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Article

Effects of Steel Slag Used as Substrate on the Growth of Hydrangea macrophylla Cuttings

by
Jundan Mao
1,2,†,
Huijie Chen
1,†,
Huimin Zhou
1,
Xiangyu Qi
1,
Shuangshuang Chen
1,
Jing Feng
1,
Yuyan Jin
1,
Chang Li
1,
Yanming Deng
1,3,* and
Hao Zhang
2,4,*
1
Provincial Key Laboratory for Horticultural Crops Genetics and Improvement, Institute of Leisure Agriculture, Jiangsu Academy of Agricultural Sciences, Nanjing 210014, China
2
School of Architecture and Engineering, Anhui University of Technology, Maanshan 243032, China
3
State Key Laboratory of Efficient Production of Forest Resources, Beijing Forestry University, Beijing 100083, China
4
School of Metallurgical Engineering, Anhui University of Technology, Maanshan 243032, China
*
Authors to whom correspondence should be addressed.
†
These authors contributed equally to this work.
Horticulturae 2024, 10(10), 1053; https://doi.org/10.3390/horticulturae10101053
Submission received: 30 August 2024 / Revised: 30 September 2024 / Accepted: 30 September 2024 / Published: 2 October 2024
(This article belongs to the Special Issue Abiotic Stress Responses in Ornamental Crops: The State of the Art 2024)
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Versions Notes

Abstract

:
Steel slag is an industrial solid waste produced during the steelmaking process. To explore the application of steel slag in the agricultural field, the present experiment was carried out to study the effect of substrates with different contents of steel slag on the growth of Hydrangea macrophylla cuttings. The conventional substrate (perlite: vermiculite: peat = 1:1:1) was used as the control (CK), and the treatments were designed as T1 (steel slag: perlite: vermiculite: peat = 1:3:3:3, v/v/v/v), T2 (steel slag: perlite: vermiculite: peat = 1:2:2:2, v/v/v/v), T3 (steel slag: perlite: vermiculite: peat = 1:1:1:1, v/v/v/v), and T4 (steel slag: perlite: vermiculite: peat = 1:0:0:0, v/v/v/v). The results showed that the addition of steel slag significantly increased the substrate’s bulk density, EC, and pH and improved its water retention capacity to a certain extent. There were significant differences among different treatments in morphological indicators, root growth and development, and physiological and biochemical characteristics of cutting seedlings. All traits, including plant height, fresh weight, dry weight, root length, root surface area, root volume, the number of root tips, root activity, and soluble protein content of seedlings grown in T3 were significantly higher than those in other substrates. The results indicated that the appropriate addition of steel slag is helpful to hydrangea cuttings’ growth, and the optimal mixing ratio is steel slag: perlite: vermiculite: peat = 1:1:1:1 (v/v/v/v). This is a significant innovation in applying steel slag in agricultural production.

1. Introduction

Steel slag is the molten slag produced during the steelmaking process [1]. With the rapid development of the steel industry, the production of steel and steel slag has continuously increased. Currently, steel slag is only used for road construction and other construction-related fields, but consumption cannot keep up with production. One important reason for this is its very high transportation cost. However, much steel slag is piled up on land, which leads to a serious waste of land resources and the risk of heavy metal pollution at the stacking site [2]. Previous studies have shown that steel slag can improve soil and increase crop yields because it contains high levels of calcium (Ca), magnesium (Mg), iron (Fe), silicon (Si), and other medium and trace elements. For example, Ca is an essential element for plant growth and development. It not only plays an important role in the stability of the plant cell wall and cell membrane but also acts as a major signal molecule in the cytoplasm to regulate plant growth and development [3]. Mg is an important component of chlorophyll [4], and it plays an important role in photosynthesis, fat metabolism, carbohydrate synthesis, enzyme activation, and protein synthesis in plants [5]. Fe is one of the most required elements in plants, and it participates in chlorophyll synthesis, plant photosynthesis, respiration, and electron transfer [6]. In addition, the rich Si in steel slag can be made into silicon fertilizer to promote plant growth. After high-temperature calcination, the slag’s solubility is increased, making it easy for plants to absorb. Therefore, steel slag has a high potential for agricultural use [7].
However, due to its high pH and bulk density, steel slag cannot be widely and directly used in field crops. When steel slag is used in field crops for the long term, it may lead to an imbalance of soil acidity and basicity because of increased pH value. Previous studies have shown that when steel slag was used directly as silicon fertilizer in fields, a high content of heavy metals was examined [8]. Therefore, if the steel slag is not carefully selected, it will cause soil hardening and contamination. However, potted flowers are only used as ornaments, which can prevent large soil alkalization and hardening areas, which may be a novel way to use steel slag.
Hydrangea macrophylla ((Thunb.) Ser.) is a deciduous shrub of the Hydrangeaceae family and the Hydrangea genus. Its colorful and large inflorescences have high ornamental value and can be used as cut, potted, and garden greening. Therefore, hydrangea is called one of the world’s three major garden plants [9,10]. In recent years, the consumption of hydrangea potted flowers has increased daily. Cutting propagation is an essential and primary method to rapidly obtain high-quality seedlings in many plants including hydrangea [11]. At present, the substrates used to cut hydrangea are mainly peat, perlite, and vermiculite [12]. However, these substrates are non-renewable resources with a high cost [13]. Therefore, the present study uses steel slag mixed with the above substrates to cut hydrangea seedlings. The aim is to find a new way to utilize the rich mineral elements in steel slag and reduce the production cost of hydrangea seedlings. The result is meaningful to protect the ecological environment and promote the healthy development of the flower industry.

2. Materials and Methods

2.1. Plant Materials and Steel Slag

The cutting branches were taken from H. macrophylla ‘Red Pink Beauty’ and planted in the Hydrangea Germplasm Resources Conservation Center at Jiangsu Academy of Agricultural Sciences, China. The raw materials of the matrix were perlite, vermiculite, and peat. The converter slag was obtained from the converter slag produced during the steelmaking process, and the particle size was of 28–40 mesh. The elemental contents of steel slag were based on the characteristic X-ray intensity of the elements and determined by X-ray fluorescence spectrometry XRF (ARLAdvante’X IntellipowerTM 3600 Scanning, Basel, Switzerland). The chemical composition and elemental contents of the steel slag are shown in Table 1. The major components of the steel slag used in this experiment were calcium oxide (CaO), silicon dioxide (SiO2), hematite (Fe2O3), alumina (Al2O3), magnesium oxide (MgO), and phosphorus pentoxide (P2O5), which accounted for 90% of the composition. The secondary elements included manganese (Mn) and sulfur (S) compounds.
In this experiment, the horizontal oscillation method was used to simulate the situation of steel slag under the condition of water leaching (refer to Solid waste-Extraction procedure for leaching toxicity-Horizontal vibration method (HJ 557-2010) [14] for the technique). The content of heavy metal ions in the leaching solution was determined by ICP-MS (Inductively Coupled Plasma Mass Spectrometer -ZX-07, Skyray, Dallas, TX, USA). The results were compared with the limits of heavy metals in surface water (refer to Environmental quality standards for surface water (GB 3838-2002) [15]) (Table 2). The contents of Cr, Mn, Co, Ni, Zn, and Pb ions were below the surface-water standards for heavy metals. This result suggested that the selected converter slag could be used as the substrate, and its leachate would not cause pollution to the environment or water bodies.

2.2. Experimental Design

Five treatments with different substrates were designed to cut seedlings, the conventional substrate (perlite: vermiculite: peat = 1:1:1, v/v/v) was used as the control (CK), and the treatments were designed as T1 (steel slag: perlite: vermiculite: peat = 1:3:3:3, v/v/v/v), T2 (steel slag: perlite: vermiculite: peat = 1:2:2:2, v/v/v/v), T3 (steel slag: perlite: vermiculite: peat = 1:1:1:1, v/v/v/v), and T4 (steel slag: perlite: vermiculite: peat = 1:0:0:0, v/v/v/v) (Table 3). The cutting pots were 36 cm × 14 cm × 16 cm (L × W × H). Before cutting, each pot was covered with about 10 cm of different substrates and watered thoroughly.
The cuttings were taken from vigorous semi-lignified branches without pests and diseases. The branches were cut into 4–6 cm long pieces, and each cutting had two half leaves and two axillary buds (flower buds were removed). The tops of the cuttings were cut into a flat section at a distance of 0.5 cm from the buds, and the ends were cut into a 45° oblique.
A total of 32 seedlings were cut into one cutting box (4 columns × 8 rows) for each treatment. There were three boxes as replicates for each treatment. The cuttings were inserted into the substrate with a depth of about 2/3 of the stems. Three cuttings were randomly selected from each treatment every ten days during the experiment, and the traits of rooting, sprouting, and bud growth were observed. All samples were taken from the box 50 days after cutting to determine their physiological and biochemical characteristics.

2.3. Experimental Methods

The substrates’ pH, EC, bulk density, total porosity, aeration porosity, and water-holding porosity were measured. Five substrates were mixed evenly according to different ratios, and three samples of each treatment were taken back to the laboratory as replicates to determine their physical characteristics. The physical and chemical properties of the substrate were determined by Zhang’s method [16] and Lian’s method [17], respectively.
At 50 d after cutting, five representative seedlings were selected from each treatment. After washing them with running water, the root morphological characteristics were determined using the Scan Maker i800Plus scanner (Microtek, Shanghai Zhongjing Technology Co., Ltd., Shanghai, China). Plant height was measured from the bottom of the first reserved shoot to the apical new shoot (accurate to 0.1 cm). The stem diameter was measured with a vernier caliper (accurate to 0.01 mm) (MNT-431; Shanghai Meinet Industrial Co., Ltd., Shanghai, China) around the bottom of the reserved shoot. Fresh weight (FW) was obtained from the fresh seedling samples using an electronic scale (JM-A6002; Yuyao Jiming Weighing and Calibration Equipment Co., Ltd., Yuyao, China), and the dry weight (DW) was obtained from the same samples that were placed in an oven (OHG-9075A blast drying oven; LISK Instrument Equipment (Nanjing) Co., Ltd., Nanjing, China) and dried to a constant weight at 60 °C.
The third to fifth mature leaves from the top of the plants were selected as samples to determine related physiological and biochemical indexes. Malondialdehyde (MDA) content was examined using the thiobarbituric acid method [18]. The contents of soluble sugar and protein were measured by the anthrone colorimetric method and the Coomassie Brilliant Blue G-250 method [19]. Root activity was determined by the TTC reduction method [20]. The chlorophyll content was examined by a chlorophyll-content analyzer (SPAD-502Plus; Spectrum Technologies, Tokyo, Japan).

2.4. Data Analysis and Comprehensive Evaluation Method

Excel 2023 was used for data collation, and SPSS 26.0 was used for one-way analysis of variance (ANOVA) and Duncan’s multiple comparisons.

3. Results

3.1. Physical and Chemical Properties of Different Substrates

The physical and chemical properties of tested substrates differed from each other. As shown in Table 4, the addition of steel slag significantly increased the pH and bulk density of the substrate by 22.38~87.17% and 60.71~439.29%, respectively, compared with CK. The EC values of different treatments were also significantly different. The EC of T1, T2, and T3 were significantly higher than that of CK, which increased by 90.40%, 61.25%, and 31.02% compared with CK, respectively. After adding different proportions of steel slag to the conventional substrates, the total porosity and aeration porosity of the mixed substrates gradually decreased by 4.59~27.68% and 15.16~72.18%, respectively, compared with CK. There was no significant difference in the total porosity of CK, T1, and T2, but there was a significant difference in aeration porosity among all treatments. There was no significant difference in water-holding porosity among CK, T1, T2, and T3 treatments. The water-holding porosity of T3 was the highest, which increased by 2.71% compared with CK.

3.2. Effects of Different Substrates on Survival Rates of the Cuttage

The survival rates of seedlings on the 50th day post-cutting in different treatments are shown in Table 5. The highest survival rate was 98.96% (T1 and T2). The lowest survival rate was T4 (81.25%), which may have resulted from hardened steel slag and high pH value. The survival rates in the T1, T2, and T3 treatments all exceeded 90%; this indicated a significant enhancement compared to T4. This underscored that steel slag mixing with conventional substrates could improve the survival of cuttings.

3.3. Effects of Different Substrates on the Growth and Morphology of Seedlings

As shown in Figure 1, there was no significant difference between treatments on the 20th day of cutting. The growth of CK, T1, T2, and T3 was normal on the 30–40th day of cutting. However, on the 50th day of cutting, only a few plants in T4 had new leaves, and the growth condition of other treatments was better. At the same time, the leaf color of plants in T1, T2, and T3 was slightly yellow compared with that of CK.
The morphological indexes of hydrangea cuttings in different substrates are shown in Table 6. There was a significant difference in plant height among different treatments. The plant height of T3 was the highest and was significantly higher than other treatments, which increased by 22.50% compared with CK. There was a significant difference in stem diameter among different treatments. The CK had the highest stem diameter and was significantly higher than that of other treatments. T3 had the largest fresh weight value, which increased by 1.32% compared with CK, and the fresh weight of T3 was significantly higher than T2 and T4. The dry weight value of T3 was the largest, which increased by 12.12% compared with CK. The dry weight of T3 was significantly different from that of T1, T2, and T4 treatments. The chlorophyll value of CK was the highest, significantly higher than that of other treatments. The chlorophyll values of T3 and T4 were significantly higher than T1 and T2.

3.4. Effects of Different Substrates on Root Growth of Seedlings

There were significant differences in the root growth of each treatment (Figure 2). The rooting status in T3 and CK treatments was better than other treatments, while the T4 treatment was the worst one. There were significant differences in root length and surface area among treatments (Table 7). The T3 treatment had the largest root length and surface area which were significantly higher than other treatments, which increased by 40.17% and 42.88% compared with CK, respectively. There was also a significant difference in root volume among different treatments. T3 had the largest root volume and was significantly higher than other treatments, which increased by 63.66% compared with CK. The number of root tips was significantly different among treatments. T3 had the largest number of root tips and was significantly higher than other treatments, which increased by 68.68% compared with CK. After adding a certain proportion of steel slag to the conventional substrates, the root activities of T1, T2, and T3 were significantly increased compared with CK. The root activity of T3 was the highest and significantly higher than that of other treatments, which increased by 135.13% compared with CK.

4. Discussion

The physical and chemical properties are essential indexes reflecting the seedling substrates’ structural characteristics and nutrient status [21,22]. The results of this study show that the addition of steel slag increased the substrate pH, EC, and bulk density to some extent and reduced the substrate’s porosity. The pure steel slag (T4)‘s pH value and bulk density were 11.96 and 1.50 g·cm−3, respectively. This indicated that it was not suitable for cutting hydrangea. However, when mixed with perlite, vermiculite, and peat, the pH value and bulk density were significantly reduced. The growth of cuttings in T1, T2, and T3 treatments was better than in T4, indicating that the reduced pH values of the mixed substrates were suitable for hydrangea. The EC values of all treatments in this experiment were lower than the limited EC value of substrates (2.6 mS·cm−1) [16]. The EC values of mixed treatments were significantly increased compared with CK and T4. The reason may be that some oxides (such as free calcium oxide, etc.) and silicates in steel slag were dissolved in soil aqueous medium, and silicate ions could also release phosphate ions fixed in the soil [23,24,25]. Therefore, many ions were released, increasing the treatment’s EC value. With the increase of steel slag content, the pH values of mixed treatments gradually improved. Some metal ions in the steel slag formed hydroxide precipitate, which could adsorb silicate or form silicate precipitate [26,27]. The ion content decreased, and the EC value decreased gradually. The large bulk weight of the substrate reduced its water-holding and fertilizer-holding capacity, which is harmful to the growth of plant roots. The small bulk density was not conducive to the growth and development of plant roots. The total porosity reflects the permeability and water retention of the substrate. According to a former study [28], the total porosity and bulk density of an ideal growing medium for plants were appropriate at 0.1–0.8 g·cm−3 and 54–96%, respectively. In the present study, the bulk density and total porosity of T4 were out of the range, while other treatments were all in the range. Thus, pure steel slag was not suitable as a growing medium. However, steel slag reduced the substrate’s aeration and increased water retention. He et al. [29] found that adding fine sand would increase the matrix water content and decrease the porosity and air permeability. Our study was consistent with that conclusion.
The plant height, stem diameter, and fresh and dry weights of plants are the primary growth indicators that reflect the quality of seedlings [30,31]. According to the present study, the plant height, fresh weight, and dry weight of T3 were higher than other treatments. He et al. [29] found that adding fine sand increased the bulk density of soil and the contact area between roots and soil, which was conducive to nutrient absorption and promoted above-ground parts’ growth. Appropriately increasing the proportion of steel slag was conducive to developing the above-ground parts.
The growth and distribution of roots result from a plant’s interaction with the environment during its development and reflect the ability of the plant to absorb and transfer water and nutrients [32,33,34]. Root activity is a physiological index to judge the growth and development characteristics of plants and reveal their adaptability, biosynthesis ability, and health status [35]. In this study, root length, root surface area, root volume, root tip number, and root activity in T3 were significantly higher than those in other treatments. Carvalho Pupatto et al. [36] found that steel slag could promote plant root growth and distribution in soil profiles. Islam et al. [37] studied the addition of steel slag, which improved soil fertility and promoted plant growth and nutrient absorption. Combined with previous studies and our results, we speculated that a certain proportion of steel slag in the substrate could promote the growth and development of plant roots and the absorption of nutrients. It is preliminarily hypothesized that this enhancement may be linked to the bulk density of the substrate. Ola et al. [38] concluded that bulk density significantly influences plant root development by promoting elongation of root cells. Plants must withstand greater substrate reaction forces in substrates with higher bulk density, potentially enhancing root activity. Wang et al. [39] thought that the appropriate matrix compactness was conducive to the growth of root diameter. Therefore, root length, surface area, and root volume increased significantly in the T3 treatment, and it was the most suitable mixed substrate for cuttings.
Malonaldehyde (MDA) is the end product of membrane lipid peroxidation, and its content will reflect the degree of environmental persecution of the organism [40]. In this study, the content of malondialdehyde in CK and T4 was significantly higher than in other treatments. The content of malondialdehyde in mixed treatments improved with increased steel slag content. The content of soluble silicon in steel slag was higher, and the leaves of plants became thicker after absorbing soluble silicon, which can induce plant photosynthesis to become stronger while increasing biomass [41,42]. The mechanical or physical barrier provided by Si deposition in the cell wall helps to enhance resistance and improve seedling roots [43]. In the same growth conditions, the photosynthesis of leaves in the treatment group was enhanced, and the water loss due to transpiration was reduced compared with CK [44]. Therefore, the malondialdehyde content in CK was higher than that of T1, T2, and T3. The results showed that the steel slag and conventional cutting substrate mixture significantly reduced environmental stress on cuttings. The reason may be consistent with the study of Chen et al. [45]. The low content of steel slag did not induce oxidative stress in plants, reduced membrane lipid peroxidation, and improved antioxidant properties to some extent. Studies have shown that adding steel slag could improve soil enzyme activity and fertility [42,46]. Therefore, adding steel slag reduced the environmental stress of the substrate to the root system. The malondialdehyde content in T3 was higher than that of T1 and T2, but the growth performance was better than others. The reason can be inferred from two aspects: on the one hand, the high content of calcium and silicon in steel slag made the root system stronger and promoted the growth of plants, nutrient absorption, and biomass increase [44,47]; on the other hand, plant roots were significantly affected by the bulk density of the substrate. The appropriate substrate compactness (bulk weight) could promote the coarse growth of plant roots [48]. Therefore, the growth performance of T3 was better than that of T1 and T2.
Root primordium induction, elongation, and growth of adventitious roots in the rooting process of plant spike cuttings require a large amount of nutrients. Furthermore, plants enhance their stress resistance by accumulating soluble protein during stress [49,50]. In this study, the soluble protein content of T3 was significantly higher than that of other treatments. Different contents of steel slag had significant effects on soluble protein in leaves. With the increase of steel slag content, the soluble protein content first increased and then decreased; the overall trend was gradually upward. Our results were consistent with the results of Zheng et al. [51]; they found that the soluble protein content of plants in different ratios of yellow sand and slag first increased and then decreased, and the overall trend was upward. The result was inconsistent with the study of Zhou et al. [52]. The reason may be that the physical and chemical properties of the substitute substrate were quite different from those of steel slag, which resulted in various plant growth environments, and therefore the ability to accumulate soluble protein was different.

5. Conclusions

This study analyzed the effects of steel slag used as the substrate on the growth, root development, and physiology and biochemistry of H. macrophylla seedlings. The results showed that the T3 treatment (steel slag: perlite: vermiculite: peat = 1:1:1:1) was the most suitable mixed substrate for the cutting of H. macrophylla seedlings. The present study found a novel way to utilize the solid waste of steel slag in agricultural production instead of traditional substrates.

Author Contributions

Conceptualization, Y.D. and H.C.; methodology, H.C. and J.M.; software, J.M. and H.Z. (Huimin Zhou); validation, H.C., S.C. and Y.J.; formal analysis, J.M. and H.C.; investigation, J.M. and Y.J.; resources, X.Q. and H.Z. (Huimin Zhou); data curation, J.M.; writing—original draft preparation, J.M. and H.C.; writing—review and editing, Y.D.; visualization, J.M. and J.F.; supervision, H.Z. (Hao Zhang) and Y.D.; project administration, Y.D. and C.L.; funding acquisition, H.C., X.Q. and H.Z. (Hao Zhang). All authors have read and agreed to the published version of the manuscript.

Funding

This work was supported by the Open Project Program of Key Laboratory of Metallurgical Emission Reduction & Resources Recycling (Anhui University of Technology), Ministry of Education (No. JKF24-05), the Fund for Independent Innovation of Agricultural Sciences in Jiangsu Province (CX (24)3058), Provincial Quality Engineering Project of New Era Education (Graduate Education) (2023qygzz016), and Maanshan City Rural and Social Development Field Science and Technology Program [2022KN-13].

Data Availability Statement

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

Conflicts of Interest

The authors declare no conflicts of interest.

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Horticulturae 10 01053 g001
Figure 1. Hydrangea seedlings grown in different substrates.
Figure 1. Hydrangea seedlings grown in different substrates.
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Figure 2. The root systems of hydrangea seedlings grown in different substrates.
Figure 2. The root systems of hydrangea seedlings grown in different substrates.
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Table 1. Chemical composition and the content of single elements.
Table 1. Chemical composition and the content of single elements.
ClassificationNameContent
OxideCaO42.11 ± 0.25 (%)
SiO217.64 ± 0.19 (%)
Fe2O313.89 ± 0.17 (%)
Al2O310.53 ± 0.15 (%)
MgO6.45 ± 0.12 (%)
P2O53.14 ± 0.09 (%)
Single elementCa30.11 ± 0.18 (%)
Si8.25 ± 0.09 (%)
Fe9.72 ± 0.12 (%)
Al5.57 ± 0.08 (%)
Mg3.89 ± 0.07 (%)
P1.37 ± 0.04 (%)
Table 2. Heavy metals of the tested steel slag.
Table 2. Heavy metals of the tested steel slag.
Heavy MetalGB3838-2002 Standard Limit (mg·L−1)Heavy Metal Ion Content in Steel Slag (mg·L−1)
Cr0.011.34 × 10−3
Mn0.100.94 × 10−3
Co1.000.08 × 10−3
Ni0.020.24 × 10−3
Zn0.050.37 × 10−3
Pb0.010.65× 10−3
Table 3. Proportions of different substrates (Volume ratio) (Volume unit: L).
Table 3. Proportions of different substrates (Volume ratio) (Volume unit: L).
TreatmentSteel SlagPerliteVermiculitePeat
CK0111
T11333
T21222
T31111
T41000
Table 4. Comparison of physical and chemical properties of different substrates.
Table 4. Comparison of physical and chemical properties of different substrates.
TreatmentspHEC (μs·cm−1)Bulk Density (g·cm−3)Total Porosity (%)Water-Holding Porosity (%)Aeration Porosity (%)
CK6.39 ± 0.13e375.00 ± 10.69d0.28 ± 0.01e61.27 ± 1.09a46.89 ± 0.95a14.38 ± 0.17a
T17.82 ± 0.04d714.00 ± 17.35a0.45 ± 0.03d58.46 ± 0.58b46.26 ± 0.54a12.20 ± 0.09b
T28.08 ± 0.01c604.67 ± 8.35b0.55 ± 0.04c57.03 ± 0.37bc46.58 ± 0.36a10.46 ± 0.11c
T38.28 ± 0.02b491.33 ± 9.94c0.67 ± 0.06b55.76 ± 0.86c48.16 ± 0.77a7.59 ± 0.10d
T411.96 ± 0.02a216.33 ± 1.86e1.51 ± 0.00a44.31 ± 0.28d40.31 ± 0.37b4.00 ± 0.12e
Notes: All the measured data are shown as mean ± standard error (SE). N = 3. Different small letters after data in the same column indicate significant difference between treatments (p < 0.05).
Table 5. Survival rate of seedlings in different substrates.
Table 5. Survival rate of seedlings in different substrates.
TreatmentThe Number of Total Plants The Number of Surviving PlantsSurvival Rate (%)
CK969498.92
T1969598.96
T2969598.96
T3968891.67
T4967881.25
Table 6. The morphological characters of hydrangea cuttings grown in different substrates.
Table 6. The morphological characters of hydrangea cuttings grown in different substrates.
TreatmentPlant Height (cm)Stem Diameter (mm)Fresh Weight (FW, g)Dry Weight (DW, g)Chlorophyll (SPAD %)
CK3.20 ± 0.16b3.39 ± 0.02a3.80 ± 0.10a0.33 ± 0.03ab37.08 ± 0.46a
T12.40 ± 0.24c2.74 ± 0.02c3.54 ± 0.16a0.31 ± 0.00bc16.90 ± 0.66c
T22.56 ± 0.15c2.60 ± 0.04c2.77 ± 0.15b0.27 ± 0.02c15.76 ± 0.35c
T33.92 ± 0.12a3.05 ± 0.05b3.85 ± 0.08a0.37 ± 0.02a32.76 ± 0.73b
T41.42 ± 0.16d2.09 ± 0.14d3.09 ± 0.10b0.26 ± 0.00c33.44 ± 1.59b
Notes: All the measured data are shown as mean ± standard error (SE). N = 5. Different small letters after data in the same column indicate significant difference between treatments (p < 0.05).
Table 7. The root characters of hydrangea seedlings grown in different substrates.
Table 7. The root characters of hydrangea seedlings grown in different substrates.
TreatmentRoot Length (cm)Root Surface Area (cm2)Root Volume (cm3)Number of Root TipsRoot Activity (μg TTC·(g·h)−1)
CK241.10 ± 13.74b149.59 ± 8.88b9.55 ± 0.41b92.60 ± 3.47b70.49 ± 3.66c
T1114.00 ± 4.55c68.64 ± 2.28c4.57 ± 0.35d86.40 ± 4.03b129.89 ± 7.85b
T2136.51 ± 3.36c88.86 ± 8.07c6.64 ± 0.60c88.60 ± 6.05b145.83 ± 2.71b
T3337.94 ± 18.78a213.73 ± 11.99a15.63 ± 0.83a156.20 ± 11.85a165.74 ± 8.67a
T411.13 ± 1.06d7.16 ± 0.61d0.69 ± 0.09e10.60 ± 1.40c57.06 ± 2.67c
Notes: All the measured data are shown as mean ± standard error (SE). N = 5. Different small letters after data in the same column indicate significant difference between treatments (p < 0.05).
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MDPI and ACS Style

Mao, J.; Chen, H.; Zhou, H.; Qi, X.; Chen, S.; Feng, J.; Jin, Y.; Li, C.; Deng, Y.; Zhang, H. Effects of Steel Slag Used as Substrate on the Growth of Hydrangea macrophylla Cuttings. Horticulturae 2024, 10, 1053. https://doi.org/10.3390/horticulturae10101053

AMA Style

Mao J, Chen H, Zhou H, Qi X, Chen S, Feng J, Jin Y, Li C, Deng Y, Zhang H. Effects of Steel Slag Used as Substrate on the Growth of Hydrangea macrophylla Cuttings. Horticulturae. 2024; 10(10):1053. https://doi.org/10.3390/horticulturae10101053

Chicago/Turabian Style

Mao, Jundan, Huijie Chen, Huimin Zhou, Xiangyu Qi, Shuangshuang Chen, Jing Feng, Yuyan Jin, Chang Li, Yanming Deng, and Hao Zhang. 2024. "Effects of Steel Slag Used as Substrate on the Growth of Hydrangea macrophylla Cuttings" Horticulturae 10, no. 10: 1053. https://doi.org/10.3390/horticulturae10101053

APA Style

Mao, J., Chen, H., Zhou, H., Qi, X., Chen, S., Feng, J., Jin, Y., Li, C., Deng, Y., & Zhang, H. (2024). Effects of Steel Slag Used as Substrate on the Growth of Hydrangea macrophylla Cuttings. Horticulturae, 10(10), 1053. https://doi.org/10.3390/horticulturae10101053

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