EFFECT OF INCREASED CO2 CONCENTRATION AND TEMPERATURE ON THE PHYLLOSPHERE MYCOFLORA OF WINTER-WHEAT FLAG LEAVES DURING RIPENING

The impact of elevated carbon dioxide (CO2, 600/700 mu mol mol(-1)) an d temperature (+ 4 degrees C) on phyllosphere fungi colonising flag le aves of mini crops of winter wheat cv. Mercia between anthesis and har vest was determined in a computer-controlled environment facility in 1 993 and 1994. In both years the total fungal populations (cm(2) leaf) were found to have increased due to exposure to either elevated CO2 an d elevated CO2 + temperature treatments. This was mainly due to signif icant increases in populations of Cladosporium spp. (C. cladosporioide s and C. herbarum) on the flag leaves during ripening. Other phyllosph ere component species such as white and pink yeasts were not markedly affected by treatments. The range of fungal species found in such cont rolled environment chambers was narrower than that commonly found on n ag leaves of field grown crops. Common and important colonisers of lea ves and ripening ears such as Aureobasidium pullulans, Epicoccum nigru m and Fusarium spp. were seldom isolated.