Diversity and efficiency of rhizobia nodulating hedysarum flexuosum l. In northwestern of Morocco in relation to soil properties

Abstract

Based on their morphological aspect, 45 strains of rhizobia isolated from root nodules of the wild forage legume Hedysarum flexuosum L. Sampled from four soil regions of Morocco were tested for their physiological and biochemical characteristics. Their host plants were submitted to analysis of nodule intensity, dry matter yield, and nitrogen content. Moreover, soil samples from the sampling sites of nodulation surveys were collected and analyzed in order to assess the relationship between diversity of Hedysarum rhizobia and some soil properties. Even though many of the isolates were from the same plant, they exhibited a wide range of phenotypic diversity in relation to geographical origin. An overall increase in zinc and manganese was the main factor driving compositional differences among rhizobial populations. Their symbiotic efficiency appears to be sensitive to chlorine and aluminum. Although, high chromium in soil may have a positive effect on nodulation and subsequent nitrogen fixation.