Urea as sole source of nitrogen for plant growth : II. Urease and the metabolism of urea in Spirodela oligorrhiza.

Liberation of (14)CO2 from (14)C urea by Spirodela oligorrhiza plants was proportional to their level of urease as assayed by formation of ammonia in extracts. The composition of the soluble nitrogen pool of plants growing on urea differed from that of plants growing on ammonium, mainly with regard to levels of amides and arginine. Neither level of urea in the medium nor of ammonia in the tissues appeared to have a major effect on level of urease activity.