After foliar application, unabsorbed compounds remaining on the leaf surface can be removed by dipping or rinsing plant leaves in various dilutions of organic solvents in water. However, interactions between the solvent mixtures and the epicuticular wax layer have received little attention, and information on potential physical and chemical intactness to the plant surface by this method is limited. In this study, wheat leaves were dipped in organic solvents (methanol, ethanol, isopropanol, acetonitrile, and acetone) at different dilutions with water, and the major component of the leaf epicuticular wax layer, 1-octacosanol, was analyzed in the solutions to assess damage to the wax layer. Isopropanol and acetone removed more 1-octacosanol compared to methanol, ethanol, and acetonitrile; however, the extractable 1-octacosanol recovered in isopropanol and acetone was still less than 15% of that extracted in chloroform. Dipping leaves in dilutions of organic solvent as low as 60% by volume resulted in very low levels of 1-octacosanol, while no 1-octacosanol was detected in any mixtures containing less than 40% organic solvent. The differential extraction of 1-octacosanol in leaf samples by the solutions was found to be correlated with solubility of pure 1-octacosanol in the respective solutions. Furthermore, analysis of leaf surfaces by scanning electron microscopy showed structural intactness of the epicuticular wax layer, particularly when dipped in 20% or 40% organic solvent, which further supports our analytical data. Therefore, our results demonstrate that the epicuticular wax layer of wheat leaves is not altered physically or chemically by organic solvent solutions up to 40% by volume, and these findings provide new insights into the interaction of organic solvents with plant leaf surfaces.

Interaction of organic solvents with the epicuticular wax layer of wheat leaves

246th National Meeting (2013)

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