RELACIÓN BRADYRIZOBIUM-CAUPÍ EN CONDICIONES DE SALINIDAD: SU INFLUENCIA EN LA TOLERANCIA AL ESTRÉS SALINO

Abstract

<p><strong>Background:</strong> The introduction of species with tolerance to salinity is one of the strategies to reduce the harmful effect of salts in the eastern region of Cuba. The species <em>Vigna unguiculata</em> L., shows rusticity and capability of adaptation, however, it is necessary to search for cultivars with greater tolerance and symbiotic nitrogen fixation possibilities to increase yields. <strong>Objective: </strong>To determine the behavior of the <em>bradyrizobium</em>-cowpea bean relationship under salinity conditions, based on variables related to symbiotic nitrogen fixation, growth and development. <strong>Methodology:</strong> An experiment was carried out under controlled glass house conditions at the CSIC, Madrid, Spain. Two cultivars were used; IITA-Precoz and IT 86 D-715, which were inoculated with Strain VIBA-1 of <em>Bradyrhizobum liaoningense.</em> Treatments were Hoagland nutrient solution (control) and nutrient solution with 150 mM NaCl (saline). A completely randomized design with eight replications was used. At 40 days after germination, variables related to symbiotic nitrogen fixation, growth and development, protein concentration of the cytosolic soluble fraction of leaves and nodules were evaluated.<strong> Results: </strong>Although salinity negatively affected both cultivars, the damage did not manifest with the same intensity. IT 86 D-715 was less affected by showing less damage on the variables number of nodules, ARA, protein concentration in nodules and leaves, accumulation of leaf and root biomass, so its tolerance was greater. The IITA-Precoz cultivar was more susceptible, all the variables were notably affected under stress conditions, therefore, its tolerance level is lower. <strong>Implications:</strong> The cultivar IT 86 D-715 can be used in salinized soils due to its high tolerance, which is evidenced in variables of growth development and atmospheric nitrogen fixation. <strong>Conclusions: </strong>The cultivar IT 86 D-715 presents a greater capacity for symbiotic nitrogen fixation under salinity conditions and the tolerance index in all the growth and development variables evaluated was higher than IITA-Precoz, for which it presents a high susceptibility level.</p>