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The deposition of silicon linked to the reduction in susceptibility to strawberry powdery mildew

Carmilla Asiana: University of Hertfordshire

<div>An important disease of protected strawberries in the UK is strawberry powdery mildew (<em>Podosphaera aphanis</em>), controlled by the frequent use of fungicides. Our work has shown that the weekly use of a silicon nutrient in the fertigation tubes, results in reduced disease susceptibility. The work reported here aims to quantify deposition of silicon applied through the roots in a glasshouse. The glasshouse plants were treated weekly via the roots either with silicon nutrient or deionised water. After 8 weeks the plants were harvested, then sections of the leaves, petioles and roots were cut and stained with a fluorescence dye, Lyso tracker yellow HCK-123. Samples were examined using a confocal microscope at x400 magnification and a wavelength set at 450nm. Results showed that the silicon had accumulated in the epidermis and palisade layer of the leaves, and in the vascular bundles of the petiole and roots. Silicon treated plants contained larger amounts of silicon than the untreated and measurements of fluorescence intensity confirmed this. Silicon treated leaves measured 7.923W/m<sup>2</sup> and untreated 2.209W/m<sup>2</sup>, treated petioles 7.770W/m<sup>2</sup> and untreated 1.913W/m<sup>2</sup>, treated root 11.594 W/m<sup>2</sup> and untreated 1.266W/m<sup>2</sup>. This showed that the application of the silicon through the roots is taken up and deposited in the plant system. Analysis of epidemics from the field trial showed statistically significant disease reduction in the treated plants, with silicon deposited in the leaves.</div>