Summary Priming of defence is a strategy employed by plants exposed to stress to enhance resistance against future stress episodes with minimal associated costs on growth. Here, we test the hypothesis that application of priming agents to seeds can result in plants with primed defences. We measured resistance to arthropod herbivores and disease in tomato (Solanum lycopersicum) plants grown from seed treated with jasmonic acid (JA) and/or β‐aminobutryric acid (BABA). Plants grown from JA‐treated seed showed increased resistance against herbivory by spider mites, caterpillars and aphids, and against the necrotrophic fungal pathogen, Botrytis cinerea. BABA seed treatment provided primed defence against powdery mildew disease caused by the biotrophic fungal pathogen, Oidium neolycopersici. Priming responses were long‐lasting, with significant increases in resistance sustained in plants grown from treated seed for at least 8 wk, and were associated with enhanced defence gene expression during pathogen attack. There was no significant antagonism between different forms of defence in plants grown from seeds treated with a combination of JA and BABA. Long‐term defence priming by seed treatments was not accompanied by reductions in growth, and may therefore be suitable for commercial exploitation.

The effect of continuous exposure to ozone on quality changes during the storage of red bell peppers, cucumbers and zucchini was investigated. Peppers were stored at 14 °C and were exposed to ozone at 0.1 and 0.3 µmol mol -1 , while cucumbers and zucchini were stored at 12 and 8 °C, respectively and exposed to ozone at 0.1 µmol mol -1 . The content of fructose (2.75 g/100 g FW) and glucose (2.00 g/100 g FW) in red bell peppers exposed to ozone at 0.1 µmol mol -1 was increased by 8 and 7%, respectively when compared to controls. Continuous exposure to ozone at 0.3 µmol mol -1 , on the other hand, had no effect on fructose (2.52 g/100 g FW) and glucose (1.88 g/100 g FW) content. The content of vitamin C was significantly enhanced in red bell peppers exposed to ozone at 0.1 and 0.3 µmol mol -1 after 7 days of storage, however, this effect was not maintained. After 14 days, vitamin C content in peppers exposed to ozone at 0.1 µmol mol -1 was not significantly different from the control, whereas it was reduced at 0.3 µmol mol -1 . Total phenolics content was increased in peppers exposed to ozone at 0.1 µmol mol -1 , but was unaffected at 0.3 µmol mol -1 . Continuous exposure of red bell peppers to ozone at 0.1 and 0.3 µmol mol -1 had no significant effect on weight loss, texture and colour. In cucumbers and zucchini, continuous exposure to ozone at 0.1 µmol mol -1 reduced weight loss by more than 40% and improved texture maintenance, while having no significant effect on their biochemistry. The findings from this study suggest that continuous exposure to ozone at 0.1 µmol mol -1 is a promising method for shelf-life extension of cucumbers and zucchini. Even though in red bell peppers continuously exposed to ozone at 0.1 µmol mol -1 sugars and phenolics content was increased, further work is still needed to better understand the exact mechanism of ozone action and its potential for the industrial use.

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