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Article

Effects of Vermicompost on Quality and Physiological Parameters of Cucumber (Cucumis sativus L.) Seedlings and Plant Productivity

Institute of Horticulture, Lithuanian Research Centre for Agriculture and Forestry, Kaunas District, LT-54333 Babtai, Lithuania
*
Author to whom correspondence should be addressed.
Horticulturae 2022, 8(11), 1009; https://doi.org/10.3390/horticulturae8111009
Received: 6 October 2022 / Revised: 24 October 2022 / Accepted: 27 October 2022 / Published: 31 October 2022
(This article belongs to the Section Vegetable Production Systems)

Abstract

:
Cucumbers productivity and fruit quality depend on seedlings’ quality. The success of seedling cultivation largely depends on the choice of a suitable substrate. Therefore the aim of this research is to determine the effect of peat-vermicompost substrates on cucumber seedling quality and crop yield. The research was carried out in a greenhouse covered with double polymeric film in the Institute of Horticulture, Lithuanian Research Centre for Agriculture and Forestry. Cucumber seedlings were grown in different substrates: peat, peat + 10% vermicompost, peat + 20% vermicompost, and peat + 30% vermicompost. The growth of cucumber seedlings in peat and vermicompost substrates was induced. They were 1.9–18.6% taller, and the leaf area of this seedlings was 1.2–1.4 time larger. Furthermore, the fresh leaves mass of these seedlings was 22.7–33.1%, and the fresh root mass was 1.1–1.5 time bigger. The addition of vermicompost to peat substrate has a positive effect on the physiological parameters in the leaves of cucumber seedlings. The total yield of cucumbers grown in peat-vermicompost substrates was 7.4–11.1% higher than that of plants whose seedlings grew in peat substrate.

1. Introduction

The quality and productivity of seedlings is influenced by the substrate. Therefore it is important to select a suitable substrate for their growth. Many materials can be used as growing media. They must be rich in nutrients and have sufficient water absorption and good aeration properties. The price of the substrate is also important; it should not be expensive. Recently, there has been increasing interest in the potential of vermicompost and its use in vegetable cultivation in the fields and as a supplement of substrates. The use of biological fertilizers such as vermicompost contributes to the preservation of the environment [1]. Vermicompost is an organic fertilizer resulting from the interaction between Californian earthworms (Eisenia fetida) and microorganisms, which break down organic matter into forms that are readily available to plants [2]. Most agricultural, urban or industrial organic wastes can be used for vermicompost production, but it must be free of toxic substances that can harm earthworms [3]. Vermicomposting is an ecological and economical way to manage agricultural waste [4]. Hence, vermicompost is an important component of organic agriculture [5]. From an ecological point of view, vermicompost is an excellent alternative to mineral fertilizers. It is a very valuable organic fertilizer containing macro- and micro-nutrients, enzymes, soil antibiotics, vitamins, growth and development hormones and humic substances [6,7]. Greenhouse and field studies examined the effects of vermicompost on vegetables, ornamental plants and field crops. Most of this research confirmed that vermicompost has positive effects on plant growth [6]. Studies show that vermicompost stimulates seed germination and promotes vegetative plant growth and root development [8,9]. Others have shown that vermicompost can improve the quality of seedlings [10]. In addition, the use of vermicompost can increase plant yield [8,11,12,13]. According to other researchers, vermicompost may increase the nutritional quality of some vegetables [14,15,16]. Lazcano and Domínguez [13] showed that the effects of vermicompost vary depending on the plant species. Vermicompost is similar to peat, with high porosity, aeration and drainage and good water retention [17]. Therefore, it is a suitable medium for growing vegetable seedlings, used alone or in a mixture with peat [18].
There are a number of reports on the incorporation of vermicompost into the soil, but there are few studies on the use of vermicompost in potting substrates. According to Atiyeh and other researchers, vermicompost has the potential for improving plant growth when added to greenhouse container media [6,19]. Bachman and Metzger [20] report that a positive effect on plant growth can be observed when 10–20% vermicompost is added to the substrate. Vermicompost is mainly used in outdoor horticulture for the fertilization of ornamental plants, while only little is known about its use in growing seedlings of these plants. According to Pour et al. [21], the effect of vermicompost on the growth and development of cabbage seedlings was not only nutritional but also affected the hormonal and biochemical properties of cabbage plants. Furthermore the use of large amounts of vermicompost, especially at the seedling stage, is not only economical but may also have a negative effect on the plant. Ievinsh [22] also noticed that a certain amount of vermicompost can have a negative impact on plant growth. According to his data, as the concentration of vermicompost in the substrate increased, seed germination and seedling growth were inhibited. Thus, the findings of this study suggest that it is important to determine the optimum amount of vermicompost in a substrate to obtain a positive effect.
Our hypothesis is that the addition of the optimum amount of vermicompost to peat substrate improves the quality of cucumber seedlings and increases plant yield. In order to verify this hypothesis, the aim of this study was to assess the effect of different rates of vermicompost on seedling growth, physiological parameters and the yield of cucumber under greenhouse conditions.

2. Materials and Methods

2.1. Growing Conditions

The investigations were carried out at the Institute of Horticulture, Lithuanian Research Centre for Agriculture and Forestry (55°60′ N, 23°48′ E), Babtai, Lithuania. Cucumbers (Cucumis sativus L.) were grown in a Multi Rovero 640 TR (“Rovero”, The Netherlands) greenhouse covered with a double polymer film in 2018–2020. The cucumbers were sown at the end of February. Cucumber seeds were sown directly into pots (12 cm diameter) filled with a substrate. The pots were arranged on racks. The nursery was heated. The plants were watered when necessary. The seedlings were cultivated for 30 days. During seedling cultivation, the day/night temperature was 20–23/15–18 °C, and the relative air humidity was 50–60%. The investigation object was the cucumber hybrid ‘Mandy’. Different substrates were investigated: peat (Profi 1, Durpeta, Lithuania), peat + 10% vermicompost, peat + 20% vermicompost, peat + 30% vermicompost. At the beginning of April, the seedlings were transplanted in the greenhouse (Figure 1A). There they were cultivated in 20 L peat bags (1 bag—2 plants). The plant density in the greenhouse was 2.5 plants per m−2 (Figure 1B). The cucumbers in the greenhouse were fertilized with “Nutrifol” (brown NPK 14 9 25 and green NPK 8 11 35) (YARA Poland, Sp. z.o.o., Poland, calcium nitrate (Yara Suomy Oy, Finland), magnesium sulfate (Zlotniki, S.A., Poland) and ammonium nitrate (PULAWY, S.A., Poland), with respect to the growth stage. The water was acidified with nitric acid. The final salt concentration was EC 2.8–3.0, acidity—pH 5.5–5.8. The end of the experiment was on 30 June. During plant cultivation, the day/night temperature was 19–26/15–19 °C, and the relative air humidity was 60–80%. The plot area was 4.8 m2. Three replications were done in a randomized block design.

2.2. Biometric Measurements

The biometrical observations were carried out at the end of the seedling growth. The seedling height was measured to the tip of the youngest leaf. The leaf area of the seedlings was measured by a “WinDias” leaf area meter (Delta-T Devices Ltd. Co-operative company, Cambridge, UK). During the investigation, the plant height and the number of leaves per plant were measured three times during vegetative growth each 10 days after transplanting the seedlings in the greenhouse. These measurements were performed in ten replicates (n = 10).

2.3. Determination of Dry Matter

To determine dry matter content in cucumber leaves, they were dried in a drying oven (Venticell, MBT, 2 Czech Republik) at 105 °C for 24 h. The measurements were performed in four replicates (n = 4).

2.4. Determination of Photosynthetic Parameters

Photosynthetic rate (Pr, μmol CO2 m−2 s−1), transpiration rate (Tr, mmol H2O m−2 s−1), stomatal conductance (gs, mol H2O m−2 s−1) and intercellular to ambient CO2 concentration (Ci/Ca) was determined 9:00–12:00 a.m. by using an LI-6400XT portable open-flow gas-exchange system (Li-COR 6400XT Biosciences, Lincoln, NE, USA). The third developed leaf of five plant was measured, each for one minute. Reference air [CO2], light intensity and the flow rate of the gas pump were set to 400 μmol mol−1, 1000 μmol m−2 s−1 and 500 mmol s−1, according to Laužikė et al. [23].

2.5. Nondestructive Measurements

Nondestructive measurements of leaf chlorophyll (CHL) and nitrogen balance (NBI) indices were performed using the Dualex 4 Scientific® (FORCE-A, Orsay, France) meter.
Spectral reflectance was measured with a leaf spectrometer (CID Bio-Science, Camas, WA, USA) from 9 to 12 a.m. Reflection spectra obtained from the leaves were used to calculate various indices according to formulas.
The normalized difference vegetation index (NDVI) shows changes in biomass content:
NDVI = (R800 − R680)/(R800 + R680)
where R800 and R680 represent the leaf reflectance integrated over a 10 nm wavelength band centered on 800 and 680 nm, respectively.
PRI shows changes in the xanthophyll cycle, using the following formula:
PRI = (R570 − R531)/(R570 + R531)
where R570 and R531 represent the leaf reflectance integrated over a 10 nm wavelength band centered on 570 and 531 nm, respectively [24,25,26].

2.6. Determination of Mineral Elements in Substrates and Leaves

The following substrate agrochemical parameters were established: acidity pH(KCl) was determined by the potentiometric method according to LST ISO 10390:2005. Electrical conductivity EC was measured by the conductometric method according to LST EN 13040:2008. Total nitrogen was determined by the Kjeldahl method according to ISO 11261:1995. The content of mobile K2O, P2O5, Ca and Mg in the substrates was determined by the Egner–Riehm–Domingo (A-L) method. In an extract of 1 M lactic acid, 3 M acetic acid and 1 M ammonium acetate buffer solution (pH−3.7), soil-to-extraction-agent ratio 1:20, was shaken for 4 h. The concentration of K2O was measured by flame emission spectroscopy. The concentration of P2O5 was measured spectrometrically using ammonium molybdate. The concentration of Ca and the concentration of Mg were measured by flame atomic absorption spectrometry.
The mineral element content was determined in seedling leaves. The total nitrogen was determined by the Kjeldahl method. Phosphorus was determined calorimetrically according to Directive 71/393 EEC. Potassium was determined by the flame photometric method according to Directive 71/250 EEC. Calcium was determined by the atomic absorption spectrometric method according to Directive 71/250 EEC, and magnesium was determined by the atomic absorption spectrometric method according to Directive 73/46/ EEC.

2.7. Yielding of Plants

The cucumber yield was recorded at every harvest. Cucumber fruits were harvested three times a week; next they were separated into marketable and non-marketable (irregularly shaped, with spots, etc.) ones. The total yield was calculated by aggregating each harvest.

2.8. Determination of Nitrates

The nitrate concentration in cucumber fruits was measured by a potentiometric method [27] using an ion meter (Oakton, Fairfax, VA, USA) combined with a nitrate ion selective electrode HI4113 (HANNA instruments, Woonsocket, RI, USA).

2.9. Statistical Analysis

Statistical analysis was performed using Microsoft Excel 2016 and Addinsoft XLSTAT 2022.1 XLSTAT statistical and data analysis (Long Island, NY, USA). The data are presented as means of three replicates (n = 3) linked to the sampling points. One-way analysis of variance (ANOVA), followed by Tukey’s significant difference test (p < 0.05) for multiple comparisons, were used to evaluate differences between means of measurements.

3. Results

The agrochemical characteristics of different substrates are shown in Table 1. The addition of vermicompost to peat substrate had an impact on the content of macronutrients (Table 1). The contents of phosphorus and magnesium in peat–vermicompost substrates were almost unchanged compared to the peat substrate. The addition of vermicompost into peat substrate had the greatest effect on potassium content; its content in peat + 30% vermicompost substrate increased 5.8 times compared to the potassium content in peat substrate.
Vermicompost added to a peat substrate had an effect on the biometric parameters of the seedlings. Seedlings grown in peat and vermicompost substrates were taller, had more leaves and had a larger leaf area compared to seedlings grown in peat substrate alone (Table 2, Figure 1). Seedlings grown in peat + 20% vermicompost substrate were the tallest. The largest area of leaves was formed by seedlings grown in peat + 30% vermicompost substrate. These seedlings had more leaves, did not elongate and, significantly, had the largest diameter of stem.
Vermicompost added to a peat substrate had a positive effect on the fresh leaf and root mass of seedlings. The fresh leaf mass was 22.7–33.1% higher, and the fresh root mass was 1.5 times higher for seedlings grown on peat substrate without vermicompost (Figure 2A). The dry matter accumulation in the leaves of cucumber seedlings was significantly affected by substrates. The addition of more vermicompost to the peat substrate increased the dry matter content up to 12.4–19.0% in the seedling leaves compared to peat without vermicompost (Figure 2B). Seedlings grown in peat+30% vermicompost substrate accumulated the highest dry matter content in the leaves. However, the amount of added vermicompost did not differ significantly.
The addition of vermicompost to the peat substrate increased the mineral content in the leaves of cucumber seedlings (Table 3). Seedlings grown on peat–vermicompost substrates accumulated 6.1–18.8% more nitrogen, 5–13.3% more phosphorus, 1.4–1.8 times more potassium, 2.3–4.6% more calcium and 10–35% more magnesium in their leaves than seedlings grown in peat without vermicompost. Significantly higher amounts of nitrogen, potassium and magnesium were determined in cucumber seedlings leaves grown in peat + 30% vermicompost substrate.
Cucumber seedlings grown in different peat–vermicompost substrates grew and developed unequally (Table 4). In all three measurements, seedlings grown in the peat–vermicompost substrate were the tallest. They were 5.9–15.8%, respectively, taller than seedlings grown in peat without vermicompost. After 3 weeks of transplantation, seedlings grown in peat + 30% vermicompost substrate were the tallest and formed the most leaves.
The leaves of cucumber seedlings grown in both peat and peat–vermicompost substrates had almost the same chlorophyll index (except for seedlings grown in peat + 20% vermicompost substrate) (Figure 3A). During the growing season, both chlorophyll and NBI indices (Figure 3B) were higher in the leaves of cucumbers whose seedlings were grown in peat–vermicompost substrates than in the leaves of plants whose seedlings were grown only in peat. When a larger amount of vermicompost was added to the peat substrate during seedling growth, the chlorophyll and NBI indices were higher in the leaves of the plants at the time of fruiting.
Vermicompost added to peat substrate increased the functional activity of the photosynthetic apparatus of cucumber plants. As the amount of vermicompost in the peat increased, the photosynthetic rate, intercellular CO2 and transpiration rate increased in the leaves of cucumber seedlings (Table 5). The highest photosynthetic parameters were found in the leaves of seedlings grown in peat + 30% vermicompost substrate. This trend was maintained throughout the growing season.
The NDVI and PRI indices were almost equal in the leaves of seedlings grown in the different substrates. However, during the growing season, these indices were higher in the leaves of plants whose seedlings were grown on peat–vermicompost substrates (Figure 4). Thus, the NDVI and PRI values showed that the plants were subject to very good conditions during plant vegetation. At the peak of fruiting and the end of the harvest, NDVI and PRI indices in the leaves of plants whose seedlings were grown in peat + 30% vermicompost substrate were the tallest.
Yield data of cucumbers whose seedlings were grown in peat–vermicompost substrates are shown in Figure 5A. The addition of vermicompost into the peat substrate had a positive effect on the yield of cucumbers. As the vermicompost rate increased, the overall yield increased. The early yield of cucumbers whose seedlings were grown in peat–vermicompost substrates was 4.7–21.5% taller than that of cucumbers whose seedlings were grown in peat substrates. The total yield of these cucumbers was also 7.4–11.1% higher, compared to the yield of plants whose seedlings grew in peat substrate. The highest early yields were cucumbers whose seedlings were grown in peat + 10% vermicompost substrates. The cucumber whose seedlings grew in peat + 20% vermicompost and peat + 30% vermicompost substrates had the highest total yield.
Growing seedlings in peat–vermicompost substrates had a negative effect on the biochemical parameters of cucumber fruit: the content of total sugar and ascorbic acid in the fruit decreased, and the content of nitrates increased. When the highest amount of vermicompost was added to peat (30%), the cucumber fruit accumulated the highest nitrate content (Figure 5B).
The analyzed indices differ significantly between seedlings grown in peat without vermicompost and in peat with different ratios of vermicompost (Figure 6). Peat + 10% vermicompost substrates had the least influence on the investigated indices. Seedlings grown in peat + 30% vermicompost substrates had more leaves and the largest leaf area. These seedlings accumulated more minerals in their leaves. This substrate also had the greatest positive effect on photosynthetic parameters in the leaves of the seedlings.
The PCA scatterplot shows an average of all measurement results that were presented in this experiment (Figure 7). The main two factors of PCA explained 65.42% of the total variance in response to the substrate. According to F1, peat and peat + 10% vermicompost were significantly different from peat with 20% and 30% vermicompost. Meanwhile, according to F2, peat was different from peat with 10% vermicompost. Summarizing these results we can say that vermicompost has a significant effect for cucumbers; meanwhile, there are no significant differences between 20% and 30% added vermicompost.

4. Discussion

An increase in plant growth because of the addition of vermicompost to the substrate has been reported in different studies. Biologically active materials in vermicompost promote plant growth [11,28,29]. It was determined that vermicompost stimulates the growth of tomatoes, peppers, garlic, and sweet corn [6,8,11,12,14,28,29,30]. Joshi et al. [31] reported that the application of vermicompost increased seed germination, stem height, leaf number, leaf area, leaf dry weight, root length, root number, total yield, chlorophyll and nutrients content and improved fruit and seed quality. Sheep-manure vermicompost as a soil supplement increased tomato plant height significantly [14]. Adding 10% vermicompost to the soil increased the biomass and leaf area of the studied plants (radish, calendula, etc.) [29]. In agreement with the findings of these researchers, the results of our study showed that vermicompost added to peat substrate had a positive effect on the biometric parameters of cucumber seedlings (Table 1). Seedlings grown in peat–vermicompost substrates were taller and had more leaves and a larger leaf area. Vermicompost application in growing media has an impact on the fresh and dry weight of plants. Azarmi et al. [32] reported an increase in the leaf dry weight of cucumber grown in a substrate with vermicompost. Other researchers indicate that the application of vermicompost results in the faster growth and higher dry weight of cucumber seedlings than seedlings grown without vermicompost [33,34,35]. Vermicompost in the transplant media resulted in greater fresh shoot weights. In addition, 20% of vermicompost is enhanced shoot and root weight, leaf area and shoot: root ratios of marigold seedlings [36]. In our study, cucumber seedlings grown in peat–vermicompost substrates had a higher fresh leaf and fresh root mass than seedlings grown in peat alone. The dry matter content in leaves was also higher (Figure 2).
The addition of vermicompost into the soil or substrate has a positive effect on the accumulation of mineral elements in the leaves of plants. According to Azarmi et al. [30], vermicompost application to the soil had a significant positive effect on the growth of tomato plants in the field, on yield and on the mineral element content in the leaves of the plants compared to the control. Treatments with vermicompost showed increased accumulation of P, K, Ca and Fe in chickpea seedlings [37]. Lazcano and Domínguez [11] indicate that plants cultivated with vermicompost showed a slightly higher foliar P content. The use of different amounts of vermicompost significantly increased the content of Zn and auxin in the leaves of cabbage seedlings [21]. In agreement with the data of these authors, the results of our study showed that cucumber seedlings grown in a peat–vermicompost substrate accumulated more minerals in the leaves, and their content depended on the amount of vermicompost in the substrate.
The content of chlorophyll in leaves is influenced by several factors: nutrient concentration, plant genotype, different stress factors, etc. [38,39,40]. Chlorophyll is involved in photosynthesis and other metabolic processes. Therefore, it is important to know whether growing media affect the total chlorophyll content in plants. According to Bhat et al. [41], organic substrates did not have a positive effect on the chlorophyll index in lettuce leaves. In other experiments, the chlorophyll index gradually increased during the growing season in leaves of lettuce, tomato and cauliflower grown in substrates with vermicompost [42]. Azarmi et al. [32] reported that leaf dry weight, chlorophyll content and the number of leaves of cucumber increased when vermicompost was applied. The nitrogen balance index (NBI) is one of the important indicators of plant growth. The NBI indicates the nitrogen status of plants [43]. Padila and other [44] research data demonstrated that fluorescent indices (chlorophyll content, flavonol content and nitrogen balance index (NBI)) can be used as indicators of nitrogen status in cucumber crops. In our experiment, the chlorophyll and NBI indices of cucumber leaves increased during the growing season with increasing vermicompost content in the substrate (Figure 3).
Vegetation indices, the normalized difference vegetation index (NDVI), photochemical reflectance index (PRI) and modified chlorophyll absorption in reflectance index (MCARI), help to analyze crop growth, vigor and several other vegetation indices, including biomass and chlorophyll content [45]. Studies by Prasad and other researchers [46] have shown that there were no significant differences in the value of the normalized difference vegetation index (NDVI) in the leaves of strawberries grown in different substrates, but there were significant differences in the values of the photochemical reflectance index (PRI) and the modified chlorophyll absorptance reflectance index (MCARI). Our data showed that the addition of vermicompost to peat substrate increased the NDVI and PRI indices values in cucumber leaves (Figure 4A,B).
Several reports have demonstrated that the type of growing media used for some vegetable growing influences yield parameters. Various studies have demonstrated that the use of vermicompost has a positive effect on plant yield. The addition of vermicompost to the substrate resulted in a higher total yield of strawberry [47], fruit yield of eggplant [11], total yield of cucumber [32], higher marketable yield of tomato [14,29] and yield of lettuce [48]. In agreement with the results of many authors, the addition of vermicompost into a peat substrate in our study resulted in a higher cucumber yield (Figure 5A). In addition, plant growth and yield depend on the amount of vermicompost added to the substrate [11,32,49]. Some researchers report that the addition of 15–25% vermicompost to the substrate promotes better yields of lettuce, cauliflower and tomatoes [42]. Arankon and others [12] argue that peppers grown in potting mixtures containing 40% food-waste vermicompost yielded 45% higher fruit weight than those grown in substrate without vermicompost. Low doses of vermicompost (10%) and high doses (40%) produced lower yields in the tomato plants. However, the addition of 20% vermicompost resulted in the highest tomato yield [49]. Our study showed that cucumbers whose seedlings were grown in peat + 30% vermicompost substrates generated the highest yield (Figure 5A).
According to some researchers, the use of vermicompost in the cultivation of vegetables affects their internal quality [50]. Wang et al. [16] state that vermicompost application significantly increased the contents of soluble sugar, soluble protein, vitamin C, total phenols, and total flavonoids in Chinese cabbage leaves. According Zhao et al. [51], after the application of 3000 kg ha−1 of vermicompost to the soil, the difference between the nitrate contents of cucumber fruits was not significant between the vermicompost amendment and the lack of fertilizer amendment. Contrary to Wang and other research [16], our research results showed that vermicompost incorporated in peat had no positive effect on cucumber fruit quality. The addition of more vermicompost to the peat substrate resulted in higher nitrate accumulation in cucumber fruits (Figure 5B).

5. Conclusions

The addition of vermicompost to the peat substrate influenced the biometric parameters of cucumber seedlings, the physiological parameters and the content of minerals in the leaves, as well as the early and total yield of the plants. Seedlings grown in peat–vermicompost substrates were 1.9–18.6% taller, had more leaves and 1.2–1.4 times larger leaf area. The addition of vermicompost to the peat substrate resulted in the accumulation of more minerals in the leaves of the cucumber seedlings. Thus, the positive effect of the admixture of vermicompost into peat substrate on photosynthetic parameters in the leaves of cucumber seedlings was observed. As the amount of vermicompost in the peat increased, the photosynthetic rate, intercellular CO2 and transpiration rate increased in leaves of cucumber seedlings. The total yield of cucumbers grown in peat–vermicompost substrates was 7.4–11.1% higher than that of plants whose seedlings grew in peat substrate.

Author Contributions

Conceptualization, J.J., K.L. and D.K.; methodology, J.J., K.L. and D.K.; software, K.L.; validation, J.J.; formal analysis, J.J.; investigation, J.J. and K.L.; resources, J.J.; data curation, J.J. and K.L.; writing—original draft preparation, J.J.; writing—review and editing, J.J., K.L. and D.K.; visualization, J.J.; supervision, K.L. and D.K. All authors have read and agreed to the published version of the manuscript.

Funding

This research received no external funding.

Institutional Review Board Statement

Not applicable.

Data Availability Statement

Not applicable.

Acknowledgments

This work was carried out within the framework of the long-term research program “Horticulture: agro-biological basics and technologies” implemented by the Lithuanian Research Centre for Agriculture and Forestry.

Conflicts of Interest

The authors declare no conflict of interest. The funders had no role in the design of the study; in the collection, analyses, or interpretation of data; in the writing of the manuscript, or in the decision to publish the results.

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Figure 1. Cucumber seedlings grown in peat–vermicompost substrates (1—peat; 2—peat + 10% vermicompost; 3—peat + 20% vermicompost; 4—peat + 30% vermicompost) (A), trial of cucumbers in the greenhouse (B).
Figure 1. Cucumber seedlings grown in peat–vermicompost substrates (1—peat; 2—peat + 10% vermicompost; 3—peat + 20% vermicompost; 4—peat + 30% vermicompost) (A), trial of cucumbers in the greenhouse (B).
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Figure 2. The effect of peat–vermicompost substrates on the fresh leaf and root mass (A) of cucumber seedlings and dry matter content (B) in the leaves of seedlings: 1—peat; 2—peat + 10% vermicompost; 3—peat + 20% vermicompost; 4—peat + 30% vermicompost. Means with different letters are significantly different at the p < 0.05 level according to Tukey’s significant difference test. Error bars shows standard deviation.
Figure 2. The effect of peat–vermicompost substrates on the fresh leaf and root mass (A) of cucumber seedlings and dry matter content (B) in the leaves of seedlings: 1—peat; 2—peat + 10% vermicompost; 3—peat + 20% vermicompost; 4—peat + 30% vermicompost. Means with different letters are significantly different at the p < 0.05 level according to Tukey’s significant difference test. Error bars shows standard deviation.
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Figure 3. The effect of peat–vermicompost substrates on chlorophyll (A) and NBI (B) indices in the leaves of cucumbers seedlings: 1—peat; 2—peat+10% vermicompost; 3—peat+20% vermicompost; 4—peat+30% vermicompost. Different letters above the columns are significantly different at the p < 0.05 level according to Tukey’s significant difference test. Error bars show standard deviation.
Figure 3. The effect of peat–vermicompost substrates on chlorophyll (A) and NBI (B) indices in the leaves of cucumbers seedlings: 1—peat; 2—peat+10% vermicompost; 3—peat+20% vermicompost; 4—peat+30% vermicompost. Different letters above the columns are significantly different at the p < 0.05 level according to Tukey’s significant difference test. Error bars show standard deviation.
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Figure 4. The effect of peat–vermicompost substrates on NDVI (A) and PRI (B) indices in the leaves of cucumbers: 1—peat; 2—peat + 10% vermicompost; 3—peat + 20% vermicompost; 4—peat + 30% vermicompost. Means with different letters are significantly different at the p < 0.05 level according to Tukey’s significant difference test. Error bars show standard deviation.
Figure 4. The effect of peat–vermicompost substrates on NDVI (A) and PRI (B) indices in the leaves of cucumbers: 1—peat; 2—peat + 10% vermicompost; 3—peat + 20% vermicompost; 4—peat + 30% vermicompost. Means with different letters are significantly different at the p < 0.05 level according to Tukey’s significant difference test. Error bars show standard deviation.
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Figure 5. The effect of peat–vermicompost substrates on early and total cucumber yield (A), nitrate content in fruit of cucumber (B): 1—peat; 2—peat + 10% vermicompost; 3—peat + 20% vermicompost; 4—peat + 30% vermicompost. Means with different letters are significantly different at the p < 0.05 level according to Tukey’s significant difference test. Error bars show standard deviation.
Figure 5. The effect of peat–vermicompost substrates on early and total cucumber yield (A), nitrate content in fruit of cucumber (B): 1—peat; 2—peat + 10% vermicompost; 3—peat + 20% vermicompost; 4—peat + 30% vermicompost. Means with different letters are significantly different at the p < 0.05 level according to Tukey’s significant difference test. Error bars show standard deviation.
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Figure 6. Relationships of peat–vermicompost substrates according to biometric parameters, macroelement content and photosynthetic parameters in cucumber seedling leaves.
Figure 6. Relationships of peat–vermicompost substrates according to biometric parameters, macroelement content and photosynthetic parameters in cucumber seedling leaves.
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Figure 7. The principal component analysis (PCA) scatterplot, indicating distinct differences in all of the measurements results presented in this paper.
Figure 7. The principal component analysis (PCA) scatterplot, indicating distinct differences in all of the measurements results presented in this paper.
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Table 1. Agrochemical characteristics of different substrates.
Table 1. Agrochemical characteristics of different substrates.
TreatmentsMineral Element Content, mg L−1Electrical Conductivity EC, mS/cmAcidity,
pH
NitrogenPhosphorusPotassiumCalciumMagnesium
Peat18052120289552.25.4
Peat + 10% vermicompost12962324195502.35.7
Peat + 20% vermicompost12461457173522.85.9
Peat + 30% vermicompost16556697139543.66.3
Table 2. The effect of peat–vermicompost substrates on the biometric parameters of cucumber seedlings.
Table 2. The effect of peat–vermicompost substrates on the biometric parameters of cucumber seedlings.
TreatmentsPlant Height,
cm
Hypocotyl Lenght, cmStem Diameter, mmNumber of Leaves, UnitLeaf Area, cm2
Peat24.41 b7.24 a5.89 b4.10 b578.22 c
Peat + 10% vermicompost27.93 a7.04 a6.16 b4.67 a715.38 b
Peat + 20% vermicompost28.96 a7.00 a6.27 b4.74 a778.51 ab
Peat + 30% vermicompost24.88 b5.65 b7.02 a4.93 a824.09 a
Means with different letters are significantly different at the p < 0.05 level according to Tukey’s significant difference test.
Table 3. The effect of peat–vermicompost substrates on mineral element content in the cucumber seedling leaves.
Table 3. The effect of peat–vermicompost substrates on mineral element content in the cucumber seedling leaves.
TreatmentsMineral Element Content (% DM)
NitrogenPhosphorusPotassiumCalciumMagnesium
Peat2.76 c0.60 a2.29 c2.59 a0.60 b
Peat + 10% vermicompost2.93 b0.68 a3.54 b2.67 a0.66 b
Peat + 20% vermicompost2.96 b0.63 a3.27 b2.65 a0.71 ab
Peat + 30% vermicompost3.28 a0.67 a4.15 a2.71 a0.81 a
Means with different letters are significantly different at the p < 0.05 level according to Tukey’s significant difference test.
Table 4. The effect of peat–vermicompost substrate on plant height and number of leaves.
Table 4. The effect of peat–vermicompost substrate on plant height and number of leaves.
TreatmentI MeasureII MeasureIII Measure
Plant Height, cmNumber of Leaves, unitPlant Height, cmNumber of Leaves, unitPlant Height, cmNumber of Leaves, unit
Peat68.07 a7.70 a91.15 a10.29 a117.66 b14.51 a
Peat + 10% vermicompost69.91 a7.94 a98.44 a11.10 a127.60 ab14.17 a
Peat + 20% vermicompost70.74 a7.61 a99.49 a10.78 a126.52 ab14.15 a
Peat + 30% vermicompost72.11 a7.63 a100.91 a10.77 a136.24 a15.42 a
Means with different letters are significantly different at the p < 0.05 level according to Tukey’s significant difference test.
Table 5. The effect of peat–vermicompost substrates on photosynthetic parameters in the leaves of cucumber seedlings.
Table 5. The effect of peat–vermicompost substrates on photosynthetic parameters in the leaves of cucumber seedlings.
TreatmentPhotosynthetic Rate, (µmol CO2 m−2 s−1)Stomatal Conductance,
(H2O mol m−2 s−1)
Intercellular CO2, (µmol CO2 mol−1)Transpiration Rate, (mmol
H2O m−2 s−1)
Seedlings
Peat5.75 c0.20 d327.90 c1.32 d
Peat + 10% vermicompost6.24 bc0.38 a334.24 bc1.58 c
Peat + 20% vermicompost6.58 b0.27 c343.22 b1.76 b
Peat + 30% vermicompost7.41 a0.32 b357.29 a1.99 a
The peak of fruiting
Peat5.05 c0.62 c365.33 d2.78 c
Peat + 10% vermicompost6.75 b0.96 bc369.89 c3.14 b
Peat + 20% vermicompost7.96 a1.11 b375.51 b3.49 a
Peat + 30% vermicompost9.00 a1.94 a377.94 a3.72 a
The end of the harvest
Peat4.51 d0.15 a258.61 d0.60 c
Peat + 10% vermicompost5.91 c0.17 a295.32 c0.82 bc
Peat + 20% vermicompost7.42 b0.19 a319.98 b1.09 b
Peat + 30% vermicompost8.82 a0.13 a346.57 a1.47 a
Means with different letters are significantly different at the p < 0.05 level according to Tukey’s significant difference test.
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Jankauskienė, J.; Laužikė, K.; Kavaliauskaitė, D. Effects of Vermicompost on Quality and Physiological Parameters of Cucumber (Cucumis sativus L.) Seedlings and Plant Productivity. Horticulturae 2022, 8, 1009. https://doi.org/10.3390/horticulturae8111009

AMA Style

Jankauskienė J, Laužikė K, Kavaliauskaitė D. Effects of Vermicompost on Quality and Physiological Parameters of Cucumber (Cucumis sativus L.) Seedlings and Plant Productivity. Horticulturae. 2022; 8(11):1009. https://doi.org/10.3390/horticulturae8111009

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Jankauskienė, Julė, Kristina Laužikė, and Danguolė Kavaliauskaitė. 2022. "Effects of Vermicompost on Quality and Physiological Parameters of Cucumber (Cucumis sativus L.) Seedlings and Plant Productivity" Horticulturae 8, no. 11: 1009. https://doi.org/10.3390/horticulturae8111009

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