Rev. Bras. Ciênc. Solo.2020;44:e0200070.
Comparison of water and osmotic potentials on Vigna unguiculata stress response
Hidelblandi Farias de Melo 
, Edivan Rodrigues de Souza , Pablo Rugero Magalhães Dourado , Cíntia Maria Teixeira Lins , Hugo Rafael Bentzen Santos , Danilo Rodrigues Monteiro , Martha Katharinne Silva Souza Paulino , Brivaldo Gomes de Almeida , Monaliza Alves dos Santos
11/Nov/2020
DOI: 10.36783/18069657rbcs20200070
Graphical Abstract
Highlights
In cowpea plants, tolerance is higher to water stress than to the salt stress.
The osmotic potential is important for the evaluation of tolerance in Vigna unguiculata.
Osmotic potential can subsidize the evaluation of the tolerance level of unguiculata.
Cowpea plants at flowering are more sensitive to salt stress than at the vegetative stage.
ABSTRACT
Drought and soil salinity are the main abiotic stresses in semiarid regions of the world. This study aims to evaluate the effect of water tensions generated by the reduction of soil moisture and salt on the leaf water potential of cowpea (Vigna unguiculata L. Walp). The experiments were conducted in a randomized complete block design, with a 6 × 2 factorial arrangement consisted of six soil water tensions (0.025, 0.265, 0.485, 0.705, 0.925, and 1.145 MPa) and two tension sources (water deficit and salt), with four replications. Two experiments were performed with the same environmental conditions to evaluate the influence of the tensions on vegetative and reproductive stages. Water and osmotic potentials, relative water content, leaf succulence, and shoot biomass yield were evaluated. Soil water tension was not the main factor of changes on water and osmotic potentials of V. unguiculata plants; the water deficit treatments at soil water tensions of up to 1.145 MPa did not reduce the water and osmotic potentials either at the vegetative or flowering phenological stages; high correlations were found between shoot biomass yield and the leaf water potential at seven days after stress. The osmotic potential was the main indicator of stress in plants at the vegetative and flowering stages subjected to water deficit by the presence of salts in the soil solution.
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