Assessment of growth, nodulation and nitrogen fixation of lesser-known Leucaena species inoculated with different Rhizobium strains in greenhouse conditions

The symbiotic behaviour of lesser-known Leucaena species was studied in a greenhouse experiment where 14 Leucaena species were inoculated with seven Rhizobium strains isolated from Leucaena diversifolia, L. leucocephala, Calliandra calothyrsus and Prosopis juliflora. The Rhizobium strain LDK4 isolated from L. diversifolia gave the highest shoot and nodule dry weight and shoot total nitrogen content for the majority of the Leucaena species tested. There were significant strain x species interactions, suggesting that the significant differences in growth, nodulation and nitrogen fixation in Leucaena species are the results of the Rhizobium strain x host plant genotype interaction. The Leucaena species were sorted into three groups according to their growth and capacity to fix atmospheric nitrogen. The best species were L. trichodes, L. macrophylla, L. leucocephala, L. shannonii and L. pallida. However, all these results need to be confirmed by further experiments in field conditions.