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Article

The Effect of Increasing Doses of Heavy Metals on Seed Germination of Selected Ornamental Plant Species

by
Olzacki Marcin
1,
Maciej Bosiacki
1 and
Sławomir Świerczyński
2,*
1
Department of Plant Physiology, Poznan University of Life Sciences, Wołyńska 35, 60-637 Poznan, Poland
2
Department of Ornamental Plants, Dendrology and Pomology, Poznan University of Life Sciences, J.H. Dąbrowskiego 159, 60-594 Poznan, Poland
*
Author to whom correspondence should be addressed.
Agronomy 2025, 15(6), 1262; https://doi.org/10.3390/agronomy15061262
Submission received: 30 April 2025 / Revised: 19 May 2025 / Accepted: 20 May 2025 / Published: 22 May 2025
(This article belongs to the Special Issue Seed Production and Technology)
Versions Notes

Abstract

:
The primary goal of this study was to assess how two techniques for applying progressively higher doses of zinc and cadmium impact seed germination of selected ornamental plant species. The experiments were conducted in the accredited laboratory of the W. Legutko Breeding and Seed Company in Jutrosin, along with the Department of Plant Physiology at Poznań University of Life Sciences. Seeds from two ornamental species, Eschscholzia californica Cham. and Coreopsis lanceolata, were utilized. Two methods were used to treat the seeds with heavy metal solutions, involving four distinct two-factor experiments, each comprising eight combinations. This methodology adhered to the current ISTA guidelines. Germination energy was assessed after 7 days, while germination capacity was measured after 14 days. The two methods exhibited different effects on germination capacity and energy. The technique for treating seeds with heavy metal solutions and the duration of exposure to the metals play a significant role in germination. Soaking Eschscholzia californica Cham. seeds in increasing doses of zinc and cadmium solutions for 10 min before sowing showed no significant effect on their energy or germination capacity. Likewise, soaking Coreopsis lanceolata seeds in zinc solutions for 10 min before sowing did not significantly influence their energy and germination capacity. However, soaking Coreopsis lanceolata seeds in cadmium solutions for 10 min before sowing did not notably affect their germination capacity but significantly diminished their germination energy. Extended exposure of seeds placed on blotting paper soaked in cadmium sulfate and zinc sulfate solutions across all concentrations reduced energy and germination capacity for Eschscholzia californica Cham. and Coreopsis lanceolata seeds.

1. Introduction

Heavy metals naturally occur in nature, but as a result of human activity, their concentrations can reach values at which toxicity symptoms appear in living organisms. This is particularly evident in industrial areas and developed urbanization and agriculture [1]. These elements enter the environment in the form of industrial gases, traffic dust, sewage, and municipal waste. They are also a component of mineral fertilizers and plant protection products. Heavy metal contamination includes air and water, as well as soil. Through these pathways, they directly affect plants, animals and humans, and enter the food chain [2,3,4]. Some of them, i.e., copper, zinc, manganese, and iron, are micronutrients essential for the functioning of living organisms. Nowadays, however, many factors related to human activity, including industrial development, urbanization, and agricultural chemization, contribute to excessive concentrations of heavy metals in soil, air, and water. Increasing pollution by these elements affects the entire ecosystem, causing negative health effects for all living beings [1,4,5].
Plants differ in their sensitivity to heavy metals [6]. They react differently to high concentrations with modifications of physiological processes. The frequent effect of heavy metals in inhibiting the elongation of roots is one of the first signs of toxic amounts; this is the reason why the root growth tolerance index is considered a valuable indicator of the sensitivity of different plants to heavy metal toxicity. It has been observed that the effects of plant exposure to the elements can manifest themselves, for example, in stunted shoot growth, interference with nutrient or water uptake, chlorosis, and leaf necrosis. In addition, changes in the structure of chloroplasts and mitochondria, disruption of cytokinesis, disruption of DNA polymerase, RNA defects, damage to cell membranes, oxidative stress on cells, and many other effects of accumulating high concentrations of trace metals have been reported [7].
Different plant species exhibit different levels of trace metal element accumulation, taking on selected of the following forms: passive uptake of metals from the soil, characteristic of so-called indicator plants; development of a defense mechanism related to hindering heavy metal uptake and maintaining low levels in the plant through, for example, secretion of compounds that react with metals in the soil or detoxification in the form of removal of excess ions from cells; active accumulation of metals in plant tissues [8].
In addition, there are mechanisms in nature for plant resistance to heavy metals. These can take various forms, including limiting the entry of elements into the symplast, preventing further transport of metal ions in the cell by blocking them in the cell wall, and inducing the synthesis of phytochelatins and the detoxification of metals from the plant [9].
Seed germination is the basic process by which plants grow from a seed into a plant [10,11] and has a significant impact on achieving optimal yield in quantity and quality [12]. The process of seed germination includes various stages of embryo growth and its evolution into the germ and seedling. Among them, a distinction is made between seed hydration (swelling, imbibition), the activation of metabolism, cell elongation, translocation of metabolites from spare tissues and intensification of bioenergetic metabolism during germ formation, formation of growth zones in the roots and stem, increased cell division and elongation of new cells, germ growth, formation of cotyledons, and transformation of the germ into a self-living seedling [13].
According to Gallardo et al. [14], in the initial stage of germination, seeds rapidly absorb water, which affects their swelling and the softening of the seed husk. Germination begins with the penetration of water into the seed in three stages [13]. The first of these is short-lived. It is also possible to reverse its effects without losing the viability of the diaspores. The second stage, on the other hand, is much longer and gives rise to consequences in the form of increased seed volume (swelling). Then, there is the hydrolysis of spare compounds and the gradual release of biologically active substances. The reversal of this phase is associated with the loss of seed viability. In the final, third stage of water penetration, the embryonic root or roots appear. During this period, which lasts from several to several hours, the metabolism is activated, involving the gradual activation of enzymes. Enzymes activate three groups of processes: (I) the breakdown of spare substances and transport of hydrolysis products to the embryo, (II) respiratory processes, and (III) the synthesis of macromolecular compounds in the growing parts of the embryo [13,14].
During germination, hydrolytic enzymes break down spare substances, activating phytohormones, vitamins, and other enzymes. Gas exchange is intensified, as well as ATP production. Existing mitochondria are rebuilt, and new ones are shaped. Gene expression also takes place, resulting in the synthesis of new proteins [13,15]. The initiation of embryo growth takes place through the growth of the embryonic root, the sublingual embryonic stem, or both organs. Therefore, a distinction is made between epigeal germination, hypogeal germination, and their intermediate forms. It is worth noting that the viability and strength of seed germination translate into further plant development and yield [13].
Germination involves the breaking of seed dormancy. In the case of relative dormancy (also known as physical dormancy or shallow dormancy), the germination process begins after the right external conditions are provided. In contrast, if the seed is subject to absolute dormancy, endogenous factors play the main role in initiating germination. Only priming, or the additional introduction of gibberellins, accelerates the interruption of this state [16]. There are many elements that affect the germination process [13,17], including the following influencing factors: internal (such as varietal characteristics, heterogeneity, development of structural elements, maturity, and ripeness), and external (temperature, light, water availability, aeration, damage, microorganisms, and others).
In addition, seeds can be stimulated with biopreparations, as well as chemical or physical methods. Adequate stimulation is a treatment that prepares seeds for sowing, which translates into an acceleration of the germination process and subsequent improvement in crop quality. Due to the potential risks to the environment posed by stimulation with chemical agents (their penetration into the soil), physical methods of germination stimulation are increasingly being used. The literature mentions physical stimulating agents, among which are light from incandescent lamps, magnetic fields, electric fields, laser, microwave, and ionizing or ultrasonic radiation [18,19,20].
In addition, other factors influence the germination process, for example, the type and concentration of macronutrients and micronutrients, and heavy metals. Phytohormones, sugar, and magnetism also affect germination [21,22,23,24,25]. Sugar is very important because it affects both trophic and signaling activity in plant growth [26,27]. Nitrogen (N) is another important factor in seed germination, important for amino acid synthesis [28]. The appropriate level of phosphorus [29,30] also has a beneficial effect on seed germination and seedling growth, while potassium increases seed vitality and protects seeds against deformation and discoloration of the embryo and seed coat [13,31].
The germination process depends primarily on the genotype of the plant. The physiological condition is also important. Gniazdowska et al. [32] and Kępczyńska [16] list among the internal factors regulating germination: hormones (abscysinic acid, gibberellins, ethylene, brassinosteroids, jasmonic acid), growth regulators (polyamines), and low-molecular signaling molecules (nitric oxide, reactive oxygen species, hydrogen cyanide).
In the case of soil conditions, factors of importance include the physical properties of the soil, nutrient content, allelopathy, soil moisture, oxygenation, and the presence of pathogens or harmful substances. The content of pathogens and harmful substances (for example, heavy metals in contaminated soils) can result in damage to seeds and developing plants or negatively affect the germination process.
The present study focuses on the selected heavy metals—zinc and cadmium.
The aim of the study is to compare the usefulness of short-term and long-term seed exposure to different levels of zinc and cadmium to determine the effect of these heavy metals on germination energy and the germination capacity of selected ornamental plant species. Two species were selected for the study: Eschscholzia californica Cham. and Coreopsis lanceolata. These species are gaining popularity as components of grass mixtures for sowing highway verges, whose soils may be contaminated with heavy metals.

2. Materials and Methods

The experiment was conducted in an accredited laboratory at “W. Legutko Przedsiębiorstwo Hodowlano-Nasienne Sp. z o.o.”. The seeds of two species of ornamental plants were the material for the study: Eschscholzia californica Cham. and Coreopsis lanceolata. Coreopsis lanceolata is a perennial herb belonging to the Asteraceae, native to North America. It is characterized by an upright and erect habit, which can take a bushy form, and it can reach a height of up to 50 cm. The bright green leaves growing in the lower part of the shoots are entire-edged and lanceolate, with a strongly visible nerve up to 15 cm long. Nachilles blooms from June to August. On thin, erect stems, it sets numerous single or semi-full inflorescences. The flowers are yellow and tongue-shaped. It is a thermophilic plant with low requirements, so the ideal position will be sunny, moderately moist, with not too fertile and permeable soil. Nachilles tolerates periodic drought and is completely frost hardy; moreover, it does not require special fertilization, which should even be limited to ensure abundant flowering. It is propagated by sowing seeds or by plant division.
Eschscholzia californica Cham. is an annual plant belonging to the poppy family (Papaveraceae) naturally found in California and characterized by a branching habit. It reaches a height of up to 40 cm. The leaves are pinnate, with a gray-green color, and it has single flowers, 3 cm in diameter, which bloom from June to September. They are set on long and thin stalks, taking on a golden yellow color. Garden varieties take on different colors and are larger. Eschscholzia californica Cham. also does not have exorbitant requirements; it likes sunny positions on light and sandy soils. It is propagated by sowing into the ground.
Two heavy metals, zinc and cadmium, were used in the study in the form of solutions of zinc sulfate ZnSO4 7H2O and cadmium sulfate 3CdSO4 8H2O (prepared at the Department of Plant Physiology). These were applied in increasing doses to treat the tested seeds of ornamental plants. The following doses were applied:
  • − Zn (control, 1; 5; 10 mg dm−3),
  • − Cd (control, 1.5; 2; 2.5 mg dm−3).
The mmol concentration for each dose was: Zn 1 mg dm−3 (0.015 mmol dm−3); 5 mg dm−3 (0.077 mmol dm−3); 10 mg dm−3 (0.154 mmol dm−3) and Cd 1.5 mg dm−3 (0.013 mmol dm−3); 2 mg dm−3 (0.018 mmol dm−3); and 2.5 mg dm−3 (0.022 mmol dm−3).
The study used two techniques for treating the seeds with heavy metal solutions. The first consisted of soaking the seeds for 10 min in zinc sulfate and cadmium sulfate and then lining the seeds in sterile Petri dishes on tissue paper soaked in distilled water. The second technique involved lining the seeds in sterile Petri dishes on blotting paper soaked in zinc sulfate and cadmium sulfate. In both the first and second techniques, 10 mL of test solution was used for each repetition (one Petri dish—50 seeds). The control was ornamental plant seeds lined in sterile Petri dishes on blotting paper soaked in 10 mL of distilled water. During the analysis, i.e., over the course of 14 days, the filter paper was wetted only once (after 7 days), using a sprayer from below (without spraying the seeds) in all the repetitions and combinations.
Four separate two-factor experiments were carried out, consisting of eight combinations. Each combination was performed in four replicates, and one replicate consisted of 50 seeds of the ornamental plant species under study.
According to the current ISTA [33] methodology, the germination energy for Coreopsis lanceolata and Eschscholzia californica Cham. is defined as the percentage of seeds whose seedlings were classified as normal after 4–7 days of germination under optimal conditions. For Coreopsis lanceolata, the temperature was 20–30 °C, while for Echscholzia californica, the temperature was 15 °C. The experiment was conducted in temperature-controlled seed germination chambers: a seed germination chamber with a variable temperature of 20–30 °C (8 h temperature of 30 °C and light, and 16 h temperature of 20 °C); and a seed germination chamber with a constant temperature of 15 °C. In the conducted tests, after 7 days, the germination energy of the seeds was evaluated for all the repetitions. After 14 days for all the repetitions, the seed germination capacity of the tested ornamental species was evaluated by counting the number of seeds that produced normal seedlings.
The results obtained were statistically processed in the STAT BAT program. An analysis of variance measured the germination energy and seed germination capacity of the studied ornamental plant species under increasing doses of heavy metals and metal application techniques. Duncan’s test was applied, determining differences between the averages at a significance level of p = 0.05.

3. Results

Depending on the application technique of the zinc solution, different germination energy results were obtained for Eschscholzia californica Cham. (Table 1). Despite statistically insignificant differences after soaking the seeds for 10 min for all the zinc concentrations tested, higher germination energy was observed compared to the control sample. On the other hand, prolonged contact of this element with seeds through blotting paper soaked in the ZnSO4 7H2O solution resulted in a total reduction of this parameter, regardless of the value of zinc concentration in the solution.
A similar relationship was found for the germination capacity of Eschscholzia californica Cham. seeds under increasing doses of zinc (Table 1). No significant differences in seed germination capacity were observed after pre-sowing in brief contact with the metal (10 min). However, a stimulating effect of this zinc application technique and increasing concentrations of zinc on the germination capacity of Eschscholzia californica Cham. seeds were observed. In contrast, the application of the solution to blotting paper, which involved prolonged contact of the seed with the heavy metal, resulted in a complete loss of germination capacity for each of the zinc concentrations.
During the conduct of the study, the number of abnormal seedlings obtained was determined (Table 2). The pre-sowing soaking of seeds in solutions with different concentrations of zinc did not significantly affect the formation of abnormal seedlings. In addition, the number of dead seeds of Eschscholzia californica was lower than in the control sample. In contrast, when the seeds were exposed to blotting paper soaked in the ZnSO4 7H2O solutions, only abnormal seedlings or dead seeds were obtained at all three doses.
Analysis of the Coreopsis lanceolata seedlings that were soaked in the Zn solution and lined up on clean tissue paper (Table 3) did not show a statistically significant reduction in seed germination energy compared to the control sample. However, there was a reduction in germination energy compared to the control. When the solution with increasing doses of zinc was applied to the blotting paper, a total loss of germination energy of the Coreopsis lanceolata was observed compared to the germination energy of seeds from the control.
Analyzing two techniques for watering Coreopsis lanceolata seeds with increasing concentrations of zinc, higher germination energy was found by soaking the seeds for 10 min before placing them on blotting paper.
Performing a test of the germination capacity of the Coreopsis lanceolata seeds (Table 3), the stimulating effect of soaking seeds in solutions with increasing zinc content was found compared to watering seeds on blotting paper with these solutions. Increasing doses of zinc used in the technique of soaking seeds for 10 min did not significantly affect their germination capacity. However, it was noted that soaking the seeds for 10 min with solutions with zinc concentrations of 1 and 5 mg dm−3 resulted in higher germination capacity compared to the control. When using the technique with blotting paper soaked in zinc solution, contact of the seeds with each dose of this metal resulted in a loss of germination capacity.
Using the first zinc application technique, the number of developed abnormal seedlings accounted for a small percentage of the results obtained and also decreased with increasing Zn concentration (Table 4). After soaking the seeds with zinc solutions at doses of 1 and 5 mg dm−3, fewer dead seeds were obtained than in the control trial. At the highest concentration of the ZnSO4 7H2O solution, more dead seeds were obtained than in the control trial.
High values of dead seeds and abnormal seedlings were obtained after applying the solution technique to blotting paper. Regardless of the value of the Zn dose, all emergences were characterized by anomalous seeds of at least one part of the plant. The remaining seeds were marked as dead. Zinc doses of 1 and 5 mg dm−3 induced the germination of abnormal seedlings.
Using the first cadmium application technique (soaking for 10 min), despite the statistically insignificant differences found, a relationship was observed—the higher the cadmium dose, the lower the germination energy of Eschscholzia californica Cham. (Table 5).
In addition, using the technique of soaking blotting paper in cadmium solutions, high values of abnormal seedlings (62–72%) were obtained, decreasing with increasing cadmium dosage. Hard seeds and fresh seeds were not observed (Table 6).
Using watering of Coreopsis lanceolata seeds with increasing doses of cadmium for 10 min, statistically significant differences were found in their germination energy (Table 7). The effect of increasing doses of cadmium on reducing seed germination energy was observed in this watering technique compared to the control.
On the other hand, using the technique of watering Coreopsis lanceolata seeds with cadmium solutions on tissue paper, it was found that the contact of each dose of this metal with the seed was associated with the disappearance of germination energy.
Despite statistically insignificant differences, the germination capacity of seeds after using the first application technique of cadmium sulfate solution increased slightly compared to the control sample. In contrast, no normal seedlings were obtained when the seeds were laid out on blotting paper soaked with this solution (Table 7).
Increasing doses of cadmium did not significantly increase the number of abnormal seedlings when, pre-sowing, the seed was soaked for 10 min in cadmium sulfate solution. In addition, at each cadmium concentration tested, the percentage of dead seeds was below the value obtained for the control sample (Table 8).
The results obtained are significantly different from the effect obtained with the second technique, that is, after the application of cadmium sulfate solution to blotting paper. Compared to the control trial, the solution of 3CdSO4 8H2O caused the formation of a significant number of abnormal seedlings and affected the number of dead seeds. The increase in Cd concentration translated into an increase in the number of dead seeds of the Coreopsis lanceolata.

4. Discussion

The toxicity of heavy metals with doses exceeding acceptable levels is revealed during the germination process. The response of the plant to a certain concentration of an element depends on the permeability of the seed husk, the taxon, the population, and the dose of Cd and Zn, as confirmed by many authors studying selected plant species [7,34,35]. The effects of the negative influence of heavy metals on the process of seed germination include a reduction in germination capacity, a decrease in germination energy, or inhibition of this process, morphological and anatomical changes in seedlings, a decrease in biomass, and chromosome mutations [7].
All over the world, plant species useful for phytoremediation of heavy metals, including zinc and cadmium, from contaminated soils are sought [6]. In the conducted studies, zinc and cadmium stress on the germination process of Eschscholzia californica Cam. and Coreopsis lanceolata seeds was tested. The tested species were selected based on great interest in using them in grass mixtures for planting soils along communication routes and highways. The study analyzed the effects of two heavy metals on seed germination. The first element (zinc) in small amounts is a basic microelement that affects the course of life processes of living organisms. Both its deficiency and excess are associated with negative consequences. Zinc is an important micronutrient for plants. It takes part in the metabolic processes of plants and physiological processes, including enzyme activation [36,37]. Too-high concentrations of zinc in the soil can cause various changes in plants. According to Kaur and Garg [38], plants may react to high zinc concentrations with reduced growth, photosynthetic and respiratory rates, imbalanced mineral nutrition, and enhanced generation of reactive oxygen species.
The second of the metals, cadmium, is referred to as a ballast toxic element. As a result of developing civilization, cadmium contamination of the world’s soils is on the rise. The literature emphasizes that the accumulation of relatively low amounts of Cd can cause toxic symptoms [37]. According to Vijayaragavan et al. [39], cadmium constrains seed germination rates via different mechanisms, such as the impairment of water uptake in seeds, which ultimately limits the water availability for embryo development. Cadmium can reduce photosynthetic capacity, lead to plant growth retardation and oxidative stress, and affect secondary metabolism [40]. Kuriakose and Prasad [41] found that cadmium causes impaired translocation of sugars towards the developing embryonic axis and ultimately results in starvation of the developing embryo.
Sethy and Gosh [5] cited, among the negative effects of cadmium on seeds and seedlings during the germination process, the following detail: damage to cell membranes, impaired ability to absorb nutrients, accumulation or excessive accumulation of lipid peroxidation products in seeds, inhibition of plant embryo development and biomass distribution, reduction of α-amylase and invertase activities, mitochondrial damage, reduction in water content, and germinal development. A cadmium-induced decrease in α-amylase activity was found by [42,43]. Cadmium stress also causes membrane damage and leakage of amino acids and sugars [44].
The effects of seed exposure and plants in the early stages of growth were described by, among others, Drab et al. [34] in an experiment conducted on Sinapis alba L., Brassica napus oleifera L., Secale cereale L., and Tritcum aestivum L. The authors demonstrated that increasing concentrations in solutions of Cd(NO3)2 and Pb(NO3)2 reduced the number of germinated seeds, with the highest doses of metals having the most toxic effect. On the other hand, Mozdżeñ et al. [35] proved in their study that for radish (Raphanus sativus L. var sativus) cv. ‘Rowa’, the concentration of cadmium and zinc showing the toxicity of both elements is 0.25%, while it was observed that radish seedlings were characterized by higher susceptibility to Cd contamination of the substrate than Zn. A cadmium stress response when testing the activities of hydrolytic enzymes in germinating seeds of Vigna radiata was also found by Anwar et al. [45]. The authors found that exposure of Vigna radiata seeds to cadmium stress (concentrations of 0, 25, 50, 75, and 100 mg L−1 used in the study) reduced seed germination rate and early seedling growth traits, including root and shoot length and fresh and dry plant biomass. They emphasize that the negative effects of Cd were more prominent in terms of shoot length than root length.
Anwar et al. [45] observed that the highest supplementation of Cd (100 mg L−1) caused maximum damage to plants and decreased the germination percentage (27%), shoot length (63%), and root length (27%) compared to the control (0 mg L−1) plants. Further, a 100 mg Cd L−1 application displayed a significant decrease in shoot and root fresh mass by 28% and 61%, respectively, compared to non-treated plants.
In subsequent studies conducted by Zaari et al. [46], germinating wheat seeds were tested in nine concentrations of Cd (0, 0.125, 0.25, 0.375, 0.5, 0.675, 0.75, 0.875, and 1 g L−1) where germination rate, biomass production, shoot and root length, vigor index, growth inhibition, and tolerance indices were assessed. The authors found that Cd negatively affected wheat germination and that the negative effect of cadmium on shoot and root length was more pronounced during seedling development than during germination.
The above experimental results confirm the findings of the authors of the scientific publications. First of all, the study highlighted differences in the responses of Coreopsis lanceolata and Eschscholzia californica Cham. to contact with heavy metals. The germination energy of Coreopsis lanceolata seeds, after soaking for 10 min in the heavy metal solution, decreased compared to the germination energy obtained from the control sample. However, in the case of Eschscholzia californica Cham., the treatment of seeds with doses of Zn and Cd had a stimulating effect on seed germination energy. The phenomenon of differences in the responses of plant species to heavy metal toxicity was described in their scientific papers by, among others, Siwek [7] and Drab et al. [34].
Each dose of zinc and cadmium applied to blotting paper tested in the study resulted in the inhibition of the energy and germination capacity of Eschscholzia californica Cham. and Coreopsis lanceolata seeds. In addition, they caused the development of a significant number of abnormal seedlings. Anomalies in the morphology of radish seedlings treated with different doses of Zn and Cd were also noted by Mozdżeñ et al. [35].
In the study conducted, as cadmium concentrations increased, the proportion of dead seeds in the results increased, while increasing zinc doses did not show a clear correlation between increasing dose values and an increasing number of dead seeds. The phenomenon of the effect of increasing doses of Cd and Zn on reducing the number of germinated seeds was also observed by Drab et al. [34], studying the responses of Brassica napus oleifera L. and Sinapis alba L.
According to Carvalho et al. [47], the effect of Cd on seed germination and vigor encompasses not only negative outcomes but also neutral and positive ones. It depends on the Cd concentration, chemical, physical and biological properties of the substrate, plant species and genotypes, development stage, and plant organ.
According to the study by Mishra et al. [48], who presented a successful and reproducible protocol of eco-friendly green synthesis of ZnO NPs and highlight its application in improving seedling growth parameters of finger millet under in vitro, conditioning seed treatment with lower doses of ZnO NPs (100 mg L−1 and 500 mg L−1) is a successful strategy for promoting seedling development in Eleusine coracana. The authors claim that in the future, applying green-synthesized ZnOs may improve seed germination and the plant growth promotion of other crops.

5. Conclusions

The selection of plants for contaminated soils must be carefully considered, based on research results on the tolerance of these species to increasing concentrations of zinc and cadmium from the moment of germination to plant growth. The technique for treating seeds with heavy metal solutions and the duration of exposure to the metals play a significant role in germination. Soaking Eschscholzia californica Cham. seeds in increasing doses of zinc and cadmium solutions for 10 min before sowing showed no significant effect on their energy or germination capacity. Likewise, soaking Coreopsis lanceolata seeds in zinc solutions for 10 min before sowing did not significantly influence their energy and germination capacity. However, soaking Coreopsis lanceolata seeds in cadmium solutions for 10 min before sowing did not notably affect their germination capacity but significantly diminished their germination energy. Extended exposure of seeds placed on blotting paper soaked in cadmium sulfate and zinc sulfate solutions across all concentrations reduced energy and germination capacity for both Eschscholzia californica Cam. and Coreopsis lanceolata seeds. The authors argue that further research is necessary to determine the potential usefulness of Eschscholzia californica Cam. and Coreopsis lanceolata for phytoremediation of zinc and cadmium in contaminated soils.

Author Contributions

Conceptualization, M.B. and O.M.; methodology, O.M., M.B. and S.Ś.; material preparation, data collection, and analysis were performed by O.M., M.B. and S.Ś.; data curation, M.B.; writing—original draft preparation, M.B., O.M. and S.Ś.; writing—review and editing, M.B. and S.Ś. All authors have read and agreed to the published version of the manuscript.

Funding

This research received no external funding.

Data Availability Statement

The original contributions presented in the study are included in the article; further inquiries can be directed to the corresponding author.

Conflicts of Interest

The authors declare no conflicts of interest related to this article.

References

  1. Hou, D.; Jia, X.; Wang, L.; McGrath, S.P.; Zhu, Y.G.; Hu, Q.; Zhao, F.Z.; Bank, M.S.; O’Connor, D.; Nriagu, J. Global soil pollution by toxic metals threatens agriculture and human health. Science 2025, 388, 316–321. [Google Scholar] [CrossRef]
  2. Kabata-Pendias, A.; Pendias, H. Biogeochemistry of Trace Elements; PWN: Warszawa, Poland, 1999; pp. 144–156. [Google Scholar]
  3. Ociepa-Kubicka, A.; Ociepa, E. Toxic effects of heavy metals on plants, animals and humans. Inż. Ochr. Środowiska 2012, 15, 169–180. [Google Scholar]
  4. Bosiacki, M.; Bednorz, L.; Fedeńczak, K.; Górecki, T.; Mizgajski, A.; Poniży, L.; Spiżewski, T. Soil Quality as a Key Factor in Producing Vegetables for Home Consumption—A Case Study of Urban Allotments in Gorzów Wielkopolski (Poland). Agronomy 2021, 11, 1836. [Google Scholar] [CrossRef]
  5. Sethy, S.K.; Ghosh, S. Effect of heavy metals on germination of seeds. J. Nat. Sci. Biol. Med. 2013, 4, 272–275. [Google Scholar]
  6. Bosiacki, M.; Kleiber, T.; Markiewicz, B. Continuous and Induced Phytoextraction-Plant-Based Methods of Remove Heavy Metals from Contaminated Soil. In Environmental Risk Assessment of Soil Contamination; Hernandez-Soriano, M.C., Ed.; InTech: Rijeka, Croatia, 2014; Volume 20, pp. 575–612. ISBN 978-953-51-1235-8. [Google Scholar]
  7. Siwek, M. Plants in postindustrial sites, contaminated with heavy metals. Part 1. Uptake, transport and toxicity of heavy [trace] metals. Wiad. Bot. 2008, 52, 7–22. [Google Scholar]
  8. Szatanik-Kloc, A. Effect of pH and selected heavy metals in soil on their content in plants. Acta Agrophys. 2004, 4, 177–183. [Google Scholar]
  9. Kaczyńska, A.; Zajączkowski, M.; Grzybiak, M. Cadmium toxicity in plants and humans. Ann. Acad. Med. Gedan. 2015, 45, 65–70. [Google Scholar]
  10. Rajjou, L.; Duval, M.; Gallardo, K.; Catusse, J.; Bally, J.; Job, C.; Job, D. Seed germination and vigor. Annu. Rev. Plant Biol. 2012, 63, 507–533. [Google Scholar] [CrossRef]
  11. Miransari, M.; Smith, D.L. Plant hormones and seed germination. Environ. Exp. Bot. 2014, 99, 110–121. [Google Scholar] [CrossRef]
  12. Gan, Y.; Stobbe, E.H.; Njue, C. Evaluation of selected nonlinear regression models in quantifying seedling emergence rate of spring wheat. Crop Sci. 1996, 36, 165–168. [Google Scholar] [CrossRef]
  13. Duczmal, K.; Tucholska, H. Seeding; Państwowe Wydawnictwo Rolnicze i Leśne: Poznań, Poland, 2000; Volume 1, pp. 164–181. [Google Scholar]
  14. Gallardo, K.; Job, C.; Steven, P.; Groot, C.; Puype, M.; Demol, H.; Vandekerckhove, J.; Job, D. Proteomic analysis of Arabidopsis seed germination and priming. Plant Physiol. 2001, 126, 835–848. [Google Scholar] [CrossRef] [PubMed]
  15. Lewicki, P. Sprouts as source of valuable nutritients. Żywność Nauka Technol. Jakość 2010, 6, 18–33. [Google Scholar] [CrossRef]
  16. Gniazdowska, A.; Budnicka, K.; Krasuska, U. Regulacja spoczynku i kiełkowania nasion—Czynniki endogenne i oddziaływania środowiskowe w: Różnorodność biologiczna—Od komórki do ekosystemu. In Rośliny i Grzyby w Zmieniających się Warunkach Środowiska Pod Red; Ciereszko, I., Bajguza, A., Eds.; Polskie Towarzystwo Botaniczne Białystok, Agencja Wydawnicza EkoPress: Białystok, Poland, 2013; pp. 25–33. [Google Scholar]
  17. Xue, X.; Du, S.; Jiao, F.; Xi, M.; Wang, A.; Xu, H.; Jiao, Q.; Zhang, X.; Jiang, H.; Chen, J.; et al. The regulatory network behind maize seed germination: Effects of temperature, water, phytohormones, and nutrients. Crop J. 2021, 9, 718–724. [Google Scholar] [CrossRef]
  18. Gładyszewska, B. Matematyczne metody oceny wpływu procesów przedsiewnej stymulacji na kiełkowanie nasion. Acta Agrophys. 2004, 3, 443–452. [Google Scholar]
  19. Kornarzyński, K.; Pietruszewski, S. Influence of alternating magnetic field on the germination of seeds with low germination capacity. Acta Agrophys. 2008, 11, 429–435. [Google Scholar]
  20. Jakubowski, T. Eevaluation of the impact of pre-sowing microwave stimulation of bean seeds on the germination process. Agric. Eng. 2015, 2, 45–56. [Google Scholar]
  21. Casal, J.J.; Sánchez, R.A. Phytochromes and seed germination. Seed Sci. Res. 1998, 8, 317–329. [Google Scholar] [CrossRef]
  22. Dekkers, B.J.W.; Schuurmans, J.A.M.J.; Smeekens, S.C.M. Glucose delays seed germination in Arabidopsis thaliana. Planta 2004, 218, 579–588. [Google Scholar] [CrossRef] [PubMed]
  23. Florez, M.; Carbonell, M.V.; Martínez, E. Exposure of maize seeds to stationary magnetic fields: Effects on germination and early growth. Environ. Exp. Bot. 2007, 59, 68–75. [Google Scholar] [CrossRef]
  24. Xing, Y.U.; Jia, W.; Zhang, J. AtMKK1 and AtMPK6 are involved in abscisic acid and sugar signaling in Arabidopsis seed germination. Plant Mol. Biol. 2009, 70, 725–736. [Google Scholar] [CrossRef]
  25. Johnson, T.R.; Kane, M.E.; Pérez, H.E. Examining the interaction of light, nutrients and carbohydrates on seed germination and early seedling development of Bletia purpurea (Orchidaceae). Plant Growth Regul. 2011, 63, 89–99. [Google Scholar] [CrossRef]
  26. Hu, X.; Jiang, X.; Hwang, H.; Liu, S.; Guan, H. Promotive effects of alginate-derived oligosaccharide on maize seed germination. J. Appl. Phycol. 2004, 16, 73–76. [Google Scholar] [CrossRef]
  27. Xia, H.; Yandeau-Nelson, M.; Thompson, D.B.; Guiltinan, M.J. Deficiency of maize starch-branching enzyme results in altered starch fine structure, decreased digestibility and reduced coleoptile growth during germination. BMC Plant Biol. 2011, 11, 95. [Google Scholar] [CrossRef] [PubMed]
  28. Limami, A.M.; Rouillon, C.; Glevarec, G.; Gallais, A.; Hirel, B. Genetic and physiological analysis of germination efficiency in maize in relation to nitrogen metabolism reveals the importance of cytosolic glutamine synthetase. Plant Physiol. 2002, 130, 1860–1870. [Google Scholar] [CrossRef] [PubMed]
  29. Hegeman, C.E.; Grabau, E.A. A novel phytase with sequence similarity to purple acid phosphatases is expressed in cotyledons of germinating soybean seedlings. Plant Physiol. 2011, 126, 1598–1608. [Google Scholar] [CrossRef]
  30. Nadeem, M.; Mollier, A.; Morel, C.; Vives, A.; Prud’homme, L.; Pellerin, S. Maize (Zea mays L.) endogenous seed phosphorus remobilization is not influenced by exogenous phosphorus availability during germination and early growth stages. Plant Soil 2012, 357, 13–24. [Google Scholar] [CrossRef]
  31. Grzesik, M.; Janas, R.; Górnik, K.; Romanowska-Duda, Z. Biological and physical methods of seed production and processing. J. Res. Appl. Agric. Eng. 2012, 57, 147–152. [Google Scholar]
  32. Kępczyńska, E. In vitro germination and conversion of somatic embryos. Biotechnologia 2006, 4, 78–94. [Google Scholar]
  33. International Rules for Seed Testing. Handbook of Vigour Test Methods; International Rules for Seed Testing: Wallisellen, Switzerland, 1995; pp. 92–103. [Google Scholar]
  34. Drab, M.; Greinert, A.; Kostecki, J.; GRzechnik, M. Seed germination of selected plants under the influence of heavy metals. Civ. Environ. Eng. Rep. 2011, 7, 47–57. [Google Scholar]
  35. Możdżeń, K.; Barabasz-Krasny, B.; Puła, J.; Lepiarczyk, A. Impact of compounds of cadmium and zinc in early stages of growth of radish (Raphanus sativus L. var. sativus). Fragm. Agron. 2017, 34, 45–54. [Google Scholar]
  36. Hamzah Saleem, M.; Usman, K.; Rizwan, M.; Al Jabri, H.; Alsafran, M. Functions and strategies for enhancing zinc availability in plants for sustainable agriculture. Front. Plant Sci. 2022, 13, 1033092. [Google Scholar] [CrossRef] [PubMed]
  37. Rasafi, E.; Oukarroum, A.; Haddioui, A.; Song, H.; Kwon, E.E.; Bolan, N.; Tack, F.M.G.; Sebastian, A.; Prasad, M.N.V.; Rinklebe, J. Cadmium stress in plants: A critical review of the effects, mechanisms, and tolerance strategies. Crit. Rev. Environ. Sci. Technol. 2020, 52, 675–726. [Google Scholar] [CrossRef]
  38. Kaur, H.; Garg, N. Zinc toxicity in plants: A review. Planta 2021, 253, 129. [Google Scholar] [CrossRef]
  39. Vijayaragavan, M.; Prabhahar, C.; Sureshkumar, J.; Natarajan, A.; Vijayarengan, P.; Sharavanan, S. Toxic effect of cadmium on seed germination, growth and biochemical contents of cowpea (Vigna unguiculata L.) plants. Int. Multidiscip. Res. J. 2011, 1, 1–6. [Google Scholar]
  40. Fan, P.; Wu, L.; Wang, Q.; Wang, Y.; Luo, H.; Song, J.; Yang, M.; Yao, H.; Chen, S. Physiological and molecular mechanisms of medicinal plants in response to cadmium stress: Current status and future perspective. J. Hazard. Mater. 2023, 450, 131008. [Google Scholar] [CrossRef]
  41. Kuriakose, S.V.; Prasad, M.N.V. Cadmium stress affects seed germination and seedling growth in Sorghum bicolor (L.) Moench by changing the activities of hydrolyzing enzymes. Plant Growth Regul. 2008, 54, 143–156. [Google Scholar] [CrossRef]
  42. Kalai, T.; Bouthour, D.; Manai, J.; Ben Kaab, L.B.; Gouia, H. Salicylic acid alleviates the toxicity of cadmium on seedling growth, amylases and phosphatases activity in germinating barley seeds. Arch. Agron. Soil Sci. 2016, 62, 892–904. [Google Scholar] [CrossRef]
  43. He, J.Y.; Ren, Y.F.; Pan, X.B.; Yan, Y.P.; Zhu, C.; Jiang, D. Salicylic acid alleviates the toxicity effect of cadmium on germination, seedling growth, and amylase activity of rice. J. Plant Nutr. Soil Sci. 2010, 173, 300–305. [Google Scholar] [CrossRef]
  44. Basahi, M. Humic acid improved germination rate, seedling growth and antioxidant system of pea (Pisum sativum L. var. Alicia) grown in water polluted with CdCl2. AIMS Environ. Sci. 2021, 8, 358–370. [Google Scholar] [CrossRef]
  45. Anwar, S.; Shafiq, F.; Nisa, Z.U.; Usman, U.; Ashraf, M.Y.; Ali, N. Effect of cadmium stress on seed germination, plant growth and hydrolyzing enzymes activities in mungbean seedlings. J. Seed Sci. 2021, 43, e202143042. [Google Scholar] [CrossRef]
  46. Zaari Jabri, N.; Ait-El-Mokhtar, M.; Mekkaoui, F.; Amghar, I.; Achemrk, O.; Diria, G.; Hmyene, A. Impacts of cadmium toxicity on seed germination and seedling growth of Triticum durum cultivars. Cereal Res. Commun. 2024, 52, 1399–1409. [Google Scholar] [CrossRef]
  47. Carvalho, M.E.A.; Agathokleous, E.; Nogueira, M.L.; Brunetto, G.; Brown, P.H.; Azevedo, R.A. Neutral-to-positive cadmium effects on germination and seedling vigor, with and without seed priming. J. Hazard. Mater. 2023, 448, 130813. [Google Scholar] [CrossRef] [PubMed]
  48. Mishra, D.; Chitara, M.K.; Negi, S.; Pal Singh, J.; Kumar, R.; Chaturvedi, P. Biosynthesis of zinc oxide nanoparticles via leaf extracts of Catharanthus roseus (L.) G. Don and Their Application in Improving Seed Germination Potential and Seedling Vigor of Eleusine coracana (L.) Gaertn. Hindawi Adv. Agric. 2023, 2023, 7412714. [Google Scholar] [CrossRef]
Table 1. Effect of increasing zinc dose on energy and germination capacity of Eschscholzia californica Cham.
Table 1. Effect of increasing zinc dose on energy and germination capacity of Eschscholzia californica Cham.
Dose of Zinc mg·dm−3Germination Energy
Eschscholzia californica Cham.
(%)		Germination Capacity
Eschscholzia californica Cham.
(%)
Application Technique of the Solution
Seed Soaking 10 minTissue Paper Soaked in SolutionSeed Soaking 10 minTissue Paper Soaked in Solution
Control83 b *83 b85 b85 b
188 b0 a89 b0 a
590 b0 a93 b0 a
1085 b0 a87 b0 a
* followed by the same letters do not differ significantly at p = 0.05.
Table 2. Effect of increasing zinc dose on the number of abnormal seedlings, dead, hard, and fresh seeds of Eschscholzia californica Cham.
Table 2. Effect of increasing zinc dose on the number of abnormal seedlings, dead, hard, and fresh seeds of Eschscholzia californica Cham.
Dose of Zinc mg·dm−3Number of Abnormal Seedlings, Dead, Hard, and Fresh Seeds
Eschscholzia californica Cham.
(%)
Application Technique of the Solution
Seed Soaking 10 minTissue Paper Soaked in Solution
Abnormal SeedlingsDead SeedsHard SeedsFresh SeedsAbnormal SeedlingsDead SeedsHard SeedsFresh Seeds
Control0150001500
111000633700
51600742600
1001300693100
Table 3. Effect of increasing zinc dose on energy and germination capacity of Coreopsis lanceolata.
Table 3. Effect of increasing zinc dose on energy and germination capacity of Coreopsis lanceolata.
Dose of Zinc
mg·dm−3		Germination Energy
Coreopsis lanceolata
(%)		Germination Capacity
Coreopsis lanceolata
(%)
Application Technique of the Solution
Seed Soaking 10 minTissue Paper Soaked in SolutionSeed Soaking 10 minTissue Paper Soaked in Solution
Control49 b *49 b77 b77 b
137 b0 a80 b0 a
541 b0 a84 b0 a
1031 b0 a71 b0 a
* followed by the same letters do not differ significantly at p = 0.05.
Table 4. Effect of increasing zinc dose on the number of abnormal seedlings, dead, hard, and fresh seeds of Coreopsis lanceolata.
Table 4. Effect of increasing zinc dose on the number of abnormal seedlings, dead, hard, and fresh seeds of Coreopsis lanceolata.
Dose of Zinc mg·dm−3Number of Abnormal Seedlings, Dead, Hard, and Fresh Seeds
Coreopsis lanceolata
(%)
Application Technique of the Solution
Seed Soaking 10 minTissue Paper Soaked in Solution
Abnormal SeedlingsDead SeedsHard SeedsFresh SeedsAbnormal SeedlingsDead SeedsHard SeedsFresh Seeds
Control5180051800
181200554500
561000782200
1012800663400
Table 5. Effect of increasing cadmium dose on energy and germination capacity of Eschscholzia californica Cham.
Table 5. Effect of increasing cadmium dose on energy and germination capacity of Eschscholzia californica Cham.
Dose of Cadmium mg·dm−3Germination Energy
Eschscholzia californica Cham.
(%)		Germination Capacity
Eschscholzia californica Cham.
(%)
Application Technique of the Solution
Seed Soaking 10 minTissue Paper Soaked in SolutionSeed Soaking 10 minTissue Paper Soaked in Solution
Control83 a *83 a85 b85 b
1.591 a0 a91 b3 a
2.087 a0 a87 b0 a
2.580 a0 a80 b1 a
* followed by the same letters do not differ significantly at p = 0.05.
Table 6. Effect of increasing cadmium dose on the number of abnormal seedlings, dead, hard, and fresh seeds of Eschscholzia californica Cham.
Table 6. Effect of increasing cadmium dose on the number of abnormal seedlings, dead, hard, and fresh seeds of Eschscholzia californica Cham.
Dose of Cadmium mg·dm−3Number of Abnormal Seedlings, Dead, Hard, and Fresh Seeds
Eschscholzia californica Cham.
(%)
Application Technique of the Solution
Seed Soaking 10 minTissue Paper Soaked in Solution
Abnormal SeedlingsDead SeedsHard SeedsFresh SeedsAbnormal SeedlingsDead SeedsHard SeedsFresh Seeds
Control0150001500
1.52700722500
2.011200703000
2.531700623700
Table 7. Effect of increasing cadmium dose on energy and germination capacity of Coreopsis lanceolata.
Table 7. Effect of increasing cadmium dose on energy and germination capacity of Coreopsis lanceolata.
Dose of Cadmium mg·dm−3Germination Energy
Coreopsis lanceolata
(%)		Germination Capacity
Coreopsis lanceolata
(%)
Application Technique of the Solution
Seed Soaking 10 minTissue Paper Soaked in SolutionSeed Soaking 10 minTissue Paper Soaked in Solution
Control49 c *49 c77 b77 b
1.538 b0 a81 b0 a
2.032 b0 a84 b0 a
2.529 b0 a81 b0 a
* followed by the same letters do not differ significantly at p = 0.05.
Table 8. Effect of increasing cadmium dose on the number of abnormal seedlings, dead, hard, and fresh seeds of Coreopsis lanceolata.
Table 8. Effect of increasing cadmium dose on the number of abnormal seedlings, dead, hard, and fresh seeds of Coreopsis lanceolata.
Dose of Cadmium mg dm−3Number of Abnormal Seedlings, Dead, Hard, and Fresh Seeds
Coreopsis lanceolata
(%)
Application Technique of the Solution
Seed Soaking 10 minTissue Paper Soaked in Solution
Abnormal SeedlingsDead SeedsHard Seeds Fresh Seeds Abnormal SeedlingsDead SeedsHard Seeds Fresh Seeds
Control5180051800
1.551400762400
2.051100752500
2.561300673300
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Marcin, O.; Bosiacki, M.; Świerczyński, S. The Effect of Increasing Doses of Heavy Metals on Seed Germination of Selected Ornamental Plant Species. Agronomy 2025, 15, 1262. https://doi.org/10.3390/agronomy15061262

AMA Style

Marcin O, Bosiacki M, Świerczyński S. The Effect of Increasing Doses of Heavy Metals on Seed Germination of Selected Ornamental Plant Species. Agronomy. 2025; 15(6):1262. https://doi.org/10.3390/agronomy15061262

Chicago/Turabian Style

Marcin, Olzacki, Maciej Bosiacki, and Sławomir Świerczyński. 2025. "The Effect of Increasing Doses of Heavy Metals on Seed Germination of Selected Ornamental Plant Species" Agronomy 15, no. 6: 1262. https://doi.org/10.3390/agronomy15061262

APA Style

Marcin, O., Bosiacki, M., & Świerczyński, S. (2025). The Effect of Increasing Doses of Heavy Metals on Seed Germination of Selected Ornamental Plant Species. Agronomy, 15(6), 1262. https://doi.org/10.3390/agronomy15061262

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