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

Abstract

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.

An Inert Pesticide Adjuvant Synergizes Viral Pathogenicity and Mortality in Honey Bee Larvae

“…It is theorized that this activity is dependent on the polarity of the cationic surfactant48. OSS’s are nonionic, and available literature has shown OSS facilitated membrane penetration to occur via the stomatal pores at high concentrations (300–1000 ppm)4950. Further research is needed to determine whether OSS’s can alter cellular membrane fluidity and how this might affect viral infections, but the low concentration of OSS used in this study suggests a different mechanism resulted in the observed mortality.…”

Effects of ‘inactive’ ingredients on bees

“…Organosilicones cause a greater reduction in surface tension than both nonionic surfactants and crop oil concentrates, making them extreme surfactants and super-penetrants and this action may lead to learning impairment in adult bees [36]. This potent surfactant activity can drive the stomatal uptake of even large bacterial-sized mineral particles [37], and thus may aid movement of pathogens into bee tissues.…”

Recent advances and perspectives in crop biofortification

“…These are expected to have improved ability to be absorbed and utilized in the plant tissues. Kaiser et al (2014) reported that application with surfactant improves absorption of microparticles by stomatal pathway. Mobility of compounds within the plant tissues is of great importance, because it improves utilization of nutrient applied.…”