Resumen

IZAGUIRRE, María Luisa. Distribucion geografica, nodulacion y comportamiento agronomico de tres especies  de sebanias nativas de zonas inundables en Venezuela. Agronomía Trop. [online]. 2005, vol.55, n.1, pp.63-82. ISSN 0002-192X.

The aim of this work was to study the growth and nodulation of three Sesbania species native of seasonally flooded areas in Venezuela. The species S. punicea (Sp) and S. sericea (Ss) were collected in the Miranda State, while S. exasperata (Se) in the Aragua State. All individuals were nodulated with nodules located in submerged roots, which were like embedded in a white aerenchyma. Rhizobial isolation from nodules yielded seven isolates from Sp, seven from Ss, and ten from Se. The bulk of isolates were fast growers and did not tolerate NaCl concentrations above 1%. All isolates from Sp were acid producers, while a greater variability was observed within isolates from Ss and Se. All isolates shown a high symbiotic efficiency in their original hosts, but only those from Sp formed effective nodules in Vigna unguiculata. Seed germination of Sesbania occurred exclusively after chemical scarification with concentrated sulfuric acid for 1 h. However, seedlings did not survive in controlled-sterile conditions in spite of the effective nodulation with their corresponding isolates. In the other hand, an optimal growth and prolific nodulation was observed in plants growing in flooded fields during the rainy season, although growth was hampered during the dry season, probably due to a marked decreases in the level of the water

Palabras clave : Sesbania exasperate; Sesbania sericea; Sesbania punicea; native rhizobios.