Germination, Growth and Root Responses of Selected Kenyan Cowpea Varieties under Salt Stress
Keywords:
Vigna unguiculata; salt resistance; germination; biomass; root developmentAbstract
Walp.) is an important crop in the semi-arid parts of Kenya, but its response to salt stress is poorly documented. Seventeen Kenyan cowpea varieties were screened in the greenhouse under six NaCl treatments (electrical conductivity, EC, of 0, 4, 8, 12, 14 and 15 dS m⁻¹). Plants were harvested 40 days after planting. We measured germination, plant height, leaf number, shoot fresh and dry weight, root number and total root length. Salinity above 8 dS m⁻¹ delayed germination and reduced germination percentage, biomass and root development, and no seeds germinated at 15 dS m⁻¹. Between the control and 14 dS m⁻¹, mean germination time rose from 5.7 to 18.5 days and germination percentage fell from 98.7% to 55.6%. Across varieties, mean plant height at 14 dS m⁻¹ was about 80% lower than in the control. Kunde Kubwa and Ken Kunde ranked consistently among the best performers. At 14 dS m⁻¹, Kunde Kubwa had the highest shoot fresh weight (2.29 g) and kept 80% germination, and Ken Kunde had the tallest plants (12.1 cm). Kunde Mboga, Kunde Faulu, Black Kunde, Khaki and M 66 performed poorly across several traits at 14 dS m⁻¹. These results show substantial variation in salt response among Kenyan cowpea varieties. They also show that combining establishment, growth, biomass and root traits gives a stronger basis for early-stage salinity screening than any single indicator. Kunde Kubwa and Ken Kunde are recommended for validation under saline field conditions.
References
Abraha, R. H. (2025). The promoting underutilized legumes for food security to small-scale farming communities: Evidence from developing countries and genetic diversity perspectives: Underutilized legumes for food security to small-scale farming communities. African Journal of Rural Development, 10(2), 206–227.
Affrifah, N. S., Phillips, R. D., & Saalia, F. K. (2022). Cowpeas: Nutritional profile, processing methods and products—A review. Legume Science, 4(3), e131.
Afonso, P., Castro, I., & Carvalho, M. (2025). Salt-resilient cowpeas: Early identification through growth parameters and gene expression at germination stage. International Journal of Molecular Sciences, 26(5), 1892.
Arifuddin, W., & Al Banna, M. Z. (2025). Phytochemical profiling and nutritional assessment of indigenous cowpea (Vigna unguiculata L.) cultivars from Bulukumba, South Sulawesi, Indonesia. Chempublish Journal, 9(2), 300–312.
Dadlani, M., & Yadava, D. K. (2023). Seed science and technology: Biology, production, quality (p. 430). Springer Nature.
Dong, L., Ravelombola, W., Weng, Y., Qin, J., Bhattarai, G., Zia, B., … Shi, A. (2019). Seedling salt tolerance for above ground-related traits in cowpea (Vigna unguiculata (L.) Walp). Euphytica, 215(3), 53.
Hasanuzzaman, M., Raihan, M. R. H., Masud, A. A. C., Rahman, K., Nowroz, F., Rahman, M., … Fujita, M. (2021). Regulation of reactive oxygen species and antioxidant defense in plants under salinity. International Journal of Molecular Sciences, 22(17), 9326.
Islam, M. M., Haque, M. S., & Sarwar, A. G. (2019). Salt tolerance of cowpea genotypes during seed germination and seedling growth: Salt tolerance in cowpea genotypes in Bangladesh. Journal of the Bangladesh Agricultural University, 17(1), 39–44.
Jan, S., Ashraf Bhat, M., Kumar, A., Altaf Wani, M., Ahmad Bhat, F., Kanth, R. H., … Naik, Z. A. (2025). Plants response to different abiotic stresses. Journal of Crop Health, 77(5), 139.
Jayawardhane, J., Goyali, J. C., Zafari, S., & Igamberdiev, A. U. (2022). The response of cowpea (Vigna unguiculata) plants to three abiotic stresses applied with increasing intensity: Hypoxia, salinity, and water deficit. Metabolites, 12(1), 38.
Karahara, I., & Horie, T. (2021). Functions and structure of roots and their contributions to salinity tolerance in plants. Breeding Science, 71(1), 89–108.
Le, L. T. T., Kotula, L., Siddique, K. H., & Colmer, T. D. (2021). Na+ and/or Cl− toxicities determine salt sensitivity in soybean (Glycine max (L.) Merr.), mungbean (Vigna radiata (L.) R. Wilczek), cowpea (Vigna unguiculata (L.) Walp.), and common bean (Phaseolus vulgaris L.). International Journal of Molecular Sciences, 22(4), 1909.
Lu, Y., & Fricke, W. (2023). Salt stress—Regulation of root water uptake in a whole-plant and diurnal context. International Journal of Molecular Sciences, 24(9), 8070.
Manono, B. O. (2026). Effects of salinity on seed germination: Mechanisms, impacts, and mitigation strategies. Seeds, 5(1), 1.
Munns, R. (2002). Comparative physiology of salt and water stress. Plant, Cell & Environment, 25(2), 239–250.
Munns, R., & Tester, M. (2008). Mechanisms of salinity tolerance. Annual Review of Plant Biology, 59, 651–681.
Murillo-Amador, B., Troyo-Diéguez, E., García-Hernández, J. L., López-Aguilar, R., Avila-Serrano, N. Y., Zamora-Salgado, S., … Kaya, C. (2006). Effect of NaCl salinity in the genotypic variation of cowpea (Vigna unguiculata) during early vegetative growth. Scientia Horticulturae, 108(4), 423–431.
R Core Team. (2025). R: A language and environment for statistical computing [Computer software]. R Foundation for Statistical Computing. https://www.R-project.org/
Rai, S. K., Kumar, R., Dayal, A., Reddy, M. L. S. S., & Gupta, N. (2025). Optimizing NaCl concentration for screening salt tolerance in cowpea (Vigna unguiculata L. Walp.) genotypes at germination stage using salt injury index. Vegetable Science, 52(01), 77–83.
Ravelombola, W. S., Shi, A., Weng, Y., Clark, J., Motes, D., Chen, P., & Srivastava, V. (2017). Evaluation of salt tolerance at germination stage in cowpea [Vigna unguiculata (L.) Walp]. HortScience, 52(9), 1168–1176.
Ravelombola, W., Shi, A., Weng, Y., Mou, B., Motes, D., Clark, J., … Sugihara, Y. (2018). Association analysis of salt tolerance in cowpea (Vigna unguiculata (L.) Walp) at germination and seedling stages. Theoretical and Applied Genetics, 131(1), 79–91.
Santos, A. S. D., Neto, M. F., Melo, H. Y. D. A., Filho, R. A. R., Oliveira, F. D. C. D., Medeiros, J. F. D., … Sá, F. V. D. S. (2025). Growth, physiology and yield of traditional cowpea varieties under salt stress using exogenous magnesium. Plants, 14(22), 3524.
Tanyeer, [initials], et al. (2010). [Full reference to be added by the authors.]
Tavares, D. S., Fernandes, T. E. K., Rita, Y. L., Rocha, D. C., Sant’Anna-Santos, B. F., & Gomes, M. P. (2021). Germinative metabolism and seedling growth of cowpea (Vigna unguiculata) under salt and osmotic stress. South African Journal of Botany, 139, 399–408.
Thiam, M., Champion, A., Diouf, D., & Ourèye SY, M. (2013). NaCl effects on in vitro germination and growth of some Senegalese cowpea (Vigna unguiculata (L.) Walp.) cultivars. International Scholarly Research Notices, 2013(1), 382417.
Zou, Y., Zhang, Y., & Testerink, C. (2022). Root dynamic growth strategies in response to salinity. Plant, Cell & Environment, 45(3), 695–704.
