Twenty-two accessions of seven Sesbania (Leguminosae) species: S. emerus, S. rostrata, S. tetraptera, S. exasperata (annuals), S. grandiflora, S. sesban and S. virgata (perennials), used for ruminant fodder, firewood, wood products, soil improvement, and human food, were investigated, with the aim of characterizing both inter- and intraspecific genetic variability, estimating genetic parameters for the characters evaluated and appraising the forage potential of the accessions. These were planted at the Instituto de Zootecnia, Nova Odessa, SP, Brazil, in a randomized complete block design with 22 treatments and four replications. Seventeen morphological and 17 agronomic characters were evaluated. Genetic parameters coefficient of intraspecific genetic diversity (bi) and coefficient of intraspecific genetic variation (CVgi) were obtained for the species represented by more than one accession. Highly significant differences were observed among as well as within species for most characters, showing considerable genetic variability. S. exasperata showed intraspecific genetic variability for the largest number of morphological characters. The same was observed for S. sesban for the agronomic characters. Most of the characters gave high bi values, above 0.80, indicating the possibility of selecting superior genotypes. The CVgi values, on the other hand, which indicate the magnitude of the existing genetic variability relative to the character mean, varied according to the species and character evaluated. Differences between annual and perennial species were observed, with higher biomass yields presented by the annuals at the first cut and by the perennials after the second cut, reaching the highest yield at the third cut. The annual species had higher seed production. Accession NO 934 of S. sesban gave the highest biomass yields and regrowth vigor, showing promise as a forage legume plant.
