The Combination of Salicylic Acid, Nicotinamide, and Proline Mitigates the Damage Caused by Salt Stress in Nasturtium (Tropaeolum majus)

Thainan Sipriano Dos Santos¹, Marcos Roberto Santos Correia¹, Luma Santos Sena¹, Laura Pereira Dos Santos Santana¹, Geovanna Buique Gualberto da Silva¹, Keilane Silva Lima¹, Elienay Vinícius da Silva Dutra¹, Myriam El Adas¹, Maria Carolina Borges de Oliveira Ribeiro¹, João Everthon da Silva Ribeiro², Rogério Ferreira Ribas¹, Elania Freire da Silva^{2

3}, Alfredo Emilio Rubio-Casal³, Aurélio Paes Barros Júnior², Xuguang Tang⁴, Thieres George Freire da Silva⁵, Alexandre Maniçoba da Rosa Ferraz Jardim⁶, Toshik Iarley da Silva¹

Affiliations

¹ Center for Agrarian, Environmental, and Biological Sciences, Universidade Federal do Recôncavo da Bahia, Cruz das Almas 44380-000, BA, Brazil.
² Department of Agricultural and Forestry Sciences, Federal Rural University of the Semi-Arid, Mossoró 59625-900, RN, Brazil.
³ Department of Plant Biology and Ecology, University of Seville, Av. Reina Mercedes, s/n, 41012 Sevilla, Spain.
⁴ Institute of Remote Sensing and Geosciences, Hangzhou Normal University, Hangzhou 311121, China.
⁵ Department of Agricultural Engineering, Federal Rural University of Pernambuco, Dom Manoel de Medeiros Avenue, s/n, Dois Irmãos, Recife 52171-900, PE, Brazil.
⁶ Department of Biodiversity, Institute of Biosciences, São Paulo State University-UNESP, Rio Claro 13506-900, SP, Brazil.

PMID: 40284044
PMCID: PMC12030097
DOI: 10.3390/plants14081156

The Combination of Salicylic Acid, Nicotinamide, and Proline Mitigates the Damage Caused by Salt Stress in Nasturtium (Tropaeolum majus)

Thainan Sipriano Dos Santos et al. Plants (Basel). 2025.

. 2025 Apr 8;14(8):1156.

doi: 10.3390/plants14081156.

Authors

Affiliations

¹ Center for Agrarian, Environmental, and Biological Sciences, Universidade Federal do Recôncavo da Bahia, Cruz das Almas 44380-000, BA, Brazil.
² Department of Agricultural and Forestry Sciences, Federal Rural University of the Semi-Arid, Mossoró 59625-900, RN, Brazil.
³ Department of Plant Biology and Ecology, University of Seville, Av. Reina Mercedes, s/n, 41012 Sevilla, Spain.
⁴ Institute of Remote Sensing and Geosciences, Hangzhou Normal University, Hangzhou 311121, China.
⁵ Department of Agricultural Engineering, Federal Rural University of Pernambuco, Dom Manoel de Medeiros Avenue, s/n, Dois Irmãos, Recife 52171-900, PE, Brazil.
⁶ Department of Biodiversity, Institute of Biosciences, São Paulo State University-UNESP, Rio Claro 13506-900, SP, Brazil.

PMID: 40284044
PMCID: PMC12030097
DOI: 10.3390/plants14081156

Abstract

Salinity represents a significant challenge for agriculture, especially in semi-arid regions, affecting the growth and productivity of plants such as nasturtium (Tropaeolum majus), which is valued for its ornamental, medicinal, and food uses. Salt stress disrupts biochemical, physiological, and anatomical processes, limiting plant development. This study investigated the application of attenuators, including salicylic acid, nicotinamide, and proline, to mitigate the effects of salt stress on nasturtium cultivated in a hydroponic system. The treatments involved different combinations of these compounds under saline conditions (40 mM NaCl). The attenuators reduced the negative impacts of salt stress, promoting improvements in gas exchange, such as increased net photosynthesis, water-use efficiency, and stomatal conductance. Additionally, the treatments enhanced vegetative and reproductive growth, increasing the dry biomass of leaves, stems, and flowers, as well as the number of flowers and flower buds. The combination of salicylic acid, nicotinamide, and proline stood out by providing greater efficiency in carbon assimilation, stability of photosynthetic pigments, and higher tolerance to salt stress. These findings reinforce the potential of using attenuators to optimize the cultivation of nasturtium in saline environments, promoting higher productivity and plant quality.

Keywords: abiotic stress; amino acids; edible flowers; gas exchange; inorganic and organic solutes; plant hormones; vitamin B3.

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Conflict of interest statement

The authors declare no conflicts of interest.

Figures

**Figure 1**
(a) Stomatal conductance (gs), (b) net photosynthesis (A), (c) transpiration rate (E), (d) intercellular CO₂ concentration (Ci), (e) intrinsic carboxylation efficiency (iCE), (f) instantaneous water-use efficiency (WUE), (g) intrinsic water-use efficiency (iWUE), and (h) Ci/Ca ratio of *Tropaeolum majus* subjected to salt stress and the application of salicylic acid (SA), nicotinamide (NAM), and proline (Pro). T0 = control (0 mM NaCl); T1 = 40 mM NaCl; T2 = 40 mM NaCl + Pro; T3 = 40 mM NaCl + SA; T4 = 40 mM NaCl + NAM; T5 = 40 mM NaCl + Pro + SA; T6 = 40 mM NaCl + Pro + NAM; T7 = 40 mM NaCl + SA + NAM; and T8 = 40 mM NaCl + Pro + SA + NAM. Means followed by the same letter do not differ according to the Scott–Knott test (p ≤ 0.05). Bars are means ± standard error (n = 4).

**Figure 2**
(a) Chlorophyll a, (b) chlorophyll b, (c) total chlorophyll, and (d) carotenoids of *Tropaeolum majus* subjected to salt stress and the application of salicylic acid (SA), nicotinamide (NAM), and proline (Pro). T0 = control (0 mM NaCl); T1 = 40 mM NaCl; T2 = 40 mM NaCl + Pro; T3 = 40 mM NaCl + SA; T4 = 40 mM NaCl + NAM; T5 = 40 mM NaCl + Pro + SA; T6 = 40 mM NaCl + Pro + NAM; T7 = 40 mM NaCl + SA + NAM; and T8 = 40 mM NaCl + Pro + SA + NAM. Means followed by the same letter do not differ according to the Scott–Knott test (p ≤ 0.05). Bars are means ± standard error (n = 4).

**Figure 3**
(a,b) Sodium (Na⁺), (c,d) potassium (K⁺), (e,f) chloride (Cl⁻), and (g,h) Na⁺/K⁺ ratio in leaves and flowers, respectively, of *Tropaeolum majus* subjected to salt stress and the application of salicylic acid (SA), nicotinamide (NAM), and proline (Pro). T0 = control (0 mM NaCl); T1 = 40 mM NaCl; T2 = 40 mM NaCl + Pro; T3 = 40 mM NaCl + SA; T4 = 40 mM NaCl + NAM; T5 = 40 mM NaCl + Pro + SA; T6 = 40 mM NaCl + Pro + NAM; T7 = 40 mM NaCl + SA + NAM; and T8 = 40 mM NaCl + Pro + SA + NAM. Means followed by the same letter do not differ according to the Scott–Knott test (p ≤ 0.05). Bars are means ± standard error (n = 4).

**Figure 4**
(a) Soluble carbohydrates, (b) free amino acids, (c) soluble proteins, (d) free proline in flowers, and (e) free proline in leaves of *Tropaeolum majus* subjected to salt stress and the application of salicylic acid (SA), nicotinamide (NAM), and proline (Pro). T0 = control (0 mM NaCl); T1 = 40 mM NaCl; T2 = 40 mM NaCl + Pro; T3 = 40 mM NaCl + SA; T4 = 40 mM NaCl + NAM; T5 = 40 mM NaCl + Pro + SA; T6 = 40 mM NaCl + Pro + NAM; T7 = 40 mM NaCl + SA + NAM; and T8 = 40 mM NaCl + Pro + SA + NAM. Means followed by the same letter do not differ according to the Scott–Knott test (p ≤ 0.05). Bars are means ± standard error (n = 4).

**Figure 5**
(a) Plant height, (b) number of leaves, (c) number of flowers, (d) number of flower buds, (e) stem dry mass, (f) leaves dry mass, (g) flower dry mass, and (h) root dry mass of *Tropaeolum majus* subjected to salt stress and the application of salicylic acid (SA), nicotinamide (NAM), and proline (Pro). T0 = control (0 mM NaCl); T1 = 40 mM NaCl; T2 = 40 mM NaCl + Pro; T3 = 40 mM NaCl + SA; T4 = 40 mM NaCl + NAM; T5 = 40 mM NaCl + Pro + SA; T6 = 40 mM NaCl + Pro + NAM; T7 = 40 mM NaCl + SA + NAM; and T8 = 40 mM NaCl + Pro + SA + NAM. Means followed by the same letter do not differ according to the Scott–Knott test (p ≤ 0.05). Bars are means ± standard error (n = 4).

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The Combination of Salicylic Acid, Nicotinamide, and Proline Mitigates the Damage Caused by Salt Stress in Nasturtium (Tropaeolum majus)

Affiliations

The Combination of Salicylic Acid, Nicotinamide, and Proline Mitigates the Damage Caused by Salt Stress in Nasturtium (Tropaeolum majus)

Authors

Affiliations

Abstract

Conflict of interest statement

Figures

References

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