The level and distribution of amines in barley as affected by potassium nutrition,arginine level,temperature fluctuation and mildew infection

Summary 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.