Impact of saline water stress on nutrient uptake and growth of cowpea

Soil salinity is a major limitation to crops production in many areas of the world. The present study reports the impact of salt stress on seeds germination, plant growth parameters and leaf ions accumulation in three cowpea Vigna unguiculata (L.) Walp Indian cultivars: Akshay102, Gomti vu-89 and Pusa Falguni. The electrical conductivity (EC) of the soil was 0.75 dS m−1 and the NaCl treatments increased it to 2, 4, 6, 8 and 10 dS m−1. Germination percentage was recorded 10 days after sowing, while shoot and root dry weights were measured in 45 days old plants. Leaf ion concentrations for Na+, K+, Ca2+, Cl− and proline content were determined. The results showed that the germination percentage of seeds was highly affected by salinity in all cultivars in all salinity levels from 2 to 10 dS m−1. On the other hand, height and weight of all cultivars were less affected by the salt stress. Only at 10 dS m−1 EC, significant reduction in plant height and root length could be found for all three cultivars. Salinity induced a significant increase in Na+, Cl− and proline concentrations, while reduced the accumulation of K+ and Ca2+ in leaves of all the cultivars. Moreover, the tolerance difference between the cultivars was better observed at the lowest levels of salt stress, as reveled in the measurements of K+/Na+ ratio and proline content. In conclusion, this study characterizes Akshay102 as the most tolerant cultivar and establishes the measurements of germination capacity, K+/Na+ ratio and proline accumulation as an important features to be explored in programs for selection and/or development of tolerant cultivars which make possible the utilization of waste saline water as well as the cultivation of vast areas of the tropical world affected by salinity.