LEVEL AND DISTRIBUTION OF AMINES IN BARLEY AS AFFECTED BY POTASSIUM NUTRITION, ARGININE LEVEL, TEMPERATURE FLUCTUATION AND MILDEW INFECTION

In potassium-deficient barley, the arginine content was increased three-fold above that of controls, while the amines agmatine and putrescine (derived from arginine) increased about 10-fold and 40-fold respectively. From the 6th-7th leaf stage onwards, fluctuations in the level of putrescine were negatively correlated with changes in temperature, while those of arginine and agmatine level were positively correlated. Both a mass action effect of arginine and temperature-induced changes in enzyme activity are postulated as contributory factors towards putrescine accumulation. The youngest fully expanded leaves, which were normally used for analysis, had a lower amine content than older leaves, and a higher content than the stem and roots. Within a leaf, amines and aminoacids increased in concentration from the base to the tip, while potassium and phosphorus showed a gradient in the opposite direction. Mildew infection caused a significant increase in putrescine and agmatine (by about 100 and 50 per cent respectively) in leaves of potassium-deficient barley. © 1969 Martinus Nijhoff.