The impact of silicon fertilisation on the chemical ecology of grapevine, Vitis vinifera; constitutive and induced chemical defences against arthropod pests and their natural enemies

There is a large body of literature reporting the benefits of silicon (Si) fertilisation to agricultural crops, however, much of this research has focused on high Si-accumulating crops such as sugarcane, Saccharum officinarum (L.), rice, Oryza spp., and wheat, Triticum aestivum (L.), and medium Si-accumulators such as cucumber, Cucumis sativus (L.). This research project has investigated the role of Si in a low Si-accumulating crop, grapevine, Vitis vinifera (L.). Silicon fertilisation is known to improve the physical strength of plants through the deposition of amorphous silicate in the epidermal cells of the stems, leaves and roots of the plant. Numerous studies have shown that the improved mechanical strengthening of the plant as a result of Si fertilisation directly improves plant constitutive defences against arthropod pests, including folivores, borers, phloem and xylem feeders. Studies have also shown that Si fertilisation directly reduces pest damage by enhancing the induced chemical defences of plants following insect herbivore attack. Defensive enzymes, released upon arthropod pest attack, are believed to contain deterrent, toxic and anti-nutritional properties. Silicon fertilisation may also indirectly affect plant pests via induced chemical defences by altering and enhancing the production of herbivore-induced plant volatiles (HIPVs). HIPVs are released by the plant upon herbivore damage or oviposition, and can result in increased attractiveness of the plant to the pest's natural enemies; predatory and parasitic (beneficial) arthropods.