Journal of Horticultural Science
with the collaboration of Iranian Scientific Association for Landscape (ISAL)

The Effect of Humic Acid and Amino Acid Fertigation on Morpho-Physiological Changes in Greenhouse Tomato (Solanum lycopersicum L.) (cv. Termeh) under Deficit Irrigation Conditions

Document Type : Research Article

Authors

M. Shahriari
H. Aroiee
B. Abedy

Department of Horticultural Science and Landscape Architecture, Faculty of Agriculture, Ferdowsi University of Mashhad, Mashhad, Iran

https://doi.org/10.22067/jhs.2025.95540.1464
Abstract
Introduction
Water scarcity is a fundamental challenge to global food security, necessitating the optimization of water use in agriculture. Deficit irrigation (DI) has emerged as a key strategy to enhance water productivity, involving the controlled reduction of water application to minimize yield impact while significantly saving water. However, DI can induce physiological stress, disrupting vital processes like photosynthesis, nutrient uptake, and hormonal balance, ultimately compromising crop yield and quality. Greenhouse cultivation provides a controlled environment ideal for implementing DI strategies. To mitigate the adverse effects of water stress, the application of natural bio-stimulants like humic acid (HA) and amino acids (AA) has gained considerable attention. Humic acid improves soil structure, enhances water retention, and stimulates the absorption of macro and micronutrients. Amino acids play crucial roles as protein building blocks,
osmo-regulators, and precursors to hormones, aiding in stress tolerance. This study aimed to evaluate the individual and comparative effects of humic acid and amino acid fertigation on the growth, yield, fruit quality, and nutrient uptake of greenhouse tomato (Solanum lycopersicum L. cv. Termeh) under deficit irrigation conditions.

Materials and Methods
The research was conducted in a commercial greenhouse in Mashhad, Iran. Two independent factorial experiments were laid out in a randomized complete block design (RCBD) with four replications. The experimental factors were: 1) Irrigation regime at two levels: full irrigation (100% of crop water requirement) and deficit irrigation (70% of crop water requirement); 2) Humic acid at two levels (0 and 3 g.L⁻¹) in the first experiment; and 3) Amino acid at two levels (0 and 1 g.L⁻¹) in the second experiment. The commercial HA product (70% humic acid, 15% fulvic acid, 12% K₂O) and AA product (80% free amino acids, 12.8% total nitrogen) were applied via fertigation at three growth stages: two weeks after transplanting, flowering initiation, and fruit set. A wide range of morphological traits, leaf nutrient content, quantitative qualitative fruit traits were measured at the fruit ripening stage. Data were analyzed using SPSS software (v.21), and means were compared using Duncan's multiple range test at a 5% probability level.

Results and Discussion
Morphological Traits: Deficit irrigation significantly reduced all morphological parameters. Main stem length decreased by 7%, internode number dropped from 34.75 to 29.75, internode length from 4.17 cm to 3.53 cm, and leaf area by 13.58%. Shoot fresh and dry weight and root volume were also significantly reduced. Application of both HA and AA significantly improved all growth traits under both irrigation regimes. Humic acid not only compensated for the negative effects of drought stress but also enhanced growth beyond the full irrigation control level in many cases. Comparative analysis revealed the superior efficacy of HA over AA. This superiority was consistent under stress conditions, attributed to HA's multifaceted role in improving the rhizosphere environment and enhancing simultaneous water and nutrient availability.

Leaf Nutrient Content: Deficit irrigation caused a significant decrease in the concentration of all measured macro and micronutrients. Both bio-stimulants significantly enhanced nutrient uptake. Humic acid was more effective than AA in improving the uptake of nutrients especially P, Ca, and Fe under stress. This is likely due to HA's ability to stimulate root development, increase membrane permeability, and enhance microbial activity, thereby improving nutrient solubility and absorption.

Quantitative and Qualitative Fruit Traits: DI led to a 29% reduction in fruit number per cluster, a 6% reduction in single fruit weight, and a consequent 19% reduction in total yield (from 9.45 to 7.69 kg plant⁻¹). Both HA and AA application increased yield under DI, HA increased yield by 31% and AA by 29%. Regarding quality, DI reduced TSS and vitamin C content but increased carotenoids and lycopene. HA was particularly effective in increasing TSS by 59%, vitamin C by 18%, carotenoids by 17%, and lycopene by 10% under DI. AA showed positive but generally lesser effects on quality parameters. On average, HA demonstrated a 17.1% greater improvement in quantitative traits and a significant 42.5% greater improvement in qualitative traits compared to AA.

Conclusion
This study demonstrates that deficit irrigation at 70% of field capacity significantly impairs the growth, yield, and quality of greenhouse tomatoes. The application of both humic acid (3 g.L⁻¹) and amino acids (1 g.L⁻¹) effectively mitigated these negative impacts, often enhancing traits beyond the well-watered control. However, humic acid proved to be a superior bio-stimulant than amino acids in improving morphological development, enhancing nutrient uptake (particularly N, P, K, and Ca), and boosting both quantitative yield and qualitative fruit characteristics. Therefore, humic acid fertigation is recommended as a highly effective management strategy for sustaining greenhouse tomato production under water-limited conditions, ensuring higher yield and premium fruit quality while optimizing water use efficiency.

Keywords

Fertigation
Fruit yield
Growth traits
Nutrient elements
Organic acids
Subjects

Authors retain the copyright. This is an open access article distributed under Creative Commons Attribution 4.0 International License (CC BY 4.0).

 

1.       Ali, H., Mahmood, I., Ali, M. F., Waheed, A., Jawad, H., Hussain, S., Abasi, F., Zulfiqar, U., Siddiqui, M. H., & Alamri, S. (2024). Individual and interactive effects of amino acid and paracetamol on growth, physiological and biochemical aspects of Brassica napus L. under drought conditions. Heliyon, 10(11), e31544. https://doi.org/10.1016/j.heliyon.2024.e31544
2.       Amankwaa-Yeboah, P., Aruna Akoriko, F., Amponsah, W., Yeboah, S., Brempong, M. B., & Keteku, A. K. (2023). Combining deficit irrigation and nutrient amendment enhances the water productivity of tomato (Solanum lycopersicum L.) in the tropics. Frontiers in Sustainable Food Systems, 7, 1199386. https://doi.org/10.3389/fsufs.2023.1199386
3.       Aslani, S., Barzegar, T., & Nikbakht, J. (2019). Effect of humic acid on physiological and biochemical indices and yield of tomato under deficit irrigation. Journal of Crops Improvement, 21(2), 221-232. (in Persian). https://doi.org/10.22059/jci.2019.272278.2137
4.       Chand, J. B., Hewa, G., Hassanli, A., & Myers, B. (2021). Deficit irrigation on tomato production in a greenhouse environment: A review. Journal of Irrigation and Drainage Engineering, 147(2), 04020041. https://doi.org/10.1061/(ASCE)IR.1943-4774.0001529
5.       Chen, X., Dong, H., Qi, Z., Gui, D., Ma, L., Thorp, K. R., Malone, R., Wu, H., Liu, B., & Feng, S. (2025). Potential deficit irrigation adaptation strategies under climate change for sustaining cotton production in hyper–arid areas. Agricultural Water Management, 132, 109417. https://doi.org/10.1016/j.agwat.2025.109417
6.       El-Beltagi, H. S., Abuarab, M. E., Fahmy, M. A., Abdelaziz, S. M., Abdel-Hakim, S. G., Abdeldaym, E. A., & Tawfic, G. A. (2023). Impact of biostimulants based amino acids and irrigation frequency on agro-physiological characteristics and productivity of broccoli plants. Notulae Botanicae Horti Agrobotanici Cluj-Napoca, 51(4), 13454. https://doi.org/10.15835/nbha51413454
7.       Elshamly, A. M., Iqbal, R., Ali, B., Ahmed, I., Akram, M. I., Ali, S., Ditta, A., ÇIĞ, F., Elshikh, M. S., Mustafa, A. E. Z. M., & Hamed, M. H. (2024). Zinc and amino acids improve the growth, physiological, and biochemical attributes of corn under different irrigation levels. Rhizosphere, 29, 100820. https://doi.org/10.1016/j.rhisph.2023.100820
8.       Fayaz, E., Sorooshzadeh, A., & Heidarzadeh, A. (2024). Effect of foliar application of amino acids under water deficit conditions during late-season on yield and yield components of oil rapeseed (Brassica napus L.). Iranian Journal of Field Crop Science, 55(1), 139-149. (in Persian). https://doi.org/10.22059/ijfcs.2024.368145.655044
9.       Fisk, C. L., Silver, A. M., Strik, B. C., & Zhao, Y. (2008). Postharvest quality of hardy kiwifruit (Actinidia arguta ‘Ananasnaya’) associated with packaging and storage conditions. Postharvest Biology and Technology, 47(3), 338–345. https://doi.org/10.1016/j.postharvbio.2007.07.015
10.    Gholami, H., Ghani, A., Raouf Fard, F., Saharkhiz, M. J., & Hazrati, H. (2019). Changes in photosynthetic pigments and uptake of some soil elements by chicory supplied with organic fertilizers. Acta Ecologica Sinica, 39(3), 250-256. https://doi.org/10.1016/j.chnaes.2018.09.003
11.    Haghighi, M., Saadat, S., & Abbey, L. (2020). Effect of exogenous amino acids application on growth and nutritional value of cabbage under drought stress. Scientia Horticulturae, 272, 109561. https://doi.org/10.1016/j.scienta.2020.109561
12.    Heidarzadeh, A. (2025). Role of amino acids in plant growth, development, and stress responses: A comprehensive review. Discover Plants, 2, 237. https://doi.org/10.1007/s44372-025-00322-0
13.    Khan, S., Iqbal, M. Z., Solangi, F., Azeem, S., Bodlah, M. A., Zaheer, M. S., Niaz, Y., Ashraf, M., Abid, M., Gul, H., Yu, H., Li, Q., Weijie, J., Rizwan, M., & Manoharadas, S. (2025). Impact of amino acid supplementation on hydroponic lettuce (Lactuca sativa L.) growth and nutrient content. Scientific Reports, 15(1), 1-9. https://doi.org/10.1038/s41598-025-00294-x
14.    Khorasani, H., Rajabzadeh, F., Mozafari, H., & Pirbalouti, A. G. (2023). Water deficit stress impairment of morphophysiological and phytochemical traits of stevia (Stevia rebaudiana Bertoni) buffered by humic acid application. South African Journal of Botany, 154, 365-371. https://doi.org/10.1016/j.sajb.2023.01.030
15.    Lichtenthaler, H. K. (1987). Chlorophylls and carotenoids: Pigments of photosynthetic bio membranes. Methods in Enzymology, 148, 350-382. https://doi.org/10.1016/0076-6879(87)48036-1
16.    Locatelli, S., Barrera, W., Verdi, L., Nicoletto, C., Dalla Marta, A., & Maucieri, C. (2024). Modelling the response of tomato on deficit irrigation under greenhouse conditions. Scientia Horticulturae, 326, 112770. https://doi.org/10.1016/j.scienta.2023.112770
17.    Mehrnia, M., Filizadeh, Y., & Naji, A. (2024). Evaluation the effects of shade and humic acid on the eco-physiological traits of roselle (Hibiscus sabdariffa L.) under different irrigation regimes. Journal of Medicinal plants and By-products, 13(4), 1026-1036. (in Persian). https://doi.org/10.22034/jmpb.2024.364076.1625
18.    Mukherjee, S., Dash, P. K., Das, D., & Das, S. (2023). Growth, yield and water productivity of tomato as influenced by deficit irrigation water management. Environmental Processes, 10, 10. https://doi.org/10.1007/s40710-023-00624-z
19.    Mukherjee, S. P., & Choudhuri, M. A. (1983). Implication of water stress-induced changes in the levels of endogenous ascorbic acid and hydrogen peroxide in Vigna seedlings. Journal of Plant Physiology, 58, 166-170. https://doi.org/10.1111/j.1399-3054.1983.tb04162.x
20.    Najafi, M., Arouiee, H., & Aminifard, M. H. (2022). Effects of humic acid and amino acid on some growth traits on super daminus cucumber (Cucumis sativus L.) under drought stress. Journal of Horticultural Science, 35(4), 521-533. (in Persian). https://doi.org/10.22067/jhs.2021.61892.0
21.    Ride, R. S., Ahmed, S., Monami, S. A., & 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), 12189. https://doi.org/10.55779/nsb16412189
22.    Rostami, M., Shokouhian, A., & Mohebodini, M. (2022). Effect of humic acid, nitrogen concentrations and application method on the morphological, yield and biochemical characteristics of strawberry ‘Paros.’ International Journal of Fruit Science, 22(1), 203–214. https://doi.org/10.1080/15538362.2021.2022566
23.    Sadeghi Chah-Nasir, A., Abootalebi Jahromi, A., Behrooznam, B., Hassanzadeh Khankahdani, H., & Ejraei, A. (2023). Effect of humic acid and amino acid foliar applications on the growth characteristics, yield, and fruit quality of tomato (Solanum lycopersicom L.). International Journal of Horticultural Science and Technology, 10(3), 309-318. (in Persian). https://doi.org/10.22059/ijhst.2022.325793.477
24.    Sadler, G., Davis, J., & Dezman, D. (1990). Rapid extraction of lycopene and β-carotene from reconstituted tomato paste and pink grapefruit homogenates. Journal of Food Science, 55(5), 1460–1461. https://doi.org/10.1111/j.1365-2621.1990.tb03958.x
25.    Singh, M., Ameta, K. D., Dubey, R. B., Pareek, S., Meena, N. L., Meena, S., & Lal, S. (2017). Effect of humic acid and micro nutrients on growth and yield of poly house grown capsicum (Capsicum annum L.). Chemical Science Review and Letters, 6(22), 1189–1193.
26.    Tüzel, Y., Biyke, H., Harouna, O. S., Durdu, T., Tepecik, M., Oztekin, G. B., Tunalı, U., & Gruda, N. S. (2024). Deficit irrigation response and climate resilience of Mediterranean tomato landraces. Horticulturae, 11(1), 74. https://doi.org/10.3390/horticulturae11010074
27.    Wang, X., Zhang, Y., Xu, W., Cheng, J., Liu, J., Pei, W., Wang, J., & Chuang, S. (2023). Amino acid fertilizer strengthens its effect on crop yield and quality by recruiting beneficial rhizosphere microbes. Journal of the Science of Food and Agriculture, 103(12), 5970-5980. https://doi.org/10.1002/jsfa.12667
28.    Wu, W., Liu, M., Wu, X., Wang, Z., & Yang, H. (2022). Effects of deficit irrigation on nitrogen uptake and soil mineral nitrogen in alfalfa grasslands of the inland arid area of China. Agricultural Water Management, 269, 107724. https://doi.org/10.1016/j.agwat.2022.107724
29.    Xu, J., Li, X., Wan, W., Zhu, X., Li, C., Zhao, X., Zhao, Y., Pang, S., & Diao, M. (2024). Impact of regulated deficit irrigation on the dynamics of quality changes in processing tomato fruits during ripening. Agricultural Water Management, 304, 109068. https://doi.org/10.1016/j.agwat.2024.109068
 
 
 
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Journal of Horticultural Science
Volume 40, Issue 3
Summer 2026
Pages 569-549

  • Receive Date 20 September 2025
  • Revise Date 20 December 2025
  • Accept Date 23 December 2025
  • First Publish Date 23 December 2025

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