Effectiveness in N2 Fixation of Sesbania speciosa and Sesbania rostrata Rhizobia Isolated from Different Locations

Abstract

Sesbania speciosa and Sesbania rostrata are high potential symbiotic N-fixing legumes to be used as green manuring for both field crops and rice. Due to both Sesbania species are introduced crops thus we hypothesised that the suitable effective strains for these two Sesbania species may not present in Thai soil the objective of this study was to determine the effective strains of rhizobia for the two Sesbania species from soils in different part of Thailand. It was found that Sesbania speciosa rhizobia were different in terms of strains, population density and effectiveness in different locations. Most soils contained very low to moderately effective strains of rhizobia. For Sesbania rostrata, variation in rhizobial strains was not great most soil contained moderately effective strains. However from the study we found some high effective strains of rhizobia for both Sesbania species were isolated. Therefore, to be most benefitial from using both Sesbania as green manuring the plants should be inoculated with their effective rhizobial strains isolated from this study for every new introducing areas.