Next Article in Journal
Boesenbergia Kuntze (Zingiberaceae) in Cambodia: Four New Records with Notes on Their Potential Horticultural Significance, Cultivation Guidelines, and Lectotypification of B. xiphostachya (Gagnep.) Loes.
Previous Article in Journal
CPPU and Ethylene Inhibitors as an Environmentally Friendly Strategy for Improving Fruit Retention, Yield, and Quality in Avocado
 
 
Search for Articles:
Title / Keyword
Author / Affiliation / Email
Journal
Article Type
 
 
Advanced Search
 
Section
Special Issue
Volume
Issue
Number
Page
 
Journals
Horticulturae
Volume 11
Issue 2
10.3390/horticulturae11020179
horticulturae-logo
Submit to this Journal Review for this Journal Propose a Special Issue
► Article Menu

Article Menu

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

The Role of Vitekang Soil Conditioner and Arbuscular Mycorrhizae Fungi in Mitigating Cadmium Stress in Solanum lycopersicum Plants

by
Qianqian Wang
1,
Yue Liu
1,
Guangxin Chen
1,
Xing Liu
1,
Mohsin Tanveer
2,
Yongjun Guo
3,
Peng Zeng
1 and
Liping Huang
1,*
1
School of Agricultural and Bioengineering, Foshan University, Foshan 528225, China
2
Xinjiang Institute of Ecology and Geography, Chinese Academy of Sciences, Urumqi 830011, China
3
Foshan Ecological Plant Protection Technology Co., Ltd., Foshan 528225, China
*
Author to whom correspondence should be addressed.
Horticulturae 2025, 11(2), 179; https://doi.org/10.3390/horticulturae11020179
Submission received: 30 December 2024 / Revised: 19 January 2025 / Accepted: 28 January 2025 / Published: 7 February 2025
(This article belongs to the Section Vegetable Production Systems)
Browse Figures
Versions Notes

Abstract

:
Solanum lycopersicum, a widely cultivated vegetable crop globally, faces soil cadmium (Cd) contamination issues due to Cd’s high mobility, posing potential threats to Solanum lycopersicum growth and human health. In light of this, this study selected three representative Solanum lycopersicum varieties: Micro Tom, Red Guanyin, and Taiwan Pink King, and designed a series of experiments to investigate their growth performance under Cd stress. Experimental treatments included the sole application of different concentrations of Vitekang soil conditioner (VT), as well as the individual and combined application of VT and arbuscular mycorrhizal fungi (AMF). By thoroughly analyzing agronomic traits, cellular membrane lipid peroxidation levels, the activities of antioxidant enzymes (Catalase (CAT), Superoxide Dismutase (SOD), and Peroxidase (POD)), and the expression levels of genes related to Cd transport and detoxification (SLNRAMP6 and SlHMA3), this study comprehensively evaluated the effectiveness of different treatments in mitigating Cd stress in the three Solanum lycopersicum varieties. The results indicated that when VT was applied at a concentration of 2.4 g/kg in combination with AMF, it significantly reduced the detrimental effects of Cd on Micro Tom, Red Guanyin, and Taiwan Pink King. The specific experimental outcomes were as follows: (i) significantly decreased Cd accumulation in Solanum lycopersicum roots and leaves; (ii) effectively mitigated cellular membrane lipid peroxidation; (iii) significantly increased antioxidant enzyme activities; and (iv) influenced expression patterns of genes related to Cd transport and detoxification. This study further confirms that, compared to the sole application of VT or AMF, the combined application of these two treatments serves as a more effective practical method, exhibiting significant advantages in alleviating soil Cd contamination, promoting Solanum lycopersicum growth, and improving agronomic traits. This study not only advances research progress on VT and AMF in Solanum lycopersicumes, providing a solid theoretical and experimental foundation for cultivating high-quality Solanum lycopersicumes, but also holds significant importance for improving and optimizing the “VIP+N” technology, achieving farmland soil protection, and enhancing agricultural product quality.

1. Introduction

Soil, as the cornerstone of human survival and progress, holds immense importance. However, in the wave of industrialization and urbanization, soil faces severe challenges from heavy metal pollution from substances such as lead and cadmium. According to the national soil pollution survey bulletin, the pollution status of cultivated soil in China is alarming, with a site exceedance rate of 19.4%, and the exceedance rate for cadmium specifically reaching 7.0% [1]. Cadmium pollution is particularly prominent among heavy metal pollutants due to its wide coverage, strong persistence, and difficulty in degradation.
Cadmium stress not only leads to soil hardening and decreased fertility, but also causes many negative effects on plant physiological responses, such as photosynthesis and respiration, resulting in reduced plant biomass and further affecting crop yield and quality [2]. More seriously, cadmium is a heavy metal pollutant with a high bioavailability, which easily accumulates in agricultural products and enters the human body through the food chain, posing a serious threat to human health [3].
To address this challenge, scholars are actively seeking effective soil improvement methods. Qin et al. [4] found that soil conditioners such as lime and peat, which are inorganic fertilizers, have significant effects on improving soil physicochemical properties, enhancing soil fertility, and inhibiting heavy metal stress. By applying soil conditioners, soil potential can be activated, residual nutrients released, and plant absorption and the utilization of nutrients in the soil promoted, thereby improving crop stress resistance and yield.
Zhao et al. [5] and Wang et al. [6] have confirmed this through experiments with Chinese cabbage and chili peppers, respectively. They found that after applying soil conditioners, the growth of crops improved significantly, and the absorption and accumulation of heavy metals were effectively controlled. Zhang et al. [7] found that the use of lime to repair cadmium-contaminated soil could effectively reduce the concentration of cadmium in rice. Liu et al. [8] found that the application of nano-hydroxyapatite and its combined materials could effectively reduce the effectiveness of cadmium in soil, and then reduce the enrichment of cadmium by potato tubers. Moscowskiy Bio-organic catalyst, Inc. [9] used Phyto-CatTM soil conditioner to improve the seed germination rate and seedling characteristics of wheat, corn, Solanum lycopersicum, pepper, and cabbage. The results showed that the appropriate concentration of the soil conditioner had a significant improvement effect on the seedling traits of the test crops.
In addition, arbuscular mycorrhizal fungi (AMF), as beneficial microorganisms in soil, play an important role in improving the soil microenvironment, promoting Solanum lycopersicum nutrient absorption and utilization, and enhancing plant stress resistance [10,11]. Studies by Li et al. [12] and Chen et al. [13] have shown that inoculating AMF can effectively alleviate the impact of heavy metal stress on plant growth and reduce the transport and absorption of heavy metals in plants. AMF achieves the remediation and improvement of heavy metal-contaminated soil by secreting specific proteins and promoting heavy metal chelation [14,15].
Currently, there is limited research on the combined use of Vitekang soil conditioner and inoculation with AMF (Arbuscular Mycorrhizal Fungi) to mitigate cadmium stress and enhance Solanum lycopersicum growth. Therefore, one of the objectives of this study is to investigate the effects of different concentrations of Vitekang soil conditioner on cadmium reduction and growth promotion in Solanum lycopersicum seedlings, in order to determine the optimal treatment concentration. Another objective of this study is to evaluate the feasibility of the combined treatment of Vitekang soil conditioner and AMF inoculation as an effective strategy to alleviate cadmium stress and improve Solanum lycopersicum growth, in an attempt to develop a new approach to reduce the harm of cadmium to Solanum lycopersicum. The results of this study will advance the research progress on VT (presumably referring to Vitekang soil conditioner) and AMF in Solanum lycopersicum and provide theoretical and experimental foundations for cultivating high-quality Solanum lycopersicum.

2. Materials and Methods

To reveal the impact of different concentrations of Vitekang soil conditioner on three agronomic traits of Solanum lycopersicum under cadmium stress, and to evaluate the effectiveness of combined treatment with AMF and Vitekang soil conditioner in reducing cadmium stress and enhancing the quality of Solanum lycopersicum seedlings, two experiments were conducted: a seedling tray experiment (Experiment 1) and a pot experiment (Experiment 2) [16]. Both experiments were carried out at the R&D test park of Zhibao Ecological Technology Co., Ltd., Foshan City, Guangdong Province, located at North 23°3′3″, East 113°6′26″.

2.1. Experimental Materials

In this study, Solanum lycopersicum varieties with different genotypes were used: Micro Tom, Red Guanyin, and Taiwan Pink King. Micro Tom is a dwarf Solanum lycopersicum variety, with a plant height of about 35 cm. It is suitable for planting in small spaces such as on a balcony or indoors. Its growth cycle is short, the fruit is small, and the taste is crisp. It is a limited growth type. It was purchased from Baige gene technology (Jiangsu, China) Co., Ltd. Red Guanyin Solanum lycopersicum usually shows a bright red color, with a moderate sweet and sour taste, a juicy and delicate pulp, a moderate growth cycle, and strong adaptability, belonging to an infinite growth type. Taiwan Pink King is a new generation variety purified from Taiwan’s unique pink fruit hybridization. It is an early-growing, high-sex variety with strong growth. Its fruit is oval, pink in color and bright in appearance. It is an infinite growth type. Red Guanyin and Taiwan Pink King were purchased from Guangzhou Huaye Seedling Technology Co., Ltd., Guangzhou, China.
Vitekang soil conditioner was used in the experiment. The soil conditioner used oyster shell, limestone, mineral humic acid, Stevia rebaudiana, and other plant-derived organic substances as raw materials. It was rich in organic matter, active calcium, magnesium, silicon, and other nutrients, and its index content was Cao ≥ 20%; SiO2 ≥ 10%; Organic matter ≥ 12%. According to the product introduction, the conditioner has the effect of promoting the growth and reproduction of soil probiotics and passivating cadmium and other heavy metal pollution in the soil, and this intoduction is provided by Foshan Zhibao Ecological Technology Co., Ltd., Foshan, China.

2.2. Experimental Soil

The experimental soil is lateritic red soil, which was selected from Cadmium Contaminated Farmland Soil in Yinghong Town, Yingde City, Guangdong Province, located at North 23°50′41′′ and East 112°47′30′′. The soil was collected on 22 October 2023. The returned soil was exposed to the sun on the roof and dried. The soil was crushed and sterilized by hammering and then stored for future use. The total Cd content of the soil was 0.62 mg/kg and the effective Cd was 0.42 mg/kg. According to the provisions of the GB 15618-2018 soil environmental quality control standards for soil pollution risk of agricultural land (Trial) [17], the soil was moderately Cd polluted. The basic physical and chemical properties of the soil were as follows: the pH value was 6.15, total organic matter was 38.6 g/kg, total nitrogen was 2.27 g/kg, alkali hydrolyzable nitrogen was 144 g/kg, available phosphorus was 18.1 g/kg, and available potassium was 98.5 g/kg.

2.3. AMF Propagation with Clover Culture

Clover was used as the host plant to inoculate AMF. The tested matrix soil was provided by the International Center for membrane biology and environmental research. The matrix soil was sterilized at a high temperature and stored for 2 days. Use 15 cm × 15 cm plastic flowerpots for bacterial culture, clean, and sterilize for standby. Trifolium repens seeds were sterilized with 10% H2O2 for 10 min, rinsed with pure water, and put on wet filter paper for germination. Put the sterilized substrate into the plastic flowerpot, spread the glomus Moses (from the International Center for membrane biology and environmental research) on the substrate, evenly sow the sterilized clover seeds on the strain, cover it with a layer of substrate, wet it with water spray, and spray it with 10 times diluted standard Hoagland nutrient solution every two days. Trifolium repens was placed in a controlled greenhouse (culture temperature 25/16 °C, relative humidity 70–75%, and illumination time 16 h/d) for 8–9 weeks to obtain the inoculum containing spores, mycelium and segmented mycorrhiza. They were then air dried, sieved (2 mm), and stored at 4 °C for subsequent AMF inoculation experiments on Solanum lycopersicum [18].

2.4. Experimental Design

2.4.1. Experiment 1

The specific experimental design is shown in Table 1. Trial 1 was a double-factor (variety × soil conditioner concentration) experiment conducted on seedling cultivation using seed trays with three replicates at the R&D and Experimental Park of Foshan Zhibao Ecological Technology Co., Ltd., Foshan, China. Prior to the experiment, the soil was exposed to sunlight, crushed, and thoroughly mixed. The soil conditioner, Vitekang (VT), was applied at four concentration levels: no soil conditioner added (CK); 1.2 g/kg soil conditioner (T1); 2.4 g/kg soil conditioner (T2); and 4.8 g/kg soil conditioner (T3) [19]. After mixing the designed concentrations of soil conditioner with cadmium-contaminated soil, the mixture was placed into 50-hole seed trays (each hole was 6 cm × 6 cm × 11 cm). We used the TDR150 Portable Soil Moisture Meter (Aurora, IL, USA) to measure soil moisture, deionized water was added to adjust the soil moisture content to 75% of the field capacity [20], and the trays were allowed to equilibrate for one week.
Solanum lycopersicum seeds of three varieties—Micro Tom, Red Guanyin, and Taiwan Pink King—were selected, provided they were full, healthy, and free of pests and diseases. The seeds were disinfected with 10% sodium hypochlorite for 30 min, rinsed several times with distilled water, and then soaked in warm water at 45–55 °C for 4 h. The soaked seeds were then planted in the seed trays for the experiment, with 50 seeds per treatment and 3 replicates. The growth period was from 3 November 2023 to 24 November 2023 (daytime temperature ranging from 22 °C to 26 °C, nighttime temperature from 16 °C to 19 °C, average daily sunshine duration of 8 h, and relative humidity between 45% and 65%). The soil was watered daily to ensure adequate moisture. After 21 days of growth, when the seedlings reached the five-leaf stage with one heart leaf, sampling was conducted to measure the agronomic traits and physiological indicators of the seedlings.

2.4.2. Experiment 2

Experiment 2 was a pot experiment that investigated the individual and combined effects of VT and AMF. Five treatments were set up for each Solanum lycopersicum variety: −Cd, CK, Cd+VT, Cd+AMF, and Cd+VT+AMF, with three replicates for each treatment [21]. Specifically, −Cd represented the treatment with soil without cadmium contamination; CK represented the treatment with cadmium-contaminated soil as a blank control; Cd+VT represented the treatment with cadmium-contaminated soil amended with VT; Cd+AMF represented the treatment with cadmium-contaminated soil inoculated with AMF; and Cd+VT+AMF represented the combined treatment with cadmium-contaminated soil amended with both VT and AMF.
The pots used in the pot experiment had a lower diameter of 18 cm, an upper diameter of 22 cm, and a height of 20 cm. Before planting the Solanum lycopersicum seedlings, 4 kg of soil without cadmium contamination was placed in the −Cd treatment pots, while 4 kg of cadmium-contaminated soil collected from Yingde City was placed in the other treatment pots. In the Cd+VT and Cd+VT+AMF treatments, the soil conditioner concentration of 2.4 g/kg, which was selected from previous experiments, was evenly spread on the soil surface, thoroughly mixed with the soil through rotary tillage and plowing, and allowed to equilibrate for one week.
Five days after seed germination, fifteen healthy and uniform Solanum lycopersicum seedlings of each variety were selected and transferred to the respective treatment groups for the pot experiment. One seedling was planted in each pot, with three replicates for each treatment. Therefore, there were 15 pots for the 5 treatments of each variety, totaling 45 pots for the 3 varieties [22]. All experimental pots were placed in the R&D and Experimental Park of Foshan Zhibao Ecological Technology Co., Ltd. One week after transferring the seedlings to the pots, AMF was added to the Cd+AMF and Cd+VT+AMF treatments at a ratio of 1.2% of the soil mass. The planting period was from 20 April 2024 to 30 May 2024 (daytime temperature ranging from 24 °C to 28 °C, nighttime temperature from 19 °C to 23 °C, average daily sunshine duration of 9 h, and relative humidity between 50% and 70%). During the seedling cultivation period, water and fertilizer were applied regularly to ensure normal growth.

2.5. Sampling and Growth Index Measurement

After harvesting Solanum lycopersicum seedlings from experimental soil as samples, the yield was weighed with an electronic balance (Foshan, China) and the diameter and length were measured with 15 randomly selected Solanum lycopersicum seedlings from each experimental treatment (each replication harvested 5 Solanum lycopersicum seedlings and each treatment takes 3 repetitions). Then, those Solanum lycopersicum seedlings were divided into two groups, one stored at −80 °C in a refrigerator for determination of the antioxidant protective enzyme activity and relative expression level of chlorophyll, using a SPAD-502 chlorophyll meter (Nanjing, China), and another group dried to constant weight at 60 °C in an oven, for measurement of Cd. Each experiment had 3 technical replications.

2.6. Determination of Cadmium Content

Pre-processed dried samples are crushed and mixed uniformly according to the treatment labels. Weigh 0.1 g of the dried soil sample from each treatment and place it in a 20 mL digestion tube, add 1 mL of concentrated nitric acid, and let it stand overnight in a fume hood. The next day, transfer the digestion tube to a digestion apparatus, adjust the temperature to 100 °C for 2 h of digestion, and then adjust the temperature to 180 °C for continued digestion [23]. Supplement acid in a timely manner during digestion to prevent drying out. Continue until the digestion solution becomes clear and transparent. Add distilled water to the digested sample liquid to a volume of 10 mL and filter it. The filtration process uses a 10 mL syringe and a 2.5 μm filter head. Before using the flame atomic absorption spectrometer (Shanghai, China), AAS; ZEEnit700 P/650 P), dilute the filtered sample again, take 10 mL of the sample liquid, and detect it on the instrument.

2.7. Methods for Physiological Measurements

The determination of MDA was carried out using the thiobarbituric acid method. MDA can react with thiobarbituric acid (TBA) to form a reddish brown trimethyl complex, which has a maximum absorption peak at 532 nm. At the same time, in order to eliminate interference from other substances, it is necessary to measure the absorbance at 600 nm. By calculating the difference in absorbance values at two wavelengths, the amount of MDA and TBA reaction products can be accurately reflected, thereby indirectly determining the content of MDA in the sample [24].
The determination of SOD activity is determined by measuring the amount of reduced nitroblue tetrazole. The determination method of catalase (CAT) is the UV absorption method. Hydrogen peroxide (H2O2) has strong absorption at a wavelength of 240 nm, and CAT can catalyze the decomposition of H2O2 into water and oxygen, causing the absorbance (A240) of the reaction solution to decrease with reaction time. POD activity was determined by measuring the changes in POD activity at 470 nm, using the guaiacol method [25]. The generation rate of superoxide anion (O2-) is detected using Nitro Blue Tetrazolium Chloride (NBT) staining to assess superoxide radicals. The leaves are immersed in a staining solution (containing 0.5 mg mL−1 of NBT and 50 mM sodium phosphate buffer at a pH of 7.5) overnight, followed by decolorization of the leaves using 75% ethanol. Observe the blue-colored parts of the leaves.

2.8. RNA Extraction and QRT–PCR Analysis

Total RNA was isolated from Solanum lycopersicum roots and leaves using TRIzol (Hangzhou, China). The cDNA was synthesized from the total RNA using the M-MLV Reverse Transcriptase kit (Hangzhou, China). QRT– PCR reactions were performed using Tip Green SuperMix (Shanghai China). The relative expression was calculated using the 2−ΔΔCt method [26].

2.9. Statistical Analysis

The collected data were organized using Microsoft Office Excel 2022 and analyzed for mean comparison and one-way ANOVA (p < 0.05) using the Least Significant Difference (LSD) and Duncan’s new multiple range test methods in SPSS 27.0.1 software. The data are presented as the mean ± standard error (SE) for each treatment, and the graphs were plotted using GraphPad Prism 9.5.

3. Results

3.1. Effects of Different Soil Conditioner Concentrations on Cadmium Content and Agronomic Biofortification in Solanum lycopersicumes (Experiment 1)

3.1.1. Cadmium Content in Roots and Leaves

For the three Solanum lycopersicum varieties, the cadmium content in the roots was higher than that in the leaves under all treatments. This may be due to the direct contact between the roots and cadmium in the soil, resulting in greater damage to the roots than to the aerial parts. It also indicates that the Solanum lycopersicum roots are the main accumulation organ for cadmium [27].
Analysis of the effects of different concentrations of Wedikang Vitekang soil conditioner on cadmium content in the roots and leaves of cherry Solanum lycopersicum under cadmium stress, as shown in Table 2, revealed that compared with the control group (CK), the application of T1, T2, and T3 concentrations of Wedikang Vitekang soil conditioner significantly reduced the cadmium content in the roots and leaves of Micro Tom, Red Guanyin, and Taiwan Pink King. This indicates that the application of Vitekang soil conditioner at appropriate concentrations can effectively reduce the cadmium content in the roots and leaves of Solanum lycopersicum, with T2 and T3 concentrations showing the best overall reduction effect [28].
At the T2 concentration, the cadmium content in the roots of Micro Tom, Red Guanyin, and Taiwan Pink King decreased by 23.12%, 18.62%, and 24.26%, respectively, compared with the CK, while the cadmium content in the leaves decreased by 21.16%, 19.36%, and 20.56%, respectively. At the T3 concentration, the cadmium content in the roots of Micro Tom, Red Guanyin, and Taiwan Pink King decreased by 23.53%, 18.88%, and 24.80%, respectively, compared with the CK, while the cadmium content in the leaves decreased by 21.44%, 19.94%, and 20.25%, respectively.

3.1.2. Agronomic Traits

Using the five-point sampling method, phenotypic images were taken of three Solanum lycopersicum varieties treated with different concentrations of soil ameliorants under cadmium stress, as shown in Figure 1. Then, their agronomic traits were measured, and the results are shown in Table 3 below.
From the phenotypic images in Figure 1 and the agronomic traits in Table 3, it can be observed that compared with CK, the application of Vitekang soil ameliorant at T1, T2, and T3 concentrations significantly improved the agronomic traits of Micro Tom, Red Guanyin, and Taiwan Pink King seedlings. Moreover, different treatments had different primary effects on the parts of the crops. Among them, T2 and T3 had the best overall improvement effects, and there was no significant difference between T2 and T3.
Among the three Solanum lycopersicum varieties, the treatment effects of T1 and T3 were significant, and fell between CK and T2. Compared to CK, the treatment with a Vitekang soil conditioner concentration of 2.4 g/kg (T2) had the best effect. For Micro Tom, the plant height, stem diameter, chlorophyll relative expression, fresh and dry weights of the aboveground part, and fresh and dry weights of the underground part significantly increased by 8.90%, 21.23%, 12.06%, 37.39%, 45.68%, 13.92%, and 15.55%, respectively. For Red Guanyin, these parameters significantly increased by 42.59%, 22.66%, 9.78%, 54.95%, 73.09%, 66.04%, and 88.56%, respectively. For Taiwan Pink King, the increases were 13.38%, 10.36%, 12.10%, 27.38%, 32.57%, 8.93%, and 26.98%, respectively.

3.1.3. MDA Content and Antioxidant Enzyme Activities

MDA, a product of membrane lipid peroxidation, serves as an indicator of the degree of membrane lipid peroxidation in plants under stress conditions. An increase in MDA indicates an increase in oxidative damage to plant cells. The effects of different concentration treatments on MDA content in Solanum lycopersicum roots are shown in Figure 2a. It can be observed that the application of Vitekang soil conditioner under cadmium stress reduced the MDA content in the leaves of the three Solanum lycopersicum varieties, with better effects at T2 and T3 concentrations compared to T1.
At the T2 concentration, the MDA content in the leaves of Micro Tom decreased by 16.09% compared to the CK treatment, Red Guanyin decreased by 16.86%, and Taiwan Pink King decreased by 14.93%. At the T3 concentration, the MDA content in the leaves of Micro Tom decreased by 16.74% compared to the CK treatment, Red Guanyin decreased by 17.26%, and Taiwan Pink King decreased by 15.69%. The results indicate that treatments with T2 and T3 concentrations alleviated the oxidative damage to plant cell membranes caused by Cd stress, and that the alleviating effects of the two concentrations were not significantly different.
CAT, as one of the important antioxidant enzymes in plants, catalyzes the decomposition of hydrogen peroxide into water and oxygen, thereby reducing its toxic effects on cells. An increase in CAT activity helps improve the ability of Solanum lycopersicum seedlings to adapt to and resist heavy metal stress. SOD and POD also play vital roles under heavy metal stress. SOD scavenges reactive oxygen species (ROS), protecting plant cells from oxidative damage. Within a certain concentration range, it can maintain or enhance plant tolerance, mitigating the toxicity of heavy metals to plants. POD participates in the plant’s antioxidant defense system, assisting plants in coping with oxidative stress induced by heavy metal stress.
Previous studies have shown that under cadmium stress, the activities of CAT and SOD in Solanum lycopersicum leaves increase to respond to heavy metal stress [23]. Other studies have indicated that higher concentrations of cadmium stress can inhibit POD, leading to a decrease in its activity. Changes in the activities of these three enzymes, as shown in Figure 2b–d, can reflect the plant’s response and adaptation to heavy metal stress. From the figures, it can be seen that under Cd stress, with different concentrations of Vitekang soil conditioner treatments, the activities of CAT and SOD in the leaves of the three Solanum lycopersicum varieties increased compared to the CK treatment. The POD activity decreased at the T1 concentration compared to the CK treatment, but as the concentration increased, the POD activity under T2 and T3 treatments increased compared to the CK treatment.
Under Cd stress, compared to the CK, the CAT activity in the leaves of the three Solanum lycopersicum varieties treated with T1, T2, and T3 showed a trend of CK < T1 < T3 < T2, with the T2 treatment showing the greatest increase in CAT activity in all three Solanum lycopersicum varieties.
Under Cd stress, compared to the CK, the activities of SOD in the leaves of the three Solanum lycopersicum varieties gradually increased with the application of T1, T2, and T3 treatments. The POD activity decreased with the T1 treatment compared to the CK, while it gradually increased with the T2 and T3 treatments compared to the CK. Both enzyme activities improved more effectively at T2 and T3 concentrations, and there was no significant difference between the two concentration treatments. The increase in POD and SOD activities indicates that Solanum lycopersicum leaves can more effectively scavenge superoxide anions and other ROS, enhancing the antioxidant capacity of Solanum lycopersicum.

3.1.4. DAB and NBT Staining

Figure 3 illustrates the DAB (a) and NBT (b) staining of Solanum lycopersicum leaves under cadmium stress with different treatments. Figure 3a,b shows treatments CK, T1, T2, and T3 from left to right, and the Solanum lycopersicum varieties Micro Tom, Red Guanyin, and Taipin from top to bottom. The depth of staining in the figure indicates the level of reactive oxygen species such as H2O2 and O2− in the leaves, reflecting the oxidative stress status of Solanum lycopersicum under cadmium stress and the mitigating effect of Vitekang soil conditioners.
From the figure, it can be observed that in the CK treatment with only cadmium added, the DAB and NBT staining of Solanum lycopersicum leaves is relatively deep, indicating the accumulation of a large amount of H2O2 and O2− in the leaves. This suggests that Solanum lycopersicum under cadmium stress experience severe oxidative stress. As the concentration of Vitekang soil conditioners increases under T1 and T2 concentrations, the DAB and NBT staining of the leaves of the three Solanum lycopersicum varieties gradually becomes lighter, indicating that Vitekang soil conditioners can effectively alleviate the oxidative stress caused by cadmium stress and reduce the content of superoxide anions and hydrogen peroxide in the leaves. At T2 and T3 concentrations, there is little difference in the DAB and NBT staining among the three Solanum lycopersicum varieties, and the changes are inconsistent. Specifically, the DAB staining of Small Tom becomes lighter, while the staining of Red Guanyin and Taiwan Pink King For NBT staining, Small Tom and Red Guanyin deepen, and Taipin becomes lighter.

3.1.5. Effects of the Expression of NRAMP6 and HMA3 Genes

The NRAMP6 gene belongs to the natural resistance-associated macrophage protein (NRAMP) gene family, which is widely present in organisms. Previous studies have shown that the SLNRAMP6 gene in Solanum lycopersicum promotes the absorption and utilization of essential metal elements, participates in the transport of heavy metal ions, mitigates heavy metal toxicity, and enhances Solanum lycopersicum tolerance to heavy metals, enabling it to grow and develop normally in environments contaminated with heavy metals. The SLHMA3 gene in Solanum lycopersicum is involved in regulating the transport and absorption of heavy metals such as Pb and Cd in the aerial parts, reducing their toxicity to the aerial parts of Solanum lycopersicum, and promoting growth and development.
QRT–PCR was used to detect the expression levels of the NRAMP6 and HMA3 genes in three Solanum lycopersicum varieties treated with different concentrations of VT under cadmium stress, as shown in Figure 4. CK represents the control, with a concentration of 0, and the expression levels of the NRAMP6 and HMA3 genes in the three Solanum lycopersicum varieties under this treatment were used as the reference value of one.
In Figure 4a, the expression levels of both the NRAMP6 and HMA3 genes in Micro Tom first decreased and then increased with increasing VT concentration. At the T2 concentration, the expression values of both genes were the lowest. Compared with the CK treatment, NRAMP6 was downregulated by 64.46%, and HMA3 was downregulated by 56.27%. This may be because increasing the Vitekang soil conditioner concentration to an appropriate level alleviated cadmium stress, resulting in the downregulated expression of the two stress-resistant genes NRAMP6 and HMA3 in Micro Tom. As the concentration further increased, the effect of alleviating cadmium stress decreased, and unfavorable soil nutrient content and physicochemical properties led to increased expression of NRAMP6 and HMA3 to cope with the stress.
In Figure 4b, the expression of the NRAMP6 gene in Red Guanyin first increased and then decreased with increasing concentration. The expression of the HMA3 gene, except for upregulation at T1, showed a trend of first decreasing and then increasing with increasing concentration. Specifically, NRAMP6 expression was highest at the T2 concentration, upregulated by 386.10% compared with the CK concentration, while HMA3 expression was lowest at the T2 concentration, downregulated by 54.07% compared with the CK concentration. This may be because as the Vitekang soil conditioner concentration increased, it promoted upregulation of the NRAMP6 gene in Red Guanyin to cope with cadmium stress, with T3 being the optimal concentration. For HMA3, the T3 concentration had the best effect on alleviating cadmium stress, leading to the greatest downregulation of HMA3 gene expression.
In Figure 4c, the expression of the NRAMP6 gene in Taiwan Pink King first increased and then decreased with increasing concentration. The HMA3 gene was significantly upregulated compared with CK at T1, T2, and T3 concentrations, with no significant difference among these three concentrations. Specifically, the expression values of both genes were highest at the T2 concentration. Compared with the CK concentration, NRAMP6 was upregulated by 543.33%, and HMA3 was upregulated by 318.61%. This may be because increasing the Vitekang soil conditioner concentration promoted the upregulation of the NRAMP6 and HMA3 genes in Taiwan Pink King to cope with cadmium stress, with T2 being the optimal concentration.
By analyzing the expression of the NRAMP6 and HMA3 genes in the three varieties at different concentrations, we can conclude the following: there are differences in the expression of NRAMP6 and HMA3 genes among different genotypes of Solanum lycopersicum; within the same Solanum lycopersicum variety, there are also differences in the expression of NRAMP6 and HMA3 genes at different concentrations.

3.2. Effects of VT and AMF Treatments Alone and in Combination on Cadmium Content and Quality of Solanum lycopersicum (Experiment 2)

3.2.1. Cadmium Content in Roots and Leaves

For the three Solanum lycopersicum varieties, the cadmium content in the roots was higher than that in the leaves under all treatments. This may be due to the direct contact between the roots and cadmium in the soil, resulting in greater damage to the roots than the aerial parts. It also indicates that the Solanum lycopersicum roots are the primary accumulation organ for cadmium [29].
An analysis of the cadmium content in the roots of the three Solanum lycopersicum varieties under cadmium stress in Figure 5a shows that Cd+VT, Cd+AMF, and Cd+VT+AMF treatments all reduced the cadmium content in the Solanum lycopersicum roots compared to the control group (CK). Among them, the Cd+VT+AMF combined treatment resulted in the lowest cadmium content in the Solanum lycopersicum roots. Specifically, Micro Tom, Red Guanyin, and Taiwan Pink King showed reductions of 35.57%, 26.27%, and 31.48%, respectively, compared to the CK control, with Micro Tom and Taiwan Pink King showing larger reductions.
An analysis of the cadmium content in the leaves of the three Solanum lycopersicum varieties under cadmium stress in Figure 5b shows that Cd+VT, AMF, and Cd+VT+AMF treatments all reduced the cadmium content in the Solanum lycopersicum leaves compared to the control group (CK). Among them, the Cd+VT+AMF combined treatment resulted in the lowest cadmium content in the Solanum lycopersicum leaves. Specifically, Micro Tom, Red Guanyin, and Taiwan Pink King showed reductions of 28.89%, 23.29%, and 29.95%, respectively, compared to the CK control, with Micro Tom and Taiwan Pink King showing larger reductions.
In general, the Cd+VT+AMF combined treatment significantly reduced the cadmium content in both the roots and leaves of the three Solanum lycopersicum varieties, indicating a good mitigating effect against soil cadmium stress.

3.2.2. Agronomic Traits

Agronomic trait measurements were conducted on three Solanum lycopersicum varieties subjected to treatments including -Cd, CK, Cd+VT, Cd+AMF, and Cd+VT+AMF. The results are shown in Table 4 below. Changes in agronomic traits can reflect the impact of heavy metal stress on Solanum lycopersicum. According to Table 4, compared with the -Cd treatment, all agronomic traits in the CK treatment were significantly reduced, indicating that Solanum lycopersicum seedlings in the CK treatment suffered severe cadmium stress, which affected their normal growth. In this study, under cadmium stress, the application of Cd+VT, Cd+AMF, and Cd+VT+AMF treatments resulted in significant increases in plant height, stem diameter, chlorophyll relative expression, and biomass for all three Solanum lycopersicum varieties compared to the CK treatment, suggesting that single or combined treatments reduced cadmium stress and improved agronomic traits. When compared to the -Cd treatment, single treatments of Cd+VT and Cd+AMF showed significantly lower agronomic traits for all three Solanum lycopersicum varieties. However, for Micro Tom and Taiwan Pink King, the agronomic traits obtained from the Cd+VT+AMF combined treatment were higher than those of the -Cd treatment, while for Red Guanyin, the effect of the Cd+VT+AMF combined treatment was close to that of the -Cd treatment. Overall, all three Solanum lycopersicum varieties exhibited improved agronomic traits. However, the effect of single treatments was lower than that of the cadmium-free treatment, while the combined treatment traits approached those of the cadmium-free treatment, significantly reducing cadmium stress.
For Micro Tom, compared with the CK treatment, the Cd+VT+AMF, Cd+AMF, and Cd+VT treatments increased plant height by 78.24%, 47.24%, and 28.05%, respectively; stem diameter by 44.06%, 26.92%, and 22.33%; chlorophyll relative expression by 30.75%, 19.50%, and 22.17%; aboveground fresh weight by 80.04%, 37.95%, and 31.40%; belowground fresh weight by 123.07%, 88.93%, and 62.67%; aboveground dry weight by 70.72%, 32.89%, and 26.17%; and belowground dry weight by 116.49%, 77.32%, and 51.03%.
For Red Guanyin, compared with the CK treatment, the Cd+VT+AMF, Cd+AMF, and Cd+VT treatments increased plant height by 40.40%, 28.13%, and 27.17%, respectively; stem diameter by 55.09%, 37.79%, and 38.78%; chlorophyll relative expression by 39.24%, 31.77%, and 28.21%; aboveground fresh weight by 64.65%, 25.68%, and 22.41%; belowground fresh weight by 47.75%, 31.07%, and 9.57%; aboveground dry weight by 52.53%, 7.52%, and 12.76%; and belowground dry weight by 44.98%, 28.51%, and 9.64%.
For Taiwan Pink King, compared with the CK treatment, the Cd+VT+AMF, Cd+AMF, and Cd+VT treatments increased plant height by 25.36%, 11.10%, and 5.88%, respectively; stem diameter by 46.88%, 38.70%, and 34.35%; chlorophyll relative expression by 37.05%, 28.70%, and 30.14%; aboveground fresh weight by 54.11%, 30.69%, and 13.49%; belowground fresh weight by 39.90%, 35.12%, and 9.34%; aboveground dry weight by 54.33%, 30.26%, and 12.60%; and belowground dry weight by 40.08%, 35.32%, and 9.52%.

3.2.3. MDA Content and Antioxidant Enzyme Activities

MDA, as an indicator of membrane lipid peroxidation in plants under stress conditions, can effectively reflect the oxidative damage suffered by plants. Figure 6a illustrates the impact of different treatments on MDA content in Solanum lycopersicum roots. It is evident that compared with the -Cd treatment, the MDA content of all three Solanum lycopersicum varieties significantly increased with the CK treatment, indicating severe oxidative damage to plant cells after CK treatment. However, when treated with Cd+VT, Cd+AMF, and Cd+VT+AMF, the MDA content in the leaves of the three Solanum lycopersicum varieties under Cd stress was significantly lower than that in the CK treatment with Cd alone. Moreover, the MDA content in the Cd+VT+AMF combined treatment was significantly lower than that in the Cd+VT and Cd+AMF single treatments.
In the case of single applications of Cd+VT and Cd+AMF, the Cd+VT treatment resulted in a larger decrease in MDA content for the Red Guanyin variety, while Cd+AMF had a more pronounced effect in reducing MDA content in Micro Tom and Taiwan Pink King.
In the Cd+VT+AMF combined treatment, the MDA content in Micro Tom leaves decreased by 63.00% compared with the CK treatment, with a reduction of 66.06% for Red Guanyin and 48.46% for Taiwan Pink King.
These results indicate that both single and combined treatments alleviated the oxidative damage to plant cell membranes caused by Cd stress, and the combined application had a better alleviating effect.
The experimental results indicate that under Cd stress with the CK treatment, the CAT activity in the leaves of the three Solanum lycopersicum varieties increased compared to the -Cd treatment, while the SOD and POD activities decreased. This suggests that at this concentration of Cd contamination, the increased CAT activity in the three Solanum lycopersicum varieties helps alleviate the damage caused by Cd stress, while SOD and POD are more sensitive to the toxic effects of Cd and are therefore inhibited.
Under Cd stress, when compared to the CK treatment, the CAT activity of Micro Tom showed a trend of Cd+AMF < Cd+VT < CK < Cd+VT+AMF; for Red Guanyin, the trend was Cd+VT+AMF < Cd+AMF < CK < Cd+VT; and for Taiwan Pink King, the trend was Cd+AMF < CK < Cd+VT+AMF < Cd+VT. Analysis of the results revealed the inconsistent effects of single and combined treatments on CAT activity among the three Solanum lycopersicum varieties. Specifically, for Micro Tom, single treatments resulted in lower CAT activity than CK, while the combined treatment was higher than CK; for Red Guanyin, the CAT activity was lower than CK when treated with Cd+AMF, but higher than CK with Cd+VT alone; and for Taiwanfen, the CAT activity was lower than CK with Cd+AMF alone, but higher than CK with treatments containing Cd+VT.
Under Cd stress, compared to the CK treatment, the SOD and POD activities in the leaves of the three Solanum lycopersicum varieties gradually increased with the application of Cd+VT, Cd+AMF, and Cd+VT+AMF treatments, showing a trend of CK < Cd+VT < Cd+AMF < Cd+VT+AMF. Among them, the combined Cd+VT+AMF treatment had the greatest effect on increasing SOD and POD activities, indicating that the Solanum lycopersicum leaves could more effectively scavenge reactive oxygen species such as superoxide anions, thereby enhancing the antioxidant capacity of the Solanum lycopersicum. Compared to CK, the SOD activity of Micro Tom, Red Guanyin, and Taiwanfen under the combined treatment increased by 66.42%, 25.28%, and 24.32%, respectively, while the POD activity increased by 88.89%, 166.43%, and 131.25%, respectively. Single treatments with Cd+VT and Cd+AMF also increased the SOD and POD activities of the three Solanum lycopersicum varieties compared to CK, but the effect was not as significant as that of the combined Cd+VT+AMF treatment. The SOD and POD activities were slightly higher in the Cd+AMF treatment than in the Cd+VT treatment, but the difference between the two treatments was not statistically significant.

4. Discussion

4.1. Effects of Soil Conditioner Concentration on Solanum lycopersicum Under Cadmium Stress

The results of Experiment 1 showed that soil conditioner treatments at different concentrations were all effective in reducing Cd content in Solanum lycopersicum roots and leaves, with a decreasing trend in Cd content observed as the soil conditioner concentration increased. When the soil conditioner concentration reached 4.8 g/kg, although Cd content decreased, the reduction was not significant compared to the treatment at 2.4 g/kg. After applying soil conditioner, the agronomic traits of Solanum lycopersicum significantly improved, specifically manifesting as increased plant height, stem diameter, chlorophyll relative expression, and dry and fresh weights of both aboveground and belowground parts. Among them, treatment at a concentration of 2.4 g/kg (T2) showed the best effect, demonstrating significant improvement across different Solanum lycopersicum varieties. This indicates that soil conditioner at an appropriate concentration can not only reduce Cd content in Solanum lycopersicum, but also promote their growth and development, enhancing their stress resistance.
The experimental results also revealed that after applying soil conditioner, the MDA content in Solanum lycopersicum leaves significantly decreased, with a greater reduction observed as the soil conditioner concentration increased. Meanwhile, the activities of antioxidant enzymes CAT, SOD, and POD also increased. DAB and NBT staining results showed that with increasing soil conditioner concentration, the staining of Solanum lycopersicum leaves gradually became lighter, effectively alleviating the oxidative stress state caused by Cd stress and reducing the content of superoxide anions and hydrogen peroxide in the leaves. This suggests that soil conditioners have significant antioxidant and stress-resistance effects, protecting Solanum lycopersicum from the damage caused by Cd stress. The expression of NRAMP6 and HMA3 genes showed that there were differences in gene expression among different Solanum lycopersicum genotypes under the same concentration treatment, and the gene expression trends also varied for the same Solanum lycopersicum variety under different concentration treatments. This may be related to the genetic characteristics of the Solanum lycopersicum varieties, the composition of the soil conditioner, and the degree of Cd stress. However, overall, soil conditioner at an appropriate concentration can regulate the expression of the NRAMP6 and HMA3 genes, improving Solanum lycopersicum tolerance to Cd and promoting its normal growth and development in environments contaminated with heavy metals.

4.2. Effects of AMF Inoculation on Solanum lycopersicum Under Cadmium Stress

Based on the analysis of Experiment 1, it was determined that soil conditioner at an appropriate concentration could enhance Solanum lycopersicum ability to mitigate cadmium (Cd) stress. We aimed to explore whether any method could further effectively reduce the toxic effects of Cd stress on Solanum lycopersicum growth and further promote Solanum lycopersicum development. Many studies have shown that the application of AMF can protect plants from various abiotic stresses, such as drought, salinity [30], arsenic, and heavy metal stress [31]. Therefore, Experiment 2 was designed to investigate the ability of combined treatment with Vitekang soil conditioner and AMF inoculation to alleviate Cd stress and enhance Solanum lycopersicum growth, with the goal of developing a new approach to mitigate the harm of Cd to crops.
The results of Experiment 2 showed that the combined Cd+VT+AMF treatment exhibited significant advantages in reducing Cd accumulation, improving agronomic traits, alleviating oxidative damage, and enhancing antioxidant capacity. Different Solanum lycopersicum varieties responded differently to Cd stress, and also showed varying responses to treatment measures. For example, Micro Tom and Taiwan Pink King showed significant improvements in agronomic traits under the Cd+VT+AMF treatment, while Red Guanyin responded relatively weakly. This may be related to the genetic characteristics and physiological mechanisms of the different varieties. Therefore, in practical applications, appropriate treatment measures should be selected based on Solanum lycopersicum varieties.
AMF can reduce Cd toxicity in host plants through various mechanisms, including altering the rhizosphere microenvironment to affect Cd absorption and transport or secreting low-molecular-weight organic acids (LMWOAs) to form chelates with Cd ions, thereby reducing Cd toxicity [32]. AMF can also regulate glutathione (GSH) metabolism and keto-aldehyde translocase activity in plants, maintain a balanced level of reactive oxygen species (ROS) in cells, and thus alleviate oxidative damage to plants caused by Cd stress [33]. The application of soil conditioner provides nutrients to the soil, improves the soil environment, and creates better living conditions for mycorrhizal fungi, promoting coexistence between AMF and plant roots. In addition, AMF can release organic compounds in the rhizosphere to accelerate nutrient cycling in the soil, facilitating the absorption and utilization of nutrients released by the soil conditioner. This may explain why Solanum lycopersicum treated with soil conditioner combined with AMF have lower Cd content, better agronomic traits, and more robust growth compared to those without AMF inoculation.

5. Conclusions

Adding soil conditioner at an appropriate concentration (2.4 g/kg) to soil contaminated with the heavy metal cadmium can significantly improve various agronomic traits of three Solanum lycopersicum varieties, reduce Cd stress, and promote healthy Solanum lycopersicum growth. Compared to single treatments, combined treatment with soil conditioner and arbuscular mycorrhizal fungi (AMF) can better alleviate Cd stress, advancing research progress on AMF and soil conditioner for Solanum lycopersicum and providing theoretical and experimental foundations for cultivating high-quality Solanum lycopersicum in Cd-contaminated environments. Future research plans to further explore the impact of different treatments on Solanum lycopersicum fruit quality and optimize treatment measures to enhance practical application effects, providing practical evidence for improving “VIP+N” technology, farmland protection, and agricultural product quality enhancement.

Author Contributions

Conceptualization, L.H., P.Z. and M.T.; methodology, L.H., M.T., Y.G. and Q.W.; software, X.L. and Q.W.; validation, Q.W., G.C. and Y.L.; formal analysis, Q.W.; investigation, L.H. and Q.W.; resources, L.H. and Y.G.; data curation, Q.W.; writing—original draft preparation, Q.W.; writing—review and editing, Q.W., G.C. and Y.L.; visualization, Q.W.; supervision, L.H.; project administration, L.H. and Q.W.; funding acquisition, L.H., Y.G. and Q.W. All authors have read and agreed to the published version of the manuscript.

Funding

This research was funded by the Joint Training Program of the National Excellent Engineer Innovation Research Institute for Advanced Manufacturing Industry in the Guangdong Hong Kong Macao Greater Bay Area (Foshan) (2023FCXM019) and the Guangdong Provincial Key Laboratory of Intelligent Food Manufacturing, Foshan University, China. Financial support for this work was provided by the National Natural Science Foundation of China (grants 31901202, 42377042), the Higher Education Department of Guangdong Province (2020KCXTD025), and the KeyLaboratory Project of Guangdong Province (grant No. 2022B1212010015).

Data Availability Statement

The data presented in this study are available upon request from the corresponding author due to legal reasons.

Conflicts of Interest

Author Yongjun Guo was employed by the company Foshan Ecological Plant Protection Technology Co., Ltd. The remaining authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest.

References

  1. Chen, N.C.; Zheng, Y.J.; He, X.F.; Li, X.F.; Zhang, X.X. Analysis of the Bulletin on the Nationwide Survey of Soil Pollution. J. Agro-Environ. Sci. 2017, 36, 1689–1692. [Google Scholar]
  2. Cao, L.; Ren, W.; Liu, L.; Zheng, J.; Tao, C.; Zhu, W.; Xiang, M.; Wang, L.; Liu, Y.; Zheng, P. CDR1, a DUF946 domain containing protein, positively regulates cadmium tolerance in Arabidopsis thaliana by maintaining the stability of OPT3 protein. J. Hazard. Mater. 2024, 477, 135313. [Google Scholar] [CrossRef]
  3. Dong, P.F.; Liu, T.B.; Chen, K.; Li, D.; Li, Y.; Lian, C.Y.; Wang, Z.Y.; Wang, L. Cadmium targeting transcription factor EB to inhibit autophagy-lysosome function contributes to acute kidney injury. J. Adv. Res. 2024, in press. [CrossRef] [PubMed]
  4. Qin, S.; Liu, H.; Nie, Z.; Rengel, Z.; Gao, W.; Li, C.; Zhao, P. Toxicity of cadmium and its competi-tion with mineral nutrients for uptake by plants: A review. Pedosphere 2020, 30, 168–180. [Google Scholar] [CrossRef]
  5. Zhao, H.K.; Zhang, X.Y.; Zeng, H.Y.; Deng, J.; Chen, X.; Song, L. Effects of Vitekang Soil Conditioner on soil physical and properties and physiological characteristics of non-heading Chinese cabbage. Acta Agron. Boreali-Sin. 2021, 3, 312–319. [Google Scholar]
  6. Wang, D.; Zhou, W.; Zhang, Y.Y.; Wang, M.Y. Effects of Vitekang Soil Conditioner on the improvement of severely cadmium-polluted and the accumulation of cadmium in crops. Anhui Agric. Sci. 2024, 52, 7376. [Google Scholar]
  7. Zhang, Q.; Zhang, L.; Liu, T.; Liu, B.; Huang, D.; Zhu, Q.; Xu, C. The influence of liming on cadmium accumulation in rice grains via iron-reducing bacteria. Sci. Total Environ. 2018, 645, 109–118. [Google Scholar] [CrossRef]
  8. Liu, C.; Wang, L.; Yin, J.; Qi, L.; Feng, Y. Combined amendments of nano-hydroxyapa-tite immobilized cadmium in contaminated soil-potato (Solanum tuberosum L.) system. Bull. Environ. Contam. Toxicol. 2018, 100, 581–587. [Google Scholar] [CrossRef]
  9. Moscowskiy Bio-Organic Catalyst, Inc. The Program and the Results of Pilot Study on the Use of Bio-Organic Catalyst Phyto-C3 TM for Treatment of Agricultural Plants on the Basis of JSC Agricultural Complex; Contentree: Reno, NV, USA, 2022. [Google Scholar]
  10. Wang, H.; Hao, Z.; Zhang, X.; Xie, W.; Chen, B. Arbuscular Mycorrhizal Fungi Induced Plant Resistance against Fusarium Wilt in Jasmonate Biosynthesis Defective Mutant and Wild Type of Solanum lycopersicum. J. Fungi 2022, 8, 422. [Google Scholar] [CrossRef] [PubMed]
  11. Zhang, T.; Feng, G. Arbuscular mycorrhizal fungi alleviate the negative effects of increases in phosphorus (P) resource diversity on plant community structure by improving P resource utilization. Plant Soil 2021, 461, 295–307. [Google Scholar] [CrossRef]
  12. Li, H.; Wang, H.; Zhao, J.; Zhang, L.; Li, Y.; Wang, H.; Teng, H.; Yuan, Z.; Yuan, Z. Physio-biochemical and transcriptomic features of arbuscular mycorrhizal fungi relieving cadmium stress in wheat. Antioxidants 2022, 11, 2390. [Google Scholar] [CrossRef]
  13. Chen, L.; Wang, F.; Zhang, Z.; Chao, H.; He, H.; Hu, W.; Zeng, Y.; Duan, C.; Liu, J.; Fang, L. Influences of arbuscular mycorrhizal fungi on crop growth and potentially toxic element accumulation in contaminated soils: A meta-analysis. Crit. Rev. Environ. Sci. Technol. 2023, 53, 1795–1816. [Google Scholar] [CrossRef]
  14. Wu, Z.X.; Liu, J.J.; Ma, W.D. Research Progress on Enhanced Phytoremediation of Heavy Metal-Contaminated Soils by the Combined Application of Biochar and Arbuscular Mycorrhizal Fungi. Environ. Pollut. Control. 2024, 46, 1040–1046. [Google Scholar]
  15. Cui, Q.; Beiyuan, J.; Chen, Y.; Li, M.; Qiu, T.; Zhao, S.; Zhu, X.; Chen, H.; Fang, L. Synergistic enhancement of plant growth and cadmium stress defense by Azospirillum brasilense and plant heme: Modulating the growth–defense relationship. Sci. Total Environ. 2024, 946, 174503. [Google Scholar] [CrossRef]
  16. Xin, J. Enhancing soil Health to minimize Cadmium accumulation in agro-products: The role of microorganisms, organic amendments, and nutrients. Environ. Pollut. 2024, 348, 123890. [Google Scholar] [CrossRef]
  17. GB 15618-2018; Soil Environmental Quality: Risk Management Standard for Soil Contamination of Agricultural Land (Trial). Ministry of Ecology and Environment of the People’s Republic of China; General Administration of Quality Supervision, Inspection and Quarantine: Beijing, China, 2018.
  18. Wang, Y.S.; Wang, X.Y.; Sun, H.; Zhang, S.B.; Xing, L.J. Methods for Collection, Cultivation, and Preservation of Arbuscular Mycorrhizal Fungi Species Resources. Bio Protoc. 2022, 101, e2104422. [Google Scholar]
  19. Liu, J.; Zhang, N.M.; Yuan, Q.H. Study on the effects of different passivators on the passivation lead-cadmium co-contaminated soil and influencing factors. Ecol. Environ. Sci. 2021, 30, 732–741. [Google Scholar]
  20. Zheng, H.; Wang, H.F. Research Progress in Soil Moisture Measurement Technologies. Metrol. Sci. Technol. 2022, 66, 31–36+40. [Google Scholar]
  21. Zhang, J.; Zhao, R.; Li, X.; Zhang, J. Potential of arbuscular mycorrhizal fungi for soil health. Pedosphere 2024, 34, 279–288. [Google Scholar] [CrossRef]
  22. Ashraf, M.; Shahzad, S.M.; Abid, M.; Mehmood, K.; Aziz, A.; Sarwar, A.; Akhtar, N.; Mehran, M. Ionic Homeostasis and Growth Characteristics of Solanum lycopersicum (Solanum lycopersicum L.) Grown with Municipal Wastewater by Supplying Silicon, Farmyard Manure and Plant Growth Promoting Rhizobacteria. Silicon 2022, 14, 12855–12867. [Google Scholar] [CrossRef]
  23. Zhu, H.; He, Y.Y. Effects of different Vitekang Soil Conditioners on soil properties, yield, and fruit quality of continuously Solanum lycopersicum. China Veg. 2023, 36, 104–108. [Google Scholar]
  24. Qu, M.; Qin, L.N.; Liu, Y.J.; Fan, H.C.; Zhu, S.; Wang, J.F. Comparison of two methods for detecting SOD enzyme activity. J. Food Saf. Qual. Test. 2014, 5, 3318–3323. [Google Scholar]
  25. Yan, Q.; Li, X.; Xiao, X.; Chen, J.; Liu, J.; Lin, C.; Guan, R.; Wang, D. Arbuscular mycorrhizal fungi improve the growth and drought tolerance of Cinnamomum migao by enhancing physio-biochemical responses. Ecol. Evol. 2022, 12, e9091. [Google Scholar] [CrossRef]
  26. Liang, Y.; Ma, F.; Li, B.; Guo, C.; Hu, T.; Zhang, M.; Liang, Y.; Zhu, J.; Zhan, X. A bHLH transcription factor, SlbHLH96, promotes drought tolerance in tomato. Hortic. Res. 2022, 9, uhac198. [Google Scholar] [CrossRef] [PubMed]
  27. Wu, D.J.; Yao, D.H.; Wei, Z.Q.; Wu, J.F. A study on the effect of chemical fertilizer combined with Vitekang Soil Conditioner on acidified red paddy soil. Acta Agric. Univ. Jiangxiensis 2020, 42, 1277–1284. [Google Scholar]
  28. Liang, J.; Wang, Z.; Ren, Y.; Jiang, Z.; Chen, H.; Hu, W.; Tang, M. The alleviation mechanisms of cadmium toxicity in Broussonetia papyrifera by arbuscular mycorrhizal symbiosis varied with different levels of cadmium stress. J. Hazard. Mater. 2023, 459, 132076. [Google Scholar] [CrossRef]
  29. Hou, S.S.; Pu, Z.T.; Zhang, C. Advances in research on alleviation of soil excessive trace elements and metals toxicity to plants by arbuscular mycorrhizal fungi. Soil Bull. 2023, 54, 39–749. [Google Scholar]
  30. Adedayo, A.A.; Babalola, O.O.; Prigent-Combaret, C.; Cruz, C.; Stefan, M.; Kutu, F.; Glick, B.R. The application of plant growth-promoting rhizobacteria in Solanum lycopersicum production in the agricultural system: A review. PeerJ 2022, 10, e13405. [Google Scholar] [CrossRef]
  31. Li, Y.; Zeng, J.; Wang, S.; Lin, Q.; Ruan, D.; Chi, H.; Zheng, M.; Chao, Y.; Qiu, R.; Yang, Y. Effects of cadmium-resistant plant growth-promoting rhizobacteria and Funneliformis mosseae on the cadmium tolerance of Solanum lycopersicum (Lycopersicon esculentum L.). Int. J. Phytoremediat. 2020, 22, 451–458. [Google Scholar] [CrossRef] [PubMed]
  32. de Leon, V.; Orr, K.; Stelinski, L.L.; Mandadi, K.; Ibanez-Carrasco, F. Inoculation of Solanum lycopersicum with Plant Growth Promoting Rhizobacteria Affects the Solanum lycopersicum-Potato Psyllid-Candidatus Liberibacter Solanacearum Interactions. J. Econ. Entomol. 2023, 116, 379–388. [Google Scholar] [CrossRef] [PubMed]
  33. Wang, G.Y.; Guo, W.L.; Chen, B.H.; Niu, L.; Ji, S. Effects of biological fertilizer and Vitekang Soil Conditioner on growth, fruit setting, and diseases of spring Solanum lycopersicum in plastic greenhouses. Hubei Agric. Sci. 2018, 57, 37–45. [Google Scholar]
Horticulturae 11 00179 g001
Figure 1. The diagram of agronomic traits.
Figure 1. The diagram of agronomic traits.
Horticulturae 11 00179 g001
Horticulturae 11 00179 g002
Figure 2. The effects of different treatments on MDA content (a), CAT activity (b), SOD activity (c), and POD activity (d) in Solanum lycopersicum leaves under cadmium stress, different letters in the figure represents significant difference.
Figure 2. The effects of different treatments on MDA content (a), CAT activity (b), SOD activity (c), and POD activity (d) in Solanum lycopersicum leaves under cadmium stress, different letters in the figure represents significant difference.
Horticulturae 11 00179 g002
Horticulturae 11 00179 g003
Figure 3. Different treatments of DAB (a) and NBT (b) staining of Solanum lycopersicum leaves under cadmium stress.
Figure 3. Different treatments of DAB (a) and NBT (b) staining of Solanum lycopersicum leaves under cadmium stress.
Horticulturae 11 00179 g003
Horticulturae 11 00179 g004
Figure 4. Effects of different concentration treatments on the expression of NRAMP6 (a) and HMA3 (b) genes in Solanum lycopersicum (c) seedlings under cadmium stress. Different letters in the figure represents significant difference.
Figure 4. Effects of different concentration treatments on the expression of NRAMP6 (a) and HMA3 (b) genes in Solanum lycopersicum (c) seedlings under cadmium stress. Different letters in the figure represents significant difference.
Horticulturae 11 00179 g004
Horticulturae 11 00179 g005
Figure 5. The effect of different treatments on cadmium accumulation in Solanum lycopersicum roots (a) and leaves (b) under cadmium stress. Different letters in the figure represents significant difference.
Figure 5. The effect of different treatments on cadmium accumulation in Solanum lycopersicum roots (a) and leaves (b) under cadmium stress. Different letters in the figure represents significant difference.
Horticulturae 11 00179 g005
Horticulturae 11 00179 g006
Figure 6. The effects of different treatments on MDA content (a), CAT activity (b), SOD activity (c), and POD activity (d) in Solanum lycopersicum leaves under cadmium stress, different letters in the figure represents significant difference.
Figure 6. The effects of different treatments on MDA content (a), CAT activity (b), SOD activity (c), and POD activity (d) in Solanum lycopersicum leaves under cadmium stress, different letters in the figure represents significant difference.
Horticulturae 11 00179 g006
Table 1. Solanum lycopersicum tray seedling experiment.
Table 1. Solanum lycopersicum tray seedling experiment.
TreatmentExperimental Scheme
Micro TomA-CK (0 g/kg)A-T1 (1.2 g/kg)A-T2 (2.4 g/kg)A-T3 (4.8 g/kg)
Red GuanyinB-CK (0 g/kg)B-T1 (1.2 g/kg)B-T2 (2.4 g/kg)B-T3 (4.8 g/kg)
Taiwan Pink KingC-CK (0 g/kg)C-T1 (1.2 g/kg)C-T2 (2.4 g/kg)C-T3 (4.8 g/kg)
Table 2. The effect of different concentration treatments on cadmium accumulation in roots and leaves of Solanum lycopersicum.
Table 2. The effect of different concentration treatments on cadmium accumulation in roots and leaves of Solanum lycopersicum.
Variety Micro TomRed GuanyinTaiwan Pink King
TreatmentCd in the Roots (mg/kg)Cd in the Leaves
(mg/kg)		Cd in the Roots (mg/kg)Cd in the Leaves
(mg/kg)		Cd in the Roots (mg/kg)Cd in the Leaves
(mg/kg)
CK0.0731 ± 0.0053 c0.0443 ± 0.0032 c0.0392 ± 0.0025 c0.0346 ± 0.0021 c0.0375 ± 0.0022 c0.0321 ± 0.0024 c
T10.0686 ± 0.0047 b0.0416 ± 0.0028 b0.0352 ± 0.0017 b0.0292 ± 0.0018 b0.0326 ± 0.0023 b0.0293 ± 0.0016 b
T20.0562 ± 0.0029 a0.0352 ± 0.0031 a0.0319 ± 0.0012 a0.0279 ± 0.0013 a0.0284 ± 0.0016 a0.0255 ± 0.0012 a
T30.0559 ± 0.0035 a0.0348 ± 0.0023 a0.0318 ± 0.0014 a0.0277 ± 0.0011 a0.0282 ± 0.0014 a0.0256 ± 0.0014 a
Note: Different lowercase letters indicate significant differences in cadmium content in the roots and leaves of tomato (Solanum lycopersicum) seedlings treated with different concentrations of the conditioner (p < 0.05).
Table 3. The effect of different concentration treatments on agronomic traits of Solanum lycopersicum under cadmium stress.
Table 3. The effect of different concentration treatments on agronomic traits of Solanum lycopersicum under cadmium stress.
TreatmentPlant HeightStem DiameterSPADAbove Ground
-FW		Under Ground
-FW		Above Ground
-DW		Under Ground
-DW
A-CK5.28 ± 0.117 b1.978 ± 0.053 c35.65 ± 0.708 c2.305 ± 0.081 c0.669 ± 0.041 b0.353 ± 0.013 c0.158 ± 0.005 b
A-T15.733 ± 0.063 a2.098 ± 0.039 bc37.05 ± 0.299 bc2.438 ± 0.036 bc0.658 ± 0.013 b0.398 ± 0.011 b0.16 ± 0.004 b
A-T25.75 ± 0.778 a2.398 ± 0.056 a39.95 ± 0.601 a3.358 ± 0.051 a0.773 ± 0.030 a0.485 ± 0.010 a0.18 ± 0.004 a
A-T35.243 ± 0.028 b2.17 ± 0.051 b38.55 ± 0.348 ab2.573 ± 0.109 b0.673 ± 0.023 b0.393 ± 0.005 b0.163 ± 0.003 b
B-CK8.495 ± 0.181 c1.69 ± 0.022 c33.828 ± 0.624 b1.899 ± 0.025 b0.236 ± 0.009 b0.313 ± 0.005 b0.053 ± 0.005 b
B-T19.573 ± 0.204 b1.968 ± 0.021 b32.86 ± 1.115 b1.95 ± 0.172 ab0.249 ± 0.051 b0.323 ± 0.032 b0.045 ± 0.006 b
B-T212.113 ± 0.194 a2.073 ± 0.037 a37.135 ± 0.780 a3.287 ± 0.899 a0.445 ± 0.049 a0.485 ± 0.051 a0.088 ± 0.006 a
B-T311.755 ± 0.321 a2.053 ± 0.037 ab37.515 ± 0.602 a2.555 ± 0.343 ab0.443 ± 0.058 a0.438 ± 0.053 ab0.083 ± 0.005 a
C-CK9.925 ± 0.890 a1.593 ± 0.019 c32.325 ± 1.222 b1.658 ± 0.029 b0.278 ± 0.019 b0.263 ± 0.020 b0.056 ± 0.005 a
C-T110.52 ± 0.944 a1.68 ± 0.0147 b34.775 ± 0.969 ab1.875 ± 0.057 b0.338 ± 0.009 a0.315 ± 0.006 ab0.068 ± 0.005 a
C-T211.253 ± 1.148 a1.758 ± 0.035 a36.235 ± 1.139 a2.198 ± 0.080 a0.353 ± 0.009 a0.335 ± 0.013 a0.061 ± 0.004 a
C-T310.585 ± 1.237 a1.7 ± 0.004 ab35.36 ± 1.261 ab2.333 ± 0.127 a0.36 ± 0.008 a0.308 ± 0.029 ab0.068 ± 0.009 a
Note: Different lowercase letters indicate significant differences in the agronomic traits of Solanum lycopersicum seedlings treated with different concentrations of the conditioner (p < 0.05). The same applies below. A is Micro Tom, B is Red Guanyin, C is Taiwan Pink King.
Table 4. The effect of different treatments on agronomic traits of Solanum lycopersicum under cadmium stress.
Table 4. The effect of different treatments on agronomic traits of Solanum lycopersicum under cadmium stress.
TreatmentPlant HeightStem DiameterSPADAG-FWUG-FWAG-DWUG-DW
Micro Tom-Cd15.633 ± 1.501 a8.030 ± 0.227 a46.400 ± 1.966 b10.890 ± 0.032 a1.223 ± 0.009 b1.795 ± 0.009 a0.249 ± 0.002 b
CK9.033 ± 0.273 d4.940 ± 0.290 d40.000 ± 0.961 d5.710 ± 0.015 d0.750 ± 0.006 e0.893 ± 0.022 d0.194 ± 0.003 e
Cd+VT11.567 ± 0.176 c6.043 ± 0.249 c48.867 ± 0.961 ab7.503 ± 0.242 c1.220 ± 0.006 d1.127 ± 0.060 c0.293 ± 0.005 d
Cd+AMF13.300 ± 0.625 b6.270 ± 0.202 b47.800 ± 0.961 b7.877 ± 0.018 b1.417 ± 0.015 c1.187 ± 0.019 bc0.344 ± 0.004 c
Cd+VT+AMF16.100 ± 0.896 a7.117 ± 0.163 a52.300 ± 0.961 a10.280 ± 0.081 a1.673 ± 0.009 a1.525 ± 0.013 a0.420 ± 0.004 a
Red Guanyin-Cd55.880 ± 2.517 a7.967 ± 0.342 a40.567 ± 0.961 d8.323 ± 0.109 b1.740 ± 0.046 b1.277 ± 0.016 b0.422 ± 0.010 b
CK38.033 ± 1.50 d4.030 ± 0.227 c38.400 ± 1.966 b10.890 ± 0.0322 c1.223 ± 0.009 e1.795 ± 0.009 d0.249 ± 0.002 e
Cd+VT48.367 ± 2.673 d5.593 ± 0.259 b49.233 ± 1.966 a13.330 ± 0.071 c1.340 ± 0.015 d2.024 ± 0.004 c0.273 ± 0.004
Cd+AMF48.733 ± 0.681 d5.553 ± 0.188 b50.600 ± 1.967 a13.687 ± 0.175 c1.603 ± 0.012 c1.930 ± 0.056 cd0.320 ± 0.003 c
Cd+VT+AMF53.400 ± 2.498 b6.250 ± 0.320 ab53.467 ± 1.157 a17.930 ± 0.829 b1.807 ± 0.028 b2.738 ± 0.192 b0.361 ± 0.006 b
Taiwan Pink King-Cd37.267 ± 0.410 a6.637 ± 0.122 a41.000 ± 1.097 b23.333 ± 0.622 a2.950 ± 0.046 a3.454 ± 0.143 a0.578 ± 0.005 a
CK30.633 ± 2.413 c3.057 ± 0.310 c34.733 ± 3.037 c11.860 ± 0.0589 e1.253 ± 0.017 c1.857 ± 0.004 e0.252 ± 0.003 c
Cd+VT32.433 ± 1.593 b4.107 ± 0.363 b45.200 ± 1.332 ab13.460 ± 0.068 d1.370 ± 0.032 b2.091 ± 0.011 d0.276 ± 0.006 b
Cd+AMF34.033 ± 0.884 ab4.240 ± 0.387 ab44.700 ± 1.572 ab15.500 ± 0.281 c1.693 ± 0.009 a2.419 ± 0.040 c0.341 ± 0.002 a
Cd+VT+AMF38.400 ± 0.520 a4.490 ± 0.215 ab47.600 ± 2.050 a18.277 ± 0.105 a1.753 ± 0.009 a2.866 ± 0.016 a0.353 ± 0.002 a
Note: Different lowercase letters indicate significant differences in agronomic traits among tomato (Solanum lycopersicum) seedlings subjected to different treatments (p < 0.05).
Disclaimer/Publisher’s Note: The statements, opinions and data contained in all publications are solely those of the individual author(s) and contributor(s) and not of MDPI and/or the editor(s). MDPI and/or the editor(s) disclaim responsibility for any injury to people or property resulting from any ideas, methods, instructions or products referred to in the content.

Share and Cite

MDPI and ACS Style

Wang, Q.; Liu, Y.; Chen, G.; Liu, X.; Tanveer, M.; Guo, Y.; Zeng, P.; Huang, L. The Role of Vitekang Soil Conditioner and Arbuscular Mycorrhizae Fungi in Mitigating Cadmium Stress in Solanum lycopersicum Plants. Horticulturae 2025, 11, 179. https://doi.org/10.3390/horticulturae11020179

AMA Style

Wang Q, Liu Y, Chen G, Liu X, Tanveer M, Guo Y, Zeng P, Huang L. The Role of Vitekang Soil Conditioner and Arbuscular Mycorrhizae Fungi in Mitigating Cadmium Stress in Solanum lycopersicum Plants. Horticulturae. 2025; 11(2):179. https://doi.org/10.3390/horticulturae11020179

Chicago/Turabian Style

Wang, Qianqian, Yue Liu, Guangxin Chen, Xing Liu, Mohsin Tanveer, Yongjun Guo, Peng Zeng, and Liping Huang. 2025. "The Role of Vitekang Soil Conditioner and Arbuscular Mycorrhizae Fungi in Mitigating Cadmium Stress in Solanum lycopersicum Plants" Horticulturae 11, no. 2: 179. https://doi.org/10.3390/horticulturae11020179

APA Style

Wang, Q., Liu, Y., Chen, G., Liu, X., Tanveer, M., Guo, Y., Zeng, P., & Huang, L. (2025). The Role of Vitekang Soil Conditioner and Arbuscular Mycorrhizae Fungi in Mitigating Cadmium Stress in Solanum lycopersicum Plants. Horticulturae, 11(2), 179. https://doi.org/10.3390/horticulturae11020179

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

Article Metrics

Back to TopTop