Next Article in Journal
Integrative Analysis of Metabolome and Transcriptome Profiles to Evaluate the Response Mechanisms of Carex adrienii to Shade Conditions
Previous Article in Journal
The Impact of Applying Different Fertilizers on Greenhouse Gas Emissions and Ammonia Volatilization from Northeast Spring Corn
 
 
Search for Articles:
Title / Keyword
Author / Affiliation / Email
Journal
Article Type
 
 
Advanced Search
 
Section
Special Issue
Volume
Issue
Number
Page
 
Journals
Agronomy
Volume 14
Issue 12
10.3390/agronomy14122799
agronomy-logo
Submit to this Journal Review for this Journal Propose a Special Issue
► Article Menu

Article Menu

share Share announcement Help format_quote Cite question_answer Discuss in SciProfiles thumb_up
...
Endorse textsms
...
Comment
first_page
settings
Order Article Reprints
Font Type:
Arial Georgia Verdana
Font Size:
Aa Aa Aa
Line Spacing:
Column Width:
Background:
Article

Effect of Water Retainer® During Seedling Period on Bioactive Components of Tomato (Solanum lycopersicum)

by
Rita Adél Tömösközi-Farkas
1,*,
Ágnes Molnár-Mondovics
2 and
Barbara Ildikó Schmidtné Szantner
2
1
Department of Food Chemistry and Analytical Chemistry, Institute of Food Science and Technology, Hungarian University of Agriculture and Life Sciences, 1118 Budapest, Hungary
2
Vegetable Research Center, Institute of Horticultural Sciences, Hungarian University of Agriculture and Life Sciences, 6300 Kalocsa, Hungary
*
Author to whom correspondence should be addressed.
Agronomy 2024, 14(12), 2799; https://doi.org/10.3390/agronomy14122799
Submission received: 12 September 2024 / Revised: 5 November 2024 / Accepted: 22 November 2024 / Published: 25 November 2024
(This article belongs to the Special Issue Physiological Traits of Plants Under Irrigation)
Browse Figures
Versions Notes

Abstract

:
As a result of climate change, drought and the unequal distribution of rainfall is a worldwide problem. Drought stress on plants affects not only the yield, but also the amount and ratio of bioactive components in tomato fruit. The aim of the present work was to investigate the effect of a new soil biodegradable water-retention agent (Water and Soil’s Water Retainer®, Water and Soil Ltd., Budapest, Hungary) containing natural ingredients during the seedling period and under different irrigation conditions on the product volume, dry matter content and on some characteristic secondary metabolites in tomato fruits. The study was conducted to screen four different irrigation and soil treatment combination treatments for production and quality characteristics (polyphenols, tocopherols, carotenoids, vitamin C) to check the effect of seedling-stage stress on the tomato yield and bioactive components. Significant differences were found among the treatment and the cultivation seasons for the phytochemical content of fruits. The average yield and BRIX value did not change as a result of the Water Retainer® compared to the irrigated samples, but the amount of lycopene, Vitamin C, antioxidant capacity, and total polyphenol content increased significantly with the use of the Water Retainer®. In the two cultivation seasons, the highest concentration of lycopene and Vitamin C (114.30 ± 3.18 μg.g−1 and 338.10 ± 13.70 μg.g−1 fwt, respectively) was determined in fruits of 50% irrigation + 1.5 mL/m2 WR®-treated plants. The highest measured antioxidant capacity and total polyphenol content were 21.54 ± 0.17 mMTr/kg and 504 ± 44 mg GAE/kg, respectively, in the same treated samples. We found that seedlings exposed to drought stress, and after planting, when grown under ideal conditions in the field, can be distinguished from each other, despite the fact that there was only a difference between their cultivation during the seedling period. This may prove that rehydration is not sufficient to completely restore the metabolomic processes of stressed plants.

1. Introduction

Vegetables and fruits play an increasingly important role in nutrition because of the many bioactive components they contain. Tomato (Solanum lycopersicum L.) is one of the most popular and economically important vegetable crops, grown all over the world in outdoor fields and greenhouses. Tomato is the second largest solanaceous crop after potato. Total tomato production was 186 million tons worldwide and 140 thousand tons in Hungary [1].
The consumption of fresh or processed tomatoes leads to the prevention of different diseases, such as gastrointestinal tumours, cardiovascular disease, inflammatory processes, and hypertension [2], due to their high level of lycopene, beta-carotene, tocopherols, phenolic compounds, and ascorbic acid. The biosynthesis of these antioxidant components in tomato fruit is influenced by genetic and environmental biotic and abiotic factors. The dry matter content depends on the variety, the ripeness of the berry, the fertilization, and the watering of the plants [3]. Regular and optimal irrigation can reduce the amount of green fruits and blossom-end rot [4]. Irrigation has a positive effect on the height, number of leaves, and weight of the plant. In the case of water stress, vegetative growth can be visibly reduced [5]. A study of Macua et al. [6] proved that the amount of irrigated water significantly affects the living conditions of plants. Water stress at the seedling stage affects the subsequent development of plants in greenhouses [7].
Drought or water stress is one of the most significant abiotic stresses, causing huge problems to agriculture worldwide. Vegetables are more sensitive to drought compared to many other crops [8]. Most commercial tomato cultivars are drought-sensitive at all stages of development, including germination, vegetative growth, and reproduction [9,10]. A reduction in irrigation and drought stress causes many physiological changes in biochemical processes, such as reductions in photosynthesis, and the closing of stomata. The concentrations of proline, some saccharides like glucose, fructose, and sucrose, malic acid, ascorbic acid, and citric acid increased with increasing water stress [11]. During their ripening and fruit-quality tests, Nahar and Gretzmacher [11] showed that the quality of stress-treated tomatoes did not deteriorate. On the other hand, water stress enhanced tomato sweetness by increasing glucose, fructose, and sucrose content and improved quality by increasing concentrations of important organic acids such as ascorbic acid, malic acid, and citric acid [11]. Ghanem et al. [12] concluded that water stress had a great effect on the growth, yield, and chemical composition of different tomato genotypes. Water stress significantly reduced the growth, fruit setting, and yield parameters of tomato genotypes and increased the amount of ascorbic acid, acidity, and total soluble solids. Shamim et al. [13] found that the change in total soluble solid content of tomato fruit was influenced by genotype. They found that 60% of the moisture at field capacity indicated a moisture supply sufficient for a higher crop yield and better crop size.
Water supplies are limited worldwide and there is an increasing need to reduce the amount of water used in irrigation practises. Water deficits and increasing competition for water resources between agriculture and other sectors are driving the development of new irrigation strategies that can reduce irrigation water consumption and sustain production. According to the literature, there are several ways to achieve this goal. Partial root-zone drying during irrigation increases the water use efficiency of tomato processing without significant negative effects on yield [14,15,16]. Another important method to improve water-use efficiency is deficit irrigation (DI), a strategy to reduce water consumption in which plants are deliberately allowed to maintain a certain level of water deficit (WD) and yield reduction [17,18,19]. An alternative option is the use of water-retaining materials, which can stimulate the accumulation of water and nutrients in the soil, and have a direct effect on a plant’s metabolism, ensuring the conditions for development for a longer period of time [20]. Chen and Lu [21] found that by increasing the use of a water-retention agent, they obtained a higher emergence rate of processing tomatoes. Carmen et al. [22] found that, in the case of certain bean varieties, the use of the water retainer resulted in a higher leaf area and a higher chlorophyll content, but had no effect on the dry weight of plants. Green tomatoes grown in soil containing super-water-absorbent (SWA) hydrogels were observed to have a significantly higher phenolic component, indicating increased antioxidant capacity. It was shown that the plant height, root mass, number of branches, and leaves and fruits of the soil treated with water retainer were significantly higher than those of the soil without SWA [23].
The aim of our work is to investigate the effect of drought stress at the seedling stage on the yield and the most important bioactive components of tomatoes, and to what extent a soil treatment agent that improves the water-retention capacity of the soil improves the same parameters. Furthermore, we investigate to what extent the stress at seedling stage can be compensated for by subsequent rehydration and an optimal irrigation programme during field cultivation. Unorosso F1 tomato seedlings were irrigated at different intensities and treated with a natural, 100% biodegradable soil treatment agent (Water Retainer®) produced from food by-products. In two consecutive years, the effect of the water retainer on crop yield, BRIX content, and the main bioactive components such as β-carotene, lycopene, tocopherol derivatives, phenolic compounds and vitamin C were evaluated.

2. Materials and Methods

2.1. Plants and Fielding

In our 2-year experiment, we investigated the effect of the Water Retainer® (WR®). We sowed the Unorosso F1 processing tomato type on the 8th of April. The sowing was in Kalocsa (46°30′55.9″ N 18°58′32.9″ E), at the Vegetable Research Center of the Hungarian University of Agriculture and Life Sciences Institute of Horticultural Sciences.

2.1.1. Seedling

We used 66-cell seedling trays (3.5 cm × 3.5 cm × 4 cm) with baltic peat (Pindstrup Mix + Clay, pH 6.0, 10–30 mm, 300 L). After the sowing, we sprayed 1.5 mL/m2 and 2 mL/m2 WR® on the surface of the peat. After germination, fertilization was planned based on the specific nutrient demands of the industrial tomato. The pH was 5.6, EC was 2.3, and we used complex fertilizers (NPK 15-30-15).
Four different treatments were investigated in our 2-year experiment (100% irrigation, 50% irrigation, 50% irrigation + 1.5 mL/m2 WR®, and 50% irrigation + 2 mL/m2 WR®), with 4 repetitions (4 trays–246 plants in each treatment). In order to examine the stress effects at the seedling stage, the plants were treated only during the seedling period, and were grown under the same conditions from planting to harvest.
The irrigation was based on the water demand of the 100% irrigated control group. Based on the evaporation, the seedling’s water requirement could be calculated. Tensiometers, and the visual and manual inspection of the planting medium, helped to determine the frequency of irrigation. The water pressure (bar) in the soil was determined using a tensiometer. The irrigation of vegetables should be started if the water potential of the soil is minus 0.05–0.1.
The planting medium is lighter in colour when it dries, and it shrinks due to water loss, so it separates from the wall of the cube. The wilting of the seedling was not allowed; if it was necessary, we used emergency irrigations for the 50% irrigated trays.

2.1.2. Open Fielding

After the 5-week experiment period, we planted the seedlings with 51 plant parcels in the open field on the second decade of May. Complex granulated NPK fertilizer (15-15-15) and granulated poultry manure (Orgevit, Arnhem, Netherland) were spread during the spring machine spading. Ferticare (15-30-15) (Szcecin, Holland) starter fertilizer was used (EC1.5–1.8, 0.3–0.5 L/plant) to promote root development at the time of planting. The planting and row distance were 22 cm and 130 cm. We used drip irrigation. Following the soil analysis, a nutrient supplementing plan was elaborated for specific nutrient demands of the industrial tomato. In the case of the 80 t/ha yield, the active substance requirements are as follows: 280 kg N; 120 kg P; and 352 kg K. Harvest was in the second decade of August. Machine harvest was imitated: plants were cut, all the berries were shaken off, and four categories were selected (ripe, half-ripe, green, and unhealthy); the berries were counted and measured. Red, orange, and evenly coloured fruits fell into the ripe category. A berry was considered half-ripe if it contained orange and green patches in varying proportions. Uniformly coloured green tomatoes belonged to the green category. All those tomatoes which showed the signs of bacterial or fungal infections, sun-damage, or Ca spots were considered as unhealthy.
Samples of 26 ripened berries were taken from each parcel: 20 ripened berries were pressed by a juicer. The Brix % value was measured by a portable automatic refractometer (Hanna HI96801; Woonsocket, RI, USA) in juice and the colour in an L.a.b. system with a spectrophotometer (Hunterlab ColorflexEZ, Reseton, VA, USA). The value “L” is the brightness; “a” means the red, and “b” means the yellow coordinates, and the relation of “a” and “b” (a/b) gives us the redness of the samples, which is an important quality parameter for the industry. The average refraction (Brix%) was determined at harvest from the measured values of the samples taken from four repetitions per treatment. The 6 ripened berry samples from each parcel were taken for analytical investigations.
The required amount of water was determined according to Helyes and Varga [24]; the daily potential evapotranspiration of a tomato crop can be estimated well by dividing the expected daily average temperature by 5 and expressing this in millimetres. The method for calculating the amount of irrigation is based on weather forecasting data.
Both of our experimental years can be said to be low in rainfall (Figure 1 and Figure 2). In 2019, the average daily temperature was between 13.45 °C and 26.1 °C and it increased above 20 °C on 69 days. The daily maximums were over 30 °C on 27 days. The daily minimums were under 12 °C on 20 days. During the season, the 20 cm deep soil temperature was between 14.7 °C and 25.6 °C and the soil humidity was between 18.8 V/V% and 31.8 V/V%; by planting time, it was around 16 °C and 30 V/V%; in the harvesting period, it was around 23 °C and 20 V/V%.
In 2020, the average daily temperature was between 12.2 and 26.35 and it increased above 20 °C on 63 days. The daily maximums were over 30 °C on 19 days. The daily minimums were under 12 °C on 48 days. During the season, the 20 cm deep soil temperature was between 15.8 and 26 °C and the soil humidity was between 19.3 and 32.6 V/V%; by planting time, it was around 18 °C and 22 V/V%; in the harvesting period, it was around 23 °C and 22 V/V%.
By planting time (18–21 May) in Season 2, it was warmer, and the soil humidity was lower than in Season 1. In the vegetative grooving phase (May–June), Season 1 was warmer; the soil humidity slowly decreased, because of the diminishing precipitation. Season 2 was more humid than Season 1 in this period. For the main blooming phase (20–22 June), Season 2 was cooler than Season 1; the soil humidity increased in both seasons. After the blooming (June–August), there were several heatwaves in both of the seasons. We can say that Season 2 was hotter in this period, and the temperature fluctuated more between two extreme values. The soil humidity was similar in both of the seasons. At the beginning of the harvesting period (15–30 August) in Season 1, there was precipitation, and the temperature decreased for a few days.

2.2. Chemicals

Standard ascorbic acid, lycopene, β-carotene, tocopherol standard solutions (of α, β, γ, δ), Folin–Ciocalteu reagent, gallic acid, DPPH (2,2-diphenyl-1-picrylhydrazyl), and Trolox (6-hydroxy-2,5,7,8-tetra-methylchroman-2-carboxylic acid) were purchased from Sigma-Aldrich Ltd. (St. Louis, MI, USA). HPLC and analytical-grade organic solvents (methanol, 1,2-dichloroethan, acetonitrile, hexane, ethanol, acetone) and other chemicals (quartz sand, KH2PO4, anhydrous Na2SO4, metaphosphoric acid—analytical grade, Na2CO3) were purchased from VWR International LLC (Radnor, PA, USA).
Water and Soil’s Water Retainer® concentrate (Water and Soil Ltd., Budapest, Hungary) is Hungarian-developed, natural, and comprises 100% biodegradable water-retaining product. The product is brown, has a characteristic smell, a liquid density of 1.32 kg/dm3, is more viscous than water, a min. 70% dry matter content (m/m%), and at least a min. 56% organic matter content (m/m%) (based on dry matter). The pH value in 10% water is 7 ± 0.5; the concentration of As, Cd, Co, Cr, Cu, Hg, Ni, Pb, and Se in the product is a maximum of 10, 2, 50, 100, 100, 1, 50, 100, 5 mg/kg in that order. It is a protected mixture of plant-derived food industry by-product with a high organic matter content, with absorbent, wetting agents, surfactants, and water. The mechanism of action of this hygroscopic concentrate is based on reducing evaporation and binding the moisture content of the air, thereby promoting a balanced water supply to the soil. It can be used at a quantity of 10 L/ha, diluted 10 times by spraying on the surface of the soil, or by irrigation.

2.3. Analytical Methods

2.3.1. Sample Preparation of Tomato

The tomato fruits were collected at the fully ripened stage and were immediately transported to the laboratory. The fruits were homogenized using blender and the samples were stored at −20 °C until analysis. One test sample was obtained by homogenizing tomatoes from 4 to 5 different plants; the measurements were performed with 4 parallel test samples.

2.3.2. Measurement of Polyphenol Content

Total polyphenols were quantified using the Folin–Ciocalteu method [25] after methanolic extraction (80% v/v). Polyphenol content was given in the gallic acid equivalent (GAE)/per 1000 g sample.

2.3.3. DPPH Radical Scavenging Activity

Methanol extracts (80% v/v) were used to assess the antioxidant capacity by the DPPH radical-scavenging method [26], with some modifications. A fifty μL aliquot of the extract and 2 mL of DPPH (0.1 mM) were shaken at 37 °C for 30 min and the absorbance was measured at 517 nm using a Jasco Spectrophotometer (Model 7850, Tokio, Japan). The calibration curve was prepared with 80% (v/v) methanol solution of Trolox (6-hydroxy-2,5,7,8-tetra-methylchroman-2-carboxylic acid) at 100-1000 μmol/L concentrations. The antioxidant capacity was expressed as mmol Trolox equivalents (TE)/1000 g sample fw.

2.3.4. Ascorbic Acid Determination

The analysis of ascorbic acid content was performed in accordance with to Nagy et coworkers, using RP-HPLC method with UV detection [27]. The tomato sample was extracted with metaphosphoric acid (3% w/v) and after filtration (0.45 mm PTFE syringe filter) was injected in the HPLC column. The analytical determination of ascorbic acid was performed on the C18 Nautilus 100–5 μm (150 mm × 4.6 mm i.d.) (Macherey-Nagel, Duren, Germany) column with a gradient elution of 0.01 M KH2PO4 (A) and acetonitrile (B). The absorption maximum of ascorbic acid under these conditions was detected at 265 nm. For the quantitative determination of ascorbic acid, internal standard calibration was used.

2.3.5. Determinations of Carotenoids

The separation and analysis of carotenoids was performed in accordance with to Daood and coworkers [28], using an EC 150/4.6 Nucleodur C18 Isis 3 μm (Macherey Nagel, Duren, Germany) column and a gradient elution (A: methanol; B: water, C: isopropanol-acetone-methanol) RP-HPLC method with UV detection. Tomato samples were extracted first with methanol and then by 1,2-dichloroethane in a liquid–liquid extraction. After filtration (0.45 μm Teflon syringe filter), the samples were injected and for the quantitative determination of carotenoids, internal standard calibrations were used.

2.3.6. Determination of Tocopherols

To analyze tocopherols, the tomato lipid fraction obtained by the same procedure used for the carotenoid extraction was saponified with KOH and extracted by n-hexane and analyzed by the NP-HPLC method using an EC 250/4.6 Nucleosyl 100–5 column (Macherey Nagel, Duren, Germany), isocratic elution (n-hexane: ethanol-99.6:0.4), and fluorescent detection (Ext: 295 nm, Em: 320 nm), in accordance with the procedure described by Abushita et al. [29]. For the quantitative determination of tocopherols, internal standards were used.
A Waters Alliance liquid chromatographic instrument consisting of a Model 2696 Separation Module (gradient pump, auto-sampler, and column heater) and a Model 2695 photodiode-array detector (Milford, MA, USA) was used for the analysis of carotenoids and vitamin C. The operation and data processing were performed by Empower software (Milford, MA, USA). For tocopherol analysis, a combination of a Beckman 114 M isocratic pump (Brea, CA, USA), a model RF-535 Shimadzu fluorometric detector (Kioto, Japan), and a Waters-740 Data Module integrator (Milford, MA, USA) was used.

2.3.7. Statistical Analysis

For spectrophotometric and HPLC analysis, all the samples were analyzed in triplicate. All data in the tables were presented as a mean number (n = 4) and standard deviations. IBM SPSS Statistics (Chicago, IL, USA, SPSS) software was used for normality analysis (Kolmogorov–Smirnov and Shapiro–Wilk test), Pearson’s correlation analysis, ANOVA (Tukey’s test), the t-probe analysis, and discriminant analysis.

3. Results

3.1. Harvesting Results

Exactly half of the amount of water used for the 100% irrigated samples was used in the WR-treated plots. On the 50% irrigated, untreated control plots, extra irrigation had to be applied due to wilting (Table 1).
After the seedling stage, we measured the main data of the seedlings, like the plant height, number of true leaves, and stem diameter (Table 2). During our 2-year experiment, the measured plant height ranged from 8.98 cm (50% irrigated + 1.5 mL/m2 WR®) to 15.86 cm (100% irrigated plots).
The number of true leaves of a seedling enables a growth-rate estimation and is related to the health status of the plant and its yield potential [30]. The number of true leaves of the seedlings varied between 3.05 ± 0.38 (in the 50% irrigated and 50% irrigated + 2 mL/m2 WR-treated plots) and 5.39 ± 0.08 (100% irrigated plots). In both years, we found that the 100% watered seedlings had the highest number of true leaves, but we only found a significant difference in 2020.
The measurement of stem diameter is therefore important, as this parameter is an indicator of the tomato’s water status. During our experiments, the measured stem diameter ranged from 3.88 mm (50% irrigated plots) to 4.77 mm (100% irrigated plots).
Table 3 contains the field data after planting the seedlings, where irrigation and nutrient supply were the same for all samples. In the year of 2019, we found significant differences in L values. In 2020, in the field data, we found a significant difference between the groups treated in different ways in the case of only one parameter, the amount of green berries (Table 3).
The measured yield of ripened berries ranged from 120.34 to 171.54 kg/m2 (50% irrigated + 1.5 mL/m2 WR®; 50% irrigated + 2 mL/m2 WR®;) in 2019. The amount of half ripened berries varied between 23.16 and 35.20 kg/m2 (50% irrigated; 100% irrigated group) and green berries varied between 17, 32, and 40.35 kg/m2 (50% irrigated; 50% irrigated + 2 mL/m2 WR-treated). The yield of unhealthy berries ranged from 10.62 to 19.58 kg/m2 (50% irrigated + 1.5 mL/m2 WR; 100% irrigated plots), and the lowest was 10.62 kg/m2. Both of the lowest and highest total yield (183.56–245.50 kg/m2) values were measured in the 50% irrigated + 2 mL/m2 WR-treated plots. The Brix % value varied between 4.2 and 5.6% (100% irrigated; 50% irrigated + 1.5 mL/m2 WR-treated); the parameters L and a/b, which characterize the colour of the berries, varied in the range of 24.27–28.88 (100% irrigated; 50% irrigated) and 2.35–2.69 (100% irrigated; 50% irrigated + 2 mL/m2 WR), in that order.
The yield of the ripened, half ripened, green, and unhealthy berries varied over the following ranges: 48.54–86.34 kg/m2; 9.22–24.78 kg/m2; 10.10–27.72 kg/m2; and 9.26–14.82 kg/m2. Compared to the results of 2019, it can be seen that the yield in 2020 was significantly less, almost half as much. There was no significant difference in the Brix and colour values (L; a/b) between the two consecutive years; the Brix value varied in the range of 3.8–5.1% in 2020, the L value in the range of 23.71–28.3; and the a/b value in the 2.41–2.67 range.

3.2. Bioactive Component of Tomato Samples

The ANOVA tests showed that the amount of almost all bioactive components was significantly different between the tomato samples exposed to drought stress (50% irrigation) and the samples receiving both 50% irrigation and WR® treatment, in both years (Table 4). The change can be explained by the fact that the two years differed in the amount of precipitation, soil humidity, and the air and soil temperature, which affected the bioactive components.
Our results showed that while there is a significant difference in the amount of γ-tocopherol between the samples of the two years, the average amount of α-tocopherol was the same. In 2019, the γ-tocopherol content of the examined samples varied between 0.35 and 2.37 mg/g, and in 2020 between 2.4 and 4.31 mg/g.
The amount of α-tocopherol was significantly different in both years in the stressed and treated samples. The highest values were measured in the samples treated with WR® tomato in both years, in the 1.5 mL/m2 WR®-treated sample in 2019, and in the 2 mL/m2 WR®-treated sample in 2020 (13.13 ± 0.42 μg.g−1; 12.09 ± 0.55 μg.g−1). The lowest amounts of α tocopherol were measured in the sample exposed to drought stress at the seedling stage (9.95 ± 0.26 μg.g−1 and 9.82 ± 0.37 μg.g−1, respectively) in both seasons, while γ-tocopherol was the lowest in stressed samples in 2019 and in the 100% irrigated sample in 2020 (0.35 ± 0.02 μg.g−1; 2.40 ± 0.04 μg.g−1).
In 2019, the highest total tocopherol content was measured in the 1.5 mL/m2 WR®-treated sample (15.5 μg.g−1), while the lowest was seen in the 50% irrigated sample (10.3 μg.g−1). In 2020, there was not such a big difference between the samples: the highest total tocopherol concentration was measured in the 50% watered and 2 mL/m2 WR®-treated sample (16.22 μg.g−1), while the lowest was measured in the 100% watered sample (12.28 μg.g−1) (Table 4).
Samples treated with 1.5% of WR® contained the significantly highest lycopene content compared to untreated samples, in both years (89.19 ± 2.94 μg.g−1 and 114.3 ± 3.18 μg.g−1). The β-carotene concentration was the highest in the 50% irrigated sample in both seasons (Table 4).
In both years, the 50% irrigated and 1.5 mL/m2 WR®-treated samples contained the highest concentration of vitamin C, and, overall, it can be said that the use of soil conditioners increased the vitamin C content of the samples (Table 4).
In 2019, the total polyphenol content in both of the WR®-treated samples was significantly higher than in the other samples. In 2020, 1.5 mL/m2 of the WR®-treated sample had significantly higher amounts of total polyphenols than the other samples. Regarding the average values, there was no significant difference between the two vintages in any of the parameters.
Similar results were obtained for the antioxidant capacity values: in 2019, the highest value was measured in the 50% irrigated, 1.5 mL/m2 WR®-treated sample, and the lowest in the 50% irrigated sample. In 2020, the antioxidant capacity of the drought-stressed sample was also the smallest; the values of the other three samples did not differ significantly from each other (Table 4).

4. Discussion

During the analysis of tomato cultivation data and the most important bioactive components, we found a significant difference between the two investigated years, which was expected based on the literature and previous experience [31]; therefore we also evaluated the measurement results of samples from different years separately. Canonical discriminant analysis based on cultivation data and laboratory data showed that 100% of original grouped cases were correctly classified to the corresponding year, so the results of the two years cannot be evaluated together, but only separated into years (Figure 3).
During the examination of the seedlings, we compared three main parameters—the height of the plants, number of true leaves, and the stem diameter—which characterize the vitality and growth of the plants. In both investigated years, we found that the height of the 100% watered seedlings was the highest, and we observed a significant difference compared to the other treatments. In contrast to the results of Sultana et al. [23], we did not observe a significant change in the height of the plants when we applied the water-retention product.
The test results of the seedlings only showed a significant difference between the treated samples in 2020, similar to the number of true leaves; the stem diameter of the 100% watered seedlings was larger than that of the other samples.
The comparison of the results of the two years shows that there is a significant difference between the seasons, and all three examined parameters showed higher values in 2020.
In order to ensure the survival of the seedlings, the drought-stressed plants had to be given additional irrigation to prevent them from wilting. Converting the amount of all irrigations, this corresponded to 59.84%. In the case of samples treated with a water-retaining agent, no additional irrigation was necessary; the 50% irrigation amount was sufficient.
Tukey’s multiple range test for all three investigated parameters showed that the two WR®-treated samples did not differ from each other, but they differed significantly from the 50% and 100% irrigated samples as well and in all cases the results were lower, than the control samples (Table 2). Contrary to the results of Carmen et al. [22], we found that no positive effect of the water-retaining agent on the height of the seedlings, the number of true leaves, and the diameter of the stem could be demonstrated at the seedling stage.
We performed the discriminant analysis on the field data (yield, Brix, and colour values L and a/b) and found that is possible to determine, with a 78,1% probability, which treatment the samples received during seedling cultivation (Figure 4a).
The results showed that the stress effect at the seedling stage had no significant effect on the yield average, Brix value, and colour of tomatoes. Based on these observations, and similar to the research of [32], it can be said that under balanced growing conditions, the plant eliminates the stress effect, as regards growing parameters.
In contrast to the cultivation data, we found a significant difference in the amount of bioactive metabolites in tomatoes between the different treatments. We performed a discriminant analysis on the data and found that by evaluating the measurement results of only the bioactive components, it is possible to determine with 100% probability which treatment the samples received during seedling cultivation (Figure 4b). These results prove that drought stress at the seedling stage and the use of soil conditioners significantly influence the composition of the bioactive compounds of the crop.
At different stages of the plant’s development, a lack of water and drought stress cause different problems. Although the conditions of field cultivation were the same during the cultivation of the plants, the seedling stress had a significant effect on the bioactive components of the crop. Antioxidant compounds in tomatoes, like lycopene, vitamin C, and polyphenols, reacted much more sensitively to growing conditions and water supply.
The vitamin E group involves four tocopherols (α, β, δ, and γ), and four tocotrienols (α, β, δ, and γ) which are non-enzymatic lipid-soluble components with high antioxidant activity. In foods, α-tocopherol and γ-tocopherol are the more characteristic forms [33], so, in our studies, we focused on these two derivatives. Based on the results of Raiola and coworkers [33], irrigation, light, and Na levels have a significant effect on the biosynthetic pathway of tocopherol derivatives in tomato. The level of α-tocopherol increased during ripening in all tissues, though its increase was largest between the light red and red stages. Based on the data found in the literature, the total tocopherol content of tomato varies between 2 and 14.7 μg.g−1, which is the same as our measured values [34].
The results of Conti et al. [35] showed that the antioxidant activity of tomatoes exposed to drought stress was significantly higher than that of irrigated tomatoes. Tocopherols contribute to the antioxidant capacity values with their very strong antioxidant effect. Our measurements, on the other hand, showed that the tocopherol content of the samples treated with the soil treatment agent was higher. Based on this, seedling stress exerts its effect in a different way compared to the effect of drought in the field. Comparing the results of the two years, it can be seen that the use of the water retainer resulted in higher total tocopherol levels in tomato in both years compared to the stressed samples.
The red colour of tomato is a result of two carotenoid pigments, lycopene and β-carotene. From a nutritional point of view, lycopene is the most important bioactive compound in tomatoes due to its beneficial effects on human health [32]. The regulation of carotenoid biosynthesis and the accumulation of lycopene during tomato fruit ripening are widely studied. Riggi et al. [36] and Atkinson et al. [37] described how as a result of drought stress, the lycopene content decreases compared to irrigated plants; however, the β-carotene content showed a positive increase. In contrast, Theobald and coworkers [38] found that lycopene content increased in fruits exposed to drought. Our results agree with these previous studies, despite the fact that the samples were only exposed to drought stress at the seedling stage.
The β-carotene concentration was the highest in the 50% irrigated sample in both seasons, which means that this compound was produced in the plants exposed to the greatest seedling stress. The two most important pigments of tomatoes, β-carotene and lycopene, developed in opposite ways under stress and under the influence of the soil treatment agent, which shows that the biosynthesis of pigments is already significantly affected by abiotic influences at the seedling stage. When comparing the two seasons, it can be seen that while the amount of β-carotene was on average higher in 2019 than in 2020, the amount of lycopene was lower. In terms of the total amount of carotene, it was significantly higher in 2020 than in 2019, which can be explained by the difference between the years.
Vitamin C is a water-soluble vitamin, and acts as a cofactor of numerous enzymes in the human body. The degradation of vitamin C in tomato is affected by the circumstances of the storage and injuries, while its formation increases under better light conditions and is also affected by fruit maturity, the season, soil, and agricultural technologies [39]. Conti and co-workers [35] found that pulps and peel of several Italian tomato varieties contain a lower concentration of ascorbic acid under drought stress compared to irrigated plants and control groups. Our experience supported the same conclusion, where during the seedling stage drought stress also reduced the amount of vitamin C in tomato fruit.
Oxidative free radicals can be considered as the causes of many diseases in the human body, such as cancer, inflammation, and coronary diseases, amongst others. The antioxidants found in our food, such as vitamin C, tocopherols, carotenoids, and the phenolic compounds present in tomatoes, scavenge free radicals, which explains their health-promoting effect; they can reduce the potential stress caused by free radicals [40].
Klunklin and Savage [41] investigated four tomato cultivars under well-watered and drought stress conditions and found that the results of DPPH radical scavenging activity showed significantly higher levels when the plants had been exposed to drought stress. Their result concerning total phenolic content was similar, with the drought-stressed tomatoes showing significantly higher values than the well-watered ones. Our results show that tomatoes exposed to drought stress at the seedling stage contained the least polyphenols and lowest antioxidant capacity as well (Table 4), which proves that seedling stress had the opposite effect on the antioxidant activity and total polyphenol content of the fruits.
Vitamin C, antioxidant capacity, and total polyphenol values were also the highest in the sample treated with 1.5 mL/m2 WR® (338.1 ± 13.7 μg/g; 1.54 ± 0.17 mMTr/kg; mg GAE/kg) in 2019, and the same was observed in 2020 (221.5 ± 11.1 μg/g; 0.91 ± 0.07 mMTr/kg; 504 ± 44 GAE/kg). Overall, we found that the antioxidant components in tomatoes treated with WR® were higher compared to the untreated samples (Table 4).
It has been observed in the literature that abiotic and biotic stresses stimulate the excessive production of reactive oxygen species (ROS) [42,43]. Several studies support the claim that the plant protects itself against the effects of ROS by increasing antioxidant enzyme activity and the production of antioxidant compounds in cases of infections and injuries [44,45].
Our results did not fully confirm this, since only the amount of β-carotene was significantly higher in the fruits of plants exposed to drought stress, while the amount of antioxidant capacity, polyphenols, and vitamin C was higher in the fruits of plants that received a balanced water supply in the seedling phase.
The positive effect of insufficient irrigation on tomato fruit quality has been reported in several publications [32,46]. This was mainly due to the reduced water content of fruit and low dilution of bioactive components in fruits rather than the accumulation of various compounds such as sugars. Since we found no differences in the Brix value, which correlates well with the dry matter content, between the samples we examined, the higher values of bioactive components in tomato fruits are not caused by the concentrating.
Chen et al. [32] found that tomato fruit quality was not affected by water restriction in the seedling stage, the effect of which is too early for that. Hao et al. [45] described how most photosynthetic indicators showed a decreasing trend under water stress, so they had a negative effect on the physiological values of tomatoes, but they partially returned to the initial value after rehydration. It was also shown that water stress had a greater effect on physiological parameters during the anthesis period than during seedling and fruit growth.
This is contradicted by our results regarding bioactive components, since in both years we found that seedlings exposed to drought stress, grown under ideal conditions, and treated with soil conditioners can be distinguished from each other, despite the fact that there was only a difference between their cultivation during the seedling period. All of this may prove that rehydration is not sufficient to completely restore the metabolomic processes of stressed plants.

5. Conclusions

The seedling drought stress and the water retainer treatments significantly influenced the composition of the bioactive components of the crop, but at the same time, it can be said that the seasonal effect was also significant. Although, as described in the literature, the effect of drought stress at the seedling stage is reversible, our results proved the opposite. The amount and composition of the most important bioactive components in the tomato crop change significantly compared to seedlings grown under optimal conditions. Using water-retaining agents that improve the water-retaining effect of the soil, similar values are obtained for some significant components in treated samples and those irrigated with a 100% intensity, which proves that the use of water-retaining agents also has a positive effect on the development of tomatoes during the seedling stage. Although the biochemical processes caused by drought stress for tomato seedlings cannot be completely reversed, the difference in cultivation does not cause a significant change in the quantity and quality of the crop in the case of the Unorosso variety.
However, the results lead to the conclusion that this difference can be significant for other genotypes, so it is worth paying attention to the use of soil treatment agents under open fielding and to investigate different varieties of tomato. It can be emphasized that this effect can be achieved with a water retainer produced completely naturally and degradable food industry by-products.

Author Contributions

Conceptualization, R.A.T.-F. and B.I.S.S.; methodology, R.A.T.-F. and B.I.S.S.; formal analysis, Á.M.-M.; investigation, R.A.T.-F. and B.I.S.S.; resources, data curation, R.A.T.-F.; writing—original draft preparation, B.I.S.S.; writing—review and editing, R.A.T.-F. All authors have read and agreed to the published version of the manuscript.

Funding

This research received no external funding.

Data Availability Statement

The raw data supporting the conclusions of this article will be made available by the authors on request.

Conflicts of Interest

The authors declare no conflicts of interest.

References

  1. FAOSTAT. Statistical Databases; Food and Agriculture Organization of the United Nations, FAOSTAT: Rome, Italy, 2020; Available online: http://www.fao.org/faostat/en/#data/QC (accessed on 13 December 2022).
  2. Giovannucci, E.; Ascherio, A.; Rimm, E.B.; Stampfer, M.J.; Colditz, G.A.; Willett, W.C. Intake of carotenoids and retino in relation to risk of prostate cancer. J. Natl. Cancer Inst. 1995, 87, 1767–1776. [Google Scholar] [CrossRef] [PubMed]
  3. Mahakun, N.; Leeper, P.W.; Burns, E.E. Acidic constituents of various tomato fruit types. J. Food Sci. 1979, 44, 1241–1244. [Google Scholar] [CrossRef]
  4. Warner, J.; Tan, C.S.; Zhang, T.Q. Water management strategies to enhance fruit solids and yield of drip irrigated processing tomato. Can. J. Plant Sci. 2007, 87, 345–353. [Google Scholar] [CrossRef]
  5. Ragab, M.E.; Arafa, Y.E.; Sawan, O.M.; Fawzy, Z.F.; El-Sawy, S.M. Effect of irrigation systems on vegetative growth, fruit yield, quality and irrigation water use efficiency of tomato plants (Solanum lycopersicum L.) grown under water stress conditions. Acta Sci. Agric. 2019, 3, 172–183. [Google Scholar]
  6. Macua, J.I.; Lahoz, I.; Arzoz, A.; Garnica, J. The influence of irrigation cut-off time on the yield and quality of processing tomatoes. Acta Hortic. 2003, 613, 151–153. [Google Scholar] [CrossRef]
  7. Nuruddin, M.M.; Madramootoo, C.A.; Dodds, G.T. Effects of Water Stress at Different Growth Stages on Greenhouse Tomato Yield and Quality. HortScience 2003, 38, 1389–1393. [Google Scholar] [CrossRef]
  8. Kumar, R.; Solankey, S.; Singh, M. Breeding for drought tolerance in vegetables. Veg. Sci. 2012, 39, 1–15. [Google Scholar]
  9. Zdravković, J.; Jovanović, Z.; Djordjević, M.; Girek, Z.; Zdravković, M.; Stikić, R. Application of stress susceptibility index for drought tolerance screening of tomato populations. Genetika 2013, 45, 679–689. [Google Scholar] [CrossRef]
  10. Helyes, L.; Bőcs, A.; Pék, Z. Effect of water supply on canopy temperature, stomatal conductance and yield quantity of processing tomato (Lycopersicon esculentum Mill.). Int. J. Hortic. Sci. 2010, 16, 13–15. [Google Scholar] [CrossRef]
  11. Nahar, K.; Gretzmacher, R. Effect of water stress on nutrient uptake, yield and quality of tomato (Lycopersicon esculentum Mill.) under subtropical conditions. Bodenkultur 2002, 53, 45–51. [Google Scholar]
  12. Ghanem, K.h.M.; Abou-Shleel, S.M.; El-Saka, Z.I. Evaluating Different Tomato Genotypes for Drought. Egypt. J. Plant Breed. 2016, 20, 995–1008. [Google Scholar] [CrossRef]
  13. Shamim, F.; Farooq, K.; Waheed, A. Effect of different water regimes on biometric traits of some tolerant and sensitive tomato genotypes. J. Anim. Plant Sci. 2014, 24, 1178–1182. [Google Scholar]
  14. Giuliani, M.; Nardella, E.; Gagliardi, A.; Gatta, G. Deficit Irrigation and Partial Root-Zone Drying Techniques in Processing Tomato Cultivated under Mediterranean Climate Conditions. Sustainability 2017, 9, 2197. [Google Scholar] [CrossRef]
  15. Urlić, B.; Runjić, M.; Mandušić, M.; Žanić, K.; Selak, G.V.; Matešković, A.; Dumičić, G. Partial root-zone drying and deficit irrigation effect on growth, yield, water use and quality of greenhouse grown grafted tomato. Agronomy 2020, 10, 1297. [Google Scholar] [CrossRef]
  16. Casa, R.; Rouphael, Y. Effects of partial root-zone drying irrigation on yield, fruit quality, and water-use efficiency in processing tomato. J. Hortic. Sci. Biotechnol. 2014, 89, 389–396. [Google Scholar] [CrossRef]
  17. Patanè, C.; Tringali, S.; Sortino, O. Effects of deficit irrigation on biomass, yield, water productivity and fruit quality of processing tomato under semi-arid Mediterranean climate conditions. Sci. Hortic. 2011, 129, 590–596. [Google Scholar] [CrossRef]
  18. Al-Selwey, W.A.; Alsadon, A.A.; Al-Doss, A.A.; Solieman, T.H.; Dewir, Y.H.; Ibrahim, A.A. Effect of deficit irrigation on total yield, fruit physical characteristics, and nutritional value of four drought tolerant tomato (Solanum lycopersicum L.) genotypes. J. Agric. Sci. Technol. 2021, 23, 1105–1118. [Google Scholar]
  19. Medyouni, I.; Zouaoui, R.; Rubio, E.; Serino, S.; Ahmed, H.B.; Bertin, N. Effects of water deficit on leaves and fruit quality during the development period in tomato plant. Food Sci. Nutr. 2021, 9, 1949–1960. [Google Scholar] [CrossRef]
  20. El-Hady, O.A.; Abd El-Kader, A.A.; Shafi, A.M. Physico-bio-chemical properties of sandy soil conditioned with acrylamide hydrogels after cucumber plantation. Aust. J. Basic Appl. Sci. 2009, 3, 3145–3151. [Google Scholar]
  21. Chen, F.; Lu, X. Effects of Soil Texture and Water Retaining Agent on the Emergence of Processing Tomatoes. J. Agric. Sci. 2009, 1, 148. [Google Scholar] [CrossRef]
  22. Carmen, B.; Sumalan, R.; Schmidt, B.; Sumalan, R.L. Researches Concerning the Effects of Incorporation Into the Soil of Water-Retainer Polymers on Morpho-Physiological Traits in Bean (Phaseolus sativum L.) plantlets Subjected to Drought. J. Hortic. For. Biotechnol. 2018, 22, 35. [Google Scholar]
  23. Sultana, S.; Shariff, M.A.; Hossain, M.A.; Khatun, A.; Huque, R. Effect of Super water absorbent (SWA) hydrogel on productivity and quality of Tomato. Arch. Appl. Sci. Res. 2016, 8, 5–9. [Google Scholar]
  24. Helyes, L.; Varga, G. Irrigation demand of tomato according to the results of three decades. Acta Hortic. 1994, 376, 323–328. [Google Scholar] [CrossRef]
  25. Singleton, V.L.; Orthofer, R.; Lamuela-Raventós, R.M. Analysis of total phenols and other oxidation substrates and antioxidants by means of folin-ciocalteu reagent. Methods Enzymol. 1999, 299, 152–178. [Google Scholar] [CrossRef]
  26. Brand-Williams, W.; Cuvelier, M.E.; Berset, C. Use of a free radical method to evaluate antioxidant activity. LWT-Food Sci. Technol. 1995, 28, 25–30. [Google Scholar] [CrossRef]
  27. Nagy, Z.; Daood, H.; Ambrózy, Z.; Helyes, L. Determination of Polyphenols, Capsaicinoids, and Vitamin C in New Hybrids of Chili Peppers. J. Anal. Methods Chem. 2015, 2015, 102125. [Google Scholar] [CrossRef]
  28. Daood, H.G.; Bencze, G.; Palotás, G.; Pék, Z.; Sidikov, A.; Helyes, L. HPLC analysis of carotenoids from tomatoes using cross-linked C18 column and MS detection. J. Chromatogr. Sci. 2014, 52, 985–991. [Google Scholar] [CrossRef]
  29. Abushita, A.A.; Hebshi, E.A.; Daood, H.G.; Biacs, P.A. Determination of antioxidant vitamins in tomatoes. Food Chem. 1997, 60, 207–212. [Google Scholar] [CrossRef]
  30. Dobrescu, A.; Scorza, L.C.T.; Tsaftaris, S.A.; McCormick, A.J. A “Do-It-Yourself” phenotyping system: Measuring growth and morphology throughout the diel cycle in rosette shaped plants. Plant Methods 2017, 13, 95. [Google Scholar] [CrossRef]
  31. Schmidt-Szantner, B.; Gasztonyi, M.; Milotay, P.; Tömösközi-Farkas, R. Effect of irrigation and fertilisation on the biologically active components of tomato. Acta Aliment. 2022, 51, 270–281. [Google Scholar] [CrossRef]
  32. Chen, J.; Kang, S.; Du, T.; Qiu, R.; Guo, P.; Chen, R. Quantitative response of greenhouse tomato yield and quality to water deficit at different growth stages. Agric. Water Manag. 2013, 129, 152–162. [Google Scholar] [CrossRef]
  33. Raiola, A.; Tenore, G.C.; Barone, A.; Frusciante, L.; Rigano, M.M. Vitamin E Content and Composition in Tomato, Fruits: Beneficial, Roles and Bio-Fortification. Int. J. Mol. Sci. 2015, 16, 29250–29264. [Google Scholar] [CrossRef] [PubMed]
  34. Zanfini, A.; Franchi, G.G.; Massarelli, P.; Corbini, G.; Dreassi, E. Phenolic compounds, carotenoids and antioxidant activity in five tomato (Lycopersium esculentum Mill.) cultivars. Ital. J. Food Sci. 2017, 29, 90–99. [Google Scholar]
  35. Conti, V.; Romi, M.; Guarnieri, M.; Cantini, C.; Cai, G. Italian Tomato Cultivars under Drought Stress Show Different Content of Bioactives in Pulp and Peel of Fruits. Foods 2022, 11, 270. [Google Scholar] [CrossRef]
  36. Riggi, E.; Patanè, C.; Ruberto, G. Content of carotenoids a different ripening stages in processing tomato in relation to soil water availability. Aust. J. Agric. Res. 2008, 59, 348–353. [Google Scholar] [CrossRef]
  37. Atkinson, N.J.; Dew, T.P.; Orfila, C.; Urwin, P.E. Influence of combined biotic and abiotic stress on nutritional quality parameters in tomato (Solanum lycopersicum L.). J. Agric. Food Chem. 2011, 59, 9673–9682. [Google Scholar] [CrossRef]
  38. Theobald, J.C.; Bacon, M.A.; Davies, W.J. Delivering enhanced fruit quality to the UK tomato industry through implementation of partial root-zone drying. Comp. Biochem. Physiol. Part A Mol. Integr. Physiol. 2007, 146, S241. [Google Scholar] [CrossRef]
  39. Valšíková-Frey, M.; Komár, P.; Rehuš, M. The effect of varieties and degree of ripeness to vitamin C content in tomato fruits. Acta Hortic. Regiotect. 2017, 2, 44–48. [Google Scholar] [CrossRef]
  40. Pellegrini, N.; Riso, P.; Porrini, M. Tomato consumption does not affect the total antioxidant capacity of plasma. Nutrition 2000, 16, 268–271. [Google Scholar] [CrossRef]
  41. Klunklin, W.; Savag, G. Effect on Quality Characteristics of Tomatoes Grown Under Well-Watered and Drought Stress Conditions. Foods 2017, 6, 56. [Google Scholar] [CrossRef]
  42. Murshed, R.; Lopez-Lauri, F.; Sallanon, H. Effect of water stress on antioxidant systems and oxidative parameters in fruits of tomato (Solanum lycopersicon L, cv. Micro-tom). Physiol. Mol. Biol. Plants 2013, 19, 363–378. [Google Scholar] [CrossRef] [PubMed]
  43. Zhang, Z.; Cao, B.; Gao, S.; Xu, K. Grafting improves tomato drought tolerance through enhancing photosynthetic capacity and reducing ROS accumulation. Protoplasma 2019, 256, 1013–1024. [Google Scholar] [CrossRef] [PubMed]
  44. Sánchez-Rodríguez, E.; Moreno, D.A.; Ferreres, F.; Rubio-Wilhelmi, M.D.M.; Ruiz, J.M. Differential responses of five cherry tomato varieties to water stress: Changes on phenolic metabolites and related enzymes. Phytochemistry 2011, 72, 723–729. [Google Scholar] [CrossRef] [PubMed]
  45. Hao, S.; Cao, H.; Wang, H.; Pan, X. The physiological responses of tomato to water stress and re-water in different growth periods. Sci. Hortic. 2019, 249, 143–154. [Google Scholar] [CrossRef]
  46. Patanè, C.; Cosentino, S.L. Effects of soil water deficit on yield and quality of processing tomato under a Mediterranean climate. Agric. Water Manag. 2010, 97, 131–138. [Google Scholar] [CrossRef]
Agronomy 14 02799 g001
Figure 1. Meteorological data (precipitation, daily minimum, maximum, and average temperature, soil humidity, and soil temperature) in Season 1.
Figure 1. Meteorological data (precipitation, daily minimum, maximum, and average temperature, soil humidity, and soil temperature) in Season 1.
Agronomy 14 02799 g001
Agronomy 14 02799 g002
Figure 2. Meteorological data (precipitation, daily minimum, maximum, and average temperature, soil humidity, and temperature) in Season 2.
Figure 2. Meteorological data (precipitation, daily minimum, maximum, and average temperature, soil humidity, and temperature) in Season 2.
Agronomy 14 02799 g002
Agronomy 14 02799 g003
Figure 3. Canonical discriminant analysis results based on the evaluation of the data of cultivation and bioactive components in 2019 and 2020.
Figure 3. Canonical discriminant analysis results based on the evaluation of the data of cultivation and bioactive components in 2019 and 2020.
Agronomy 14 02799 g003
Agronomy 14 02799 g004
Figure 4. The results of the canonical discriminant analysis based on the two-year evaluation of the harvest data (a) and the amount of bioactive components (b) in the groups treated in different ways (1: 100% irrigation; 2: 50% irrigation + 1.5% WR®; 3: 50% irrigation + 2% WR®; 4: 50% irrigation).
Figure 4. The results of the canonical discriminant analysis based on the two-year evaluation of the harvest data (a) and the amount of bioactive components (b) in the groups treated in different ways (1: 100% irrigation; 2: 50% irrigation + 1.5% WR®; 3: 50% irrigation + 2% WR®; 4: 50% irrigation).
Agronomy 14 02799 g004
Table 1. The amount and percentage of the irrigated water in 2019 and 2020 in the seedling stage.
Table 1. The amount and percentage of the irrigated water in 2019 and 2020 in the seedling stage.
Amount of the irrifated water
2019
100% irrigation50% irrigation50% irrigation + 1.5 mL/m2 WR50% irrigation + 2 mL/m2 WR
amount (L/m2)9456.2547.0547.05
percentage (%)10059.8450.0550.05
2020
100% irrigation50% irrigation50% irrigation + 1.5 mL/m2 WR50% irrigation + 2 mL/m2 WR
amount (L/m2)113.0056.5056.5061.50
percentage (%)100.0059.8450.0550.05
Table 2. Measurement data (plant height, number of true leaves, stem diameter) of seedlings at different irrigation intensities and WR® dosing. (a,b,c: Tukey’s multiple range test (p < 0.05)).
Table 2. Measurement data (plant height, number of true leaves, stem diameter) of seedlings at different irrigation intensities and WR® dosing. (a,b,c: Tukey’s multiple range test (p < 0.05)).
YearTreatmentPlant Height [cm]Number of True LeavesStem Diameter [mm]
Mean ± SDMean ± SDMean ± SD
201950% irrigation10.59 ± 0.88 b3.05 ± 0.38 a3.54 ± 0.15 a
50% irrigation + 1.5 mL/m2 WR®10.07 ± 1.00 b3.2 ± 0.16 a3.55 ± 0.02 a
50% irrigation + 2 mL/m2 WR®11.87 ± 1.62 a,b3.2 ± 0.37 a3.6 ± 0.19 a
100% irrigation13.87 ± 1.58 a3.65 ± 0.3 a3.59 ± 0.05 a
202050% irrigation14.24 ± 1.29 a4.88 ± 0.05 b4.31 ± 0.05 b
50% irrigation + 1.5 mL/m2 WR®11.88 ± 0.28 b4.45 ± 0.34 c4.10 ± 0.10 b,c
50% irrigation + 2 mL/m2 WR®11.92 ± 1.41 b4.33 ± 0.17 c3.85 ± 0.23 c
100% irrigation15.26 ± 0.74 a5.39 ± 0.08 a4.59 ± 0.12 a
Table 3. The harvesting results (ripened, half-ripe, green, unhealthy berries, yield, Brix, and colour values) of tomato samples obtained from tomato seedlings irrigated in different ways (a,b,c: Tukey’s multiple range test (p < 0.05)).
Table 3. The harvesting results (ripened, half-ripe, green, unhealthy berries, yield, Brix, and colour values) of tomato samples obtained from tomato seedlings irrigated in different ways (a,b,c: Tukey’s multiple range test (p < 0.05)).
YearTreatmentRipened Berries (kg/m2)Half-Ripe Berries
(kg/m2)		Green Berries (kg/m2)Unhealty Berries (kg/m2)Yield (kg/m2)Brix%Laba/b
Mean ± SDMean ± SDMean ± SDMean ± SDMean ± SDMean ± SDMean ± SDMean ± SDMean ± SDMean ± SD
201950% irrigation11.26 ± 0.36 a3.11 ± 0.54 a1.06 ± 0.28 a1.18 ± 0.13 a16.61 ± 0.43 a4.60 ± 0.23 a27.16 ± 1.17 a31.49 ± 1.47 a12.91 ± 0.66 a2.44 ± 0.04 b
50% irrigation + 1.5 mL/m2 WR®12.27 ± 1.33 a2.72 ± 0.56 a1.48 ± 0.29 a0.90 ± 0.21 a17.37 ± 1.73 a5.05 ± 0.42 a26.25 ± 0.75 ab32.86 ± 0.82 a12.46 ± 0.51 a2.64 ± 0.06 a
50% irrigation + 2 mL/m2 WR®10.81 ± 0.66 a3.20 ± 0.84 a1.61 ± 0.43 a0.87 ± 0.25 a16.49 ± 1.27 a4.57 ± 0.17 a26.85 ± 0.41 a31.98 ± 1.02 a12.64 ± 0.53 a2.53 ± 0.13 ab
100% irrigation11.98 ± 0.85 a 3.11 ± 0.70 a1.46 ± 0.46 a1.17 ± 0.25 a17.73 ± 1.66 a4.48 ± 0.19 a25.03 ± 0.91 b27.97 ± 1.31 b11.23 ± 0.33 b2.49 ± 0.10 ab
202050% irrigation5.01 ± 0.90 a1.68 ± 0.30 a1.28 ± 0.42 a,b0.68 ± 0.28 a8.65 ± 1.11 a4.13 ± 0.17 a24.42 ± 0.59 a30.93 ± 1.71 b12.01 ± 0.56 b2.58 ± 0.06 a
50% irrigation + 1.5 mL/m2 WR®4.53 ± 0.99 a1.71 ± 0.38 a1.35 ± 0.28 a,c0.84 ± 0.21 a8.43 ± 1.37 a4.08 ± 0.22 a25.05 ± 0.19 a31.06 ± 1.31 b12.21 ± 0.66 b2.54 ± 0.03 a
50% irrigation + 2 mL/m2 WR®4.38 ± 0.86 a1.55 ± 0.27 a1.94 ± 0.61 a0.74 ± 0.06 a8.59 ± 0.24 a4.05 ± 1.17 a26.2 ± 0.93 a31.96 ± 0.70 ab12.73 ± 0.44 b2.51 ± 0.04 a
100% irrigation6.15 ± 1.55 a1.15 ± 0.35 a0.97 ± 0.30 b0.72 ± 0.12 a8.99 ± 0.60 a4.53 ± 0.48 a27.29 ± 1.14 a33.96 ± 1.02 a13.48 ± 0.55 a2.52 ± 0.08 a
Table 4. The amount of bioactive components (α- and γ-tocopherol, lycopene, β-carotene, DPPH, total polyphenol and Vitamin C content) of tomato samples obtained from tomato seedlings irrigated in different ways. a,b,c,d: Tukey’s multiple range test (p < 0.05).
Table 4. The amount of bioactive components (α- and γ-tocopherol, lycopene, β-carotene, DPPH, total polyphenol and Vitamin C content) of tomato samples obtained from tomato seedlings irrigated in different ways. a,b,c,d: Tukey’s multiple range test (p < 0.05).
YearTreatmentα-Toco Pherol (μg/g)γ-Toco Pherol
(μg/g)		Lycopene (μg/g)β-Carotene (μg/g)Vitamin C (μg/g)DPPH (mMTr/kg)Total Polyphenol (mg GAE/kg)
Mean ± SDMean ± SDMean ± SDMean ± SDMean ± SDMean ± SDMean ± SD
201950% irrigation9.95 ± 0.26 d0.35 ± 0.02 c66.65 ± 1.34 c7.93 ± 0.53 a262.20 ± 10.60 b0.85 ± 0.13 b405 ± 31 b
50% irrigation + 1.5 mL/m2 WR®13.13 ± 0.42 a2.37 ± 0.06 a89.19 ± 2.94 a5.18 ± 0.37 b338.10 ± 13.70 a1.54 ± 0.17 a498 ± 27 a
50% irrigation + 2 mL/m2 WR®10.55 ± 0.23 c0.72 ± 0.06 b71.77 ± 1.66 b3.75 ± 0.10 c192.70 ± 6.70 c0.91 ± 0.11 b496 ± 22 a
100% irrigation 12.35 ± 0.27 b0.65 ± 0.03 b69.51 ± 1.73 c5.40 ± 0.42 b267.27 ± 5.60 b1.04 ± 0.16 b377 ± 33 b
202050% irrigation9.82 ± 0.37 c4.31 ± 0.17 a71.83 ± 1.93 c5.23 ± 0.08 a169.20 ± 7.50 b0.78 ± 0.07 b433 ± 24 b
50% irrigation + 1.5 mL/m2 WR®11.04 ± 0.3 b4.23 ± 0.19 a114.30 ± 3.18 a2.90 ± 0.11 d221.50 ± 11.10 a0.91 ± 0.07 a504 ± 44 a
50% irrigation + 2 mL/m2 WR®12.09 ± 0.55 a4.13 ± 0.13 a91.91 ± 2.85 b4.02 ± 0.09 b202.50 ± 8.20 a0.99 ± 0.07 a382 ± 33 b
100% irrigation9.99 ± 0.29 c 2.40 ± 0.04 b83.37 ± 1.73 c3.54 ± 0.08 c168.10 ± 6.60 b0.98 ± 0.14 b409 ± 29 b
Disclaimer/Publisher’s Note: The statements, opinions and data contained in all publications are solely those of the individual author(s) and contributor(s) and not of MDPI and/or the editor(s). MDPI and/or the editor(s) disclaim responsibility for any injury to people or property resulting from any ideas, methods, instructions or products referred to in the content.

Share and Cite

MDPI and ACS Style

Tömösközi-Farkas, R.A.; Molnár-Mondovics, Á.; Schmidtné Szantner, B.I. Effect of Water Retainer® During Seedling Period on Bioactive Components of Tomato (Solanum lycopersicum). Agronomy 2024, 14, 2799. https://doi.org/10.3390/agronomy14122799

AMA Style

Tömösközi-Farkas RA, Molnár-Mondovics Á, Schmidtné Szantner BI. Effect of Water Retainer® During Seedling Period on Bioactive Components of Tomato (Solanum lycopersicum). Agronomy. 2024; 14(12):2799. https://doi.org/10.3390/agronomy14122799

Chicago/Turabian Style

Tömösközi-Farkas, Rita Adél, Ágnes Molnár-Mondovics, and Barbara Ildikó Schmidtné Szantner. 2024. "Effect of Water Retainer® During Seedling Period on Bioactive Components of Tomato (Solanum lycopersicum)" Agronomy 14, no. 12: 2799. https://doi.org/10.3390/agronomy14122799

APA Style

Tömösközi-Farkas, R. A., Molnár-Mondovics, Á., & Schmidtné Szantner, B. I. (2024). Effect of Water Retainer® During Seedling Period on Bioactive Components of Tomato (Solanum lycopersicum). Agronomy, 14(12), 2799. https://doi.org/10.3390/agronomy14122799

Note that from the first issue of 2016, this journal uses article numbers instead of page numbers. See further details here.

Article Metrics

Back to TopTop