Gernns Effects of AM on shoot disease development, yield and physiological background. In contrary to increased resistance against root pathogens, AM barley-plants were more susceptible to the shoot pathogen Erysiphe graminis . AM eliminates the positive correlation between disease intensity and yield-loss. Under field and greenhouse conditions the physiological symptoms underlying the AM effects were investigated. Parameters are the carbohydrate and nitrogen metabolism and senescence development, investigated in the different sink and source parts of the plant.
Special attention is directed towards the fructan pool.
Development of the biotrophic pathogen on barley hindered the filling of fructan pools in the internodia of the plants. In AM plants the carbohydrate allocation an reallocation were less disturbed. In spite of the increased pathogen activity AM plants were able to accumulate higher amounts of stored stem reserves than non-AM plants. Better filling of this long-time storage pools and a good utilisation of these stem reserves during grain filling can be base of a better compensation of pathogen attack in tolerant plants.