Ammonium nitrogen was shown to foster arginine and amides and lead to a large increase of free guanidine compounds , .
In leaves nourished by nitrate as the sole source of nitrogen guanidine compounds were less prominent .
Ammonium nitrogen was shown to foster arginine and amides and lead to a large increase of free guanidine compounds , whereas in leaves nourished by nitrate as the sole source of nitrogen guanidine compounds were less prominent .