RAÚL C. LÓPEZ SÁNCHEZ1, ERNESTO GÓMEZ PADILLA1, BETTINA EICHLER-LOEBERMANN2, MERCEDES FERNÁNDEZ-PASCUAL3, BEATRIZ RUIZ-DÍEZ3, ROELAND SAMSON4, PATRICK VAN DAMME5
1University of Granma, Faculty of Agricultural Sciences, Cuba
2University of Rostock, Faculty of Agricultural and Environmental Sciences, Germany
3Council of Higher Scientific Investigation, Spain
4University of Antwerp, Department of Bioscience Engineering, Belgium
5University of Ghent, Department of Plant Production - Laboratory for Tropical Agronomy, Belgium
In Cuba, about 1.000.000ha of crop soils are affected by salinity. This also causes considerable losses in pasture yields and animal production. One of the alternatives to improve the fertility of these soils is the use of salt-tolerant legume species. Legumes may help to (1) improve the quality of salt"=affected soils due to their capacity to fix atmospheric nitrogen (N) in symbiosis with Rhizobium; (2) increase soil organic matter; (3) serve as a protection against erosion; and (4) improve soil structure. The response of two tropical legume species, i.e. Clitoria ternatea and Vigna unguiculata, inoculated with native and commercial Rhizobium and Bradyrhizobium strains was studied under soil salt stress conditions. The study was carried out under field conditions. The effect of three Rhizobium strains (Jd19, 1031 and 1032) in C. ternatea and two Bradyrhizobium strains (VIBA"=1 and VIBA"=2) in V. unguiculata were compared to a control (without fertilisation and inoculation). using yield and nitrogen fixation parameters. In C. ternatea, Jd 19 had the highest effects on dry matter yield, ureide content and N accumulation. The inoculation effectiveness index was very close to the nitrogen response index for this species. In V. unguiculata, results show Bradyrhizobium strains to have a beneficial effect on different variables. Especially VIBA"=1, improved nodule number, their dry mass and specific nitrogen fixation, as well as eventual crop yield. The highest effectiveness index value was also obtained when using VIBA"=1.VIBA"=2 showed better results than control. Positive linear and highly significant correlations were found between nodulation and nitrogen fixation, and total nitrogen content in plant tissue and plant yield.
Keywords: Legumes, nitrogen fixation, salt stress