Effects of inert dust on olive (Olea europaea L.) leaf physiological parameters

Background. Cement factories are major pollutants for the surrounding areas. Inert dust deposition has been found to affect photosynthesis, stomatal functioning and productivity. Very few studies have been conducted on the effects of cement kiln dust on the physiology of perennial fruit crops. Our goal was to study some cement dust effects on olive leaf physiology. Methods. Cement kiln dust has been applied periodically since April 2003 onto olive leaves. Cement dust accumulation and various leaf physiological parameters were evaluated early in July 2003. Measurements were also taken on olive trees close to the cement factory. Results. Leaf dry matter content and specific leaf weight increased with leaf age and dust content. Cement dust decreased leaf total chlorophyll content and chlorophyll a/chlorophyll b ratio. As a result, photosynthetic rate and quantum yield decreased. In addition, transpiration rate slightly decreased, stomatal conductance to H2O and CO2 movement decreased, internal CO2 concentration remained constant and leaf temperature increased. Discussion. The changes in chlorophyll are possibly due to shading and/or photosystem damage. The changes in stomatal functioning were possibly due to dust accumulation between the peltates or other effects on stomata. Conclusions. Dust (in this case from a cement kiln) seems to cause substantial changes to leaf physiology, possibly leading to reduced olive productivity. Recommendations. Avoidance of air contamination from cement factories by using available technology should be examined together with any possible methodologies to reduce plant tissue contamination from cement dust. Perspectives. Longterm effects of dust (from cement kiln or other sources) on olive leaf, plant productivity and nutritional quality of edible parts could be studied for conclusive results on dust contamination effects to perennial crops.