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Article

Effect of 24-Epibrassinolide Plant Hormone Rates on the Level of Macronutrients in Forage Sorghum Plants Subjected to Water Deficit and Rehydration

by
Daniele Monteiro Ribeiro
1,
Sabrina de Nazaré Barbosa dos Santos
1,
Dayana Castilho dos Santos Ferreira
1,
Júlia Fernanda Ferreira de Miranda
1,
Job Teixeira de Oliveira
2,*,
Fernando França da Cunha
3,
Caio Lucas Alhadas de Paula Velloso
2,
Priscilla Andrade Silva
1 and
Cândido Ferreira de Oliveira Neto
1
1
Department of Agronomy (DAA), Federal Rural University of the Amazon (UFRA), Belém 66077-830, PA, Brazil
2
Campus of Chapadão do Sul (CPCS), Federal University of Mato Grosso do Sul (UFMS), Chapadão do Sul 79560-000, MS, Brazil
3
Department of Agricultural Engineering (DEA), Federal University of Vicosa (UFV), Vicosa 36570-900, MG, Brazil
*
Author to whom correspondence should be addressed.
Grasses 2025, 4(3), 33; https://doi.org/10.3390/grasses4030033
Submission received: 10 May 2025 / Revised: 10 July 2025 / Accepted: 28 July 2025 / Published: 12 August 2025
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Abstract

Forage sorghum (Sorghum bicolor (L.)) is a cereal native to Africa and belongs to the family Poaceae. It is a forage with a C4 photosynthetic pathway that stands out for its ability to adapt to different environments; it is able to produce even in unfavorable circumstances. The objective of this study was to analyze the attenuating effect of the brassinosteroid hormone in the form of 24-epibrassinolide on forage sorghum plants subjected to water deficit and rehydration. A completely randomized design (CRD) was used in the experiment. A 2 × 3 × 5 factorial arrangement was used, with two water conditions (water deficit and rehydration), three brassinosteroid doses (0 nM, 50 nM, and 100 nM as 24-epibrassinolide), and five replicates. The experiment was conducted in a greenhouse. Sorghum seeds were sown in pots with a capacity of 3 kg of substrate. Analyses were performed on the roots and leaves of sorghum plants at different growth stages. The macronutrients (N, P, K, Ca, and Mg) were analyzed in the soil physics laboratory. As a result, the content of N, P, K, Ca, and Mg decreased under a water deficit and was then restored by the hormone 24-epibrassinolide, which was able to restore these nutrients. The effect of the hormone under rehydration had a positive effect, increasing the levels of nutrients. Given the above, it was possible to conclude that there were no significant divergences between the treatments during the period of irrigation suspension. Among the tested concentrations, 50 nM of 24-epibrassinolide showed the most consistent improvements in nutrient concentrations under water-deficit conditions, suggesting a potential role in mitigating nutritional imbalance during stress. Rehydrated plants maintained nutrient levels similar to the controls regardless of 24-epibrassinolide application. However, it is important to note that nutritional quality indices such as crude protein and total digestible nutrients (TDN) were not evaluated in this study, which limits direct conclusions about the forage nutritional value.

1. Introduction

Brassinosteroids (BRs) are endogenous plant hormones involved in the regulation of several physiological processes related to plant growth and development [1]. They are steroid hormones, which play a crucial role in regulating several physiological activities and induce growth and development, delay senescence, increase agricultural productivity, regulate male and female fertility, maintain stem cells and vascular development, and much more [2].
Water is the main resource for life on Earth, and is indispensable for several human activities, including plant cultivation, acting in several physiological processes, such as photosynthesis and nutrient absorption. Water deficiency is the lack of water in the soil, affecting seed germination and plant growth and development. Fresh matter production is attributed to the plant structure, which, depending on its stage of development, has a high water content, resulting in an increase in fresh mass and substantial plant growth [3].
Among the plants used for planting, sorghum (Sorghum bicolor) stands out. According to Conab [4], sorghum was planted in the 2024/2025 harvest in an area of 1462.2 thousand hectares with a productivity of 3121 kg ha−1, producing 4563.8 thousand tons. It is a crop with energy characteristics, high digestibility, productivity, and adaptation to the most diverse environments; it is used for various purposes, such as green cutting, silage, grazing, animal feed, and human consumption [5]. Sorghum genotypes have great potential for the development of cultivars with high nutritional value, especially for arid and semiarid regions, and can contribute to food security [6].
Sorghum is recognized for its moderate tolerance to water stress [7]. This crop has physiological characteristics that allow it to stop growing or reduce metabolic activities during water stress, and, after the end of a water stress period, the plants can even grow faster than those that did not suffer stress [8].
Research on forage sorghum crops is essential because it can generate results that enable the use of appropriate technologies for the agronomic development of the plant. In this sense, the objective of this study is to evaluate the nutritional status of sorghum plants subjected to water deficit, using the brassinosteroid in the form of 24-epibrassinolide as an attenuator.

2. Materials and Methods

2.1. Study Area and Experimental Conditions

The experiment was conducted in a greenhouse at the Institute of Agricultural Sciences, part of the Federal Rural University of the Amazon (UFRA), in Belém, Pará, Brazil. The climate classification in the experimental environment, according to Köppen and Geiger, is Af, with an average temperature of 26.8 °C and relative humidity of 95% [9]
The sorghum seeds were supplied by the company KWS, which is part of the GDM business group. A chemical analysis of the soil was performed, and the black soil samples were classified as having a sandy clay loam texture (Table 1) [10]. The substrate used for plant growth was black soil, which was corrected by liming based on the analysis values (Table 2) [11] to reduce the pH for a period of 30 days, followed by fertilization. To correct soil acidity, agricultural lime with a Relative Power of Total Neutralization (PRNT) of 100% was applied at an equivalent rate of 15.4 t ha−1, which is sufficient to raise the soil pH from 3.5 to 5.5 (CaCl2), based on the desired base saturation of 60%. Considering the soil mass per pot (3 kg), 23 g of lime was applied to each experimental unit. After incorporation, the pots were maintained at field capacity moisture for 30 days before sowing, to allow the proper reaction of the lime in the soil.
Based on soil analysis indicating low phosphorus and potassium levels, 1.2 g of granular NPK fertilizer (04-14-08) was applied per 3 kg pot and was mixed into the substrate seven days before sowing. This rate corresponds to typical field recommendations adjusted for pot volume and ensures adequate initial nutrient supply. Pots with a capacity of 3 kg were used to allocate the substrate. Five seeds were sown per pot (plant/experimental unit). Thinning was performed 7 days after seed germination, leaving one plant per pot.

2.2. Experimental Design

The experimental design was completely randomized (CRD). The factorial scheme 2 × 3 × 5 was used with two water conditions (water deficit and rehydration) and three doses of brassinosteroid in the form of 24-epibrassinolide (0 nM, 50 nM, and 100 nM) with 5 replicates. The total was 30 experimental units. The plants were irrigated daily in the early morning and late afternoon. 24-epibrassinolide was chosen as the hormone for the present study due to the ease of finding the product for sale in Brazil. Many companies market this product.

2.3. Application of 24-Epibrassinolide and Onset of Water Deficiency

The sorghum seedlings received 4 foliar applications (spray), at concentrations of 0, 50, and 100 nM; all the leaves of each plant were sprayed. The applications occurred weekly, with an interval of 5 days between each application, totaling approximately 3 weeks. After the hormone application was complete, followed by 4 days of acclimatization, plant irrigation was suspended. The water deficiency treatment was maintained for a period of 7 more days. The sorghum plants were rehydrated immediately after, with only the control plants being irrigated. Measurements began at the 6-leaf stage (V6) of the sorghum plant, 20 days after their emergence in the pot.

2.4. Nutritional Parameters Measured in Roots and Leaves

Macronutrient analyses (N, P, K, Ca, and Mg) were carried out in the Soil Physics laboratory of the research campus of the Museu Paraense Emílio Goeldi (MPEG, Belém—PA), according to the methodology recommended by Teixeira et al. [11].

2.5. Sample Digestion

The collected leaf and root samples were washed and oven-dried at 65 °C for 72 h until a constant weight was reached. After drying, the material was ground and passed through a 1 mm sieve to ensure homogeneity prior to weighing for digestion. Once the dried and ground material of the roots and leaves was obtained, 200 mg of each sample was weighed and placed in digestion tubes. A volume of 1 mL of 30% H2O2, 2 mL of concentrated H2SO4, and 700 mg of the digestion mixture (Na2SO4, CuSO4, 5H2O, and Selenium) was added to the tubes. The tubes were initially taken to the digestion block at 160–180 °C (until the water evaporated). Subsequently, the temperature was increased to 350–375 °C, and tubes were kept at this temperature after clarification (greenish-yellow color) for one hour. The flasks were removed from the digestion block, and after cooling, the volume was completed with distilled H2O to 50 mL. The contents of the digestive tubes were transferred to 50 mL Falcon tubes, thus obtaining the extract from which the aliquots for the determinations were removed.

2.6. Nitrogen (N)

A volume of 10 mL of the digestion extract was pipetted into a 100 mL distillation flask, adding 5 mL of 10 M NaOH, thus starting the distillation with a vapor distillation distiller (micro-Kjeldahl). Distillation was carried out until approximately 35–40 mL was collected, followed by titration with 0.025 M H2SO4. Each ml of 0.025 M H2SO4 used in the titration corresponded to 700 µg of N. Calculations were made using the following formula: %N = (mL H + am − ml H + br) × 700 × 5 × 5/10,000 [11].

2.7. Phosphorus (P)

A volume of 1 mL of the digestion extract was pipetted into common test tubes, adding 2 mL of distilled H2O, 3 mL of P-B solution (ammonium molybdate), and 3 drops of P-C solution (1-amino-2-naphthol-4-sulfonic acid). Stirring followed, and after 15 min, the readings were taken in a spectrophotometer at an absorbance of 660 nm [11]. Each 0.002 absorbance corresponds to approximately 0.0015% of P in the sample.

2.8. Potassium (K)

A volume of 1 mL of the digestion extract was pipetted into common test tubes, adding 10 mL of distilled H2O, and then the light emission was determined in the flame photometer [11].

2.9. Calcium (Ca) and Magnesium (Mg)

A volume of 2.5 mL of the digestion extract was pipetted into common test tubes, adding 2.5 mL of distilled H2O, and 5 mL of the 0.3% Sr (Strontium) solution in 0.2 M HCl. The absorbance of Ca was determined in the absorption photometer. In total, 5 mL of the extract was used to determine the absorbance at which Ca was removed, adding 10 mL of distilled H2O, and the absorbance of Mg was determined in the absorption photometer.

2.10. Data Analysis

Statistical analysis of the macronutrient variables and generation of graphs were performed using R-Studio software, version 3.6.0+ (R Project for Statistical Computing, RRID: SCR_001905) [12]. To identify statistical differences between water conditions and the 24-epibrassinolide hormone, the ExpDes.pt package and the “fat2.dbc” function were used. Normality analysis of the residues was performed using the Shapiro–Wilk test, and the homoscedasticity test was also performed using the Levene test. Afterward, Anova was performed, followed by Tukey’s post hoc test. A significant level of 5% was considered for all analyses.

3. Results

3.1. Nitrogen (N)

In the root system of plants under water stress, BR applications did not cause statistically significant effects. However, when compared to the water regimes, there were statistical differences, causing an approximately 35% reduction in the amount of nitrogen when compared to the control. When rehydrated, the nitrogen levels obtained values close to the control, regardless of the concentration of 24-epibrassinolide. There was no significant difference between the water treatments and amounts of 24-epibrassinolide (Figure 1).
In the leaves under water stress conditions, the nitrogen content of the plants was reduced by 30% compared to the control. The plants that received 24-epibrassinolide (50 and 100 nM) did not differ statistically, but there was a difference compared to those that did not receive 24-epibrassinolide. The water conditions showed significant differences. In the control plants, in the leaves, at a dosage of 100 nM, a greater amount of nitrogen was observed by approximately 20% compared to those without BR; however, in the stressed plants, the dosage of 50 nM obtained better efficiency, with an increase of approximately 38% when compared to the control plants. The rehydrated plants had the same amounts of N compared to the control plants, regardless of the applied concentration of BR (Figure 1).

3.2. Phosphorus (P)

In the roots, during the period of irrigation suspension, there was a 44% decrease in the amount of phosphorus in the plant when compared to the control. Figure 2 shows the influence of 24-epibrassinolide (0, 50, and 100 nM) on the phosphorus contents (leaf and root) of sorghum seedlings.

3.3. Potassium (K)

In the roots, the potassium concentration was the same in both control and water-deficit plants, regardless of the applied BR concentrations. Figure 3 shows the influence of 24-epibrassinolide (0, 50, and 100 nM) on the potassium contents (leaf and root) of sorghum seedlings.

3.4. Calcium (Ca)

In the root part, during the period of irrigation suspension, there was a 45% decrease in calcium content when compared to the control. For the application of BR, the dosage of 50 nM was more efficient, as it increased Ca levels by 35% and 45% for control and water deficit plants, respectively. During the rehydration period, the calcium levels of sorghum plants returned to the same amounts as the control, regardless of the BR dose used (Figure 4).

3.5. Magnesium (Mg)

In the roots, there was a 35% reduction in magnesium levels in plants with a water deficit when compared to the control. Figure 5 shows the influence of 24-epibrassinolide (0, 50, and 100 nM) on the magnesium levels (leaf and root) of sorghum seedlings.

4. Discussion

The application of 24-epibrassinolide influenced nitrogen (N) accumulation differently in leaves and roots under water-deficit conditions. In the leaves, N content was reduced by approximately 30% in water-stressed plants compared to the control. However, when 50 nM of BR was applied under stress, there was a 38% increase in leaf N compared to untreated stressed plants, suggesting the potential role of BR in enhancing N uptake or assimilation in shoots during drought. This effect may be associated with the BR-induced stimulation of nitrate reductase activity or improved nitrogen metabolism, as reported in other crops. In contrast, no statistically significant effect of BR was observed in the roots, indicating that the hormone’s effect on N dynamics may be more pronounced in the aerial parts, possibly due to preferential allocation or greater metabolic demand in leaves during stress adaptation. These results reinforce the importance of considering organ-specific responses when evaluating the role of brassinosteroids in nutrient use efficiency under abiotic stress.
Water is considered essential for the maintenance of existing cells in the plant, and its availability is highly relevant when it comes to plant growth. Water promotes the absorption of nutrients by plants [13]. Water deficits can significantly affect the secondary metabolite levels and nutritional quality (including nitrogen) of forage sorghum, depending on the hybrid [14].
The higher or lower efficiency experienced when using phosphorus present in the soil is caused by differences in the absorption, translocation, and use of this nutrient by the plants, as well as by the differences associated with the morphological and physiological characteristics of the plants [15]. According to the literature, plants under P deficiency increase the drain of photoassimilates to the roots in order to increase the plant’s capacity for P absorption [16].
When BR was applied to plants with a water deficit, the 50 nM dosage was more efficient, since when applied, it increased P levels by 20% when compared to plants without BR in the same treatment. For rehydration, there was no statistical difference between BR dosages within and between the control and rehydration treatments. Brassinosteroid hormones have been shown to have a beneficial effect on plant organs, boosting the processes they develop, such as root growth, their association with mycorrhizal fungi, and photosynthesis, which are processes that are closely linked to P [17].
In the leaves, there was a 30% reduction in phosphorus levels in plants with a water deficit when compared to the control. Phosphorus-deficient plants have their growth retarded because they are linked to the structural function of the nutrient and the process of energy transfer and storage [18]. For BR applications, there was no difference in any of the dosages.
After the rehydration period, phosphorus (P) concentrations in both leaves and roots returned to levels similar to those observed in control plants, regardless of the BR dosage. This finding suggests that sorghum plants are capable of restoring P uptake and redistribution efficiently once water availability is resumed, potentially due to the reactivation of root membrane transporters and improved soil P mobility under moist conditions. Similar behavior has been observed in other species, such as maize and rice, where P levels were restored after rewatering without hormonal intervention [16,19]. This recovery may indicate that BRs are not essential for P reestablishment during post-stress recovery in sorghum, although they do enhance P accumulation under active water-deficit conditions. Therefore, the effect of BR appears to be more relevant during the stress phase rather than in the rehydration phase, highlighting the context-dependent nature of BR action.
The concentration of phosphorus and potassium in the leaves and dry matter of the plant is affected by water deficit and variations in sorghum hybrids [14]. Increasing the doses of phosphorus affected plant height and ear insertion height in smaller populations per hectare of corn plants, while in higher populations per hectare, increasing the doses of phosphorus affected stem diameter [20]. These results show that an adequate choice of planting density for the sorghum plants per hectare is important, depending on the phosphorus content in the soil.
The potassium (K) availability indexes are controlled by the exchangeable ion via the release of non-exchangeable potassium from the internal layers of the minerals and by fixation; however, its availability also depends on the form in which it is applied [21].
Although 24-epibrassinolide is often associated with enhanced ion uptake and redistribution, particularly potassium (K), under water-deficit conditions, no significant changes in K concentration were observed in the roots of sorghum plants, regardless of the BR concentration applied. This result suggests that, in sorghum, osmotic adjustment in response to water stress may occur primarily in the leaves, as supported by the significant increase in K concentration in this organ. One possible explanation is that sorghum prioritizes the translocation of K to aerial tissues, where stomatal regulation and the maintenance of turgor are more critical for photosynthesis and plant survival under drought. Alternatively, the lack of response in the roots may be related to a lower sensitivity of root tissues to BRs or to a rapid redistribution of absorbed K to the shoots, preventing local accumulation. These findings suggest that the mitigation of water-deficit stress by BR application in sorghum may involve mechanisms other than K accumulation in the roots, which warrants further investigation.
Potassium availability can be controlled by some physicochemical factors that determine the balance between potassium in the soil solution and potassium associated as an exchangeable ion on the surface of the internal layers of the 2:1 mineral [21]. In addition, soil structure, mineral particle size, biological activity, and complexes of organic acids and inorganic cations in the soil solution are aspects that affect the release of potassium from the surface of the minerals [22]. In the leaves, there was a higher concentration of potassium when compared to the roots, regardless of the treatment and dose of BR applied. Potassium is generally the most abundant cation in all crops; it is present in the tissues, most often in water-soluble forms, and is considered the most mobile of the nutrients in the soil–plant–atmosphere system and particularly in the plant [23].
During the suspension period, plants with water deficit had a 13% reduction in K levels when compared to the control. When applying 50 nM, there was a 12% increase in stressed plants when compared to the control. Plants with rehydration had the same amounts of potassium as the control, regardless of the application of BR. Nutritional disorders, whether due to deficiencies or excesses of mineral nutrients, cause a decrease in the production of any crop, including sorghum [24]. This emphasizes how adequate and balanced soil nutrition is necessary.
Regarded as a vital source of nutrients, sorghum is particularly rich in calcium (Ca), phosphorus (P), potassium (K), and magnesium (Mg) [25]. The content of these nutrients can be influenced by the amount available in the soil for plant uptake, which can be increased by proper crop management, especially through fertilization [14].
Sorghum is a crop that has been expanding significantly in Brazil, especially in the succession of summer crops. The increase in productivity is directly linked to technological advances in mineral fertilization, such as the use of rock dust as an alternative source of potassium [26]. These same authors highlight that potassium doses influence the relative chlorophyll index, plant height, stem diameter, and panicle insertion height, and the sorghum crop has positive responses in its development up to the dose of 159.7 kg ha−1 of K.
Larré et al. [19], studying rice crops, stated that the application of 24-epibrassinolide at concentrations of 0.1 and 1.0 μM was able to induce an increase in root length.
Increased calcium and potassium levels within the sorghum plant, which help with water absorption, were verified with the incorporation of mycorrhiza into the soil, improving the plant’s defense system, increasing the dry matter content, keeping the leaf stomata open, and helping with the accumulation of substances, including soluble sugars, proline, glycine betaine, and organic acids [27].
In the study conducted by Fonseca and Meurer [28], an experiment with corn in a nutrient solution was carried out to investigate the antagonistic relationship between potassium and magnesium. The researchers observed that magnesium accumulation was reduced in both the roots and aerial parts of the plants when there was an increase in potassium in the solution. The authors suggested that this antagonism is related to the process of absorption of these two nutrients via the plant roots. In BR applications, at 50 nM, magnesium levels increased by 30% in plants without BR in the same treatment. For rehydration, the amounts of Mg were the same as in the control plants, regardless of the 24-epibrassinolide concentration.
In leaves, Mg levels decreased by 27% in plants with a water deficit compared to the control. In BR applications, the concentration of 50 nM increased magnesium levels by 20%. For rehydration, when compared to the control, the amounts of Mg were the same, regardless of the BR concentration. When subjected to unfavorable conditions, plants can become stressed [29]. The first response to water stress and the most sensitive to this condition is cell turgor, which is related to the higher water content in the most hydrated state. As a consequence, growth is affected by limiting the metabolism of proteins and amino acids, which causes the interruption of cell division [30]. Plant responses to the water deficit may include decreased leaf area, leaf abscission, stomatal closure, deep root growth, limited photosynthesis, and increased wax deposition on leaves [29].
The number of leaves of a plant is influenced by the presence of nutrients such as nitrogen, magnesium, and iron [31]. In addition to these nutritional factors, the height of the plant also influences the number of leaves formed. This is because the taller the plant, the more sunlight it receives, so the process of photosynthesis also increases [32].
Sorghum has several uses, among which the most important is its use in animal nutrition. Sorghum intended for silage production is a viable alternative for tropical regions, especially those subject to water restrictions, due to its tolerance to water deficit, greater competitiveness against weeds, and greater resistance to pests and diseases, making these conditions more highly recommended for forage production than forage corn [33].
The results of this study suggest that the foliar application of 24-epibrassinolide, particularly at 50 nM, has the potential to enhance nutrient accumulation in forage sorghum under water-deficit conditions, which may indirectly contribute to maintaining forage productivity in drought-prone environments. Although biomass yield was not measured in this experiment, the observed improvements in nitrogen, phosphorus, calcium, and magnesium levels under stress indicate that BRs may support key physiological processes related to plant resilience and growth. This finding is relevant for tropical and subtropical regions where rainfall irregularities limit forage production. However, a limitation of this research is the absence of direct measurements of agronomic traits such as biomass yield, forage quality, and plant water use efficiency. Future studies should include these variables under field conditions and across different climatic zones to support robust recommendations for practical use by farmers.
Although this study did not include correlation analyses, such as Pearson’s correlation between macronutrient concentrations and 24-epibrassinolide treatments under different water regimes, incorporating these analyses in future research could enhance our understanding of nutrient interrelationships and treatment effects. Correlation analysis could help identify synergistic or antagonistic nutrient responses and clarify how hormone application influences nutrient dynamics during stress and recovery phases.

5. Conclusions

Given the above, it was possible to conclude that there were no significant differences between treatments during the period of irrigation suspension.
Among the tested concentrations, 50 nM of 24-epibrassinolide showed the most consistent improvements in nutrient concentrations under water-deficit conditions, suggesting its potential role in mitigating nutritional imbalance during stress. A dosage of 50 nM of 24-epibrassinolide is recommended for forage sorghum plants under stress.
The plants with rehydration maintained the same amounts of macronutrients compared to the control plants, regardless of the application of 24-epibrassinolide.
These results have great significance for the cultivation of forage sorghum in the future, especially with increasing levels of climate change, which is expected to exacerbate the effects of abiotic stresses.
24-epibrassinolide improves the efficiency of the root system and the transport of ions such as nitrogen, phosphorus, potassium, magnesium, and calcium, contributing to the greater accumulation of nutrients in the plant, even in dry soil conditions.
Despite the positive responses in macronutrient accumulation, this study did not include nutritional quality indices such as crude protein or total digestible nutrients (TDNs), which are essential for evaluating the actual forage quality. This limitation should be considered when interpreting the practical implications of the findings for animal nutrition.

Author Contributions

Conceptualization, D.M.R. and S.d.N.B.d.S.; methodology, D.C.d.S.F. and J.F.F.d.M.; validation, D.M.R., S.d.N.B.d.S., D.C.d.S.F., J.F.F.d.M., J.T.d.O., F.F.d.C., C.L.A.d.P.V., P.A.S. and C.F.d.O.N.; formal analysis, J.T.d.O. and F.F.d.C.; investigation, C.L.A.d.P.V. and P.A.S.; resources, C.F.d.O.N.; data curation, C.F.d.O.N.; writing—original draft preparation, D.M.R.; writing—review and editing, J.T.d.O. and F.F.d.C.; visualization, D.M.R., S.d.N.B.d.S., D.C.d.S.F., J.F.F.d.M., J.T.d.O., F.F.d.C., C.L.A.d.P.V., P.A.S. and C.F.d.O.N.; supervision, P.A.S.; project administration, C.F.d.O.N.; funding acquisition, J.T.d.O. and F.F.d.C. All authors have read and agreed to the published version of the manuscript.

Funding

This research was funded by the Coordination for the Improvement of Higher Education Personnel, Brazil (CAPES), Finance Code 001, and the National Council for Scientific and Technological Development, Brazil (CNPq), Process 308769/2022-8.

Institutional Review Board Statement

Not applicable.

Informed Consent Statement

Not applicable.

Data Availability Statement

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

Acknowledgments

We thank the Department of Agriculture Engineering (DEA) and the Graduate Program in Agricultural Engineering (PPGEA) of the Federal University of Viçosa (UFV) for supporting the researchers. UFRA—Federal Rural University of the Amazon. UFMS—Federal University of Mato Grosso do Sul. Fundect—Foundation for Supporting Education, Science and Technology of the State of Mato Grosso do Sul.

Conflicts of Interest

The authors declare no conflicts of interest.

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Figure 1. Effects of 24-epibrassinolide hormone application at concentrations of 0, 50, and 100 nM on nitrogen content in leaves and roots of forage sorghum (Sorghum bicolor) under three water conditions: control (fully irrigated), water deficit (7 days without irrigation), and rehydration (after resumption of irrigation). Data represent mean values ± standard error. Statistical differences between 24-epibrassinolide concentrations and water treatments were evaluated using Anova followed by Tukey’s post hoc test at p < 0.05. Lowercase letters indicate significant differences among hormone treatments; uppercase letters indicate differences among water conditions. NS: not significant. Source: The Author (2025).
Figure 1. Effects of 24-epibrassinolide hormone application at concentrations of 0, 50, and 100 nM on nitrogen content in leaves and roots of forage sorghum (Sorghum bicolor) under three water conditions: control (fully irrigated), water deficit (7 days without irrigation), and rehydration (after resumption of irrigation). Data represent mean values ± standard error. Statistical differences between 24-epibrassinolide concentrations and water treatments were evaluated using Anova followed by Tukey’s post hoc test at p < 0.05. Lowercase letters indicate significant differences among hormone treatments; uppercase letters indicate differences among water conditions. NS: not significant. Source: The Author (2025).
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Figure 2. Effects of 24-epibrassinolide hormone application at concentrations of 0, 50, and 100 nM on phosphorus content in leaves and roots of forage sorghum (Sorghum bicolor) under three water conditions: control (fully irrigated), water deficit (7 days without irrigation), and rehydration (after resumption of irrigation). Data represent mean values ± standard error. Statistical differences between 24-epibrassinolide concentrations and water treatments were evaluated using Anova followed by Tukey’s post hoc test at p < 0.05. Lowercase letters indicate significant differences among hormone treatments; uppercase letters indicate differences among water conditions. NS: not significant. Source: The Author (2025).
Figure 2. Effects of 24-epibrassinolide hormone application at concentrations of 0, 50, and 100 nM on phosphorus content in leaves and roots of forage sorghum (Sorghum bicolor) under three water conditions: control (fully irrigated), water deficit (7 days without irrigation), and rehydration (after resumption of irrigation). Data represent mean values ± standard error. Statistical differences between 24-epibrassinolide concentrations and water treatments were evaluated using Anova followed by Tukey’s post hoc test at p < 0.05. Lowercase letters indicate significant differences among hormone treatments; uppercase letters indicate differences among water conditions. NS: not significant. Source: The Author (2025).
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Figure 3. Effects of 24-epibrassinolide hormone application at concentrations of 0, 50, and 100 nM on potassium content in leaves and roots of forage sorghum (Sorghum bicolor) under three water conditions: control (fully irrigated), water deficit (7 days without irrigation), and rehydration (after resumption of irrigation). Data represent mean values ± standard error. Statistical differences between 24-epibrassinolide concentrations and water treatments were evaluated using Anova followed by Tukey’s post hoc test at p < 0.05. Lowercase letters indicate significant differences among hormone treatments; uppercase letters indicate differences among water conditions. NS: not significant. Source: The Author (2025).
Figure 3. Effects of 24-epibrassinolide hormone application at concentrations of 0, 50, and 100 nM on potassium content in leaves and roots of forage sorghum (Sorghum bicolor) under three water conditions: control (fully irrigated), water deficit (7 days without irrigation), and rehydration (after resumption of irrigation). Data represent mean values ± standard error. Statistical differences between 24-epibrassinolide concentrations and water treatments were evaluated using Anova followed by Tukey’s post hoc test at p < 0.05. Lowercase letters indicate significant differences among hormone treatments; uppercase letters indicate differences among water conditions. NS: not significant. Source: The Author (2025).
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Figure 4. Effects of 24-epibrassinolide hormone application at concentrations of 0, 50, and 100 nM on calcium content in leaves and roots of forage sorghum (Sorghum bicolor) under three water conditions: control (fully irrigated), water deficit (7 days without irrigation), and rehydration (after resumption of irrigation). Data represent mean values ± standard error. Statistical differences between 24-epibrassinolide concentrations and water treatments were evaluated using Anova followed by Tukey’s post hoc test at p < 0.05. Lowercase letters indicate significant differences among hormone treatments; uppercase letters indicate differences among water conditions. NS: not significant. Source: The Author (2025).
Figure 4. Effects of 24-epibrassinolide hormone application at concentrations of 0, 50, and 100 nM on calcium content in leaves and roots of forage sorghum (Sorghum bicolor) under three water conditions: control (fully irrigated), water deficit (7 days without irrigation), and rehydration (after resumption of irrigation). Data represent mean values ± standard error. Statistical differences between 24-epibrassinolide concentrations and water treatments were evaluated using Anova followed by Tukey’s post hoc test at p < 0.05. Lowercase letters indicate significant differences among hormone treatments; uppercase letters indicate differences among water conditions. NS: not significant. Source: The Author (2025).
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Figure 5. Effects of 24-epibrassinolide hormone application at concentrations of 0, 50, and 100 nM on magnesium content in leaves and roots of forage sorghum (Sorghum bicolor) under three water conditions: control (fully irrigated), water deficit (7 days without irrigation), and rehydration (after resumption of irrigation). Data represent mean values ± standard error. Statistical differences between 24-epibrassinolide concentrations and water treatments were evaluated using Anova followed by Tukey’s post hoc test at p < 0.05. Lowercase letters indicate significant differences among hormone treatments; uppercase letters indicate differences among water conditions. NS: not significant. Source: The Author (2025).
Figure 5. Effects of 24-epibrassinolide hormone application at concentrations of 0, 50, and 100 nM on magnesium content in leaves and roots of forage sorghum (Sorghum bicolor) under three water conditions: control (fully irrigated), water deficit (7 days without irrigation), and rehydration (after resumption of irrigation). Data represent mean values ± standard error. Statistical differences between 24-epibrassinolide concentrations and water treatments were evaluated using Anova followed by Tukey’s post hoc test at p < 0.05. Lowercase letters indicate significant differences among hormone treatments; uppercase letters indicate differences among water conditions. NS: not significant. Source: The Author (2025).
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Table 1. Soil granulometric analysis.
Table 1. Soil granulometric analysis.
Depth (m)SandSiltClayOM *Textural Classification
g kg−1BSCS **
0–0.202126939595Sandy clay loam
* Soil organic matter, ** Brazilian Soil Classification System. Source: The Author (2025).
Table 2. Soil chemical analysis.
Table 2. Soil chemical analysis.
Depth (m)pHPKCa + MgCaAlH + AlSBCECV *m **
CaCl2mg dm−3 mmolc dm−3 %
0–0.203.56.00.66.04.018.0133.07.0140.05.072.0
pH = hydrogen potential; OM = organic matter; P = phosphorus; K = potassium; Ca = calcium; Mg = magnesium; Al = aluminum; H = hydrogen; H + Al = hydrogen + aluminum; CEC = cation exchange capacity; SB = sum of bases; * base saturation; ** aluminum saturation. Source: The Author (2025).
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MDPI and ACS Style

Ribeiro, D.M.; Santos, S.d.N.B.d.; Ferreira, D.C.d.S.; Miranda, J.F.F.d.; Oliveira, J.T.d.; Cunha, F.F.d.; Velloso, C.L.A.d.P.; Silva, P.A.; Oliveira Neto, C.F.d. Effect of 24-Epibrassinolide Plant Hormone Rates on the Level of Macronutrients in Forage Sorghum Plants Subjected to Water Deficit and Rehydration. Grasses 2025, 4, 33. https://doi.org/10.3390/grasses4030033

AMA Style

Ribeiro DM, Santos SdNBd, Ferreira DCdS, Miranda JFFd, Oliveira JTd, Cunha FFd, Velloso CLAdP, Silva PA, Oliveira Neto CFd. Effect of 24-Epibrassinolide Plant Hormone Rates on the Level of Macronutrients in Forage Sorghum Plants Subjected to Water Deficit and Rehydration. Grasses. 2025; 4(3):33. https://doi.org/10.3390/grasses4030033

Chicago/Turabian Style

Ribeiro, Daniele Monteiro, Sabrina de Nazaré Barbosa dos Santos, Dayana Castilho dos Santos Ferreira, Júlia Fernanda Ferreira de Miranda, Job Teixeira de Oliveira, Fernando França da Cunha, Caio Lucas Alhadas de Paula Velloso, Priscilla Andrade Silva, and Cândido Ferreira de Oliveira Neto. 2025. "Effect of 24-Epibrassinolide Plant Hormone Rates on the Level of Macronutrients in Forage Sorghum Plants Subjected to Water Deficit and Rehydration" Grasses 4, no. 3: 33. https://doi.org/10.3390/grasses4030033

APA Style

Ribeiro, D. M., Santos, S. d. N. B. d., Ferreira, D. C. d. S., Miranda, J. F. F. d., Oliveira, J. T. d., Cunha, F. F. d., Velloso, C. L. A. d. P., Silva, P. A., & Oliveira Neto, C. F. d. (2025). Effect of 24-Epibrassinolide Plant Hormone Rates on the Level of Macronutrients in Forage Sorghum Plants Subjected to Water Deficit and Rehydration. Grasses, 4(3), 33. https://doi.org/10.3390/grasses4030033

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