Changes in the transpiration rate of barley plants infected with powdery mildew in the light and in the dark

Abstract

Changes in the transpiration rate of intact spring barley plants, cv. “Slovensky dunajsky trh”, were studied separately in the light and in the dark under controlled temperature and illumination, after the infection withErysiphe graminis DC, during an 8 day period of the development of the fungus. In the first stage of pathogenesis, the fungus diminishes water output from the host plants in the light. An opposite phenomenon can be observed in the dark; water output from infected plants in the dark increases sharply mainly in the stage of advanced fructification. Thus, the fungus considerably diminishes the ratio of water output from the host plants in the light to that in the dark.