Current IssueSpecial IssueEditorial BoardOnline First ArticlesArchive
Current IssueSpecial IssueEditorial BoardOnline First ArticlesArchive

Full Research Article

Mitigation of Salinity Stress in Soybean [Glycine max (L.) Merrill] using Exogenous Soil Drenching with Stachytarpheta jamaicensis (L.) Vahl Extract

G
Gnanaprakasam Punithavathi1
K
Krishnagowdu Saravanan1
https://orcid.org/0000-0003-0310-1379
S
Sundarasamy Dhanapal1,*
0009-0009-3226-7897
C
Chinnaswamy Appunu2,*
0000-0002-5505-9611
A
Aslam Afzal1
1Post Graduate and Research Centre in Biotechnology, School of Life Sciences, Arignar Anna College (Arts and Science) (Affiliated to Periyar University), Krishnagiri-635 115, Tamil Nadu, India.
2Division of Crop Improvement, Indian Council of Agricultural Research-Sugarcane Breeding Institute, Coimbatore-641 007, Tamil Nadu, India.

  • Submitted01-05-2026|

  • Accepted05-08-2026|

  • First Online 04-09-2026|

  • doi 10.18805/LR-5673

ABSTRACT

Background: Salinity stress limits soybean (Glycine max) productivity by impairing growth, photosynthesis and cellular balance. This study evaluated Stachytarpheta jamaicensis (L.) Vahl leaf extract (SjE) as a natural biostimulant to mitigate salinity stress.

Methods: Soybean plants were exposed to 100 mM NaCl (SS-100) and treated with SjE (10% and 25%) via soil drenching. Growth, photosynthetic pigments, oxidative markers (LPO, H2O2) and antioxidant enzymes (SOD, CAT, POD) were assessed.

Result: Salinity reduced growth and pigments while increasing oxidative damage. SjE, especially at 10%, improved growth, restored pigments, reduced LPO and H2O2 and enhanced antioxidant enzymes. These effects are linked to phenolics and flavonoids. Overall, 10% SjE showed optimal performance, highlighting its potential as an eco-friendly biostimulant for salinity stress tolerance.

INTRODUCTION

Soybean [Glycine max (L.) Merrill; Fabaceae] is a major legume crop valued for its high protein and oil content and its role in improving soil fertility through biological nitrogen fixation (Abd-Alla et al., 2023; Dilawari et al., 2022). Although global production has increased (Hamza et al., 2024), yield is severely constrained by abiotic stresses, particularly salinity (Hasanuzzaman et al., 2022). Salinity, prevalent in arid and semi-arid regions, disrupts plant growth and productivity due to excessive salt accumulation in soils (Hussain et al., 2019; El Sabagh et al., 2020). Field studies have demonstrated that salinity significantly reduces soybean plant establishment, biomass accumulation, nodulation, pod development, seed yield and seed quality, resulting in substantial economic losses (Day and Şahin 2024; Hasanuzzaman et al., 2022; Singh, 2022; Hamwieh et al., 2011). Therefore, developing sustainable approaches to improve salinity tolerance in soybean has become an important research priority.
       
Several strategies have been developed to mitigate salinity-induced yield losses in soybean (Verma et al., 2024), including soil reclamation (Wang et al., 2024; Abiala et al., 2018), enhanced irrigation (Singh et al., 2023) and breeding for salt-tolerant cultivars (Chen et al., 2024a; Guan et al., 2021; Hamwieh et al., 2011). Advanced approaches such as transgenics and genome editing have also enhanced salt tolerance (Chen et al., 2024b; Wang et al., 2021), but require high cost, regulatory approval and advanced infrastructure. Plant biostimulants have recently emerged as eco-friendly alternatives (Johnson et al., 2024). Derived from plant extracts (Saravanan et al., 2023; Osman et al., 2021), seaweeds (Mannan et al., 2023; Repke et al., 2022), microorganisms (Tran and Hoang 2026; Jaybhay et al., 2025; Santos et al., 2023; El-Esawi et al., 2018) and organic compounds (Oliveira et al., 2024; Kim and Sang, 2023; Malekzadeh, 2015) they enhance growth, nutrient uptake, antioxidant defense and hormonal balance, largely due to bioactive compounds such as phenolics and flavonoids (Salam et al., 2023).
       
Among plant-derived biostimulants, Stachytarpheta jamaicensis (L.) Vahl (Verbenaceae) has gained attention due to its diverse phytochemical profile and adaptability (Chongloi et al., 2025). Widely distributed in tropical and subtropical regions, it is considered an aggressive invasive species (Liew and Yong, 2016). Despite this, it contains bioactive compounds such as phenolics, flavonoids, tannins and antioxidants with significant biological activity (Chongloi et al., 2025; Bliss et al., 2022; Kavitha et al., 2022; Utami et al., 2022). These compounds contribute to stress tolerance by enhancing antioxidant systems, maintaining osmotic balance and protecting cellular structures from oxidative damage (Salam et al., 2023). However, despite its rich phytochemical profile and stress-adaptive characteristics, the potential of S. jamaicensis leaf extract as a natural biostimulant for mitigating salinity stress in soybean has not yet been investigated. Therefore, the present study evaluated the effectiveness of exogenous soil drenching with S. jamaicensis leaf extract in improving growth, photosynthetic performance, antioxidant defense and oxidative stress tolerance in soybean under saline conditions. This study provides new evidence supporting the utilization of an invasive weed as a sustainable and eco-friendly biostimulant for soybean cultivation in salt-affected soils.

MATERIALS AND METHODS

Treatment procedure
 
Leaf extract of Stachytarpheta jamaicensis was prepared as protocol by Punithavathi et al., (2026). Soybean (Glycine max) seeds (cv. JS-335) were sown in plastic pots (4-inch; top diameter 13 cm, base 10 cm, height 11 cm) and maintained under controlled conditions (25±2°C; ~80% relative humidity). Five days after germination, plants were divided into six treatment groups:
1. C - Control: Plants received water alone.
2. SjE-10%: Plant received 10% S. jamaicensis extract.
3. SjE-25%: Plant received 25% S. jamaicensis extract.
4. SS-100: Plants received 100 mM NaCl alone.
5. SjE-10% + SS-100: Plants received combined treatments of 10% S. jamaicensis extract along with 100 mM NaCl.
6. SjE-25% + SS-100: Plants received combined treatments of 25% S. jamaicensis extract along with 100 mM NaCl.
       
Treatments were applied as soil drenching at 5-day intervals for a total of six applications. Plants were harvested on the 33rd day after sowing for subsequent morphological (mean number of leaves, shoot length, shoot fresh biomass, number of roots, root length and root fresh weight), physiological and biochemical analyses.
 
Physiological analysis
 
Assessment on photosynthetic pigments
 
Photosynthetic pigments were estimated following the methods of Lichtenthaler (1987) and Arnon (1949).
 
Biochemical characterization
 
Preparation of enzyme extract
 
Soybean tissues were homogenized and centrifuged and the supernatant was used for protein estimation (Bradford, 1976) and future analysis.
 
Determination of oxidative stress markers
 
Lipid peroxidation (LPO) and hydrogen peroxide (H2O2) contents were determined following Ohkawa et al., (1979) and Velikova et al., (2000), respectively.
 
Enzymatic antioxidant activities
 
Activities of superoxide dismutase (SOD), peroxidase (POD) and catalase (CAT) were assayed according to Marklund and Marklund (1974); Kar and Mishra (1976) and Aebi (1984), respectively.
 
Statistical analysis
 
Data were analysed using IBM SPSS Statistics 20 (IBM Corp., USA). Morphological data (n=5 × 2) and physiological/biochemical data (n = 4) are presented as mean ± SE. Significant differences were determined by DMRT at P≤0.05.

RESULTS AND DISCUSSION

Morphological analysis
 
Salinity stress (SS-100) significantly reduced soybean growth, with decline in leaf number (42.55%), shoot length (44.76%), shoot fresh weight (45.60%), root number (26.54%), root length (36.58%) and root fresh weight (22.91%) compared to control. SjE improved growth under non-stress conditions, particularly at 10%, increasing leaf number (34.04%), shoot length (19.53%), biomass (42.40%), root number (27.43%), root length (28.90%) and root fresh weight (62.50%). In contrast, SjE-25% reduced growth (23.40-34.92%), indicating dose-dependent inhibition. Under salinity, SjE partially restored growth. SjE-10% + SS-100 increased leaf number (74.1%), shoot length (12.3%), shoot biomass (97.1%), root number (25.3%) and root length (35.5%) over SS-100, though root fresh weight declined (35.1%). SjE-25% + SS-100 showed limited improvement. These results indicate that 10% SjE is optimal for growth enhancement (Table 1 and Fig 1).

Table 1: Influence of Stachytarpheta jamaicensis extract treatments on growth attributes of soybean plants under salinity stress conditions.



Fig 1: Effects of Stachytarpheta jamaicensis extract (SjE) on soybean under salinity stress.


       
Salinity stress markedly inhibited soybean growth by reducing leaf number, shoot and root length and biomass, reflecting the adverse effects of osmotic stress, ion toxicity and nutrient imbalance on plant development. Similar reductions in soybean growth under saline conditions have been reported by Hasanuzzaman et al., (2022), Osman et al. (2021) and where salinity impaired cell expansion, water uptake and overall biomass accumulation. In the present study, exogenous soil drenching with 10% Stachytarpheta jamaicensis extract (SjE) significantly alleviated these growth reductions, indicating its biostimulant potential. Comparable growth-promoting effects have been reported with onion extract in soybean (Saravanan et al., 2023) and maize grain extract in common bean under salinity (Rady et al., 2019). The improved growth observed in SjE-treated plants may be associated with its phenolic- and flavonoid-rich composition, which enhances antioxidant capacity, regulates auxin homeostasis, promotes root development and improves nutrient acquisition under saline conditions (Singh et al., 2021). Interestingly, the 25% extract was less effective than the 10% treatment, suggesting that excessive concentrations may interfere with normal metabolism, highlighting the importance of optimizing biostimulant dosage.
 
Physiological analysis
 
Assessment on photosynthetic pigments
 
Salinity stress reduced chlorophyll a (31.1%), chlorophyll b (42.6%), total chlorophyll (38.1%) and carotenoids (27.4%) compared to control. SjE enhanced pigment levels under non-stress conditions, with SjE-10% increasing chlorophyll a (61.5%), chlorophyll b (76.0%), total chlorophyll (70.4%) and carotenoids (2.26-fold). SjE-25% also improved pigments but to a lesser extent. Under salinity, SjE-10% + SS-100 significantly restored pigments, increasing chlorophyll a, b and total chlorophyll (~2.08-2.09-fold) and carotenoids (2.27-fold) compared to SS-100. SjE-25% + SS-100 showed moderate improvements. Overall, 10% SjE effectively alleviated pigment loss under salinity (Fig 2).

Fig 2: Effect of Stachytarpheta jamaicensis extract (SjE) on photosynthetic pigments under salinity stress.


       
Salinity-induced reductions in chlorophyll a, chlorophyll b, total chlorophyll and carotenoids indicate severe impairment of the photosynthetic apparatus. These observations agree with previous soybean studies demonstrating that salinity accelerates chlorophyll degradation, damages chloroplast ultrastructure and decreases photosynthetic efficiency (Hasanuzzaman et al., 2022; Parvin et al., 2019). Application of SjE, particularly at 10%, significantly restored pigment content under salinity stress, suggesting effective protection of the photosynthetic machinery. The phenolic and flavonoid constituents of S. jamaicensis may protect chloroplast membranes against ROS-induced damage while maintaining chlorophyll biosynthesis. Similar improvements in photosynthetic pigments have been reported following application of Moringa oleifera leaf extract in faba bean (Eleish et al., 2026), cypress leaf extract in zucchini (ElSayed et al., 2022) and yeast and carrot root extracts in maize (Abdel Latef et al., 2019). These findings collectively indicate that plant-derived biostimulants preserve photosynthetic efficiency by maintaining chloroplast integrity and reducing oxidative damage.
 
Biochemical characterization
 
Lipid peroxidation (LPO) and hydrogen peroxide (H2O2) content and enzymatic antioxidant activity
 
Salinity stress markedly increased oxidative damage, with LPO rising 2.50-fold and H2O2 3.62-fold compared to control (Fig 3). SjE application reduced these effects under salinity. SjE-10% + SS-100 decreased LPO (36.84%) and H2O2 (45.82%), while SjE-25% + SS-100 reduced LPO (~16.41%) and H2O2  (~25.73%). The 10% treatment showed stronger protection against oxidative stress (Fig 3). Salinity stress reduced SOD (48.22%), CAT (64.91%) and POD (56.27%) activities compared to control. SjE enhanced enzyme activities under non-stress conditions, with SjE-10% increasing SOD (2.4-fold), CAT (1.68-fold) and POD (2.18-fold), while SjE-25% showed lower stimulation. Under salinity, SjE improved antioxidant responses. SjE-10% + SS-100 increased SOD (2.51-fold), CAT (3.16-fold) and POD (4.56-fold). Overall, SjE, particularly at 10%, effectively restored antioxidant defense and reduced oxidative damage (Fig 4). Overall, these results demonstrate that SjE effectively reinforces the antioxidant defense machinery under salinity stress, with 10% concentration showing maximum efficiency in restoring enzymatic activities and protecting plants from oxidative damage.

Fig 3: Inhibitory effect of Stachytarpheta jamaicensis extract (SjE) on oxidative stress markers under salinity stress.



Fig 4: Effect of Stachytarpheta jamaicensis extract (SjE) on antioxidant enzymes under salinity.


       
The substantial increase in LPO and H2O2 under salinity confirms enhanced ROS generation and membrane lipid peroxidation, which are characteristic responses of soybean exposed to salt stress (Hasanuzzaman et al., 2022). SjE application significantly reduced both oxidative stress markers, indicating effective protection against ROS-mediated cellular damage. This response is likely attributable to the high antioxidant potential of S. jamaicensis, particularly its phenolics and flavonoids, which directly scavenge ROS and stabilize membrane integrity. Similar reductions in oxidative stress have been reported following application of plant-derived antioxidants (Ahmad et al., 2022) and licorice root extract in pea (Desoky et al., 2019). The enhanced activities of SOD, POD and CAT further demonstrate that SjE strengthens the soybean antioxidant defense system under salinity stress. SOD catalyzes the conversion of superoxide radicals into H2O2, whereas CAT and POD subsequently detoxify H2O2 into water and oxygen, thereby limiting oxidative injury. Similar enhancement of antioxidant enzymes has been reported in soybean inoculated with Bacillus firmus (El-Esawi et al., 2018) and tomato supplemented with microalgae–cyanobacteria biostimulants (Mutale-joan et al., 2021). The consistently greater effectiveness of the 10% extract compared with the 25% treatment further indicates that moderate concentrations are sufficient to maximize antioxidant protection without imposing metabolic constraints. Overall, the present study demonstrates that Stachytarpheta jamaicensis leaf extract effectively mitigates salinity stress by enhancing growth, preserving photosynthetic pigments, reducing oxidative damage and activating enzymatic antioxidant defenses (Fig 5). Unlike previous studies that mainly evaluated conventional plant extracts or microbial biostimulants, this study provides the first evidence that an invasive weed species, S. jamaicensis, can be successfully utilized as a sustainable and eco-friendly biostimulant to improve salinity tolerance in soybean. These findings support its potential application for sustainable soybean cultivation in salt-affected soils and provide a strong basis for future multi-season field validation.

Fig 5: Graphical illustration of Stachytarpheta jamaicensis extract (SjE) enhancing morpho-physiological traits and antioxidant activities while reducing oxidative stress in soybean under salinity conditions.

CONCLUSION

Exogenous soil drenching with Stachytarpheta jamaicensis extract effectively mitigated salinity stress in soybean (Glycine max) by improving growth, restoring photosynthetic pigments and enhancing antioxidant defense. The treatment significantly reduced oxidative damage (LPO and H2O2) while stimulating key enzymes (SOD, CAT, POD). Among the tested doses, 10% extract consistently showed superior performance compared to 25%. The findings highlight the potential of S. jamaicensis as a cost-effective and eco-friendly biostimulant. This approach offers a promising strategy for improving crop resilience under saline conditions.

ACKNOWLEDGEMENT

The authors are thankful to the management of the Arignar Anna College (Arts and Science), Krishnagiri-635 115, Tamil Nadu, India for proving the necessary research and infrastructure facilities for this research work.
 
Disclaimers
 
The views and conclusions expressed in this article are solely those of the authors and do not necessarily represent the views of their affiliated institutions. The authors are responsible for the accuracy and completeness of the information provided, but do not accept any liability for any direct or indirect losses resulting from the use of this content.

CONFLICT OF INTEREST

The authors declare that there are no conflicts of interest regarding the publication of this article. No funding or sponsorship influenced the design of the study, data collection, analysis, decision to publish, or preparation of the manuscript.

REFERENCES


  1. Abd-Alla, M.H., Al-Amri, S.M. and El-Enany, A.W.E. (2023). Enhancing rhizobium-legume symbiosis and reducing nitrogen fertilizer use are potential options for mitigating climate change. Agriculture. 13: 2092. https://doi.org/10.3390/agriculture 13112092.

  2. Abdel Latef, A.A.H., Mostofa, M.G., Rahman, M.M., Abdel-Farid, I.B. and Tran, L.S.P. (2019). Extracts from yeast and carrot roots enhance maize performance under seawater- induced salt stress by altering physio-biochemical characteristics of stressed plants. Journal of Plant Growth Regulation. 38(3): 966-979. https://doi.org/10.1007/s00 344-018-9906-8.

  3. Abiala, M.A., Abdelrahman, M., Burritt, D.J. and Tran, L.S.P. (2018). Salt stress tolerance mechanisms and potential applications of legumes for sustainable reclamation of salt degraded soils. Land Degradation and Development. 29(10): 3812-3822. https://doi.org/10.1002/ldr.3095.

  4. Aebi, H. (1984). [13] Catalase in vitro. pp. 121–126. https://doi.org/ 10.1016/S0076-6879(84)05016-3.

  5. Ahmad, A., Blasco, B. and Martos, V. (2022). Combating salinity through natural plant extracts based biostimulants: A review. Frontiers in Plant Science. 13: 862034. https://doi.org/10.3389/fpls.2022.862034.

  6. Arnon, D.I. (1949). Copper enzymes in isolated chloroplasts. Polyphenoloxidase in Beta vulgaris. Plant Physiology. 24(1): 1. https://doi.org/10.1104/pp.24.1.1.

  7. Bliss, O., Ejiofor, E., Njoku, C., Ejiofor, M. and Michael, K. (2022). GC-MS Characterization, in vitro Antioxidant and anti- inflammatory activities of essential oil from the leaves of Stachytarpheta jamaicensis. Journal of the Mexican Chemical Society. 66(4): 433-443. https://doi.org/10.29 356/jmcs.v66i4.1822.

  8. Bradford, M.M. (1976). A rapid and sensitive method for the quantitation of microgram quantities of protein utilizing the principle of protein-dye binding. Analytical Biochemistry. 72(1-2): 248-254. https://doi.org/10.1016/0003-2697(76)90527-3.

  9. Chen, L., Peng, L., Ouyang, W., Yao, H., Ye, Y., Shan, Z., Cao, D., Chen, S., Yang, Z., Huang, Y., Han, B., Sha, A., Zhou, X. and Chen, H. (2024a). Screening and identification of salt tolerance soybean varieties and germplasms. Oil Crop Science. 9(3): 204-210. https://doi.org/10.1016/ j.ocsci.2024.06.005.

  10. Chen, X., Jiang, X., Sun, X., Hu, Z., Gao, F., Wang, X., Zhang, H., Chen, R. and Jiang, Q. (2024b). Gene editing and over expression of soybean miR396a reveals its role in salinity tolerance and development. The Crop Journal. 12(6): 1655-1665. https://doi.org/10.1016/j.cj.2024.08.003.

  11. Chongloi, V., Gogoi, P.P., Sangma, S.R., Sinha, U.B., Bora, P. and Phukan, M.M. (2025). Antioxidant, antimicrobial and in silico investigations on pyrolytic bio-oil from invasive Stachytarpheta jamaicensis. Environmental Science and Pollution Research. 32(30): 18260-18277. https:// doi.org/10.1007/s11356-025-36741-5.

  12. Day, S. and Şahin, N.K. (2024). Determination of seed size properties of soybean cultivars and their response under salinity during early growth. Legume Research: An International Journal. 47(6): 945-951. doi: 10.18805/LRF-780.

  13. Desoky, E.S.M., ElSayed, A.I., Merwad, A.R.M.A. and Rady, M.M. (2019). Stimulating antioxidant defenses, antioxidant gene expression and salt tolerance in pisum sativum seedling by pretreatment using licorice root extract (LRE) as an organic biostimulant. Plant Physiology and Biochemistry. 142: 292-302. https://doi.org/10.1016/j.plaphy.2019.07. 020.

  14. Dilawari, R., Kaur, N., Priyadarshi, N., Prakash, I., Patra, A., Mehta, S., Singh, B., Jain, P. and Islam, M.A. (2022). Soybean: A key player for global food security. In Soybean improvement: physiological, molecular and genetic perspectives. Cham: Springer International Publishing. (pp. 1-46). https://doi. org/10.1007/978-3-031-12232-3_1.

  15. El-Esawi, M.A., Alaraidh, I.A., Alsahli, A.A., Alamri, S.A., Ali, H.M. and Alayafi, A.A. (2018). Bacillus firmus (SW5) augments salt tolerance in soybean (Glycine max L.) by modulating root system architecture, antioxidant defense systems and stress-responsive genes expression. Plant Physiology and Biochemistry. 132: 375-384. https://doi.org/10.1016/ j.plaphy.2018.09.026.

  16. El Sabagh, A., Hossain, A., Barutçular, C., Iqbal, M.A., Islam, M.S., Fahad, S., Sytar, O., Çiğ, F., Meena, R.S. and Erman, M. (2020). Consequences of Salinity Stress on the Quality of Crops and its Mitigation Strategies for Sustainable Crop Production: An Outlook of Arid and Semi-arid Regions. In Environment, Climate, Plant and Vegetation Growth. Cham: Springer International Publishing. (pp. 503-533). https:// doi.org/10.1007/978-3-030-49732-3_20.

  17. Eleish, A.M., Osman, M.S. and Nowwar, A.I. (2026). Eco-friendly biostimulant role of moringa oleifera in enhancing photosynthetic pigments, osmotic balance and yield quality of faba bean under salinity stress. Egyptian Journal of Botany. 66(2): 375-384. https://doi.org/10.21608/ejbo.2026.440481. 3498.

  18. ElSayed, A.I., Rafudeen, M.S., Ganie, S.A., Hossain, M.S. and Gomaa, A.M. (2022). Seed priming with cypress leaf extract enhances photosynthesis and antioxidative defense in zucchini seedlings under salt stress. Scientia Horticulturae. 293: 110707. https://doi.org/10.1016/j.scienta. 2021.110 707.

  19. Guan, R., Yu, L., Liu, X., Li, M., Chang, R., Gilliham, M. and Qiu, L. (2021). Selection of the salt tolerance gene GmSALT3 during six decades of soybean breeding in China. Frontiers in Plant Science. 12: 794241. https://doi.org/10.3389/ fpls.2021.794241.

  20. Hamwieh, A., Tuyen, D.D., Cong, H., Benitez, E.R., Takahashi, R. and Xu, D.H. (2011). Identification and validation of a major QTL for salt tolerance in soybean. Euphytica. 179(3): 451-459. https://doi.org/10.1007/s10681-011- 0347-8.

  21. Hamza, M., Basit, A.W., Shehzadi, I., Tufail, U., Hassan, A., Hussain, T., Siddique, M.U. and Hayat, H.M. (2024). Global impact of soybean production: A review. Asian Journal of Biochemistry, Genetics and Molecular Biology. 16(2): 12-20. https://doi.org/10.9734/ajbgmb/2024/v16i2357.

  22. Hasanuzzaman, M., Parvin, K., Anee, T.I., Masud, A.A.C. and Nowroz, F. (2022). Salt Stress Responses and Tolerance in Soybean. In Plant Stress Physiology-perspectives in Agriculture. IntechOpen. https://doi.org/10.5772/intechopen.102835

  23. Hussain, S., Shaukat, M., Ashraf, M., Zhu, C., Jin, Q. and Zhang, J. (2019). Salinity Stress in Arid and Semi-arid Climates: Effects and Management in Field Crops. In Climate Change and Agriculture. IntechOpen. https://doi.org/10.5772/ intechopen.87982

  24. Jaybhay, S.A., P.G., S., Tetali, S.P., Idhol, B.D., Salunkhe, D.H., Sarode, J.S. and Oak, M.D., (2025). Exploring the combined effect of microbial consortia and fertilizers on growth and yield of soybean [Glycine max (L.) Merrill.]. Legume Research. 49(7): 1243-1249. doi: 10.18805/LR-5470.

  25. Johnson, R., Joel, J.M. and Puthur, J.T. (2024). Biostimulants: The futuristic sustainable approach for alleviating crop productivity and abiotic stress tolerance. Journal of Plant Growth Regulation. 43(3): 659-674. https://doi.org/10.1007/ s00344-023-11144-3.

  26. Kar, M. and Mishra, D. (1976). Catalase, peroxidase and polyphenoloxidase activities during rice leaf senescence. Plant Physiology. 57(2): 315-319. https://doi.org/10.1104/pp.57.2.315.

  27. Kavitha, R., Chitrarasu, V., Sabaridas, M. and Pavithra, M. (2022). Phytochemical composition and in vitro antioxidant activity of aerial part of aqueous extract of Stachytarpheta jamaicensis (Verbenaceae). Indian Journal of Natural Sciences. 13(73): 46377.

  28. Kim, S.T. and Sang, M.K. (2023). Enhancement of osmotic stress tolerance in soybean seed germination by bacterial bioactive extracts. Plos One. 18(10): e0292855. https:/ /doi.org/10.1371/journal.pone.0292855.

  29. Lichtenthaler, H.K. (1987). Chlorophylls and carotenoids: Pigments of photosynthetic biomembranes. In Methods in Enzymology. Academic Press. (Vol. 148, pp. 350-382).  https://doi.org/ 10.1016/0076-6879(87)48036-1

  30. Liew, P.M. and Yong, Y.K., (2016). Stachytarpheta jamaicensis (L.) Vahl: From traditional usage to pharmacological evidence. Evidence Based Complementary and Alternative Medicine. 2016(1): 7842340. https://doi.org/10.1155/2016/7842340.

  31. Malekzadeh, P. (2015). Influence of exogenous application of glycinebetaine on antioxidative system and growth of salt-stressed soybean seedlings (Glycine max L.). Physiology and Molecular biology of Plants. 21(2): 225- 232. https://doi.org/10.1007/s12298-015-0292-4.

  32. Mannan, M.A., Yasmin, A., Sarker, U., Bari, N., Dola, D.B., Higuchi, H., Ercisli, S., Ali, D. and Alarifi, S. (2023). Biostimulant red seaweed (Gracilaria tenuistipitata var. liui) extracts spray improves yield and drought tolerance in soybean. Peer J. 11: p.e15588. https://doi.org/10.7717/peerj.15 588.

  33. Marklund, S. and Marklund, G. (1974). Involvement of the superoxide anion radical in the autoxidation of pyrogallol and a convenient assay for superoxide dismutase. European Journal of Biochemistry. 47(3): 469-474.

  34. Mutale-joan, C., Rachidi, F., Mohamed, H.A., Mernissi, N. El, Aasfar, A., Barakate, M., Mohammed, D., Sbabou, L. and Arroussi, H.E.l. (2021). Microalgae-cyanobacteria-based biostimulant effect on salinity tolerance mechanisms, nutrient uptake and tomato plant growth under salt stress. Journal of Applied Phycology. 33(6): 3779-3795. https://doi.org/ 10.1007/s10811-021-02559-0.

  35. Ohkawa, H., Ohishi, N. and Yagi, K. (1979). Assay for lipid peroxides in animal tissues by thiobarbituric acid reaction. Analytical Biochemistry. 95(2): 351-358. https://doi.org/10.1016/ 0003-2697(79)90738-3.

  36. Oliveira, P.H.D.A., Sá, S.A.D., Ribeiro, J.E.D.S., Silva, J.P.D., Lima, F.F.D., Silva, I.B., Silveira, L.M.D. and Barros, A.P. (2024). Exogenous application of melatonin mitigates salt stress in soybean. Revista Caatinga. 38: e12698. https://doi. org/10.1590/1983-21252025v3812698rc.

  37. Osman, M.S., Badawy, A.A., Osman, A.I., Abdel, A. and Abdel, H. (2021). Ameliorative impact of an extract of the halophyte Arthrocnemum macrostachyum on growth and biochemical parameters of soybean under salinity stress. Journal of Plant Growth Regulation. 40(3): 1245-1256. https://doi. org/10.1007/s00344-020-10185-2.

  38. Parvin, K., Hasanuzzaman, M., Bhuyan, M.B., Mohsin, S.M. and Fujita, M. (2019). Quercetin mediated salt tolerance in tomato through the enhancement of plant antioxidant defense and glyoxalase systems. Plants. 8(8): 247. https://doi.org/10.3390/plants8080247.

  39. Punithavathi, G., Saravanan, K., Dhanapal, S., Chelladurai, G., Appunu, C., Senthilkumar, N., Kiruthiga, N. and Anbarasu, K. (2026). Valorization of the invasive weed Stachytarpheta jamaicensis (L.) Vahl: Growth-promoting effects on soybean (Glycine max L.). Russian Journal of Plant Physiology.  73(2): 75. https://doi.org/10.1134/S1021443725607475.

  40. Rady, M.M., Talaat, N.B., Abdelhamid, M.T., Shawky, B.T. and Desoky, S.M. (2019). Maize (Zea mays L.) grains extract mitigates the deleterious effects of salt stress on common bean (Phaseolus vulgaris L.) growth and physiology. The Journal of Horticultural Science and Biotechnology. 94(6): 777-789. https://doi.org/10.1080/14620316. 2019. 1626773.

  41. Repke, R.A., Silva, D.M.R., Dos Santos, J.C.C. and de Almeida Silva, M. (2022). Increased soybean tolerance to high- temperature through biostimulant based on Ascophyllum nodosum (L.) seaweed extract. Journal of Applied Phycology. 34(6): 3205-3218. https://doi.org/10.1007/ s10811-022-02821-z.

  42. Salam, U., Ullah, S., Tang, Z.H., Elateeq, A.A., Khan, Y., Khan, J., Khan, A. and Ali, S., (2023). Plant metabolomics: An overview of the role of primary and secondary metabolites against different environmental stress factors. Life. 13: 706. https://doi.org/10.3390/life13030706.

  43. Santos, A.P., Belfiore, C., Úrbez, C., Ferrando, A., Blázquez, M.A. and Farías, M.E. (2023). Extremophiles as plant probiotics to promote germination and alleviate salt stress in soybean. Journal of Plant Growth Regulation. 42(2): 946-959. https://doi.org/10.1007/s00344-022-10605-5.

  44. Saravanan, K., Vidya, N., Halka, J., Kowsalya, K., Appunu, C., Gurusaravanan, P. and Arun, M. (2023). Mitigation of salt stress in soybean [Glycine max (L.) Merrill] using exogenous application of onion extract. Journal of Soil Science and Plant Nutrition. 23(4): 5207-5221. https:// doi.org/10.1007/s42729-023-01393-2.

  45. Singh, A. (2022). Soil salinity: A global threat to sustainable development. Soil Use and Management. 38(1): 39-67. https://doi.org/10.1111/sum.12772.

  46. Singh, B., Kaur, G., Quintana-Ashwell, N.E., Singh, G., Lo, T.H. and Nelson, K.A. (2023). Row spacing and irrigation management affect soybean yield, water use efficiency and economics. Agricultural Water Management. 277: 108087. https:// doi.org/10.1016/j.agwat.2022.108087.

  47. Singh, P., Arif, Y., Bajguz, A. and Hayat, S. (2021). The role of quercetin in plants. Plant Physiology and Biochemistry. 166: 10-19. https://doi.org/10.1016/j.plaphy.2021.05.023.

  48. Tran, T.A.T. and Hoang, T.T.H. (2026). Combined inoculation of rhizobium and nitrogen fertiliser application on nitrogen fixation in soybean (Glycine max L.) at Central Vietnam. Legume Research: An International Journal. 49(6): 1022-1026. doi: 10.18805/LRF-922.

  49. Utami, J.P., Diana, S., Arifin, R., Taufiqurrahman, I., Nugraha, K.A., Sari, M.W. and Wardana, R.Y. (2022). Antibacterial activity of Stachytarpheta jamaicensis (L.) Vahl roots extract on some bacteria proteins: An in silico and in vitro study. J Pharm Pharmacog Res. 10(6): 1087-1102. https:// doi.org/10.56499/jppres22.1474_10.6.1087.

  50. Velikova, V., Yordanov, I. and Edreva, A. (2000). Oxidative stress and some antioxidant systems in acid rain-treated bean plants. Plant Science. 151(1): 59-66. https://doi.org/ 10.1016/S0168-9452(99)00197-1.

  51. Verma, O., Sharma, S., Kumar, V., Singh, T., Kumar, R. and Auji, R. (2024). Salinity stress effect on staple food crops and novel mitigation strategies. Biologia. 79(8): 2359-2374. https://doi.org/10.1007/s11756-024-01689-3.

  52. Wang, T., Xun, H., Wang, W., Ding, X., Tian, H., Hussain, S., Dong, Q., Li, Y., Cheng, Y., Wang, C., Lin, R., Li, G., Qian, X., Pang, J., Feng, X., Dong, Y., Liu, B. and Wang, S. (2021). Mutation of GmAITR Genes by CRISPR/Cas9 genome editing results in enhanced salinity stress tolerance in soybean. Frontiers in Plant Science. 12: 779598. https:/ /doi.org/10.3389/fpls.2021.779598.

  53. Wang, Y., Yang, Y., Zhao, D., Li, Z., Sui, X., Zhang, H., Liu, J., Li, Y., Zhang, C.S. and Zheng, Y. (2024). Ensifer sp. GMS14 enhances soybean salt tolerance for potential application in saline soil reclamation. Journal of Environmental Management. 349: 119488. https://doi.org/10.1016/j.jen vman.2023.119488.
Published In
Legume Research
Article Metrics
Metrics Icon
66
Views
0
Citations
Reviewed By
Share Article
Download Article
In this Article
    Contact us
    Follow us

    Full Research Article

    Mitigation of Salinity Stress in Soybean [Glycine max (L.) Merrill] using Exogenous Soil Drenching with Stachytarpheta jamaicensis (L.) Vahl Extract

    G
    Gnanaprakasam Punithavathi1
    K
    Krishnagowdu Saravanan1
    https://orcid.org/0000-0003-0310-1379
    S
    Sundarasamy Dhanapal1,*
    0009-0009-3226-7897
    C
    Chinnaswamy Appunu2,*
    0000-0002-5505-9611
    A
    Aslam Afzal1
    1Post Graduate and Research Centre in Biotechnology, School of Life Sciences, Arignar Anna College (Arts and Science) (Affiliated to Periyar University), Krishnagiri-635 115, Tamil Nadu, India.
    2Division of Crop Improvement, Indian Council of Agricultural Research-Sugarcane Breeding Institute, Coimbatore-641 007, Tamil Nadu, India.

    • Submitted01-05-2026|

    • Accepted05-08-2026|

    • First Online 04-09-2026|

    • doi 10.18805/LR-5673

    ABSTRACT

    Background: Salinity stress limits soybean (Glycine max) productivity by impairing growth, photosynthesis and cellular balance. This study evaluated Stachytarpheta jamaicensis (L.) Vahl leaf extract (SjE) as a natural biostimulant to mitigate salinity stress.

    Methods: Soybean plants were exposed to 100 mM NaCl (SS-100) and treated with SjE (10% and 25%) via soil drenching. Growth, photosynthetic pigments, oxidative markers (LPO, H2O2) and antioxidant enzymes (SOD, CAT, POD) were assessed.

    Result: Salinity reduced growth and pigments while increasing oxidative damage. SjE, especially at 10%, improved growth, restored pigments, reduced LPO and H2O2 and enhanced antioxidant enzymes. These effects are linked to phenolics and flavonoids. Overall, 10% SjE showed optimal performance, highlighting its potential as an eco-friendly biostimulant for salinity stress tolerance.

    INTRODUCTION

    Soybean [Glycine max (L.) Merrill; Fabaceae] is a major legume crop valued for its high protein and oil content and its role in improving soil fertility through biological nitrogen fixation (Abd-Alla et al., 2023; Dilawari et al., 2022). Although global production has increased (Hamza et al., 2024), yield is severely constrained by abiotic stresses, particularly salinity (Hasanuzzaman et al., 2022). Salinity, prevalent in arid and semi-arid regions, disrupts plant growth and productivity due to excessive salt accumulation in soils (Hussain et al., 2019; El Sabagh et al., 2020). Field studies have demonstrated that salinity significantly reduces soybean plant establishment, biomass accumulation, nodulation, pod development, seed yield and seed quality, resulting in substantial economic losses (Day and Şahin 2024; Hasanuzzaman et al., 2022; Singh, 2022; Hamwieh et al., 2011). Therefore, developing sustainable approaches to improve salinity tolerance in soybean has become an important research priority.
           
    Several strategies have been developed to mitigate salinity-induced yield losses in soybean (Verma et al., 2024), including soil reclamation (Wang et al., 2024; Abiala et al., 2018), enhanced irrigation (Singh et al., 2023) and breeding for salt-tolerant cultivars (Chen et al., 2024a; Guan et al., 2021; Hamwieh et al., 2011). Advanced approaches such as transgenics and genome editing have also enhanced salt tolerance (Chen et al., 2024b; Wang et al., 2021), but require high cost, regulatory approval and advanced infrastructure. Plant biostimulants have recently emerged as eco-friendly alternatives (Johnson et al., 2024). Derived from plant extracts (Saravanan et al., 2023; Osman et al., 2021), seaweeds (Mannan et al., 2023; Repke et al., 2022), microorganisms (Tran and Hoang 2026; Jaybhay et al., 2025; Santos et al., 2023; El-Esawi et al., 2018) and organic compounds (Oliveira et al., 2024; Kim and Sang, 2023; Malekzadeh, 2015) they enhance growth, nutrient uptake, antioxidant defense and hormonal balance, largely due to bioactive compounds such as phenolics and flavonoids (Salam et al., 2023).
           
    Among plant-derived biostimulants, Stachytarpheta jamaicensis (L.) Vahl (Verbenaceae) has gained attention due to its diverse phytochemical profile and adaptability (Chongloi et al., 2025). Widely distributed in tropical and subtropical regions, it is considered an aggressive invasive species (Liew and Yong, 2016). Despite this, it contains bioactive compounds such as phenolics, flavonoids, tannins and antioxidants with significant biological activity (Chongloi et al., 2025; Bliss et al., 2022; Kavitha et al., 2022; Utami et al., 2022). These compounds contribute to stress tolerance by enhancing antioxidant systems, maintaining osmotic balance and protecting cellular structures from oxidative damage (Salam et al., 2023). However, despite its rich phytochemical profile and stress-adaptive characteristics, the potential of S. jamaicensis leaf extract as a natural biostimulant for mitigating salinity stress in soybean has not yet been investigated. Therefore, the present study evaluated the effectiveness of exogenous soil drenching with S. jamaicensis leaf extract in improving growth, photosynthetic performance, antioxidant defense and oxidative stress tolerance in soybean under saline conditions. This study provides new evidence supporting the utilization of an invasive weed as a sustainable and eco-friendly biostimulant for soybean cultivation in salt-affected soils.

    MATERIALS AND METHODS

    Treatment procedure
     
    Leaf extract of Stachytarpheta jamaicensis was prepared as protocol by Punithavathi et al., (2026). Soybean (Glycine max) seeds (cv. JS-335) were sown in plastic pots (4-inch; top diameter 13 cm, base 10 cm, height 11 cm) and maintained under controlled conditions (25±2°C; ~80% relative humidity). Five days after germination, plants were divided into six treatment groups:
    1. C - Control: Plants received water alone.
    2. SjE-10%: Plant received 10% S. jamaicensis extract.
    3. SjE-25%: Plant received 25% S. jamaicensis extract.
    4. SS-100: Plants received 100 mM NaCl alone.
    5. SjE-10% + SS-100: Plants received combined treatments of 10% S. jamaicensis extract along with 100 mM NaCl.
    6. SjE-25% + SS-100: Plants received combined treatments of 25% S. jamaicensis extract along with 100 mM NaCl.
           
    Treatments were applied as soil drenching at 5-day intervals for a total of six applications. Plants were harvested on the 33rd day after sowing for subsequent morphological (mean number of leaves, shoot length, shoot fresh biomass, number of roots, root length and root fresh weight), physiological and biochemical analyses.
     
    Physiological analysis
     
    Assessment on photosynthetic pigments
     
    Photosynthetic pigments were estimated following the methods of Lichtenthaler (1987) and Arnon (1949).
     
    Biochemical characterization
     
    Preparation of enzyme extract
     
    Soybean tissues were homogenized and centrifuged and the supernatant was used for protein estimation (Bradford, 1976) and future analysis.
     
    Determination of oxidative stress markers
     
    Lipid peroxidation (LPO) and hydrogen peroxide (H2O2) contents were determined following Ohkawa et al., (1979) and Velikova et al., (2000), respectively.
     
    Enzymatic antioxidant activities
     
    Activities of superoxide dismutase (SOD), peroxidase (POD) and catalase (CAT) were assayed according to Marklund and Marklund (1974); Kar and Mishra (1976) and Aebi (1984), respectively.
     
    Statistical analysis
     
    Data were analysed using IBM SPSS Statistics 20 (IBM Corp., USA). Morphological data (n=5 × 2) and physiological/biochemical data (n = 4) are presented as mean ± SE. Significant differences were determined by DMRT at P≤0.05.

    RESULTS AND DISCUSSION

    Morphological analysis
     
    Salinity stress (SS-100) significantly reduced soybean growth, with decline in leaf number (42.55%), shoot length (44.76%), shoot fresh weight (45.60%), root number (26.54%), root length (36.58%) and root fresh weight (22.91%) compared to control. SjE improved growth under non-stress conditions, particularly at 10%, increasing leaf number (34.04%), shoot length (19.53%), biomass (42.40%), root number (27.43%), root length (28.90%) and root fresh weight (62.50%). In contrast, SjE-25% reduced growth (23.40-34.92%), indicating dose-dependent inhibition. Under salinity, SjE partially restored growth. SjE-10% + SS-100 increased leaf number (74.1%), shoot length (12.3%), shoot biomass (97.1%), root number (25.3%) and root length (35.5%) over SS-100, though root fresh weight declined (35.1%). SjE-25% + SS-100 showed limited improvement. These results indicate that 10% SjE is optimal for growth enhancement (Table 1 and Fig 1).

    Table 1: Influence of Stachytarpheta jamaicensis extract treatments on growth attributes of soybean plants under salinity stress conditions.



    Fig 1: Effects of Stachytarpheta jamaicensis extract (SjE) on soybean under salinity stress.


           
    Salinity stress markedly inhibited soybean growth by reducing leaf number, shoot and root length and biomass, reflecting the adverse effects of osmotic stress, ion toxicity and nutrient imbalance on plant development. Similar reductions in soybean growth under saline conditions have been reported by Hasanuzzaman et al., (2022), Osman et al. (2021) and where salinity impaired cell expansion, water uptake and overall biomass accumulation. In the present study, exogenous soil drenching with 10% Stachytarpheta jamaicensis extract (SjE) significantly alleviated these growth reductions, indicating its biostimulant potential. Comparable growth-promoting effects have been reported with onion extract in soybean (Saravanan et al., 2023) and maize grain extract in common bean under salinity (Rady et al., 2019). The improved growth observed in SjE-treated plants may be associated with its phenolic- and flavonoid-rich composition, which enhances antioxidant capacity, regulates auxin homeostasis, promotes root development and improves nutrient acquisition under saline conditions (Singh et al., 2021). Interestingly, the 25% extract was less effective than the 10% treatment, suggesting that excessive concentrations may interfere with normal metabolism, highlighting the importance of optimizing biostimulant dosage.
     
    Physiological analysis
     
    Assessment on photosynthetic pigments
     
    Salinity stress reduced chlorophyll a (31.1%), chlorophyll b (42.6%), total chlorophyll (38.1%) and carotenoids (27.4%) compared to control. SjE enhanced pigment levels under non-stress conditions, with SjE-10% increasing chlorophyll a (61.5%), chlorophyll b (76.0%), total chlorophyll (70.4%) and carotenoids (2.26-fold). SjE-25% also improved pigments but to a lesser extent. Under salinity, SjE-10% + SS-100 significantly restored pigments, increasing chlorophyll a, b and total chlorophyll (~2.08-2.09-fold) and carotenoids (2.27-fold) compared to SS-100. SjE-25% + SS-100 showed moderate improvements. Overall, 10% SjE effectively alleviated pigment loss under salinity (Fig 2).

    Fig 2: Effect of Stachytarpheta jamaicensis extract (SjE) on photosynthetic pigments under salinity stress.


           
    Salinity-induced reductions in chlorophyll a, chlorophyll b, total chlorophyll and carotenoids indicate severe impairment of the photosynthetic apparatus. These observations agree with previous soybean studies demonstrating that salinity accelerates chlorophyll degradation, damages chloroplast ultrastructure and decreases photosynthetic efficiency (Hasanuzzaman et al., 2022; Parvin et al., 2019). Application of SjE, particularly at 10%, significantly restored pigment content under salinity stress, suggesting effective protection of the photosynthetic machinery. The phenolic and flavonoid constituents of S. jamaicensis may protect chloroplast membranes against ROS-induced damage while maintaining chlorophyll biosynthesis. Similar improvements in photosynthetic pigments have been reported following application of Moringa oleifera leaf extract in faba bean (Eleish et al., 2026), cypress leaf extract in zucchini (ElSayed et al., 2022) and yeast and carrot root extracts in maize (Abdel Latef et al., 2019). These findings collectively indicate that plant-derived biostimulants preserve photosynthetic efficiency by maintaining chloroplast integrity and reducing oxidative damage.
     
    Biochemical characterization
     
    Lipid peroxidation (LPO) and hydrogen peroxide (H2O2) content and enzymatic antioxidant activity
     
    Salinity stress markedly increased oxidative damage, with LPO rising 2.50-fold and H2O2 3.62-fold compared to control (Fig 3). SjE application reduced these effects under salinity. SjE-10% + SS-100 decreased LPO (36.84%) and H2O2 (45.82%), while SjE-25% + SS-100 reduced LPO (~16.41%) and H2O2  (~25.73%). The 10% treatment showed stronger protection against oxidative stress (Fig 3). Salinity stress reduced SOD (48.22%), CAT (64.91%) and POD (56.27%) activities compared to control. SjE enhanced enzyme activities under non-stress conditions, with SjE-10% increasing SOD (2.4-fold), CAT (1.68-fold) and POD (2.18-fold), while SjE-25% showed lower stimulation. Under salinity, SjE improved antioxidant responses. SjE-10% + SS-100 increased SOD (2.51-fold), CAT (3.16-fold) and POD (4.56-fold). Overall, SjE, particularly at 10%, effectively restored antioxidant defense and reduced oxidative damage (Fig 4). Overall, these results demonstrate that SjE effectively reinforces the antioxidant defense machinery under salinity stress, with 10% concentration showing maximum efficiency in restoring enzymatic activities and protecting plants from oxidative damage.

    Fig 3: Inhibitory effect of Stachytarpheta jamaicensis extract (SjE) on oxidative stress markers under salinity stress.



    Fig 4: Effect of Stachytarpheta jamaicensis extract (SjE) on antioxidant enzymes under salinity.


           
    The substantial increase in LPO and H2O2 under salinity confirms enhanced ROS generation and membrane lipid peroxidation, which are characteristic responses of soybean exposed to salt stress (Hasanuzzaman et al., 2022). SjE application significantly reduced both oxidative stress markers, indicating effective protection against ROS-mediated cellular damage. This response is likely attributable to the high antioxidant potential of S. jamaicensis, particularly its phenolics and flavonoids, which directly scavenge ROS and stabilize membrane integrity. Similar reductions in oxidative stress have been reported following application of plant-derived antioxidants (Ahmad et al., 2022) and licorice root extract in pea (Desoky et al., 2019). The enhanced activities of SOD, POD and CAT further demonstrate that SjE strengthens the soybean antioxidant defense system under salinity stress. SOD catalyzes the conversion of superoxide radicals into H2O2, whereas CAT and POD subsequently detoxify H2O2 into water and oxygen, thereby limiting oxidative injury. Similar enhancement of antioxidant enzymes has been reported in soybean inoculated with Bacillus firmus (El-Esawi et al., 2018) and tomato supplemented with microalgae–cyanobacteria biostimulants (Mutale-joan et al., 2021). The consistently greater effectiveness of the 10% extract compared with the 25% treatment further indicates that moderate concentrations are sufficient to maximize antioxidant protection without imposing metabolic constraints. Overall, the present study demonstrates that Stachytarpheta jamaicensis leaf extract effectively mitigates salinity stress by enhancing growth, preserving photosynthetic pigments, reducing oxidative damage and activating enzymatic antioxidant defenses (Fig 5). Unlike previous studies that mainly evaluated conventional plant extracts or microbial biostimulants, this study provides the first evidence that an invasive weed species, S. jamaicensis, can be successfully utilized as a sustainable and eco-friendly biostimulant to improve salinity tolerance in soybean. These findings support its potential application for sustainable soybean cultivation in salt-affected soils and provide a strong basis for future multi-season field validation.

    Fig 5: Graphical illustration of Stachytarpheta jamaicensis extract (SjE) enhancing morpho-physiological traits and antioxidant activities while reducing oxidative stress in soybean under salinity conditions.

    CONCLUSION

    Exogenous soil drenching with Stachytarpheta jamaicensis extract effectively mitigated salinity stress in soybean (Glycine max) by improving growth, restoring photosynthetic pigments and enhancing antioxidant defense. The treatment significantly reduced oxidative damage (LPO and H2O2) while stimulating key enzymes (SOD, CAT, POD). Among the tested doses, 10% extract consistently showed superior performance compared to 25%. The findings highlight the potential of S. jamaicensis as a cost-effective and eco-friendly biostimulant. This approach offers a promising strategy for improving crop resilience under saline conditions.

    ACKNOWLEDGEMENT

    The authors are thankful to the management of the Arignar Anna College (Arts and Science), Krishnagiri-635 115, Tamil Nadu, India for proving the necessary research and infrastructure facilities for this research work.
     
    Disclaimers
     
    The views and conclusions expressed in this article are solely those of the authors and do not necessarily represent the views of their affiliated institutions. The authors are responsible for the accuracy and completeness of the information provided, but do not accept any liability for any direct or indirect losses resulting from the use of this content.

    CONFLICT OF INTEREST

    The authors declare that there are no conflicts of interest regarding the publication of this article. No funding or sponsorship influenced the design of the study, data collection, analysis, decision to publish, or preparation of the manuscript.

    REFERENCES


    1. Abd-Alla, M.H., Al-Amri, S.M. and El-Enany, A.W.E. (2023). Enhancing rhizobium-legume symbiosis and reducing nitrogen fertilizer use are potential options for mitigating climate change. Agriculture. 13: 2092. https://doi.org/10.3390/agriculture 13112092.

    2. Abdel Latef, A.A.H., Mostofa, M.G., Rahman, M.M., Abdel-Farid, I.B. and Tran, L.S.P. (2019). Extracts from yeast and carrot roots enhance maize performance under seawater- induced salt stress by altering physio-biochemical characteristics of stressed plants. Journal of Plant Growth Regulation. 38(3): 966-979. https://doi.org/10.1007/s00 344-018-9906-8.

    3. Abiala, M.A., Abdelrahman, M., Burritt, D.J. and Tran, L.S.P. (2018). Salt stress tolerance mechanisms and potential applications of legumes for sustainable reclamation of salt degraded soils. Land Degradation and Development. 29(10): 3812-3822. https://doi.org/10.1002/ldr.3095.

    4. Aebi, H. (1984). [13] Catalase in vitro. pp. 121–126. https://doi.org/ 10.1016/S0076-6879(84)05016-3.

    5. Ahmad, A., Blasco, B. and Martos, V. (2022). Combating salinity through natural plant extracts based biostimulants: A review. Frontiers in Plant Science. 13: 862034. https://doi.org/10.3389/fpls.2022.862034.

    6. Arnon, D.I. (1949). Copper enzymes in isolated chloroplasts. Polyphenoloxidase in Beta vulgaris. Plant Physiology. 24(1): 1. https://doi.org/10.1104/pp.24.1.1.

    7. Bliss, O., Ejiofor, E., Njoku, C., Ejiofor, M. and Michael, K. (2022). GC-MS Characterization, in vitro Antioxidant and anti- inflammatory activities of essential oil from the leaves of Stachytarpheta jamaicensis. Journal of the Mexican Chemical Society. 66(4): 433-443. https://doi.org/10.29 356/jmcs.v66i4.1822.

    8. Bradford, M.M. (1976). A rapid and sensitive method for the quantitation of microgram quantities of protein utilizing the principle of protein-dye binding. Analytical Biochemistry. 72(1-2): 248-254. https://doi.org/10.1016/0003-2697(76)90527-3.

    9. Chen, L., Peng, L., Ouyang, W., Yao, H., Ye, Y., Shan, Z., Cao, D., Chen, S., Yang, Z., Huang, Y., Han, B., Sha, A., Zhou, X. and Chen, H. (2024a). Screening and identification of salt tolerance soybean varieties and germplasms. Oil Crop Science. 9(3): 204-210. https://doi.org/10.1016/ j.ocsci.2024.06.005.

    10. Chen, X., Jiang, X., Sun, X., Hu, Z., Gao, F., Wang, X., Zhang, H., Chen, R. and Jiang, Q. (2024b). Gene editing and over expression of soybean miR396a reveals its role in salinity tolerance and development. The Crop Journal. 12(6): 1655-1665. https://doi.org/10.1016/j.cj.2024.08.003.

    11. Chongloi, V., Gogoi, P.P., Sangma, S.R., Sinha, U.B., Bora, P. and Phukan, M.M. (2025). Antioxidant, antimicrobial and in silico investigations on pyrolytic bio-oil from invasive Stachytarpheta jamaicensis. Environmental Science and Pollution Research. 32(30): 18260-18277. https:// doi.org/10.1007/s11356-025-36741-5.

    12. Day, S. and Şahin, N.K. (2024). Determination of seed size properties of soybean cultivars and their response under salinity during early growth. Legume Research: An International Journal. 47(6): 945-951. doi: 10.18805/LRF-780.

    13. Desoky, E.S.M., ElSayed, A.I., Merwad, A.R.M.A. and Rady, M.M. (2019). Stimulating antioxidant defenses, antioxidant gene expression and salt tolerance in pisum sativum seedling by pretreatment using licorice root extract (LRE) as an organic biostimulant. Plant Physiology and Biochemistry. 142: 292-302. https://doi.org/10.1016/j.plaphy.2019.07. 020.

    14. Dilawari, R., Kaur, N., Priyadarshi, N., Prakash, I., Patra, A., Mehta, S., Singh, B., Jain, P. and Islam, M.A. (2022). Soybean: A key player for global food security. In Soybean improvement: physiological, molecular and genetic perspectives. Cham: Springer International Publishing. (pp. 1-46). https://doi. org/10.1007/978-3-031-12232-3_1.

    15. El-Esawi, M.A., Alaraidh, I.A., Alsahli, A.A., Alamri, S.A., Ali, H.M. and Alayafi, A.A. (2018). Bacillus firmus (SW5) augments salt tolerance in soybean (Glycine max L.) by modulating root system architecture, antioxidant defense systems and stress-responsive genes expression. Plant Physiology and Biochemistry. 132: 375-384. https://doi.org/10.1016/ j.plaphy.2018.09.026.

    16. El Sabagh, A., Hossain, A., Barutçular, C., Iqbal, M.A., Islam, M.S., Fahad, S., Sytar, O., Çiğ, F., Meena, R.S. and Erman, M. (2020). Consequences of Salinity Stress on the Quality of Crops and its Mitigation Strategies for Sustainable Crop Production: An Outlook of Arid and Semi-arid Regions. In Environment, Climate, Plant and Vegetation Growth. Cham: Springer International Publishing. (pp. 503-533). https:// doi.org/10.1007/978-3-030-49732-3_20.

    17. Eleish, A.M., Osman, M.S. and Nowwar, A.I. (2026). Eco-friendly biostimulant role of moringa oleifera in enhancing photosynthetic pigments, osmotic balance and yield quality of faba bean under salinity stress. Egyptian Journal of Botany. 66(2): 375-384. https://doi.org/10.21608/ejbo.2026.440481. 3498.

    18. ElSayed, A.I., Rafudeen, M.S., Ganie, S.A., Hossain, M.S. and Gomaa, A.M. (2022). Seed priming with cypress leaf extract enhances photosynthesis and antioxidative defense in zucchini seedlings under salt stress. Scientia Horticulturae. 293: 110707. https://doi.org/10.1016/j.scienta. 2021.110 707.

    19. Guan, R., Yu, L., Liu, X., Li, M., Chang, R., Gilliham, M. and Qiu, L. (2021). Selection of the salt tolerance gene GmSALT3 during six decades of soybean breeding in China. Frontiers in Plant Science. 12: 794241. https://doi.org/10.3389/ fpls.2021.794241.

    20. Hamwieh, A., Tuyen, D.D., Cong, H., Benitez, E.R., Takahashi, R. and Xu, D.H. (2011). Identification and validation of a major QTL for salt tolerance in soybean. Euphytica. 179(3): 451-459. https://doi.org/10.1007/s10681-011- 0347-8.

    21. Hamza, M., Basit, A.W., Shehzadi, I., Tufail, U., Hassan, A., Hussain, T., Siddique, M.U. and Hayat, H.M. (2024). Global impact of soybean production: A review. Asian Journal of Biochemistry, Genetics and Molecular Biology. 16(2): 12-20. https://doi.org/10.9734/ajbgmb/2024/v16i2357.

    22. Hasanuzzaman, M., Parvin, K., Anee, T.I., Masud, A.A.C. and Nowroz, F. (2022). Salt Stress Responses and Tolerance in Soybean. In Plant Stress Physiology-perspectives in Agriculture. IntechOpen. https://doi.org/10.5772/intechopen.102835

    23. Hussain, S., Shaukat, M., Ashraf, M., Zhu, C., Jin, Q. and Zhang, J. (2019). Salinity Stress in Arid and Semi-arid Climates: Effects and Management in Field Crops. In Climate Change and Agriculture. IntechOpen. https://doi.org/10.5772/ intechopen.87982

    24. Jaybhay, S.A., P.G., S., Tetali, S.P., Idhol, B.D., Salunkhe, D.H., Sarode, J.S. and Oak, M.D., (2025). Exploring the combined effect of microbial consortia and fertilizers on growth and yield of soybean [Glycine max (L.) Merrill.]. Legume Research. 49(7): 1243-1249. doi: 10.18805/LR-5470.

    25. Johnson, R., Joel, J.M. and Puthur, J.T. (2024). Biostimulants: The futuristic sustainable approach for alleviating crop productivity and abiotic stress tolerance. Journal of Plant Growth Regulation. 43(3): 659-674. https://doi.org/10.1007/ s00344-023-11144-3.

    26. Kar, M. and Mishra, D. (1976). Catalase, peroxidase and polyphenoloxidase activities during rice leaf senescence. Plant Physiology. 57(2): 315-319. https://doi.org/10.1104/pp.57.2.315.

    27. Kavitha, R., Chitrarasu, V., Sabaridas, M. and Pavithra, M. (2022). Phytochemical composition and in vitro antioxidant activity of aerial part of aqueous extract of Stachytarpheta jamaicensis (Verbenaceae). Indian Journal of Natural Sciences. 13(73): 46377.

    28. Kim, S.T. and Sang, M.K. (2023). Enhancement of osmotic stress tolerance in soybean seed germination by bacterial bioactive extracts. Plos One. 18(10): e0292855. https:/ /doi.org/10.1371/journal.pone.0292855.

    29. Lichtenthaler, H.K. (1987). Chlorophylls and carotenoids: Pigments of photosynthetic biomembranes. In Methods in Enzymology. Academic Press. (Vol. 148, pp. 350-382).  https://doi.org/ 10.1016/0076-6879(87)48036-1

    30. Liew, P.M. and Yong, Y.K., (2016). Stachytarpheta jamaicensis (L.) Vahl: From traditional usage to pharmacological evidence. Evidence Based Complementary and Alternative Medicine. 2016(1): 7842340. https://doi.org/10.1155/2016/7842340.

    31. Malekzadeh, P. (2015). Influence of exogenous application of glycinebetaine on antioxidative system and growth of salt-stressed soybean seedlings (Glycine max L.). Physiology and Molecular biology of Plants. 21(2): 225- 232. https://doi.org/10.1007/s12298-015-0292-4.

    32. Mannan, M.A., Yasmin, A., Sarker, U., Bari, N., Dola, D.B., Higuchi, H., Ercisli, S., Ali, D. and Alarifi, S. (2023). Biostimulant red seaweed (Gracilaria tenuistipitata var. liui) extracts spray improves yield and drought tolerance in soybean. Peer J. 11: p.e15588. https://doi.org/10.7717/peerj.15 588.

    33. Marklund, S. and Marklund, G. (1974). Involvement of the superoxide anion radical in the autoxidation of pyrogallol and a convenient assay for superoxide dismutase. European Journal of Biochemistry. 47(3): 469-474.

    34. Mutale-joan, C., Rachidi, F., Mohamed, H.A., Mernissi, N. El, Aasfar, A., Barakate, M., Mohammed, D., Sbabou, L. and Arroussi, H.E.l. (2021). Microalgae-cyanobacteria-based biostimulant effect on salinity tolerance mechanisms, nutrient uptake and tomato plant growth under salt stress. Journal of Applied Phycology. 33(6): 3779-3795. https://doi.org/ 10.1007/s10811-021-02559-0.

    35. Ohkawa, H., Ohishi, N. and Yagi, K. (1979). Assay for lipid peroxides in animal tissues by thiobarbituric acid reaction. Analytical Biochemistry. 95(2): 351-358. https://doi.org/10.1016/ 0003-2697(79)90738-3.

    36. Oliveira, P.H.D.A., Sá, S.A.D., Ribeiro, J.E.D.S., Silva, J.P.D., Lima, F.F.D., Silva, I.B., Silveira, L.M.D. and Barros, A.P. (2024). Exogenous application of melatonin mitigates salt stress in soybean. Revista Caatinga. 38: e12698. https://doi. org/10.1590/1983-21252025v3812698rc.

    37. Osman, M.S., Badawy, A.A., Osman, A.I., Abdel, A. and Abdel, H. (2021). Ameliorative impact of an extract of the halophyte Arthrocnemum macrostachyum on growth and biochemical parameters of soybean under salinity stress. Journal of Plant Growth Regulation. 40(3): 1245-1256. https://doi. org/10.1007/s00344-020-10185-2.

    38. Parvin, K., Hasanuzzaman, M., Bhuyan, M.B., Mohsin, S.M. and Fujita, M. (2019). Quercetin mediated salt tolerance in tomato through the enhancement of plant antioxidant defense and glyoxalase systems. Plants. 8(8): 247. https://doi.org/10.3390/plants8080247.

    39. Punithavathi, G., Saravanan, K., Dhanapal, S., Chelladurai, G., Appunu, C., Senthilkumar, N., Kiruthiga, N. and Anbarasu, K. (2026). Valorization of the invasive weed Stachytarpheta jamaicensis (L.) Vahl: Growth-promoting effects on soybean (Glycine max L.). Russian Journal of Plant Physiology.  73(2): 75. https://doi.org/10.1134/S1021443725607475.

    40. Rady, M.M., Talaat, N.B., Abdelhamid, M.T., Shawky, B.T. and Desoky, S.M. (2019). Maize (Zea mays L.) grains extract mitigates the deleterious effects of salt stress on common bean (Phaseolus vulgaris L.) growth and physiology. The Journal of Horticultural Science and Biotechnology. 94(6): 777-789. https://doi.org/10.1080/14620316. 2019. 1626773.

    41. Repke, R.A., Silva, D.M.R., Dos Santos, J.C.C. and de Almeida Silva, M. (2022). Increased soybean tolerance to high- temperature through biostimulant based on Ascophyllum nodosum (L.) seaweed extract. Journal of Applied Phycology. 34(6): 3205-3218. https://doi.org/10.1007/ s10811-022-02821-z.

    42. Salam, U., Ullah, S., Tang, Z.H., Elateeq, A.A., Khan, Y., Khan, J., Khan, A. and Ali, S., (2023). Plant metabolomics: An overview of the role of primary and secondary metabolites against different environmental stress factors. Life. 13: 706. https://doi.org/10.3390/life13030706.

    43. Santos, A.P., Belfiore, C., Úrbez, C., Ferrando, A., Blázquez, M.A. and Farías, M.E. (2023). Extremophiles as plant probiotics to promote germination and alleviate salt stress in soybean. Journal of Plant Growth Regulation. 42(2): 946-959. https://doi.org/10.1007/s00344-022-10605-5.

    44. Saravanan, K., Vidya, N., Halka, J., Kowsalya, K., Appunu, C., Gurusaravanan, P. and Arun, M. (2023). Mitigation of salt stress in soybean [Glycine max (L.) Merrill] using exogenous application of onion extract. Journal of Soil Science and Plant Nutrition. 23(4): 5207-5221. https:// doi.org/10.1007/s42729-023-01393-2.

    45. Singh, A. (2022). Soil salinity: A global threat to sustainable development. Soil Use and Management. 38(1): 39-67. https://doi.org/10.1111/sum.12772.

    46. Singh, B., Kaur, G., Quintana-Ashwell, N.E., Singh, G., Lo, T.H. and Nelson, K.A. (2023). Row spacing and irrigation management affect soybean yield, water use efficiency and economics. Agricultural Water Management. 277: 108087. https:// doi.org/10.1016/j.agwat.2022.108087.

    47. Singh, P., Arif, Y., Bajguz, A. and Hayat, S. (2021). The role of quercetin in plants. Plant Physiology and Biochemistry. 166: 10-19. https://doi.org/10.1016/j.plaphy.2021.05.023.

    48. Tran, T.A.T. and Hoang, T.T.H. (2026). Combined inoculation of rhizobium and nitrogen fertiliser application on nitrogen fixation in soybean (Glycine max L.) at Central Vietnam. Legume Research: An International Journal. 49(6): 1022-1026. doi: 10.18805/LRF-922.

    49. Utami, J.P., Diana, S., Arifin, R., Taufiqurrahman, I., Nugraha, K.A., Sari, M.W. and Wardana, R.Y. (2022). Antibacterial activity of Stachytarpheta jamaicensis (L.) Vahl roots extract on some bacteria proteins: An in silico and in vitro study. J Pharm Pharmacog Res. 10(6): 1087-1102. https:// doi.org/10.56499/jppres22.1474_10.6.1087.

    50. Velikova, V., Yordanov, I. and Edreva, A. (2000). Oxidative stress and some antioxidant systems in acid rain-treated bean plants. Plant Science. 151(1): 59-66. https://doi.org/ 10.1016/S0168-9452(99)00197-1.

    51. Verma, O., Sharma, S., Kumar, V., Singh, T., Kumar, R. and Auji, R. (2024). Salinity stress effect on staple food crops and novel mitigation strategies. Biologia. 79(8): 2359-2374. https://doi.org/10.1007/s11756-024-01689-3.

    52. Wang, T., Xun, H., Wang, W., Ding, X., Tian, H., Hussain, S., Dong, Q., Li, Y., Cheng, Y., Wang, C., Lin, R., Li, G., Qian, X., Pang, J., Feng, X., Dong, Y., Liu, B. and Wang, S. (2021). Mutation of GmAITR Genes by CRISPR/Cas9 genome editing results in enhanced salinity stress tolerance in soybean. Frontiers in Plant Science. 12: 779598. https:/ /doi.org/10.3389/fpls.2021.779598.

    53. Wang, Y., Yang, Y., Zhao, D., Li, Z., Sui, X., Zhang, H., Liu, J., Li, Y., Zhang, C.S. and Zheng, Y. (2024). Ensifer sp. GMS14 enhances soybean salt tolerance for potential application in saline soil reclamation. Journal of Environmental Management. 349: 119488. https://doi.org/10.1016/j.jen vman.2023.119488.
    In this Article
      Contact us
      Follow us
      Published In
      Legume Research

      Editorial Board

      View all (0)