• begonia
• Botrytis cinerea
• edible flowers
• integrated pest management
• nutraceutical properties.
• ozonated water
• plant resistance

New emerging challenges for agriculture in the era of climate change include the production of safe, and sustainable foods endowed with functional properties, which can benefit human health due to the presence of bioactive compounds, most of them produced by plants to cope stressful conditions. Ozone bubbled into water (OW) results as promising method for control plant diseases avoiding chemical residues on products. Edible flowers are going to gain increasing interest, since they provide food with flavour, taste, and functional properties. Few chemical solutions are available to protect them against diseases. Here, the suitability of OW to control necrotrophic pathogens and promote the productivity/quality of edible flowers has been evaluated.
Experimental activities were carried out by following two approaches aimed to characterize the indirect protective mechanism(s) of OW (200-800 ppb every two days for 14 consecutive days) through the induction of nutraceutical properties and defence responses in plants of Begonia hybrida artificially inoculated with Botrytis cinerea (Bc); evaluate the direct impact of OW against Bc providing information on the antifungal activity of OW. The effect of OW concentrations has been tested by a one-way analysis of variance (ANOVA) on flower production and total anthocyanins. The effects of time and selected OW concentration have been assessed by a two-way ANOVA on spore proliferation (in vitro test) and ethylene (Et) emission, jasmonic acid (JA) and salicylic acid (SA) content (in vivo test).
In all OW-treated plants, the number and the fresh weight of flowers increased (2- and 5-fold higher than controls). The dry matter showed a marked decrease (-47%) confirming that the rise of floral biomass may due to the increased water content. The application of 400 ppb OW positively influenced the nutraceutical profile of edible flowers (e.g., +33% of total anthocyanins). This concentration negatively affected the Bc colony development by documenting an inhibiting effect on spore germination. The biocidal effects of OW have been evaluated in in vivo test in terms of protection against Bc and suppression of Bc inoculation. In OW+ + Bc+ plants, Et peaked before JA (1 and 3 h after inoculation) indicating a crosstalk in the regulation of defence reactions. In Bc+ + OW+ ones, Et peaked before SA (1 and 3 h) suggesting a crosstalk in lesion spread to surrounding cells after Bc infection.