Effects of Polyoxyethylene Nonyiphenyl Ether and Silicon Surfactants on Penetration of Propanil through Adaxial Epidermis of <i>Commelina communis</i>

Abstract

Effects of surfactants, polyoxyethylene nonylphenyl ether and the Silwet L-77, on penetration of propanil through Commelina adaxial epidermis were investigated in terms of concentration and EO molarity of the surfactants and stomatal condition of the epidermis. The initial penetration rates of propanil varied widely. In 70% of the epidermis they were below 70 pmol/mm2/hr. On microscopical observation, most stomata on the surface remained closed throughout the penetration experiment. There was no significant correlation between the initial penetration rates and the number of stomata. The promotive effect of surfactants was high when the initial penetration rate was low, approaching 1 as the rate increased. There was an exponential relationship between the initial penetration rate (X) and the penetration rate (Y) after surfactant addition. The relationship is expressed as, Y=ea. Xb. Surfactant efficiency to promote penetration was evaluated by two approaches: (i) by substitution and (ii) by plotting coefficients a and b. There was a parabolic relationship between the EO molarity of surfactant and the promotive effect, and surfactant NP(8) was the most effective in enhancing. There was a linear relationship when coefficient b was plotted against coefficient a, and that showed a difference in effectiveness in enhancing penetration among the surfactants. The Silwet L-77 significantly promoted non-pore penetration.

Lognormal distribution of water permeability and organic solute mobility in plant cuticles

“…Usually the sample size is about five, which excludes a comparable data analysis. One very large data set for the penetration of an organic molecule through non-isolated cuticles was recently published for the penetration of the foliar applied herbicide propanil through the cuticle of Commelina communis L. (Omokawa, Takeuchi & Konnai 1993). With a sample size of 121, penetration rates differed 70-fold and the frequency distribution showed the same tail as obtained in this study.…”