“…In the same light in which pathogenicity is elusive unless the proper animal is used, so is the nitrogen-fixing potentiality of a rhizobial strain an enigma without the aid of the appropriate host plant. Current researches provide a wealth of evidence that particular strains may be highly effective on one species and ineffective on closely related ones (57,58,107,110,111,232,265,277,282,317,406).…”