Stomatal uptake of mineral particles from a sprayed suspension containing an organosilicone surfactant

Suspensions of insoluble particles are available on the market for foliar fertilizers. The question whether uptake of particles into the leaf interior is possible is under debate. The present study examines stomatal uptake of mineral particles into leaves of Avena sativa after spraying an aqueous suspension of calcium carbonate particles. By choosing a plant species with large stomata, confirming wide open stomata at the time of spraying and using a “super spreading” organosilicone surfactant, conditions were optimized for stomatal uptake. Scanning electron microscopical (SEM) examination confirmed particles in the intercellular spaces mostly in the vicinity of stomata. The number and size of particles was larger if leaves were treated with wide open than with closed stomata. The chemical identity of the particles was examined with electron‐dispersive x‐ray spectrography (EDX), confirming the presence of calcium carbonate particles among other particles of unknown origin. In conclusion, this study provides evidence for surfactant‐assisted stomatal uptake of mineral particles from sprayed suspensions in species with large stomata under specific conditions favoring stomatal uptake.