Bark stripping in cork oak (Quercus suber L.): effect of an antitranspirant application on gas exchange and water relations of the stripped surface

Quercus suber L. is the primary source of industrial cork, which can be legally collected every 9 years. The main objective of this work was to test the efficiency of an application of an antitranspirant, at three different concentrations, after the bark stripping. For this purpose, several measurements of the gas exchange, water potential, total chlorophylls and the carotenoids contents were determined in cork oak trees, at two times in a day, morning and afternoon. The antitranspirant film was applied immediately after stripping. Transpiration rate showed a significant increase in the afternoon. The parameters, water potential, photosynthetic rates, stomatal conductance and the intrinsic water use efficiency, showed a significant decrease from morning to afternoon. The difference between pigments concentration was not significant throughout the day. Water potential and transpiration rate were high in the treatments with lower antitranspirant concentration. However, the treatment with a higher paraffin concentration showed larger photosynthesis rate. This result suggests that the loss of water observed for the stripping surface can be minimized by a larger concentration of the antitranspirant.