Drought events determine performance of Quercus ilex seedlings andincrease their susceptibility to Phytophthora cinnamomi

Amsterdam

2014

S. 1-8

BandaufführungSonderdruck

199440

presentcontext of climate change. These extremes could affect forests and plant diseases driven by pathogens. It ishypothesised that simulation of weather extremes during Quercus ilex growth will influence early perfor-mance and susceptibility to the invasive oomycete Phytophthora cinnamomi. In 2010, 140 Q. ilex seedlingswere subjected to three watering regimes under greenhouse conditions: waterlogging (W), water stress(S) and optimal watering regime for growth (C). During the second vegetative period, conditions werealtered to create the following scenarios: WW, WS, SS, SW and CC. After the second vegetative period,plants were artificially infested with P. cinnamomi. Holm oak (Q. ilex) was more sensitive to flooding inthe first year of growth than in the second year. The altered scenarios produced plants with a lower fine-to-total root ratio than plants in unaltered scenarios. Plants with the highest growth rates maintainedtheir relatively rapid growth and photosynthetic activity under altered scenarios. However, plants withthe highest growth rates became the plants with the lowest growth rates when two consecutive yearsof drought occurred, indicating a trade-off by Q. ilex in growth investment, observed only if the waterstress scenario persists. Seedlings were more sensitive to water shortage than to waterlogging, especiallyif they encountered a dry scenario during the first year. Exposure to drought events increased seedlingmortality rates after P. cinnamomi infection. Waterlogging combined with subsequent water deprivationwas the worst scenario when soil was infested with P. cinnamomi, causing 100% mortality of plants.
Keywords: Climate change, weather extremes, drought, flooding, oak decline, invasive pathogen
Schlüsselwörter: Klimawandel, Wetterextreme, Dürre, Überschwemmungen, Eichenrückgang, Invasionserreger