Effect of Heavy Metals on Growth of Rhizobium Strains and Symbiotic Efficiency of Two Species of Tropical Legumes

Abstract

Study on the effect of three heavy metals (Al, Fe, Mo) were studied on two strains of rhizobia isolated from root nodules of two tropical legume species, Mucuna pruriens and Trigonella foenumgraecum. The effects were assessed for bacterial growth in culture and in symbiotic parameters such as biomass production and nodulation in host plant. Aluminium was found to have detrimental effect in both in-vitro and in-vivo condition in all its concentration. Iron was found to support bacterial growth and symbiotic parameters such as biomass production and nodulation up to 25 μM. Above 25 μM iron was found to have negative effect. Molybdenum was beneficial up to the 75 ìM concentration in culture of both strains of bacteria while in plant productivity and nodulation it was beneficial only up to 20 μM. Key words: Bacterial growth; Mucuna; Nitrogen fixation; Nodulation; Plant growth; Trigonella. DOI: 10.3126/sw.v5i5.2652 Scientific World, Vol. 5, No. 5, July 2007 27-32