10th U6+ Consortium of African Universities International Conference

Cowpea (Vigna unguiculata) is an important food security crop among smallholder farmers in Kenya's semi-arid regions, where soil salinity constrains yields and is likely to intensify under climate change. Salinity stress can further compromise cowpea productivity by disrupting its symbiotic nitrogen-fixing association with Bradyrhizobium spp., a relationship that is particularly important for crop performance in nutrient-poor soils. However, limited research has characterized the salt tolerance of Kenyan cowpea germplasm. This study assessed the salinity tolerance of selected Kenyan cowpea accession to identify those that may be suitable for cultivation in salt-affected production systems. Plants were grown in sand-filled pots under greenhouse conditions and irrigated with saline water at six salinity levels (0.3, 4.0, 8.0, 12.0, 14.0, and 15.0 dS m⁻¹), with six replicates arranged in a randomized complete block design. At 40 days after sowing, the following parameters were assessed: Number of germinated seeds, plant height, branch number, leaf number, leaf area, fresh and dry biomass, root number, root length, root-to-shoot ratio, and percentage water content. The data was subjected to analysis of variance: count and ratio data were log-transformed prior to analysis, and mean separation was performed using Tukey's test (p < 0.05). Salinity significantly reduced germination and all growth parameters assessed (p < 0.05), with no accession germinating at 15.0 dS m⁻¹. Kunde Kubwa and Ken Kunde maintained significantly higher growth than other accessions at 14dSm-1 salinity levels, indicating superior salt tolerance. These findings identify Kunde Kubwa and Ken Kunde as the most salt-tolerant cowpea accessions evaluated in this study. The two accessions could be promoted for cultivation in salt affected areas, providing a valuable genetic resource for breeding programs aimed at developing salt-tolerant cowpea cultivars for Kenya's salt-affected semi-arid agricultural systems.