ALTERATION OF ELEMENT CONTENTS IN GUARD-CELLS OF NORWAY SPRUCE (PICEA-ABIES) SUBJECTED TO OZONE FUMIGATION AND (OR) WATER-STRESS - X-RAY-MICROANALYSIS STUDY

Two clones of Norway spruce Picea abies (L.) Karst. (Gerardmer clone a nd Istebna clone) were subjected to an ozone-enriched atmosphere. The X-ray microanalysis of elements present in the guard cells showed a de crease in potassium for the Gerardmer clone along with a larger closin g of guard cells and an increase in calcium contents; for the Istebna clone, ozone did not affect these contents. When a drought stress was applied, an increase in calcium content of guard cells of the Istebna clone was also found. However, the potassium content was smaller in th is case for the two clones and could well be due to stomatal closure. When ozone and drought stress were applied together, the potassium con tent in the Istebna clone was not affected, but for the Gerardmer clon e, ozone reduced the decrease in potassium content that occurred as dr ought stress developed. However, calcium (and manganese) content incre ased significantly when the Gerardmer clone was exposed to ozone. It s eems likely that the Gerardmer clone is sensitive to ozone and when su bjected to a drought stress this sensitivity is increased. For the Ist ebna clone, the resistance to ozone is unaffected by the drought stres s treatment. The Istebna clone, however, seems sensitive to drought. T hese characteristic responses in the two different Norway spruce clone s are probably due to genetic differences and may explain the contradi ctory observations in the response of the stomata during the simultane ous implementation of the complex stresses.