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Article

Effects of Drought Stress on Photosynthetic Characteristics and Endogenous Hormone Levels in the Sweet Potato (Ipomoea batatas)

by
Shihao Huang
1,2,
Jinqiang Wang
2,
Huanyuan Wang
1,* and
Huan Li
2,*
1
Key Laboratory of Degraded and Unused Land Consolidation Engineering, Ministry of Natural Resources, Xi’an 710075, China
2
College of Resources and Environmental Sciences, Qingdao Agricultural University, Qingdao 266109, China
*
Authors to whom correspondence should be addressed.
Horticulturae 2025, 11(5), 456; https://doi.org/10.3390/horticulturae11050456
Submission received: 5 March 2025 / Revised: 12 April 2025 / Accepted: 22 April 2025 / Published: 24 April 2025
(This article belongs to the Section Biotic and Abiotic Stress)
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Abstract

:
In the context of climate change and severe water shortages in agriculture, we explored water stress responses in the sweet potato (Ipomoea batatas) in terms of endogenous hormone levels and other physiological characteristics, providing a theoretical basis for drought-resistant cultivation of sweet potato. This study was conducted from 2021–2022 in a solar greenhouse under artificially controlled water conditions. We determined biomass, agronomic indexes, photosynthetic parameters, and endogenous hormone levels in three treatments: normal water supply (CK), mild drought (LD), and severe drought (HD). The results revealed that drought stress inhibited aboveground and belowground sweet potato growth compared with CK; sweet potato yield decreased with increasing drought. The net photosynthetic rate, stomatal conductance, and transpiration rate of sweet potato leaves decreased significantly under drought stress. The leaves’ intercellular CO2 concentration (Ci) decreased with increasing drought up to 50 days after transplanting but increased with increasing drought up to 75 days after transplanting. The zeatin riboside (ZR) and indole-3-acetic acid (IAA) contents were significantly lower in sweet potato leaves and tubers in the LD and HD treatments compared with CK, whereas the abscisic acid (ABA) content was significantly higher. Within the same period, the (ZR + IAA)/ABA ratio decreased with increasing drought severity. Correlation analysis revealed that the ABA and leaf Ci were significantly positively correlated, and both indices were significantly negatively correlated with all other indices. Aboveground dry weight was significantly correlated with the ZR and IAA contents. These findings demonstrate the regulatory effects of elevated leaf ABA concentrations on stomatal conductance during drought and indicate that stomatal closure was mainly responsible for the decreased photosynthetic rate observed in the early stage of drought. The rapid decrease in the photosynthetic rate in the late stage of drought may have been caused by non-stomatal factors. These findings provide a theoretical foundation for future drought-resistant sweet potato cultivation.

1. Introduction

Endogenous hormones are regulators of plant growth activities and are essential for plant drought regulation [1]. Under drought stress conditions, plants activate sophisticated hormonal regulation mechanisms to achieve adaptive responses to environmental changes, primarily through dynamic adjustments in phytohormone biosynthesis, transport, and signaling pathways [2]. Endogenous hormones and their ratios are raised or lowered to varying degrees, and a variety of endogenous hormones are involved in the regulation of several physiological processes, including photosynthesis [3,4]. Physiological effects among endogenous hormones are characterized by interaction and coupled occurrence [5]. These makes the relationship between the endogenous hormones and physiological processes both close and complex.
Drought is a global problem facing the world today, with the annual yield losses due to drought exceeding those of all other abiotic stresses combined [6]. As an important food crop, the sweet potato has certain drought, salt, and barren tolerance characteristics. Drought stress causes stunted crop growth and reduced yields, which are mainly due to changes in plant physiological functions [7]. Drought affects a series of physiological and biochemical actions such as photosynthesis, respiration, translocation, ion uptake, nutrient metabolism, etc., and the effects of water stress on various physiological indicators in plants often vary with the degree of drought [8,9]. Additionally, drought tolerance is closely related to the regulation of various phytohormones [10]. Zhang et al. [11] found that under water stress, sweet potato’s indole-3-acetic acid (IAA), gibberellic acid, indole-3-propionic acid, and zeatin riboside (ZR) contents decreased, whereas its abscisic acid (ABA) content increased significantly. Furthermore, Zhang et al. [5] reported that drought stress at different growth periods caused decreases in gibberellins, IAA, and ZR contents and an increase in ABA content in sweet potato’s leaves and roots. Wang et al. [12] found that drought stress at different periods resulted in significant decreases in the contents of growth-promoting hormones IAA and ZR and a significant increase in the content of the growth-inhibiting hormone ABA in roots, which collectively suppressed root differentiation; this effect was more severe when drought stress was applied earlier.
Most studies on drought resistance in sweet potatoes have focused on the relationships between osmoregulatory substances, antioxidant enzyme activity [13], or photosynthetic parameters [14] with various physiological and biochemical indices, as well as differences in drought effects among sweet potato varieties [15]. These studies have examined physiological and biochemical indices such as plant morphology, growth metrics, root nutrient uptake, and dry matter accumulation [16,17]. However, few studies have explored the relationships between endogenous hormone levels and physiological characteristics such as photosynthesis in sweet potatoes under drought stress conditions, and these studies have generally focused on single physiological traits [5,18,19]. Therefore, the objective of this study was to explore the responses of the sweet potato’s endogenous hormones and physiological characteristics to water stress. Our findings will provide a theoretical basis for improving drought-resistant sweet potato cultivation.

2. Materials and Methods

2.1. Study Site

This field experiment was conducted during the 2021–2022 sweet potato cropping season at the Pingdu Experimental Station, Qingdao Agricultural University (36°53′ N, 120°13′ E, 50 m a.s.l.), located in Pingdu County, Shandong Province, China. We conducted the experiment in a solar greenhouse. The temperature inside the greenhouse was 28 °C, the temperature difference between day and night was 8 °C, and the humidity was 48%. The soil type in the study site was brown earth. The chemical composition of the 0–20-cm soil layer was 11.74 g kg−1 organic material, 60.46 mg kg−1 available nitrogen, 66.53 mg kg−1 available potassium, and 19.58 mg kg−1 available phosphate, with a bulk density of 1.27 g cm–3 and field capacity of 26.53%.

2.2. Experimental Design

In our experiments, we used seedlings of the I. batatas variety ‘Yan 25’, which is the main sweet potato variety cultivated in northern China. After transplantation, all seedlings were supplied with the same amount of water. Then, the seedlings were assigned to one of three moisture treatments, in which 75 ± 5%, 55 ± 5%, or 35 ± 5% soil volumetric water content was provided to represent normal water supply (CK), mild drought (LD), and severe drought (HD), respectively. A fully automated moisture sensor (QY-800S, Hebei Qingyi, China) was used to detect the soil’s water content and control watering through supplemental irrigation to ensure that soil moisture content remained within the target range in the drought-resistant pool. A randomized block design was used with three replications. All treatments received basal fertilization consisting of 150 kg N ha−1 as urea, 75 kg P ha−1 as superphosphate, and 150 kg K ha−1 as potassium sulphate.

2.3. Sampling and Analysis

The sweet potatoes’ biomass was determined using samples collected 30, 50, 75, 100, and 125 days after transplanting, with 10 plants collected during each sampling period. We recorded the number of leaves, vine length, and aboveground (stem and leaf) and belowground (tuber) fresh and dry weights. To obtain the aboveground fresh and dry weights, the stems and leaves were chopped and mixed evenly, weighed, and then dried at 75 °C until a constant weight was reached. This process was repeated for the tubers to obtain the belowground fresh and dry weights.
The yield and its components were determined after harvest, which took place 160 days after transplanting. Yield was determined for each plot, and then the average plot yield and fresh yield (kg ha−1) were calculated. We also selected 20 representative plants with uniform growth to record the number of sweet potatoes produced per plant and the fresh weight of the individual tubers.
Photosynthetic parameters were determined using a CIRAS-3 portable photosynthesizer ( Hansatech, King’s Lynn, UK) in a manually controlled environment, with a CO2 concentration of 400 ppm, a temperature of 25 °C, and light intensity of 1200 μmol m–2 s−1 from 9:00 to 11:00 at 30, 50, and 85 days after transplanting. The net photosynthetic rate (Pn), stomatal conductance (Gs), intercellular CO2 concentration (Ci), and transpiration rate (Tr) were measured in the fourth and fifth functional leaves of each plant.
The endogenous hormone (ABA, IAA, and ZR) contents were determined using enzyme-linked immunosorbent assays (ELISAs), with kits purchased from the Nanjing Jianjian Bioengineering Institute (Nanjing, China), according to the manufacturers’ guidelines [20]. Leaf samples were obtained from the fourth unfolded leaf of each plant, and tuber samples were cut by quartering each tuber longitudinally and removing a small piece from the middle of one quarter; the resulting 1-g samples were flash-frozen with liquid nitrogen and stored at −80 °C. For the ELISAs, endogenous hormones were extracted from the samples with a 0.1 M phosphate-buffered saline solution (pH 7.3).

2.4. Data Analysis

Data were analyzed using SPSS v20.0 (SPSS Institute Inc., Cary, NC, USA). Means were compared among the treatments using analysis of variance (ANOVA), followed by the least significant difference (LSD) test to evaluate significance. The Mantel test was conducted using R’s 4.3.2 (R Core Team, Vienna, Austria) vegan package to evaluate the matrix correlations among environmental variables (such as soil water content) and physiological indicators (such as ABA content and photosynthetic rate).

3. Results

3.1. Effect of Drought Stress on Sweet Potato Biomass

All drought stress treatments resulted in significantly lower sweet potato aboveground biomass compared with CK (p < 0.05). These decreases indicate that drought stress inhibited the stem and leaf growth rates, and this was exacerbated as the degree of drought stress increased. Prolonged severe drought stress led to early plant senescence (Figure 1).

3.2. Effect of Drought Stress on Agronomic Indices

Different degrees of drought stress resulted in significant (p < 0.05) decreases in the number of leaves and number of branches of the sweet potatoes, with severe drought outweighing mild drought in all periods (Table 1). Drought stress inhibited sweet potato leaf growth and branch production, resulting in slower growth or even leaf senescence and shedding in the middle and late stages of reproduction.

3.3. Effect of Drought Stress on Leaf Photosynthetic Parameters

The leaf Pn was significantly lower in both drought treatments as compared with CK in each growth period (p < 0.05), with a much larger decline in the HD treatment than in the LD treatment; the leaf Gs and Tr exhibited similar trends (Figure 2). In all treatments, the leaf Pn, Gs, and Tr first increased and then decreased, with maximum values reached at 75 days in CK and LD; growth rates were significantly lower in the LD treatment than in CK (p < 0.05). The leaf Ci also increased and then decreased in CK but increased linearly in the LD and HD treatments. These results indicate that decreases in photosynthesis rates in the early stage of drought stress were caused by the stomatal limitation of CO2 entering chloroplasts in the leaves, whereas in the late stage of drought stress, photosynthesis was limited by non-stomatal factors.

3.4. Effects of Drought Stress on Endogenous Hormones Levels

The ZR and IAA contents in the sweet potato leaves increased and then decreased over time, with significant differences among the treatments (p < 0.05), whereas the ABA content increased linearly. After 30 days, both drought treatments led to significantly lower leaf ZR and IAA contents (p < 0.05), with much larger decreases observed in the HD treatment than in the LD treatment. ABA content increased significantly in all treatments over time (Figure 3).
In the tubers, the ZR content increased and then decreased in all treatments, and the hormone content decreased significantly with drought stress severity during each period (p < 0.05). In the LD and HD treatments, the IAA content first increased and then decreased, with maximum values reached earlier in the HD treatment than in the LD treatment. The ABA content in the tubers increased linearly over time with the degree of drought stress, with significant differences among the treatments (p < 0.05; Figure 4).
From 30 to 75 days after transplanting, the (ZR + IAA)/ABA ratio first decreased and then increased in tubers under mild drought stress, followed by a linear decrease after 75 days. From 75 to 100 days, the decrease in the (ZR + IAA)/ABA ratio was greater aboveground than belowground, whereas the opposite trend was observed from 100 to 120 days. In the HD treatment, the (ZR + IAA)/ABA ratio gradually decreased, and was lower aboveground than belowground (Figure 5).

3.5. Production and Production Components

Both drought stress treatments resulted in significant decreases in the sweet potato yield (p < 0.05), with that in the LD and HD treatments decreasing by 26.53% and 67.31%, respectively, compared with CK. The average sweet potato weight and number of potatoes per plant were also affected by drought stress, with greater decreases in HD than in LD (Table 2).

3.6. Correlation Analysis

Aboveground and belowground ABA contents were significantly negatively correlated with all indices except leaf Ci, which had a positive correlation (p < 0.05). The aboveground and belowground ZR and IAA were significantly positively correlated with all indices (p < 0.05). The leaf Pn was not significantly correlated with any of the examined indices (p > 0.05). The Ci was significantly negatively correlated with all indices except ABA, which had a positive correlation (p < 0.05). The correlation trends were consistent between Gs and TR. Significant correlations were also detected between the root IAA content and both the yield and root dry weights, between the aboveground dry weight and aboveground and root ZR and IAA contents, and between the aboveground dry weight and aboveground Ci and Tr (p < 0.05); the number of branches was highly significantly correlated with the leaf Pn (p < 0.01) (Figure 6).

4. Discussion

4.1. Effect of Drought Stress on Sweet Potato Photosynthetic Parameters

When soil moisture content is low, stomata tend to reduce transpiration rates by partially or fully closing, reducing water loss while reducing CO2 entry, which leads to a decrease in photosynthetic rates [21]. Both stomatal and non-stomatal limitations affect photosynthesis rates in plants subjected to drought stress [22]. In this study, the sweet potato leaf Pn, Gs, and Tr were significantly reduced under drought stress and tended to first increase and then decrease over time. In contrast, the leaf Ci increased with drought severity, with drought-induced Ci rising from 75 to 120 days after transplanting; the turning points occurred at 75 days under severe drought stress and after 100 days under mild drought stress. These findings are consistent with those of Yang et al. [23], who reported that stomatal limitation was the main factor affecting photosynthesis under mild stress: the structures of the leaves, the main photosynthetic organs, were damaged under severe drought stress, whereas under mild drought stress, photosynthesis was mainly affected by the ability of the chloroplasts to fix CO2, which is a non-stomatal limitation.

4.2. Effects of Drought Stress on Endogenous Hormones Levels

Stems and leaves are the sources of plant dry-matter production and the basis for high yield, while the coordinated action of endogenous hormones in the leaves is the main intrinsic factor affecting the growth, development, and physiological functions of leaves [24]. In this study, the ZR and IAA contents in leaves decreased significantly under drought stress conditions, decreasing photosynthesis rates, slowing aboveground growth, and consequently decreasing dry matter accumulation. In contrast, the leaf ABA content increased with the degree of drought, which led to the active closure of stomata in the leaves to reduce excessive water dissipation and slow the damage caused by water stress. Under normal water supply in the pre-growth period and under mild drought stress, the leaf ZR and IAA contents increased significantly. In contrast, under severe drought stress, the ABA content did not change significantly. Thus, growth hormone contents increased most rapidly during the branching and rooting period and during the vine merging period, and drought stress during these periods weakened the growth of sweet potato stems and leaves, blocking the synthesis of leaf ZR and IAA, affecting photosynthesis and subsequently dry matter accumulation.
The root system is a source of endogenous hormone production and a reservoir for endogenous hormones produced and transported from the aboveground plant parts; it influences the hormone contents of leaves and stems by regulating hormone output and input levels [25,26], This regulation system harmonizes the developmental processes of the stems and leaves aboveground and the root system belowground. The sweet potato’s ZR, IAA, and ABA contents play dominant roles in tuber formation and expansion and are significantly positively correlated with tuber yield [27]; the ABA content is significantly and positively correlated with the increase in potato tuber size [28]. Our experimental results revealed that decreases in the tubers’ ZR and IAA contents under drought stress conditions limited the transport of photosynthetic products to the tubers, affecting their formation and expansion as well as the transport of assimilates to reservoir organs; these decreases in the tubers’ ZR and IAA contents as compared with the control were smaller in the LD treatment than in the HD treatment. Thus, drought stress impeded the transportation of photosynthetic products to tubers to a greater degree under severe drought stress than under mild drought stress.
ABA plays a key role in the conversion of adventitious roots into tubers and promotes the unloading of photosynthetic products to tubers, increasing their sizes [12,29]. Our results revealed that the ABA content in aboveground and belowground plant parts reached maximum levels at the later stage of drought in each treatment. High ABA content may be perceived as a stress signal by the root system and is transmitted upward to the leaves and stems, which can alter their morphologies and physiologies to adapt to drought stress. However, under severe drought stress, the plant may lose its normal physiological activities and produce more ABA to regulate its normal growth.

4.3. The Relationship Between Hormones and Photosynthesis

Endogenous hormones regulate plant photosynthetic parameters, which engage in feedback through the synthesis and distribution of endogenous hormones. Both IAA and ZR are endogenous hormones that promote plant growth; reduced levels of these hormones due to drought stress in turn reduce the transpiration area and water consumption, alleviating pressure on the plant to complete normal physiological activities under insufficient water supply [30,31,32]. Drought stress significantly increases the ABA content in sweet potato leaves, where it regulates stomatal closure in its role as a signalling molecule, reducing transpiration water loss and enhancing drought tolerance [33]. However, large increases in ABA content can cause leaf abscission and accelerate plant senescence, leading to lower yield [33,34]. Our findings revealed that the aboveground and belowground ZR + IAA/ABA ratios were significantly higher in the two drought treatments than in the control and decreased with increasing drought severity. We also found that the sweet potato’s ABA content was positively correlated with the leaf Ci and was significantly negatively correlated with all other photosynthetic parameters. In contrast, the ZR and IAA contents were positively correlated with the leaf Ci, Gs, and Tr and were significantly negatively correlated with all other photosynthetic parameters. These findings suggest that under drought stress, endogenous hormones reduce the CO2 supply by inducing stomatal closure, which in turn regulates the photosynthetic rate [35]. In summary, endogenous plant hormones as adversity signaling substances can be used under drought stress to mitigate the damage caused by drought by coordinating the stomata. Therefore, when the sweet potato suffers from drought stress, the balance of its endogenous hormone system can be changed by the supplemental application of exogenous hormones to achieve the purpose of yield control, and at the same time, this provides a new idea for the future regulation of chemical substances.

5. Conclusions

In this study, drought stress significantly reduced the aboveground and belowground biomass and yield of sweet potatoes, and the higher the degree of stress, the stronger the inhibitory effect. The main reason is that drought stress directly inhibited the growth and development of sweet potatoes by limiting the accumulation and transportation of photosynthetic products. Drought stress significantly reduced the Pn, Gs and Tr in the sweet potato leaves, and stomatal closure led to a decrease in the Ci under mild drought stress, and photosynthesis was mainly restricted by stomata, while in severe drought stress, the Ci gradually increased with the worsening of drought and non-stomatal factors were the main factors inhibiting photosynthesis. Under drought stress, the aboveground ZR and IAA contents were significantly reduced, and the ABA content was significantly increased. The aboveground dry weight was significantly correlated with the ZR and IAA contents, further verifying the key role of growth hormones in maintaining photosynthetic capacity and biomass accumulation under drought stress. Drought stress preferentially activates drought defense mechanisms rather than growth processes by altering the hormone balance.

Author Contributions

Conceptualization, S.H. and H.L.; methodology, S.H. and H.L.; investigation, S.H. and J.W.; resources, H.W.; writing—original draft preparation, S.H.; writing—review and editing, S.H.; editing and project administration, H.W. and H.L. All authors have read and agreed to the published version of the manuscript.

Funding

This research was funded by Key Laboratory of Degraded and Unused Land Consolidation Engineering, the Ministry of Natural Resources (No. SXDJ2024-16).

Data Availability Statement

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

Acknowledgments

We are thankful for the constructive comments received from anonymous reviewers and the editors.

Conflicts of Interest

No conflicts of interest exist in the submission of this manuscript. The work described herein was original research that has not been previously published, and is not under consideration for publication elsewhere, in whole or in part. All authors listed have approved the enclosed manuscript for publication.

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Figure 1. Dynamics of the dry weight of sweet potatoes under drought stress. Vertical bars represent standard errors.
Figure 1. Dynamics of the dry weight of sweet potatoes under drought stress. Vertical bars represent standard errors.
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Figure 2. Effects of drought stress on the photosynthetic parameters of sweet potato leaves. Different lowercase letters within the same period indicate significant differences (p < 0.05), and the same letter indicates no difference (p < 0.05).
Figure 2. Effects of drought stress on the photosynthetic parameters of sweet potato leaves. Different lowercase letters within the same period indicate significant differences (p < 0.05), and the same letter indicates no difference (p < 0.05).
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Figure 3. Effects of drought stress on endogenous hormones in the aboveground parts of sweet potatoes. Different lowercase letters within the same period indicate significant differences (p < 0.05), and the same letter indicates no difference (p < 0.05).
Figure 3. Effects of drought stress on endogenous hormones in the aboveground parts of sweet potatoes. Different lowercase letters within the same period indicate significant differences (p < 0.05), and the same letter indicates no difference (p < 0.05).
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Figure 4. Effects of drought stress on endogenous hormones in sweet potato tubers. Different lowercase letters within the same period indicate significant differences (p < 0.05), and the same letter indicates no difference (p < 0.05).
Figure 4. Effects of drought stress on endogenous hormones in sweet potato tubers. Different lowercase letters within the same period indicate significant differences (p < 0.05), and the same letter indicates no difference (p < 0.05).
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Figure 5. Effect of drought stress on the proportionality of endogenous hormones in sweet potatoes. (A) Above ground; (B) tuber. Different lowercase letters within the same period indicate significant differences (p < 0.05), and the same letter indicates no difference (p < 0.05).
Figure 5. Effect of drought stress on the proportionality of endogenous hormones in sweet potatoes. (A) Above ground; (B) tuber. Different lowercase letters within the same period indicate significant differences (p < 0.05), and the same letter indicates no difference (p < 0.05).
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Figure 6. Correlation analysis between endogenous hormones and leaf photosynthetic parameters. Pearson correlation coefficients (r values) between endogenous hormones and leaf photosynthetic parameters are shown. The color changes from blue (negative correlation) to red (positive correlation), with darker colors indicating stronger correlations. Connecting lines indicate the result of the Mantel test; the color and thickness of the connecting line indicate Mantel’s p-value and r-value, respectively. Orange indicates a significant p-value and gray indicates a non-significant p-value (ns). The thickness of the line indicates the strength of the correlation: the thicker the correlation, the stronger it is.
Figure 6. Correlation analysis between endogenous hormones and leaf photosynthetic parameters. Pearson correlation coefficients (r values) between endogenous hormones and leaf photosynthetic parameters are shown. The color changes from blue (negative correlation) to red (positive correlation), with darker colors indicating stronger correlations. Connecting lines indicate the result of the Mantel test; the color and thickness of the connecting line indicate Mantel’s p-value and r-value, respectively. Orange indicates a significant p-value and gray indicates a non-significant p-value (ns). The thickness of the line indicates the strength of the correlation: the thicker the correlation, the stronger it is.
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Table 1. Effect of exposure to drought stress on the agronomic characteristics of sweet potatoes.
Table 1. Effect of exposure to drought stress on the agronomic characteristics of sweet potatoes.
Treatment30 d50 d75 d100 d120 d
leaf numberCK23 ± 0.2 a83 ± 0.6 a140 ± 1.1 a173 ± 1.4 a192 ± 1.7 a
LD13 ± 0.1 b58 ± 0.4 b99 ± 0.8 b113 ± 0.9 b102 ± 0.9 b
HD6 ± 0 c24 ± 0.2 c32 ± 0.3 c49 ± 0.3 c42 ± 0.3 c
branch numberCK2 ± 0 a4 ± 0.5 a5 ± 0.5 a7 ± 0.5 a7 ± 0.5 a
LD1 ± 0 ab2 ± 0 b3 ± 0.5 b4 ± 0.5 b2 ± 0 b
HD0 ± 0 b0 ± 0 b1 ± 0 c2 ± 0 c2 ± 0 c
Note: The data in the table are the mean ± standard deviation. Different lowercase letters in the same column indicate significant differences (p < 0.05).
Table 2. Sweet potato production and composition.
Table 2. Sweet potato production and composition.
TreatmentYield (t·hm−2)Average Sweet Potato Weight (g·plants−1)Number of Sweet Potato per Plant
CK33.44 ± 20.58 a213.47 ± 19.52 a3.17 ± 0.05 a
LD24.57 ± 12.87 b205.36 ± 14.31 b2.87 ± 0.05 b
HD10.93 ± 9.01 c197.23 ± 12.33 c2.33 ± 0.04 c
Note: The data in the table are the mean ± standard deviation. Different lowercase letters in the same column indicate significant differences (p < 0.05).
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MDPI and ACS Style

Huang, S.; Wang, J.; Wang, H.; Li, H. Effects of Drought Stress on Photosynthetic Characteristics and Endogenous Hormone Levels in the Sweet Potato (Ipomoea batatas). Horticulturae 2025, 11, 456. https://doi.org/10.3390/horticulturae11050456

AMA Style

Huang S, Wang J, Wang H, Li H. Effects of Drought Stress on Photosynthetic Characteristics and Endogenous Hormone Levels in the Sweet Potato (Ipomoea batatas). Horticulturae. 2025; 11(5):456. https://doi.org/10.3390/horticulturae11050456

Chicago/Turabian Style

Huang, Shihao, Jinqiang Wang, Huanyuan Wang, and Huan Li. 2025. "Effects of Drought Stress on Photosynthetic Characteristics and Endogenous Hormone Levels in the Sweet Potato (Ipomoea batatas)" Horticulturae 11, no. 5: 456. https://doi.org/10.3390/horticulturae11050456

APA Style

Huang, S., Wang, J., Wang, H., & Li, H. (2025). Effects of Drought Stress on Photosynthetic Characteristics and Endogenous Hormone Levels in the Sweet Potato (Ipomoea batatas). Horticulturae, 11(5), 456. https://doi.org/10.3390/horticulturae11050456

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