarp, locule and placental tissues of tomatoes with internal bruising. J. Amer. Soc. Hort. Sci. 123:656-660.
Mukherjee, A., M. Kundu, and S. Sarkar. 2010. Role of irrigation and mulch on yield, evapotranspiration rate and water use pattern of tomato (Lycopersicon esculentum L.). Agric. Water Manag. 98:182-189.
Ozbahce, A. and A.F. Tari. 2010. Effects of different emitter space and water stress on yield and quality of processing tomato under semi-arid climate conditions. Agric. Water Manag. 97:1405-1410.
Page, A.L., R.H. Miller, and D.R. Keeney. 1982. Methods of soil analysis. Part 2. Chemical and microbiological properties. 2nd ed. Amer. Soc. Agron., Madison, WI, USA.
Pan, H.Y., K.J. Fisher, and M.A. Nichols. 1999. Fruit yield and maturity characteristics of processing tomatoes in response to drip irrigation. J. Vegetable Crop Prod. 5:13-29.
Patanè, C. and S.L. Cosentino. 2010. Effects of soil water deficit on yield and quality of processing tomato under a Mediterranean climate. Agric. Water Manag. 97:131-138.
Patanè, C., S. Tringali, and O. Sortino. 2011. Effects of deficit irrigation on biomass, yield, water productivity and fruit quality of processing tomato under semi-arid Mediterranean climate conditions. Sci. Hort. 129:590-596.
Payero, J.O., D.D. Tarkalson, S. Irmak, D. Davison, and J.L. Petersen. 2008. Effect of irrigation amounts applied with subsurface drip irrigation on corn evapotranspiration, yield, water use efficiency, and dry matter production in a semiarid climate. Agric. Water
Hayrettin Kuscu, Ahmet Turhan, Nese Ozmen, Pinar Aydinol, and Ali Osman Demir114
Manag. 95:895-908.Riggi, E., C. Patanè, and G. Ruberto. 2008. Content of carotenoids
at different ripening stages in processing tomato in relation to soil water availability. Austr. J. Agric. Res. 59:348-353.
Rodica, S., S.A. Apahidean, M. Apahidean, D. Maniutiu, and L. Paulette. 2008. Yield, physical and chemical characteristics of greenhouse tomato grown on soil and organic substratum. 43rd Croatian and 3rd Intl. Symp. Agric. Opatija. Croatia. p. 439-443.
Scholberg, J., B.L. McNeal, K.J. Boote, J.W. Jones, S.J. Locascio, and J.W. Olson. 2000. Nitrogen stress effects on growth and nitrogen accumulation by field-grown tomato. Agron. J. 95:159- 167.
Simion, V., G.H. Câmpeanu, G. Vasile, M. Artimon, L. Catană, and M. Negoiţă. 2008. Nitrate and nitrite accumulation in tomatoes and derived products. Roman. Biotechnol. Lett. 13:3785-3790.
Simonne, A.H., J.M. Fuzeré, E. Simonne, R.C. Hochmuth, and M.R. Marshall. 2007. Effects of nitrogen rates on chemical composition of yellow grape tomato grown in a subtropical climate. J. Plant Nutr. 30:927-935.
Singandhupe, R.P., G.G.S.N. Rao, N.G. Patil, and P.S. Brahmanand. 2003. Fertigation studies and irrigation scheduling in drip irrigation system in tomato crop (Lycopersicon esculentum L.). Eur. J. Agron. 19:327-340.
Tepic, A.N., B.L. Vejicic, A.J. Takac, B.D. Kristic, and L.J. Calic. 2006. Chemical heterogeneity of tomato inbred lines. Acta Period. Technol. 37:45-50.
Tigchelaar, E.C. 1986. Tomato breeding, p. 135-171. In: M.J. Basset (ed.). Breeding of vegetable crops. AVI Pub. Co., Westport, CT, USA.
Topcu, S., C. Kirda, Y. Dasgan, H. Kaman, M. Cetin, A. Yazici, and M.A. Bacon. 2007. Yield response and N-fertiliser recovery of tomato grown under deficit irrigation. Eur. J. Agron. 26:64-70.
Tzortzakis, N.G. and C.D. Economakis. 2008. Impacts of the substrate medium on tomato yield and fruit quality in soilless cultivation. Hort. Sci. 35:83-89.
Tosun, I. and N.S. Ustun. 2004. Nitrate content of lettuce grown
in the greenhouse. Bull. Environ. Contam. Toxicol. 72:109-113.TUIK. 2013. Turkish Statistical Institute. http://www.turkstat.gov.tr/
(Accessed 04.04.13).Wang, Y.T., S.W. Huang, R.L. Liu, and J.Y. Jin. 2007. Effects of
nitrogen application on flavor compounds of cherry tomato fruits. J. Plant Nutr. Soil Sci. 170:461-468.
Wang, Q., F. Li, E. Zhang, G. Li, and M. Vance. 2012. The effects of irrigation and nitrogen application rates on yield of spring wheat (longfu-920), and water use efficiency and nitrate nitrogen accumulation in soil. Austr. J. Crop Sci. 6:662-672.
Warner, J., T.Q. Zhang, and X. Hao. 2004. Effects of nitrogen fertilization on fruit yield and quality of processing tomatoes. Can. J. Plant Sci. 84:865-871.
Yang, S.M., S.S. Malhi, J.R. Song, Y.C. Xiong, W.Y. Yue, L.L. Lu, J.G. Wang, and T.W. Guo. 2006. Crop yield, nitrogen uptake and nitrate-nitrogen accumulation in soil as affected by 23 annual applications of fertilizer and manure in the rainfed region of Northwestern China. Nutr. Cycling Agroecosys. 76:81-94.
Yohannes, F. and T. Tadesse. 1998. Effect of drip and furrow irrigation and plant spacing on yield of tomato at Dire Dawa, Ethiopia. Agric. Water Manag. 35:201-207.
Zegbe, J.A., M.H. Behboudian, and B.E. Clothier. 2006. Responses of ‘Petopride’ processing tomato to partial rootzone drying at different phenological stages. Irrig. Sci. 24:203-210.
Zegbe-Dominguez, J.A., M.H. Behboudian, A. Langand, and B.E. Clothier. 2003. Deficit irrigation and partial root-zone drying maintain fruit dry mass and enhance fruit quality in ‘Petopride’ processing tomato (Lycopersicon esculentum. Mill.). Sci. Hor. 98:505-510.
Znidarcic, D. and T. Pozrl. 2006. Comparative study of quality changes in tomato cv. ‘Malike’ (Lycopersicon esculentum Mill.) whilst stored at different temperatures. Acta Agric. Slovenica 87:235-243.
Zotarelli, L., J.M. Scholberg, M.D. Dukes, R. Muňoz-Carpena, and J. Icerman. 2009. Tomato yield, biomass accumulation, root distribution and irrigation water use efficiency on a sandy soil, as affected by nitrogen rate and irrigation scheduling. Agric. Water Manag. 96:23-34.
