Germination, growth and nodulation of Trigonella foenum graecum (Fenu Greek) under salt stress

Abstract

In this work, we analyzed the effects of salinity on seed germination, growth and nodulation of fenugreek plants. The germination of fenugreek seeds was not affected by salt concentrations lower than 140 mM. Two saline tolerant indigenous rhizobia strains were isolated from the root nodules of fenugreek grown in two different soils. The two rhizobial strains were tested for their ability to grow under high salt stress and then assessed for their ability to nodulate fenugreek grown under different salt stress levels. We have found that the two strains have differential sensitivity to high salt levels. The inoculation of fenugreek with these strains results in better plant growth under salt stress than
uninoculated plants. Twenty percent of plants inoculated with strains S9D or S3G survived in 175 mM NaCl, whereas all controls supplemented or not with nitrogen did not grow. Although plants survived in these salt concentrations, many phenotypic alterations were observed, such as stems short length, small number of leaves and reduced fresh weight. No fenugreek plant grew at salt concentrations
higher than 175 mM NaCl. Stem and root proteins content was also affected by salinity. However, plants inoculated with the two rhizobial strains were more tolerant to salt than controls. The strains infectivity
as estimated by the plants nodules number was also reduced by salinity.