Screening of Croatian Native Grapevine Varieties for Susceptibility to <i>Plasmopara viticola</i> Using Leaf Disc Bioassay, Chlorophyll Fluorescence and Multispectral Imaging

• Main Authors: Petra Štambuk, Iva Šikuten, Darko Preiner, Ana Nimac, Boris Lazarević, Zvjezdana Marković, Edi Maletić, Jasminka Karoglan Kontić, Ivana Tomaz
• Format: Article
• Language: English
• Published: MDPI AG 2021-03-01
• Series: Plants
• Subjects: <i>Vitis vinifera </i>L.; downy mildew; biotic stress; chlorophyll fluorescence; spectral indices; imaging methodology
• Online Access: https://www.mdpi.com/2223-7747/10/4/661

In the era of sustainable grapevine production, there is a growing demand to define differences between <i>Vitis vinifera</i> varieties in susceptibility to downy mildew. Croatia, as a country with a long tradition of grapevine cultivation, preserves a large number of native grapevine varieties. A leaf disc bioassay has been conducted on 25 of them to define their response to downy mildew, according to the International Organisation of Vine and Wine (OIV) descriptor 452-1, together with the stress response of the leaf discs using chlorophyll fluorescence and multispectral imaging with 11 parameters included. Time points of measurement were as follows: before treatment (T₀), one day post-inoculation (dpi) (T₁), two dpi (T₂), three dpi (T₃), four dpi (T₄), six dpi (T₅), and eight dpi (T₆). Visible changes in form of developed <i>Plasmopara viticola</i> (<i>P. viticola</i>) sporulation were evaluated on the seventh day upon inoculation. Results show that methods applied here distinguish varieties of different responses to downy mildew. Based on the results obtained, a phenotyping model in the absence of the pathogen is proposed, which is required to confirm by conducting more extensive research.