Greenhouse Plant Production Journal
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Influence of Salicylic Acid Concentrations and Spraying Times on Growth and Physiology of Eggplant

Articles in Press

Document Type : Original Article

Authors

Seyed Mohammad Javad Arvin 1
Ehsan Salari 2
Hamid Reza Soufi 3

1 Department of Horticulture, Shahid Bahonar University of Kerman, Kerman, Iran

2 Department of Horticultural Sciences, Faculty of Agriculture, Shahid Bahonar University of Kerman, Kerman, Iran

3 Department of Horticultural Sciences, Faculty of Agriculture, Vali-e-Asr University of Rafsanjan, Rafsanjan, Iran

https://doi.org/10.61882/gppj.3.1.68
Abstract
Salicylic acid (SA) is a key signaling molecule that regulates plant growth, flowering, and responses to abiotic and biotic stresses. This study evaluated the effects of different SA concentrations (0, 0.5, and 1.0 mM) and application frequencies (once and twice) on the growth, pigment composition, and yield of eggplant (Solanum melongena L.) under field conditions during the 2023–2024 growing season. Eggplant seeds were sown in a cocopeat and perlite growing medium at a ratio of 3:1 and the seedlings were watered daily in greenhouse. Foliar spraying was done in two stages before transplanting (four-leaf stage) in greenhouse and before flowering in farm. After the first foliar spray, the eggplant seeds were transferred to the field and the plants were irrigated every three days throughout the growth period. A factorial experiment arranged in a completely randomized design revealed significant SA effects on most measured traits, with 0.5 mM producing the most favorable outcomes. Compared with the control, this treatment increased relative water content by 11%, reduced electrolyte leakage by 30–35%, and enhanced SPAD values, total chlorophyll, and carotenoid contents by up to 120%. Plant height, fruit number, and total yield rose by 38.1%, 85.7%, and 88.6%, respectively. Two applications further improved growth and yield compared to a single spray, indicating that repeated applications amplify the physiological benefits of SA. In contrast, 1.0 mM SA provided no additional improvement, suggesting a threshold beyond which inhibitory effects are not observed. The observed enhancements were associated with improved water balance, enhanced photosynthetic efficiency, and increased membrane integrity. Overall, applying 0.5 mM SA twice during both the vegetative and reproductive stages proved to be an optimal, low-cost, and environmentally safe strategy for enhancing eggplant growth and productivity. Future studies should elucidate SA’s molecular mechanisms and interactions with other biostimulants and stresses to optimize its use across crops and production systems.

Keywords

Electrolyte leakage
Eggplant
Foliar application
Fruit yield
Morpho-physiological Traits
Relative Water Content
Salicylic Acid
Abdolmaleki M, Morteza KK, Eshghi S, Ramezanian A. Improvement in vase life of cut rose cv." Dolce Vita" by preharvest foliar application of calcium chloride and salicylic acid. International Journal of Horticultural Science and Technology, 2(1): 55-66.
Ahmed, S., Monami, S.A. and Sarkar, M.D., 2024. Improvement in growth, yield, and fruit quality of tomato by foliar application of humic and salicylic acids. Notulae Scientia Biologicae, 16(4), pp.12189-12189.
Aires, E.S., Ferraz, A.K.L., Carvalho, B.L., Teixeira, F.P., Rodrigues, J.D. and Ono, E.O., 2022. Foliar application of salicylic acid intensifies antioxidant system and photosynthetic efficiency in tomato plants. Bragantia, 81, p.e1522.
Al-Salmi, M.R. and Nadaf, S.K., 2025. Technical Efficiency of Eggplant (Solanum melongina L.) Growing Farms in OMAN-An Opportunity to Stabilize the Agriculture Economy. Current Agriculture Research Journal, 13(1).
Al Salmi, M.R., Nadaf, S.K., Mbaga, M.D., Janke, R.R. and Al-Busaidi, W., 2020. Potential for vegetable production towards food security in Arabian peninsula: A case study of Oman. The Open Agriculture Journal, 14(1).
Anwar, I., Bibi, S., Mahmood, A., Zia, M.A., Javaid, M.M., Ali, L., Nadeem, M.A., Naeem, Z., Al-Ashkar, I., Gharzeddin, K. and Ayman, E.S., 2025. Impact of foliar spray of salicylic acid on morpho-physiological and biochemical responses of pea (Pisum sativum L.) under drought stress. BMC Plant Biology, 25(1), p.1123.
Bin-Jumah, M., Abdel-Fattah, A.F.M., Saied, E.M., El-Seedi, H.R. and Abdel-Daim, M.M., 2021. Acrylamide-induced peripheral neuropathy: manifestations, mechanisms, and potential treatment modalities. Environmental Science and Pollution Research, 28(11), pp.13031-13046.
Chaudhary, A., Mishra, A., Bola, P.K., Nagar, K.K. and Chaudhary, P., 2015. Effect of foliar application of zinc and salicylic acid on flowering and yield of African marigold cv. Pusa narangi gainda. HortFlora Research Spectrum, 4(4): 351-355.  
Dasgan, H.Y., Aksu, K.S., Zikaria, K. and Gruda, N.S., 2024. Biostimulants enhance the nutritional quality of soilless greenhouse tomatoes. Plants, 13(18), p.2587.
Dionisio-Sese, M.L. and Tobita, S., 1998. Antioxidant responses of rice seedlings to salinity stress. Plant science, 135(1), pp.1-9.
Dutra, W.F., Soares de Melo, A., Suassuna, J.F., Dutra, A.F., Chagas da Silva, D. and Maia, J.M., 2017. Antioxidative responses of cowpea cultivars to water deficit and salicylic acid treatment. Agronomy Journal, 109(3), pp.895-905.
Eberhard, S., Doubrava, N., Marfa, V., Mohnen, D., Southwick, A., Darvill, A. and Albersheim, P., 1989. Pectic cell wall fragments regulate tobacco thin-cell-layer explant morphogenesis. The Plant Cell, 1(8), pp.747-755.
El-Tayeb, M.A., 2005. Response of barley grains to the interactive e. ect of salinity and salicylic acid. Plant growth regulation, 45(3), pp.215-224.
Es-Sbihi, F.Z., Hazzoumi, Z. and Amrani Joutei, K., 2020. Effect of salicylic acid foliar application on growth, glandular hairs and essential oil yield in Salvia officinalis L. grown under zinc stress. Chemical and Biological Technologies in Agriculture, 7(1), p.26.
Esposito, A., Miceli, A., Vetrano, F., Campo, S. and Moncada, A., 2025. Effects of Salicylic Acid Application Method and Concentration on the Growth and Ornamental Quality of Poinsettia (Euphorbia pulcherrima Willd.). Horticulturae, 11(8), p.904.
Faghih, S., Zarei, A. and Ghobadi, C., 2019. Positive effects of plant growth regulators on physiology responses of Fragaria× ananassa cv.‘Camarosa’under salt stress. International Journal of Fruit Science, 19(1), pp.104-114.
Gharib, F.A., 2006. Effect of salicylic acid on the growth, metabolic activities and oil content of basil and marjoram. International journal of agriculture and biology, 4, pp.485-492.
Gruda, N.S., Dong, J. and Li, X., 2024. From salinity to nutrient-rich vegetables: Strategies for quality enhancement in protected cultivation. Critical Reviews in Plant Sciences, 43(5), pp.327-347.
Gruda, N.S., Gallegos-Cedillo, V.M., Nájera, C., Catalina, E.G., Ochoa, J. and Fernández, J.A., 2025. Advancing protected cultivation: A pathway for nutrient-rich vegetables. Critical Reviews in Plant Sciences, 44(2), pp.88-116.
Gruda, N.S., Li, X., Gallegos-Cedillo, V.M., Samouline, G., Dong, J., Weiss, J. and Fernández, J.A., 2025. From growth to table: exploring the impact of pre-harvest conditions on greenhouse vegetable quality. European Journal of Horticultural Science, 90(1).
Hussain, S.J., Khan, N.A., Anjum, N.A., Masood, A. and Khan, M.I.R., 2021. Mechanistic elucidation of salicylic acid and sulphur-induced defence systems, nitrogen metabolism, photosynthetic, and growth potential of mungbean (Vigna radiata) under salt stress. Journal of Plant Growth Regulation, 40(3), pp.1000-1016.
Ienciu, A., Bei, M., Cǎrbunar, M., Cǎrbunar, M. and Vidican, O., 2022. The functional nutritional value and the health benefits of consuming eggplant. Annals of the University of Oradea, Fascicle: Environmental Protection. 41-44.
Ikiz, B., Dasgan, H.Y., Balik, S., Aldiyab, A. and Gruda, N.S., 2025. Improved salt stress resilience, growth, and quality of soilless basil through biostimulant application. Scientific Reports, 15(1), p.35522.
İkiz, B., Dasgan, H.Y., Balik, S., Kusvuran, S. and Gruda, N.S., 2024. The use of biostimulants as a key to sustainable hydroponic lettuce farming under saline water stress. BMC Plant Biology, 24(1), p.808.
Jahan, M.S., Wang, Y., Shu, S., Zhong, M., Chen, Z., Wu, J., Sun, J. and Guo, S., 2019. Exogenous salicylic acid increases the heat tolerance in Tomato (Solanum lycopersicum L) by enhancing photosynthesis efficiency and improving antioxidant defense system through scavenging of reactive oxygen species. Scientia Horticulturae, 247, pp.421-429.
Janda, T., Szalai, G. and Pál, M., 2020. Salicylic acid signalling in plants. International Journal of Molecular Sciences, 21(7), p.2655.
Karami Chame, S., Khalil-Tahmasbi, B., ShahMahmoodi, P., Abdollahi, A., Fathi, A., Seyed Mousavi, S.J., Hossein Abadi, M., Ghoreishi, S. and Bahamin, S., 2016. Effects of salinity stress, salicylic acid and Pseudomonas on the physiological characteristics and yield of seed beans (Phaseolus vulgaris). Sci Agri, 14(2), pp.234-238.
Karlidag, H., Yildirim, E. and Turan, M., 2009. Exogenous applications of salicylic acid affect quality and yield of strawberry grown under antifrost heated greenhouse conditions. Journal of Plant Nutrition and Soil Science, 172(2), pp.270-276.
Kaur, H., Hussain, S.J., Kaur, G., Poor, P., Alamri, S., Siddiqui, M.H. and Khan, M.I.R., 2022. Salicylic acid improves nitrogen fixation, growth, yield and antioxidant defence mechanisms in chickpea genotypes under salt stress. Journal of Plant Growth Regulation, 41(5), pp.2034-2047.
Khan, A.R., Cheng, Z., Ghazanfar, B., Khan, M.A. and Yongxing, Z., 2014. Acetyl salicylic acid and 24-epibrassinolide enhance root activity and improve root morphological features in tomato plants under heat stress. Acta Agriculturae Scandinavica, Section B—Soil & Plant Science, 64(4), pp.304-311.
Khan, M.I.R., Asgher, M. and Khan, N.A., 2014. Alleviation of salt-induced photosynthesis and growth inhibition by salicylic acid involves glycinebetaine and ethylene in mungbean (Vigna radiata L.). Plant Physiology and Biochemistry, 80, pp.67-74.
Khan, M.I.R., Fatma, M., Per, T.S., Anjum, N.A. and Khan, N.A., 2015. Salicylic acid-induced abiotic stress tolerance and underlying mechanisms in plants. Frontiers in plant science, 6, p.462.
Khan, M.I.R., Iqbal, N., Masood, A., Per, T.S. and Khan, N.A., 2013. Salicylic acid alleviates adverse effects of heat stress on photosynthesis through changes in proline production and ethylene formation. Plant Signaling & Behavior, 8(11), p.e26374.
Kling, G.J. and Meyer Jr, M.M., 1983. Effects of phenolic compounds and indoleacetic acid on adventitious root initiation in cuttings of Phaseolus aureus, Acer saccharinum, and Acer griseum. HortScience, 18(3), pp.352-354.
Kowalska, I. and Smoleñ, S., 2013. Effect of foliar application of salicylic acid on the response of tomato plants to oxidative stress and salinity. Journal of Elementology, 18(2).
Li, A., Sun, X. and Liu, L., 2022. Action of salicylic acid on plant growth. Frontiers in Plant Science, 13, p.878076.
Li, J., Zhou, X., Zhou, J., Shang, R., Wang, Y. and Jing, P., 2020, January. Comparative study on several determination methods of chlorophyll content in plants. In IOP Conference Series: Materials Science and Engineering (Vol. 730, No. 1, p. 012066). IOP Publishing.
Luo, Y., Liu, M., Cao, J., Cao, F. and Zhang, L., 2022. The role of salicylic acid in plant flower development. Forestry research, 2, p.14.
Mady, E., Abd El-Wahed, A.H., Awad, A.H., Asar, T.O., Al-Farga, A., Abd El-Raouf, H.S., Randhir, R., Alnuzaili, E.S., El-Taher, A.M., Randhir, T.O. and Hamada, F.A., 2023. Evaluation of salicylic acid effects on growth, biochemical, yield, and anatomical characteristics of eggplant (Solanum melongena L.) plants under salt stress conditions. Agronomy, 13(9), p.2213.
Metwaly, E.E. and El-Shatoury, R.S., 2017. Impact of foliar application with salicylic acid on growth and yield of potato (Solanum tuberosum L.) under different irrigation water quantity. Journal of Plant Production, 8(10), pp.969-977.
Mimouni, H., Wasti, S., Manaa, A., Gharbi, E., Chalh, A., Vandoorne, B., Lutts, S. and Ahmed, H.B., 2016. Does salicylic acid (SA) improve tolerance to salt stress in plants? A study of SA effects on tomato plant growth, water dynamics, photosynthesis, and biochemical parameters. Omics: a journal of integrative biology, 20(3), pp.180-190.
Misra, N. and Saxena, P., 2009. Effect of salicylic acid on proline metabolism in lentil grown under salinity stress. Plant Science, 177(3), pp.181-189.
Mohamed, R.A., Abdelbaset, A.K. and Abd-Elkader, D.Y., 2018. Salicylic acid effects on growth, yield, and fruit quality of strawberry cultivars. Journal of Medicinally Active Plants, 6(1-4).
Moustakas, M., Sperdouli, I., Adamakis, I.D.S., Moustaka, J., İşgören, S. and Şaş, B., 2022. Harnessing the role of foliar applied salicylic acid in decreasing chlorophyll content to reassess photosystem II photoprotection in crop plants. International Journal of Molecular Sciences, 23(13), p.7038.
Muthulakshmi, S. and Lingakumar, K., 2017. Role of salicylic acid (SA) in plants—A review. Int. J. Appl. Res, 3(3), pp.33-37.
Pancheva, T.V., Popova, L.P. and Uzunova, A.N., 1996. Effects of salicylic acid on growth and photosynthesis in barley plants. Journal of plant physiology, 149(1-2), pp.57-63.
Piñero, M.C., Collado-González, J., Otálora, G., López-Marín, J. and del Amor, F.M., 2025. Effects of foliar application of salicylic acid on physiological and qualitative parameters in differently colored Swiss chard (Beta vulgaris L. ssp. cicla) under an aquaponic system. Journal of Agriculture and Food Research, 22, p.102140.
Popova, L., Pancheva, T. and Uzunova, A., 1997. Salicylic acid: properties, biosynthesis and physiological role. Bulg. J. Plant Physiol, 23(1-2), pp.85-93.
Preciado-Rangel, P., Reyes-Pérez, J.J., Ramírez-Rodríguez, S.C., Salas-Pérez, L., Fortis-Hernández, M., Murillo-Amador, B. and Troyo-Diéguez, E., 2019. Foliar aspersion of salicylic acid improves phenolic and flavonoid compounds, and also the fruit yield in cucumber (Cucumis sativus L.). Plants, 8(2), p.44.
Priya, M.D. and Singh, C.B., 2022. Effect of salicylic acid on growth, physiological traits, yield and water productivity of summer mungbean (Vigna radiata L. Wilczek) under different irrigation regimes. Annals of Plant and Soil Research, 24(4), pp.564-570.
Rafique, N., Raza, S.H., Qasim, M. and Iqbal, N.A.E.E.M., 2011. Pre-sowing application of ascorbic acid and salicylic acid to seed of pumpkin and seedling response to salt. Pak. J. Bot, 43(6), pp.2677-2682.
Raskin, I., 1992. Role of salicylic acid in plants. Annual review of plant biology, 43(1), pp.439-463.
Roshdy, A.E.D., Alebidi, A., Almutairi, K., Al-Obeed, R. and Elsabagh, A., 2021. The effect of salicylic acid on the performances of salt stressed strawberry plants, enzymes activity, and salt tolerance index. Agronomy, 11(4), p.775.
Schreinemachers, P., Simmons, E.B. and Wopereis, M.C., 2018. Tapping the economic and nutritional power of vegetables. Global food security, 16, pp.36-45.
Singh, P.K. and Gautam, S., 2013. Role of salicylic acid on physiological and biochemical mechanism of salinity stress tolerance in plants. Acta physiologiae plantarum, 35(8), pp.2345-2353.
Solberg, S., van Zonneveld, M., Rakha, M. T. , Taher, D. I. , Prohens, J., Jarret, R. van Dooijeweert, W., and Peter
Giovannini. 2022. Global strategy for the conservation and use of eggplants. Global Crop Diversity Trust. Bonn, Germany.
Souri, M.K. and Tohidloo, G., 2019. Effectiveness of different methods of salicylic acid application on growth characteristics of tomato seedlings under salinity. Chemical and Biological Technologies in Agriculture, 6(1), pp.1-7.
Taher, D., Solberg, S.Ø., Prohens, J., Chou, Y.Y., Rakha, M. and Wu, T.H., 2017. World vegetable center eggplant collection: origin, composition, seed dissemination and utilization in breeding. Frontiers in plant science, 8, p.279838.
Tohma, O. and Esitken, A., 2011. Response of salt stressed strawberry plants to foliar salicylic acid pre-treatments. Journal of plant nutrition, 34(4), pp.590-599.
Trueba, S., Pan, R., Scoffoni, C., John, G.P., Davis, S.D. and Sack, L., 2019. Thresholds for leaf damage due to dehydration: declines of hydraulic function, stomatal conductance and cellular integrity precede those for photochemistry. New Phytologist, 223(1), pp.134-149.
Tucuch-Haas, C.J., Pérez-Balam, J.V., Díaz-Magaña, K.B., Castillo-Chuc, J.M., Dzib-Ek, M.G., Alcántar-González, G., Vergara-Yoisura, S. and Larqué-Saavedra, A., 2017. Role of salicylic acid in the control of general plant growth, development, and productivity. In salicylic acid: a multifaceted hormone (pp. 1-15). Singapore: Springer Singapore.
Wang, J., Allan, A.C., Wang, W.Q. and Yin, X.R., 2022. The effects of salicylic acid on quality control of horticultural commodities. New Zealand Journal of Crop and Horticultural Science, 50(2-3), pp.99-117.
Wang, L. and Li, S., 2008. Role of salicylic acid in postharvest physiology. Fresh produce, 2(1), pp.1-5.
Yildirim, E., Guvenc, I. and Karatas, A., 2006, September. Effect of different number foliar salicylic acid applications on plant growth and yield of cucumber. In VI National Vegetable Growing Symposium (pp. 19-22).
Yildirim, E., Turan, M. and Guvenc, I., 2008. Effect of foliar salicylic acid applications on growth, chlorophyll, and mineral content of cucumber grown under salt stress. Journal of plant nutrition, 31(3), pp.593-612.
Youssef, S.M.S., Abu El-Azm, N.A.I. and Abd Elhady, S.A.E., 2017. Frequent foliar sprayings of salicylic acid with elevated concentrations enhance growth, yield and fruit quality of strawberry (Fragaria x ananassa Duch. cv. Festival) plants. Egyptian Journal of Horticulture, 44(1), pp.61-74.
Zhou, X.M., Mackenzie, A.F., Madramootoo, C.A. and Smith, D.L., 1999. Effects of stem‐injected plant growth regulators, with or without sucrose, on grain production, biomass and photosynthetic activity of field‐grown corn plants. Journal of Agronomy and Crop Science, 183(2), pp.103-110.
Zhou, X.M., Mackenzie, A.F., Madramootoo, C.A. and Smith, D.L., 1999. Effects of stem‐injected plant growth regulators, with or without sucrose, on grain production, biomass and photosynthetic activity of field‐grown corn plants. Journal of Agronomy and Crop Science, 183(2), pp.103-110.
Zhu, C.Q., Hu, W.J., Cao, X.C., Zhu, L.F., Bai, Z.G., Huang, J., Liang, Q.D., Jin, Q.Y. and Zhang, J.H., 2020. Role of salicylic acid in alleviating the inhibition of root elongation by suppressing ethylene emission in rice under Al toxicity conditions. Plant Growth Regulation, 90(3), pp.475-487.
Greenhouse Plant Production Journal

Articles in Press, Accepted Manuscript
Available Online from 01 March 2026

  • Receive Date 05 March 2026
  • Revise Date 25 April 2026
  • Accept Date 02 May 2026
  • First Publish Date 02 May 2026
  • Publish Date 01 March 2026

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