Chitin in Strawberry Cultivation: Foliar Growth and Defense Response Promotion, but Reduced Fruit Yield and Disease Resistance by Nutrient Imbalances

Abstract

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’s systemic defense response, resulting in higher strawberry yields and less 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 fungal genera towards the plant root, such as Mortierella and Umbelopsis. In addition, by the end of the experiments 87 mg mineral N/L 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 fruits: N concentration in the leaves increased over 30%, exceeding the optimal range, while P and K deficiencies occurred, with concentrations lower than 50% of the optimal range. This may explain the decreased fruit yield and disease resistance of the fruits towards 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 less 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 towards B. cinerea.

Biochar-Enhanced Resistance to Botrytis cinerea in Strawberry Fruits (But Not Leaves) Is Associated With Changes in the Rhizosphere Microbiome

“…Cold-stored bare-root strawberry ( Fragaria × ananassa , cultivar Elsanta) transplants were planted in half of the pots; the other half contained one of the BS mixtures (PS or PS + BC). Pots with and without plants were arranged in the greenhouse in a semi-randomized design as described by De Tender et al (2021) and grown at 20°C for 11 weeks. In total, six biological replicates were sampled every week per time point × growing medium combination.…”

“…Trimming, filtering, merging of the reads, dereplication, sorting, amplicon sequence variant (ASV) calling, and chimera removal were done using the DADA2 algorithm v1.10 ( Callahan et al, 2016 ) and described in detail by De Tender et al (2021) .…”

“…The other half of the plants were inoculated with sterile potato dextrose agar plugs. The resulting lesions were recorded 1 week after inoculation using a 0–4 disease scale ( De Tender et al, 2021 ). This scoring was used to calculate the disease severity index (DSI) per plant ( i ), used as input for statistical analysis.…”

“…However, the extensive use of nutrients can also be harmful to the plants. For instance, excessive N concentration can lead to increased susceptibility to plant pathogens and higher rates of infection ( Nam et al, 2006 ; Dordas, 2008 ; De Tender et al, 2021 ).…”

Bacterial Enrichment Cultures Biotransform the Mycotoxin Deoxynivalenol into a Novel Metabolite Toxic to Plant and Porcine Cells

“…Demultiplexing of the raw sequences reads was performed by the sequencing provider. Trimming, filtering, merging of the reads, dereplication, sorting, ASV calling and chimera removal were performed as described by De Tender et al [ 89 ]. After dereplication (removal of duplicate reads), reads were merged and an ASV table was built making use of the DADA2 pipeline [ 90 ].…”