Introduction

In recent years, vegetable transplant production has developed into a profitable, useful, and job-creating sector globally. Transplants may be cultivated in many contexts, including nurseries, greenhouses, planting substrates, and in vitro circumstances, contingent upon the prevailing technology, whether on a small or big commercial scale. A primary priority for transplant producers and companies is the cultivation of strong, healthy transplants that ensure high standards of quality and yield1. Greenhouse and hydroponic agriculture are progressing rapidly to deal with quality problems of crops and allow off-season production. The previous several decades have seen substantial greenhouse production advances. This improvement has frequently corresponded with the rise of soilless cropping systems, the most intensive and efficient agricultural production methods2.

In several hydroponic systems, producers use various hydroponic growth media to nourish the roots and sustain the appropriate water-to-oxygen ratio. These culture substrates provide mechanical support to the roots, sustaining the plant’s mass and maintaining its vertical orientation3. The breakdown of sphagnum moss in wetlands produces peat moss, which is used in greenhouse culture, especially in transplant production and soilless systems. Its favorable physical and chemical qualities and plentiful availability make it widely used, yet its natural resources are irreversibly depleted. Due to uncontrolled peat moss extraction and the importance of local production over imports, several academics have explored alternate media4. Palm peat, an alternative medium, is made from date palm waste. In many countries in the world using palm tree cellulose waste as a cultivation medium is cost-effective and necessary5. Perlite, an amorphous volcanic aluminosilicate rock ranging from light gray to dark black, has a water content of 2–5% by mass and is used for vegetable transplanting. Perlite is a lightmass, porous, and absorbent substance made from minerals. Commercial applications benefit from expanded pearlite’s low bulk density, thermal conductivity, thermal resistance, specific surface area, and chemical inertness6. Vermiculite, a micaceous mineral made by heating expanding plate-like particles to 745 °C, holds a lot of water and assists with aeration and drainage. Vermiculite is good at cation exchange, buffering, and potassium and magnesium delivery. Vermiculite is less durable than sand and perlite, but its chemical and physical qualities benefit the growth medium7. Vermiculite is comparable to perlite as a growth medium, however, it can store nutrients due to its high cation exchange capacity3.

Zeolite, as a growing media that nowadays is studied for hydroponic production, is a hydrated aluminosilicate used for its high cation exchange capacity, considerable ion absorption, and extensive surface adsorption8. Zeolite contains salt, calcium, potassium, and 10–20% water, which evaporates partly at 350 °C. The exchange of ammonium, phosphorous, and potassium ions in zeolite gradually releases nutrients including nitrogen, phosphorus, potassium, calcium, and magnesium for plants9. Zeolite stores aluminum and other metals inside its crystalline structure, allowing plant access and limiting leaching10. Cocopeat is a great growing medium made from coconut shells, formerly considered waste. Hydroponics uses this organic plant fiber since it decomposes slowly and provides no nutrients to plants11. Cocopeat’s neutral pH retains moisture and gives roots aeration. This substrate comes in chips and fibers. The particle size distinguishes both coconut shell products11. Numerous researchers and the greenhouse industry have adopted sawdust, a cost-effective material in hydroponic systems, to enhance the properties of growing mediums, such as porosity and water retention12. Heat-treated oak (Quercus spp.) sawdust exhibited reduced levels of glucose, phosphorus, potassium, calcium, and magnesium, alongside increased porosity and water-holding capacity, compared to untreated sawdust, which contained elevated amounts of arabinose, xylose, mannose, and galactose13,14. The substrate sand serves as a prevalent growing medium in hydroponic systems. Sand is a smaller form of stone. The smaller particle size results in slower moisture drainage compared to standard stone. Sand is commonly combined with vermiculite, perlite, or cocopeat, which assist in moisture retention and aeration of the mixture for root systems3,7.

Vermicompost is significant in agriculture, particularly greenhouse product development15. Vermicompost is made by decomposing all kinds of decomposable waste in the kitchen, market, bio-agricultural industry, food industry, etc., which the earthworm converts into a valuable plant nutrient. Similar to peat moss, the medium features porosity, ventilation, drainage, high water storage, and microbiological activity. Several organic acids, including humic acid and folic acid, and growth regulators including auxin, cytokinin, and gibberellin boost crop growth and yield4. Pumedia horticulture medium is an Iranian mineral medium composed of pumedia, perlite, and silt in specified ratios, with its granulation and texture meticulously adjusted to provide an optimal environment for greenhouse crop production. The mixture comprises pumedia, perlite, and silt in a ratio of 45:40:15, featuring a grain size range of 0.1–6 mm. Pumedia consists of 25% grains sized 3–6 mm, 50% sized 1–3 mm, and 25% sized 0.1–1 mm. Perlite contains 70% of particles sized 1–0.1 mm and 30% sized 3–1 mm. Silt is characterized by a size range of 2–0.5 mm and is of the processed variety.

In a soilless culture system, perlite offers excellent aeration but results in increased leachate inside the systems. Numerous studies indicate superior plant development and production in peat and wood fibers relative to perlite across various substrate cultivation methods, attributed to enhanced water retention, cation exchange capacity, and elevated organic content16,17,18. To find the best substrate for Chinese leaf cabbage (Brassica rapa L.), the bulk density and electrical conductivity (EC) of a medium with 50% cocopeat and 50% pearlite were significantly higher than others19. Yeganeh et al.4 studied the effect of peat, perlite, and vermicompost medium in strawberry cultivation. The maximum root fresh mass, total soluble solids, and vitamin C were recorded in the medium with vermicompost. The greatest quantity of inflorescences was associated with the medium including peat moss and the mixed substrate of 70% perlite and 30% vermicompost. In a study conducted by Čepulienė et al.20 the yields of greenhouse cucumbers in peat and wood fiber media revealed that the cucumber cultivated in wood fibers was dependent on the level of available nitrogen.

In recent years, transplant production has developed into a greatly profitable industry that not only demonstrates its productivity but also creates noteworthy employment opportunities. One of the important factors in successful and commercial vegetable transplant production is the choice of an appropriate growing medium. In particular, it is essential to prioritize locally available, cost-effective resources. This study aims to explore the feasibility of utilizing waste organic and mineral materials as substrates for transplant cultivation, focusing on their potential to replace the commonly used media that are used in transplant production. This topic has been rarely addressed in previous literature, and the current research aims to overcome this deficiency. This study’s results will provide significant insights for transplant producers and guide future research on alternate substrates to enhance transplant growth, hence increasing sustainability and cost-effectiveness.

Materials and methods

The current study was performed in a greenhouse situated at 37.23° N latitude and 46.16° E longitude, at an elevation of 1485 m above sea level, with a relative humidity of 65–75% and an average daily temperature of 25 °C, dropping to 18 °C at night. Using a completely randomized design with 26 treatments and 4 replications, the purpose of this experiment was to investigate the influence that different culture mediums have on the growth characteristics, yield, and nutritional components of greenhouse cucumber transplants of the Nagin cultivar. As seen in the following illustration, the single variable in this experiment consisted of organic, inorganic, and mixed substrates used at a ratio of 1:1 (Table 1).

Table 1 The different media types included organic, inorganic, and mixed substrates (1:1) used in the experiment.
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Cucumber seeds were purchased from the seed company of Mobin Kesht, Isfahan, Iran, and cultivated on polyethylene culture trays. Cultivation media include cocopeat, sand, perlite, peat moss, vermicompost, zeolite, and vermiculite sourced from Anoushe Arab company under the Gilda brand, as well as palm peat from Dorfam company and pumedia (a mixture of pumedia, perlite, and vermiculite in a ratio of 45:40:15) acquired from Yara Hanan Greenhouse company. Additionally, the fruit of the pine trees from the Maragheh University campus and powdered and sterilized by autoclave at 1.2 atmosphere and 121° then was utilized to prepare the pine medium. To make mixed substrates, the components were combined in a 1:1 ratio. Subsequently, the mixture was transferred to culture container trays, and before seed planting, it was washed with distilled water to diminish substrate saltiness. The seeds were immersed for 24 h before sowing to enhance germination.

Measurement of traits

To evaluate the influence of the culture medium on various attributes of cucumber transplants after 3 weeks of seed cultivation, the characteristics of the leachate, including electrical conductivity (EC) and pH, were assessed. Subsequently, the transplants were harvested from the medium, and the desired traits, encompassing morphological and growth parameters (height, internode length, crown diameter, and root length), yield (fresh and dry mass of shoots and roots), biochemical factors (chlorophyll content), and nutrient levels (phosphorus, potassium, calcium, iron, zinc, manganese), were evaluated as follows.

Plant growth traits

The height of the plant was determined using a standard ruler while maintaining an accuracy of 0.1 cm. To determine the stem diameter (hypocotyl), a digital caliper fitted with an accuracy of 0.01 cm was used. The mass of the fresh root and stem was determined by using a digital scale that had an accuracy of 0.001 g at the time of the measurement. The root and stem were placed in an envelope and placed in an oven at a temperature of 70 °C for 48 h. Following this, their masses were recorded in g. This was done to determine the dry mass of the plant.

Chlorophyll index

The SPAD of the cucumber transplant leaves was evaluated with the use of a portable chlorophyll index meter. Using this technique, three spots on the fully young leaves were assessed in each replication. After that, the SPAD was calculated by taking the average of the samples acquired for each repeat and referring to it as the SPAD (SPAD-502, Osaka, Japan)21.

Chlorophyll content

To figure out chlorophyll content, 0.5 g of fresh plant material was crushed using liquid nitrogen. Subsequently, 5 ml of 80% acetone was added to the samples, and 2 ml of the extract was transferred into microtubes and centrifuged at 6000 rpm for 10 min. Subsequently, chlorophyll a, b, and carotenoid concentrations were measured using a spectrophotometer (UV-1800 Shimadzu, Japan) at wavelengths of 663, 645, and 470 nm, respectively, then the amount of chlorophyll a, b, total, and carotenoids in mg g−1. The fresh mass of the sample was calculated22.

$${\text{Chlorophyll }}\;{\text{a}}\;{\text{ F}}.{\text{W }} = \, \left[ {{12}.{7 }\left( {{\text{A663}}} \right) \, {-}{ 2}.{69 }\left( {{\text{A645}}} \right)} \right] \, \times {\text{ V}}/{1}000\;{\text{FW}}$$
$${\text{Chlorophyll}}\;{\text{ b}}\; {\text{F}}.{\text{W }} = \, \left[ {{22}.{9 }\left( {{\text{A645}}} \right) \, {-}{ 4}.{68}\left( {{\text{A663}}} \right)} \right] \, \times {\text{ V}}/{1}000\;{\text{FW}}$$
$${\text{Chlorophyll }}\;{\text{total }}\;{\text{F}}.{\text{W }} = \, \left[ {{2}0.{2 }\left( {{\text{A645}}} \right) \, + { 8}.0{2}\left( {{\text{A663}}} \right)} \right] \, \times {\text{ V}}/{1}000\;{\text{FW}}$$
$${\text{Carotenoids }} = { 1}00\left( {{\text{A47}}0} \right) \, + { 3}.{27}\left( {{\text{mg }}\;{\text{chl}}.{\text{ A}}} \right) \, {-}{ 1}0{4}\left( {{\text{mg}}\;{\text{ chl}}.{\text{ B}}} \right)/{22}7$$

Macro- and micro-nutrient

To quantify the concentrations of K, P, and Ca in the leaves and roots of cucumber transplants by the dry digesting technique, 2 g of dried leaves and roots were first weighed, thereafter placed in a ceramic crucible, and cooked in a laboratory furnace. The furnace temperature incrementally reached 550 °C for 2 h and was maintained at this temperature for 8 h until white ash was produced. After the conclusion of this time, the furnace was deactivated and the ceramic crucibles were extracted from it. Upon cooling the ceramic crucible, the ash was moistened with a little water and covered with a watch glass, while simultaneously, 10 ml of 2 M hydrochloric acid was gradually introduced. Upon completion of the reactions, the flasks were subjected to heating in a hot water bath at 80 °C until the first white fumes were released. The contents of the ceramic crucible were then filtered via fine filter paper into a 100 ml balloon, after which the subsequent procedures for each nutrient were executed (AA-6300 F; Shimadzu, Kyoto, Japan). Phosphorus was quantified by the yellow technique, wherein 10 ml of each sample was combined with 10 ml of ammonium molybdate vanadate. Consequently, phosphorus forms a combination with molybdate, resulting in a color shift. Vanadate serves as a control in this experiment. The samples are ultimately diluted to a level of 50 ml with distilled water and analyzed using a spectrophotometer (UV-1800, Shimadzu, Japan) at a wavelength of 470 nm23.

The measurement of K was determined using a flame photometer (Jenway PFP7C)23. The flame photometer was first calibrated using pure water and a 100 ppm K solution at zero. Subsequently, 2 ml of each extracted sample was analyzed using the flame photometer.

The titration technique was used for measuring calcium23. Subsequently, 2 ml of the extracted solution, 2.5–5 ml of 4 N NaOH, and 0.05 g of ammonium purpurate reagent powder were added and titrated with 0.01 N until a color transition from pink to purple occurred.

An atomic absorption spectrophotometer was used to measure Fe and Zn in plant samples. The measurements for each element were arranged according to their relative proportions, revealing the concentration of that element in plant tissue in mg g−124.

EC and pH of leachate

The leachate from each substrate was collected weekly over 24 h, with measurements of electrical conductivity (EC) and pH taken, and the results subsequently averaged. The electrical conductivity (EC) and pH of the leachate were determined using an EC meter and a pH meter, respectively25.

Statistical analysis

The data from this experiment were analyzed using MSTATC Ver 2.1 software (A Microcomputer Program for the Design, Management, and Analysis of Agronomic Research Experiments; MSTAT Development Team; Michigan State University; 1983–1985), and average data comparisons were conducted using the Dunkan test at 1% and 5% probability levels26.

Results

Height of transplant

The results of the variance analysis demonstrate a notable influence of the substrates on the height of cucumber transplant seedlings at p ≤ 0.01 (Table 2). The findings reveal that the tallest transplants cultivated in peat moss achieved a height of 24.17 cm, showing a notable difference compared to other growing media. The combination of cocopeat and pumedia (21.17 cm) and cocopeat alone (20.17 cm) demonstrated the greatest height growth, with no significant difference observed between the two treatments. Furthermore, the combination of vermicompost with pumedia, cocopeat with palm peat, and pine with palm peat demonstrated similar effects on the height of cucumber seedlings, with no significant differences observed among these three substrates. The application of zeolite treatment led to the minimum plant height recorded at 4.883 cm. After zeolite, the combinations of sand + palm peat, sawdust + palm peat, sawdust + pumedia, and zeolite + palm peat showed the shortest seedling heights, with no significant differences observed at p ≤ 0.05 among these treatments. The comparative analysis of average data reveals that substrates containing pumedia demonstrated enhanced seedling height performance when compared to those with palm peat and the corresponding pure substrates within the same treatments (Table 3 and Fig. 1). The peat moss medium insulted in four folds height of the cucumber transplants higher than zeolite.

Table 2 The results of ANOVA for the effects of the various substrates on the characteristics of the leachate and growth characteristics of cucumber transplants.
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Table 3 The results of comparison means ± SD of various growing mediums impact on the growth parameters, electrical conductivity (EC), and pH.
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Fig. 1
figure 1

The Effects of different growing media on the morphological features of cucumber transplants, in which CO, PA, VE, SN, PI, PU, VC, SW, ZE, PL, and PE refer to cocopeat, palm peat, vermiculite, sand, pine, pumedia, vermicompost, sawdust, zeolite, perlite, and peat moss, respectively.

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Internode length

The findings of the current investigation indicated a significant difference among the various substrates examined regarding internode length at p ≤ 0.01 (Table 2). Among the compared various treatments at p ≤ 0.05, the peat moss substrate exhibited the greatest internode length (3.833 cm), which did not significantly vary from the sand substrate (3.5 cm). Cocopeat exhibited the second-greatest internode length, followed by palm peat, vermiculite + pumedia, vermicompost + pumedia, cocopeat + pumedia, and sandblast + pumedia, all of which had the maximum internode length, with no significant differences seen among them. The smallest internode length was seen in the sawdust + pumedia treatment (1.167 cm), followed by the zeolite + palm peat and pure zeolite treatments, which exhibited the lowest internode lengths and 2.2 folds lower than the transplants cultivated in peat moss. The mixed substrates including pumedia exhibited greater internode length compared to the individual substrate or the mixed substrates comprising palm peat (Table 3).

Stem diameter

Based on the presented results, the effects of different types of cultivation media on the diameter of cucumber seedlings were significant, and the types of media used had a significant difference at p ≤ 0.01 in stem diameter (Table 2). Further, the results showed that vermicompost + pumedia growing medium had the highest stem diameter (5.483), which was not significantly different from perlite, sand + pumedia, cocopeat, cocopeat + pumedia, and pine + pumedia treatments at p ≤ 0.05. Also, the lowest stem diameter was recorded in the vermiculite + palm peat medium (3.190), which was 1.7 folds lower than the highest in transplants cultivated in vermicompost + pumedia medium (Table 3).

Root length

The results of the variance analysis demonstrate a significant impact of the substrates on the root length of tomato transplants at p ≤ 0.01 (Table 2). The maximum root length of transplants was recorded in peat moss (145.5 mm), showing significant variation compared to the other growing media, including palm peat + pumedia, zeolite + pumedia, pure cocopeat, sandblast + pumedia, and vermicompost + palm peat, with a statistical significance at p ≤ 0.05. The media comprising zeolite (72.5 mm) and pumedia (74.63 mm) demonstrated the shortest length of root observed. The results demonstrate that in most mixed substrates, those containing pumedia showed greater root lengths than mixed substrates with palm peat and the respective pure substrates (Table 3). The combination of palm peat and pumedia demonstrated enhanced root length in comparison to the growing media of pure pumedia (Fig. 2).

Fig. 2
figure 2

The Effects of different growing media on the roots of cucumber transplants, in which CO, PA, VE, SN, PI, PU, VC, SW, ZE, PL, and PE refer to cocopeat, palm peat, vermiculite, sand, pine, pumedia, vermicompost, sawdust, zeolite, perlite, and peat moss, respectively.

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Root fresh mass

The findings from this study indicated a notable difference at p ≤ 0.01 regarding root fresh mass across the various substrates (Table 2). The peat moss substrate exhibited the highest root fresh mass at 5.017 g, showing no significant difference when compared to the cocopeat substrate, which measured 4.35 g at p ≤ 0.05. Furthermore, the lowest root fresh mass was observed in zeolite (0.3433 g), followed by the treatments of zeolite + palm peat and zeolite + pumedia, which also exhibited the lowest values for this attribute at p ≤ 0.05. The substrates containing pumedia exhibited superior efficiency compared to the substrates combined with palm peat (Table 3).

Root dry mass

The analysis of variance revealed significant impacts of several substrates on root dry mass on cucumber transplants at p ≤ 0.01 (Table 2). The comparative analysis of results at p ≤ 0.05 revealed that the peat mass substrate had the highest root dry mass at 0.563 g, showing no significant difference from cocopeat at 0.55 g, vermiculite + pumedia at 0.46 g, cocopeat + pumedia at 0.43 g, and sawdust + palm peat at 0.39 g. Nonetheless, the lowest root dry mass was related to zeolite (0.063 g), which was 7 times less than the application of peat moss (Table 3).

Shoot fresh mass

The analysis of variance at p ≤ 0.01 indicated significant differences of various growing medium types on the shoot fresh mass of cucumber seedlings (Table 2). The comparative findings revealed significant differences at p ≤ 0.05 among the growing media, with the cocopeat medium producing the highest shoot fresh mass at 10.67 g, with no significant difference from that of the cocopeat + pumedia and peat moss substrates. The cucumber transplants exhibited the lowest fresh mass of shoot in cucumber transplants grown in zeolite substrate (1.99 g), which was 4.3 folds lower than the cocopeat medium (Table 3).

Shoot dry mass

The research revealed a significant difference (p ≤ 0.01) in shoot dry mass among various growing media (Table 2). The peat moss medium yielded the highest shoot dry mass at 1.15 g, which was significantly greater than the other media tested. Both the cocopeat and pumice treatments produced the second-highest shoot fresh mass of 1 g, with no significant differences compared to the pure cocopeat medium. Zeolite had the lowest shoot dry mass at 0.205 g, followed closely by the sand substrate. Similar to the fresh mass of aerial components, the dry masss in mixed media outperformed those in pure substrates. Additionally, shoot dry mass was higher in mixed substrates containing pumice compared to those with palm peat (Table 3).

Chlorophyll content

The results showed that the type of culture media significantly at p ≤ 0.01 and p ≤ 0.05 affected chlorophyll a, b, total, and carotenoid levels, with notable differences in the chlorophyll content among cucumber transplants grown in various media (Table 4). The findings indicated that the highest chlorophyll a content was observed in the transplants cultivated in vermicompost + pumedia (24.72 mg g−1 FW), which was significantly at p ≤ 0.05 different from other growing media. This was followed by the zeolite + palm peat and cocopeat + pumedia combinations, which also exhibited elevated chlorophyll content. The lowest Chlorophyll a content was observed in the palm peat (1.99 mg g−1 FW) (Table 5).

Table 4 The results of ANOVA of the effects of culture substrates on chlorophyll content of cucumber transplants.
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Table 5 The comparison means ± SD of chlorophyll a, chlorophyll b, total chlorophyll, and carotenoids content in greenhouse cucumber seedlings in different growing medium.
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The results showed that the highest leaf chlorophyll b content (13.31 mg g−1 FW) obtained in the transplants was grown in the pine + palm peat growing medium, which was significantly different from the other treatments. Sand + pumedia, zeolite, pine + pumedia, zeolite + pumedia, perlite + pumedia, zeolite + palm peat, vermiculite, vermiculite + pumedia, and palm peat + pumedia had the following chlorophyll b, with no significant differences at p ≤ 0.05 noted among them. On the other hand, the lowest chlorophyll b content belonged to the palm peat medium (1.21 mg g−1 FW) (Table 5).

According to the current findings, the maximum total chlorophyll was observed in cucumber transplants cultivated in vermicompost + pumedia growing medium (28.19 mg g−1 FW). This was followed by substrates of zeolite + palm peat, zeolite, cocopeat + pumedia, and pine + pumedia, which resulted in similar chlorophyll content without significant differences at p ≤ 0.05 among them. The total chlorophyll content in palm peat medium (3.199 mg g−1 FW) was the lowest level among all the used media. The pure pumedia led to higher total chlorophyll levels compared to the combined palm peat. Conversely, the total chlorophyll concentration was decreased in media like peat moss and cocopeat in comparison to other treatments, although their superior morphological and growth attributes (Table 4). Finally, the highest carotenoid content was observed in the perlite + pumedia growing medium (7.524 mg g−1 FW), which is significantly at p ≤ 0.05 different from the other media. Although, the lowest carotenoid content was recorded in palm peat growing medium (2.502 mg g−1 FW) (Table 5).

Macronutrients of shoots and roots

Based on the results obtained from variance analysis of the data, the effects of the types of growing media used in cucumber transplants on leaf and root P, K, and Ca concentrations were significant at p ≤ 0.01 (Table 6). According to the results, the highest concentration of P in leaves in cucumber transplants grown in palm peat + pumedia growing medium (0.953%) had a significant difference at p ≤ 0.05 with other media and it was 2.3 folds higher than the concentration of leaf P was observed in the transplants grown in the sand growing medium (0.283%) which was the lowest. However, there was no significant difference at p ≤ 0.05 between sawdust + pumedia, sand + palm peat, vermiculite + pumedia, and pine + pumedia with sand medium (Fig. 3a). According to the results, the highest concentration of P was recorded in the roots of transplants grown in vermicompost + pumedia (0.5933%), which was three folds higher than the lowest concentration in palm peat (0.1467%) (Fig. 3b).

Table 6 The results of variance analysis of the effects of culture medium on macro elements of cucumber seedlings.
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Fig. 3
figure 3

The effects of the different growing mediums on the concentration of phosphorus (P) in the leaves (a) and the roots (b) of cucumber transplants. Columns with the same letters are not significantly different at the p < 0.05 probability level.

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The results showed that the highest concentration of K in the leaves of cucumber transplants obtained from vermiculite + palm peat (3.843%), perlite + palm peat (3.820%), palm peat (3.817%), and sawdust + palm peat (813.8%) was obtained. Whereas, the lowest concentration was observed in the zeolite (1.507%) and peat moss (1.56%) substrates, which was not significantly different at p ≤ 0.05 from the sand medium (Fig. 4a). According to the findings, the highest concentration of root K was achieved in vermicompost + palm peat (3.753%), which was significantly different from other growing media. The lowest K concentration was observed in the roots grown in vermiculite + palm peat (0.823%) and zeolite + pumedia (0.950%) (Fig. 4b).

Fig. 4
figure 4

Effects of the different growing mediums on potassium (K) concentration of the leaves (a) and the roots (b) of cucumber transplants. Columns with common letters are not significantly different at the p < 0.05 probability level.

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Based on the results, the highest concentration of Ca in the leaves of cucumber transplants was recorded in sawdust + palm peat (3.687%) and sawdust (3.657%). The present findings also showed that the lowest Ca concentration of leaves was observed in the zeolite + palm peat substrate (1.207%), which was two folds lower than sawdust + palm peat and sawdust media (Fig. 5a). The results showed that the highest concentration of root Ca was recorded in vermicompost + pumedia (3.213%), that it was 4.4 folds higher than the concentration of Ca observed in palm peat (0.5933%), and sand + peat moss (0.5967%) as the lowest concentration of Ca in the roots (Fig. 5b).

Fig. 5
figure 5

The effects of the different growing mediums on calcium (Ca) concentration of the leaves (a) and the roots (b) of cucumber transplants. Columns with common letters are not significantly different at the p < 0.05 probability level.

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Micronutrients of shoots and roots

The variance analysis results (Table 7) revealed that the type of growing medium utilized for cucumber transplants significantly at p ≤ 0.01 affected the concentrations of Fe, Zn, and Mn in both shoots and roots. The mean comparison showed that the highest concentration of leaf Fe was observed in the vermiculite medium (131.7 mg g−1 DW). Whereas the lowest concentration of shoot Fe was recorded in the vermiculite + pumedia medium, (43.21 mg g−1 DW), and it was two folds lower than the highest concentration (Fig. 6a). The results indicate that the highest concentration of root Fe was found in sawdust + palm peat (253.1 mg g−1 DW), while the lowest concentration was recorded in pumedia (43.29 mg g−1 DW). Finally, there are no significant differences (p ≤ 0.05) among the growing media of peat moss, pine + pumedia, perlite, zeolite + pumedia, zeolite + palm peat, perlite + pumedia, and vermicompost + pumedia (Fig. 6b).

Table 7 The results of variance analysis of the culture medium effects on micronutrients of cucumber seedlings.
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Fig. 6
figure 6

Effects of the different growing mediums on iron (Fe) concentration of the leaves (a) and the roots (b) of cucumber transplants. Columns with common letters are not significantly different at the p < 0.05 probability level.

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According to the current findings, the highest concentration of Zn in the leaves of cucumber transplant grown in palm peat + pumedia growing medium (56.22 mg g−1 DW) was obtained, which had a significant difference at p ≤ 0.05 with other media. Also, the least of shoot Zn was observed in the vermiculite + pumedia culture medium (13.11 mg g−1 DW), which was not significantly different from the pine + palm peat medium (Fig. 7a). The highest concentration of Zn in the roots of transplants grown in sawdust + palm peat (86.64 mg g−1 DW) and the lowest concentration in plants grown in cocopeat + palm peat (15.44 mg g−1 DW) which had no significance with pumedia (15.69 mg g−1 DW) and zeolite (16.34 mg g−1 DW) (Fig. 7b).

Fig. 7
figure 7

Effects of the different growing mediums on zinc (Zn) concentration of the leaves (a) and the roots (b) of cucumber transplants. Columns with common letters are not significantly different at the p < 0.05 probability level.

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The results showed that the highest and lowest concentrations of Mn in the leaves of cucumber transplants were obtained in palm peat + pumedia (65.1 mg g−1 DW) and vermiculite + pumedia (19.02 mg g−1 DW), respectively (Fig. 8a). Also, the highest concentration of Mn in roots was obtained in cocopeat medium (77.5 mg g−1 DW) and the lowest was achieved in zeolite (17.1 mg g−1 DW) (Fig. 8b).

Fig. 8
figure 8

The effects of different growing mediums on the concentration of manganese (Mn) of the leaves (a) and the roots (b) of cucumber transplants. Columns with common letters are not significantly different at the p < 0.05 probability level.

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EC of the growing media

The findings of the study revealed that the type of culture media used in cucumber transplants significantly at p ≤ 0.01 influenced the EC of the leachate from the media (Table 2). Specifically, the results demonstrated that the EC of the leachate increased in all treatments compared to the nutrient solution. Among the evaluated growing media, the highest EC value (3.952 mS/cm) was observed in the vermicompost + pumice mixture, which showed a statistically significant difference at p ≤ 0.05 compared to the other media. On the other hand, the lowest EC value (0.817 mS/cm) was recorded in the pure cocopeat, representing a 383.72% difference compared to the highest value (Table 3).

pH of the growing media

According to the results of the analysis of variance, the effects of the types of growing media on the pH of the leachate were significant at p ≤ 0.01 (Table 2). Based on the results, the highest pH was observed in vermicompost + palm peat (8.356) and there was a significant difference at p ≤ 0.05 among vermicompost + palm peat with the substrates of cocopeat + pumedia, vermicompost + pumedia, vermiculite + pumedia, zeolite + pumedia, vermiculite, pumedia, zeolite, but it did not have significant difference with palm peat and zeolite. On the other hand, the results showed that the lowest pH was obtained in the pine + palm peat substrate (7.385) (Table 3).

Discussion

The ingredients used in growth media must provide uniformity between batches while being economically feasible. The expenses for materials and the production process must remain modest to guarantee affordability. Furthermore, the growing medium must fulfill the essential biological requirements of plants, including physical, chemical, and biological characteristics. Nonetheless, no one substrate or amalgamation of substrates can fulfill the requirements of all plant species or function effectively under every cultivation circumstance27,28. The growth and development of plants in hydroponic systems are enhanced by maximizing root contact with the growth environment, as well as by optimizing nutrient content and water retention in the culture medium. Conversely, a reduction in these factors leads to diminished growth or potential plant death29. The present study examined a substantial number of cultivation substrates, a comparison not previously conducted. However, our findings regarding the comparison of organic and inorganic substrates align with earlier research16,29,30. The sawdust cultivation medium, serving as an organic growing medium, revealed growth parameters comparable to that of mineral-based media in the current study. The restricted plant growth noted in the sawdust substrate is likely attributable to its adverse physical and chemical properties. Sawdust, with its significant number of coarse pores, promotes better air circulation and increases drainage efficiency, and dries more rapidly than alternative media, potentially causing plant stress if watering is not done at regular intervals. The study’s findings indicated that growth parameters, including plant height, internode length, and root length, were more effectively enhanced by peat moss growing medium than by other purely mineral media. Also, no significant differences were observed in stem diameter between seedlings cultivated in cocopeat and those in perlite. Organic growing media showed enhanced growth attributes compared to pure mineral substrates, which these findings are in agreement with several studies. The consistent use of an identical nutrient solution across various substrates indicates that variations in plant growth may arise from enhanced conditions for cucumber root systems, especially concerning water retention and mineral nutrient uptake16. Organic substrates like peat moss and cocopeat exhibit favorable physical properties attributed to their dense organic composition. They demonstrate excellent porosity, effective water absorption and retention capabilities, and a stable, homogeneous structure. Furthermore, they function as sound absorbers of essential mineral elements29,31,32. Conversely, studies have indicated that both pure substrates and mixed substrates containing palm peat and pumedia yield comparable results33. Our results align with data that indicate the use of a mix of inorganic and organic substrates improves substrate efficiency and fosters plant development33, because of the substantial mineralization of organic nutrients combined with inorganic growing media in the first weeks and their possible leaching from container mixes, substrate-integrated organic fertilizers are often used as the only fertilizer source for short-term crops34,35. On the other hand, mineral substrates frequently present instability, resulting in water depletion within the root zone36. The incorporation of mineral materials, such as pumedia, into organic materials, along with the addition of palm peat as an organic component to mineral substrates, has likely enhanced plant growth and yield compared to pure substrates. As well as, inert materials like perlite, together with organic materials like peat moss, are crucial for efficient water and nutrient management. Inert substrates retain moisture and facilitate drainage, effectively providing nutritional solutions to plant roots while minimizing water waste. This approach decreases water use and guarantees that plants get the appropriate amount of nutrients, hence avoiding runoff and leaching. Organic substrates preserve nutrients and provide a sustainable substitute for peat moss, which researchers increasingly recognize for its environmental impact due to overexploitation35,37. Combining substrates, especially organic and inorganic substrates, improves nutrient solution maintenance, element exchange, especially cation exchange, and root zone moisture distribution. The mix of organic and inorganic substrates is crucial. Thus, they affect root formation, nutrient absorption, and plant growth38. The amount of oxygen present and the distribution of pores in the root zone both have an impact on the formation of hair roots. According to Jones Jr39 and Hydroponic40, aeration conditions are beneficial to the roots because they encourage the equal distribution of water and air inside the pores. According to Xiong et al.29 and Putra and Yuliando41, if the pores of a solid substrate contain water and air in an equal proportion, the quantity of oxygen that is present will be adequate for the growth, elongation, expansion, and normal activity of the roots. As a result, the fresh and dry mass of the roots will rise, as will the root yield.

The present findings are aligned with Yang et al.16 that conducted a study on a variety of organic and inorganic cultivation substrates for cucumbers. They found that plants grown in peat moss had a higher fresh and dry mass of the vegetative part compared to plants grown in perlite. Furthermore, they indicated that organic cultivation substrates contain a greater amount of nitrogen, phosphorus, and potassium than pearlite. It is possible to say that a substrate that has a high water holding capacity, a high porosity percentage, and as a result of proper ventilation and drainage conditions, can provide favorable conditions for the growth and development of the root and, as a result, the aerial parts of the plant42. This is when considering the fresh and dry mass of the aerial parts of the plant. On the other hand, the presence of sufficient nutrients in organic culture media leads to an increase in leaf durability43, in turn, maintains the photosynthesizing surface for a longer period. Furthermore, because the plant is exposed to more light for a longer time, it produces more dry matter, which in turn leads to an increase in the total biomass of the plant.

The results indicated significant variations in chlorophyll content relative to the culture substrates. Among the substrates examined, the pure palm peat substrate exhibited a lower concentration of pigments (chlorophyll and carotenoid), whereas the combined vermicompost and pumdeia substrate demonstrated a significantly higher content of chlorophyll content. Previous studies, including the research by Łaźny et al.31, have reported the effect of culture medium on chlorophyll content, aligning with the findings of the current study. Yang et al.16 reported that a medium-level increase in EC can lead to an increase in chlorophyll content, including chlorophyll and carotenoid. In plants with nutrient levels below the required threshold, chlorophyll breakdown occurs as a process associated with leaf aging, resulting in a decrease in chlorophyll content. The findings of this study indicate that the EC output from the substrate was maximized in the vermicompost + pumedia treatments, potentially contributing to the observed increase in chlorophyll content in this treatment relative to others.

Mineral nutrition is a crucial factor in enhancing the growth and production of secondary compounds in plants. The findings of this study demonstrate the significant impact of substrate type on the microelement content in the leaves and roots of cucumber seedlings. Phosphorus is a crucial element for plants, influenced by various factors44. The mechanisms in which organic materials affect the nutrition of plants cultivated in soilless systems may be encapsulated in the following essential points: (i) They augment nutrient availability in the root zone; (ii) their chemical characteristics facilitate efficient retention and interchange of nutritional components; (iii) they may promote microbial growth, which may beneficially influence plant nutrition. These aspects provide a chance to enhance the economic and environmental sustainability of soilless cultivation methods. It is essential to include these features into a meticulously crafted fertilization strategy to avoid excessive nutrient leaking into the environment. Excessive nutrient buildup must be managed via targeted fertilization measures to optimize nutrient use and reduce possible environmental consequences45,46. The analysis of leaf phosphorus content across various treatments indicated that substrates with palm peat exhibited higher phosphorus levels compared to those with pumedia. Additionally, in the roots, vermicompost substrates containing pumedia, palm peat, and cocopeat demonstrated the highest phosphorus concentrations. Abd El-Baset47 and Ghehsareh et al.48 reported that in their investigation of hydroponic cucumber cultivation, an increase in the level of date palm waste in the culture medium significantly enhanced the nitrogen, phosphorus, and potassium content in the plants. The results may be attributed to the capacity of date palm waste to retain nutrient solutions and water in the root development zone, facilitating enhanced nutrient absorption by plant roots. The analysis of potassium concentration in cucumber seedling leaves revealed that substrates comprising palm peat combined with vermiculite, sawdust, and perlite exhibited the highest potassium levels. In contrast, the highest potassium content in the roots was found in substrates containing vermicompost with pumedia, vermiculite, and vermicompost with palm peat, respectively. Palm peat, as an organic substrate, contains nutrients such as potassium, which enhances its availability to roots and facilitates absorption and accumulation in aerial tissues48. As well as, this impact may result from the presence of plant growth regulators, such as phytohormones, in organic fertilizers that enhance plant growth and development49,50.

The zeolite + palm peat substrate’s low calcium content may be due to its lower moisture retention capacity, which reduces water absorption and calcium transfer to the plant’s aerial organs. Plant biochemical activities including photosynthesis, cellular respiration, glucose metabolism, and enzyme production depend on iron, which is found in many enzymes and pigments43,51. The micronutrient elements examined in this study, as classified by Tripathi et al.52, were found to be within the sufficiency range, with no instances of deficiency or excess observed in any of the treatments. Yang et al.16 noted that the higher levels of iron and other micronutrients in leaves grown in mineral substrates, such as perlite and vermiculite, remain unexplained. However, they suggested that this phenomenon may be attributed to the “concentration effect,” where a decrease in yield leads to an increased concentration of nutrients in plant tissue. The variation in foliar nutrient content between perlite and organic substrates is likely attributable to nutrient retention and substrate pH17. The primary factors influencing iron absorption by roots in hydroponic culture include pH, nutrient balance, and ventilation of the culture medium53. This impact may be related to the increased concentration of all the nutrients that plants require in peat moss and other organic growing media and the fact that they are readily available49.

The characteristics of leachate extracted from the substrate indicate nutrient retention and drainage in a soilless culture, correlating with the substrate’s physical and chemical properties16. The present study demonstrated that the culture medium with vermicompost exhibited the greatest increase in the EC of the leachate when compared to the EC of the nutrient solution, suggesting a higher level of leachate waste and reduced nutrient availability for the cultivated plants. Our results align with the findings of Hajiaghaei Kamrani et al.54. The primary limitation in utilizing composted green waste, such as vermicompost, is its elevated EC and potassium concentration. Furthermore, the compost exhibits low carbon efficiency (5–10%), which contributes to a reduction in mass and volume, alongside a relatively high pH level. Vermicompost, when incorporated into the growing medium, serves as a source of fiber, providing an appropriate rooting medium, and is also a significant source of nitrogen, phosphorus, and potassium. Consequently, substrate mixtures that include vermicompost necessitate controlled solubilization owing to the nutrients supplied by the compost27. Hajiaghaei Kamrani et al.54 indicated that the enhanced efficacy of a culture medium is linked to its optimal pH range, physical properties, low electrical conductivity, and nutrient levels, facilitating customization according to plant requirements via a nutrient solution. It shows that the type of substrate influences the electrical conductivity of the root environment, subsequently impacting plant performance.

Conclusion

According to the current results, we can conclude that the combination of vermicompost and pumedia substrates demonstrated the highest electrical conductivity and pH levels in the leachate, whereas the integration of palm peat with other substrates led to an increase in the leachate’s EC. The peat moss substrate as a control treatment improved several growth parameters, such as height, internode length, and root length. Also, Cocopeat mixed with palm peat, and vermicompost mixed with pumedia showed competitive growth characteristics relative to peat moss, while the zeolite substrate displayed the least favorable growth characteristics. The plants grown in pure cocopeat, cocopeat mixed with pumedia, and vermicompost with pumedia substrates demonstrated the highest fresh and dry masss of roots and shoots, whereas the pure zeolite substrate produced the lowest yields for both roots and shoots. Seedlings grown in a vermicompost + pumedia substrate showed the highest chlorophyll content, while treatments with mineral compounds such as perlite and vermiculite resulted in increased leaf carotenoid levels.

The analysis of nutritional elements revealed that transplants grown in substrates containing palm peat displayed increased leaf potassium concentrations. The combination of palm peat and pumedia produced the highest phosphorus content, whereas sawdust mixed with pumedia achieved the highest calcium levels. The combination of vermicompost and pumedia exhibited the highest concentration of phosphorus. Potassium and calcium have root systems. The mixture of sawdust and palm peat demonstrated the highest levels of root micronutrient elements, particularly Fe, Zn, and Mn. The treatment involving palm peat and pumedia revealed the highest concentrations of leaf zinc and manganese. Mineral substrates such as vermiculite and perlite demonstrated increased Fe content. Peat moss, pure pumedia, and pure zeolite substrates demonstrated reduced concentrations of micro and macro elements in both leaves and roots relative to alternative substrates.

The analysis of all examined traits in the substrates revealed that cucumber transplants demonstrated enhanced yield in organic substrates relative to mineral substrates. The integration of palm peat with mineral substrates markedly improved the efficiency of these substrates. To enhance economic efficiency, it is advisable to combine palm peat with other substrates, especially mineral substrates, to attain satisfactory performance. Combining pumedia with organic substrates significantly improved the yield and growth of cucumber seedlings. As a result, vermicompost combined with pumedia and cocopeat combined with pumedia were identified as effective substrates in this study, presenting viable alternatives to peat moss. Finally, the current results indicate that transplant producers may substitute costly substrates like peat moss with alternative organic and agricultural waste materials in the future, a conclusion that will be further clarified by subsequent studies.