FOLIAR PENETRATION OF MICRONUTRIENTS: STUDY WITH ISOLATED PEAR LEAF CUTICLES OF CUTICULAR RETENTION AND PENETRATION OF ZINC

Cuticles were enzymatically isolated from 10 mm diameter pear leaf discs (Pyrus communis L. cv.
Passe Crassane) and micrographs of the two surfaces obtained by scanning electron microscopy were prepared.
Their mineral composition was determined by spark source mass spectrometry.
Results concerning cuticular binding of zinc showed that zinc (⁶⁵Zn) is rapidly retained by stomatous or astomatous cuticular discs.
The comparison with other micronutrients reveals that cuticular retention increases in the following order ⁵⁴Mn < ⁶⁵Zn < ⁶⁴Cu. ⁶⁵Zn retained by cuticles may be partially washed or exchanged.
Interactions with copper and calcium were considered, the cuticular retention of zinc (0.1 mmoll ^-1) was reduced to a greater extent as the concentration of copper was increased from 0.01 to 1 mmoll l^-1 than when the concentration of calcium was increased in the same way.

The cuticular penetration of zinc depended on cuticular characteristics and the nature of the receiver liquid.
It was very slow through carefully selected cuticles but was faster with diluted acid rather than with pure water in the receiver unit.

Symposium on Mineral Nutrition and Fruit Quality of Temperate Zone Fruit Trees

A. CHAMEL, B. GAMBONNET

https://doi.org/10.17660/ActaHortic.1980.92.50