Nodulation and Rhizobium Population in Root Nodules of Selected Tree Legumes.

Abstract

Nodulation and rhizobium population in root nodules of 5- year old Leucaena leucocephala; Gliricidia sepium and Acacia mangium were assessed. Nodules of these tree legumes were quantified in terms of their numbers, lateral and vertical distribution while the rhizobium population in cultured nodules was counted as colony forming unit (Cfu/g). Leucaena leucocephala has the highest number of modules (24) followed by Gliricidia sepium (23) and least in Acacia mangium (18). The number of nodules in Acacia mangium was significantly (p,>0.05) lower than those of Leucocephala and G. sepium. Lateral and vertical distribution of nodules for the tree species varies significantly, with higher number of nodules found at 60cm from the base of the tree than at 30cm from the base of the tree except for Acacia mangium. Significantly, higher number of nodules occurred at the upper 20cm soil layer than at the deeper 40cm layer for all the three legume species. Microbial population in the nodules of Gliricidia sepium (24.6cfu/g) and Acacia mangium (19.0cfv/g.) were significantly higher than for Leucaena leucocephala (13.0cfu/g).


Nigerian Journal of Soil Science Vol. 17 2007: pp. 65-70