Abstract
23 strains of rhizobia, from 14 leguminous species, were evaluated on a Thai cultivar of Voandzeia* in Leonard jar trials. The symbiosis ranged from completely ineffective through moderate effectiveness to fully effective. Bradyrhizobium sp. TAL 169, isolated from Vigna unguiculata, ranked most-effective; the widespectrum Bradyrhizobium strain CB 756 was ineffective. In a cultivar × Bradyrhizobium spp. trial, the host-genotype significantly (P ? 0.01 or P ? 0.001) influenced shoot dry weight, shoot N, nodule dry weight and nitrogenase activity. The rhizobial strains were also significant sources of variation for shoot-dry weight (P = 0.05), shoot N (P < 0.001) and nodule dry weight (P < 0.01). There were no significant host × Rhizobium interactions, indicating that no specific combination was superior over the broad range of all treatments. Percentage shoot N and specific nitrogenase activity were poor indicators of N2 fixation capacity in Voandzeia. Voandzeia cultivar No. 12 P.P. Rust in combination with Bradyrhizobium sp. TAL 169 showed high potential for growth, nodulation and N2 fixation. This study indicated that Voandzeia is specific for its rhizobial requirement for effective symbiosis.
