Strawberry cultivation is associated with high mineral fertilizer doses and extensive use of chemical plant protection products. Based on previous research, we expected that chitin application to peat substrate would increase the nutrient availability and activate the plant systemic defense response, resulting in higher strawberry yields and fewer disease symptoms. We set up two experiments in which the temporal variability and differences in initial nutrient concentrations of the growing media were taken into account. Chitin treatment resulted in the attraction of plant growth–promoting fungi toward the plant root, such as species from genera Mortierella and Umbelopsis. In addition, by the end of the experiments 87 mg of mineral nitrogen (N) per liter of substrate was mineralized, which can be related to the observed increase in plant shoot biomass. This, however, led to nutrient imbalances in plant shoots and fruit; N concentration in the leaves increased over 30%, exceeding the optimal range, while phosphorous (P) and potassium (K) deficiencies occurred, with concentrations lower than 50% of the optimal range. This may explain the decreased fruit yield and disease resistance of the fruit toward Botrytis cinerea. In contrast, chitin caused a clear defense priming effect in the strawberry leaves, with a strong induction of the jasmonic acid response, resulting in fewer foliar disease symptoms. Chitin causes positive effects on shoot growth and foliar disease resistance, but caution needs to be taken for nutrient imbalances leading to negative influences on root growth, fruit production, and disease susceptibility toward B. cinerea.

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草莓种植与高剂量的矿物肥料和广泛使用的化学植物保护产品有关。根据先前的研究，我们预计将几丁质应用于泥炭基质中会增加养分的利用率并激活植物的系统防御反应，从而导致草莓产量更高，病害症状更少。我们建立了两个实验，其中考虑了时间变异性和生长培养基中初始营养物浓度的差异。几丁质处理导致了植物生长的吸引力，从而促进了真菌向植物根部生长，例如Mortierella和Umbelopsis属的物种。此外，在实验结束时，每升底物中的矿物质氮（N）含量为87 mg，这可能与观察到的植物新芽生物量的增加有关。但是，这导致了植物嫩芽和果实中的营养失衡。叶片中的氮含量增加了30％以上，超过了最佳范围，而磷（P）和钾（K）缺乏发生了，其浓度低于最佳范围的50％。这可以解释果实产量降低和该果实对灰葡萄孢的抗病性。相反，几丁质在草莓叶中引起明显的防御启动作用，强烈诱导了茉莉酸反应，从而减少了叶病症状。几丁质对芽生长和叶面抗病性产生积极影响，但需要谨慎注意营养失衡，从而对根系生长，果实产量和对灰葡萄孢的易感性产生负面影响。

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