In the past two decades, nanostructured materials including colloidal nanocrystals,
semiconductor nanoparticles, nanotubes, nanowires and porous materials have received
a great attention thanks to their unique physicochemical properties. Titanium dioxide
nanoparticles (TiO2 NPs) excited by UV light can produce different reactive oxygen
species (ROS) such as hydroxyl radical, superoxide radical anion and singlet oxygen.
This special feature of TiO2 NPs so-called photocatalytic property can be exploited in
numerous fields, especially in water treatment technologies for removing toxic
compounds or inactivation various pathogens.
In this work we applied directly TiO2 NPs on the grapevine (Vitis vinifera cv.
Cabernet sauvignon) leaves as potential antimicrobial agent. Experiments were
performed under field conditions where the plants were exposed to sunlight.
Physiological responses, flavonol profile and micro- macroelements of the leaves were
studied. We found that TiO2 NPs with the concentration of 250 3 00 mg kg-1 increased
the stomatal conductance whereas decreased the photosynthetic rate. Despite of their
negative effect on photosynthesis, flavonol profile as a stress sensitive factor showed
only minor changes after the foliar exposure as revealed by HPLC-DAD measurements.
Elevated level of K, Mg, Ca, P and B were detected in the treated leaves which may be
related to the increased stomatal opening. Our results indicate that TiO2 NPs with the
applied concentration can be phytotoxic in the presence of UV irradiation which
probably stem from the excess of ROS production of nanoparticles. Consequently,
further studies are necessary for determining the parameters which allows safety and
efficient field applications of TiO2 NPs
