AN INVESTIGATION INTO THE EFFECTS OF OZONE AND DROUGHT, APPLIED SINGLY AND IN COMBINATION, ON THE QUANTITY AND QUALITY OF THE EPICUTICULAR WAX OF NORWAY SPRUCE

Two Norway spruce clones (Picea abies L. Karst.) were exposed to four different ozone concentrations, by means of open-top chambers. At each level of ozone, one chamber was subjected to drought, whilst the othe r was well watered. There were slight increases in the alkane content of epicuticular wax in response to ozone fumigation, but total wax wei ght, alcohol content and contact angle were unchanged. Observations of the needle surface under a scanning electron microscope revealed no d ifference in the wax structure between ozone and non-ozone treatments. In response to drought, however, wax weight and contact angle increas ed at all levels of ozone exposure and a greater quantity of epicuticu lar wax could be discerned under scanning electron microscope. There w ere no drought-associated changes in wax quality though, nor drought-o zone interactions. It is concluded that ozone had little effect on the response of the spruce epicuticular wax to drought.