The quality of horticultural products is the result of the interaction of different factors, including grower’s crop management ability, genotype, and environment. Sub-optimal environmental conditions during plant growth can induce abiotic stresses and reduce the crop performance with yield reduction and quality losses. However, abiotic stresses can induce several physiological, biochemical, and molecular responses in plants, aiming to cope with the stressful conditions. It is well known that these abiotic stresses are also elicitors of the biosynthesis of many metabolites in plants, including a wide range of bioactive compounds, which firstly serve as functional molecules for crop adaptation, but they have also a great interest for their beneficial effects on human health. Nowadays, the consumer is oriented to low-energy foods with low fat content, but at the same time, growing attention is paid to the presence of bioactive molecules, which are recognized as health-related compounds and concur to the nutraceutical value of plant-derived foods. In this context, fruit and vegetables play an important role as sources of bioactive ingredients in the diet. At the cultivation level, the understanding of crop responses to abiotic stresses and how they act in the biosynthesis/accumulation of these bioactive compounds is crucial. In fact, controlled abiotic stresses can be used as tools for improving the nutraceutical value of fruit and vegetables. This review focuses on the quality of vegetables and fruits as affected by preharvest abiotic stressors, with particular attention to the effect on the nutraceutical aspects.

Ornamental plants use unique adaptive mechanisms to overcome the negative effects of drought stress. A large number of species grown in the Mediterranean area offer the opportunity to select some for ornamental purposes with the ability to adapt to drought conditions. The plants tolerant to drought stress show different adaptation mechanisms to overcome drought stress, including morphological, physiological, and biochemical modifications. These responses include increasing root/shoot ratio, growth reduction, leaf anatomy change, and reduction of leaf size and total leaf area to limit water loss and guarantee photosynthesis. In this review, the effect of drought stress on photosynthesis and chlorophyll a fluorescence is discussed. Recent information on the mechanisms of signal transduction and the development of drought tolerance in ornamental plants is provided. Finally, drought-induced oxidative stress is analyzed and discussed. The purpose of this review is to deepen our knowledge of how drought may modify the morphological and physiological characteristics of plants and reduce their aesthetic value-that is, the key parameter of assessment of ornamental plants.

Drought stress is one of the most important abiotic stress limiting the plant survival and growth in the Mediterranean environment. In this work, two species typically grown in Mediterranean areas with different drought responses were used. Two shrubs, with slow (Photinia × fraseri Dress ‘Red Robin’) or fast (Eugenia uniflora L. ‘Etna Fire’) adaptation ability to drought, were subjected to three water regimes: well-watered (WW), moderate (MD), and severe (SD) drought stress conditions for 30 days. Net photosynthetic rate, stomatal conductance, maximum quantum efficiency of PSII photochemistry (Fv/Fm), relative water content (RWC), chlorophyll content, proline, malondialdehyde (MDA), and antioxidant enzyme activities (superoxide dismutase, catalase, and peroxidase) were measured. Results showed that RWC and proline were higher in Eugenia than in Photinia, demonstrating the greater tolerance of the latter to the water stress. The drought stress levels applied did not compromise photosynthetic efficiency through stomatal regulation, while a reduction of Fv/Fm ratio was observed at the end of the experimental period. MDA significantly increased after 30 days in both species. The antioxidant enzyme activities showed different responses to water stress conditions. In both species, the water stress scores showed positive, while proline content showed negative correlations with all physiological parameters.

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In the present study, we investigated the content and profile of polyphenols (PPH), ascorbic acid (AA), the Folin–Ciocalteu index (FCI), and antioxidant activity (1,1-diphenyl-2-picrylhydrazyl (DPPH) and peroxyl radical (ROO)) variation during three different plant growth stages (sprouts, microgreens and baby leaves) of two broccoli types, the traditional Sicilian sprouting broccoli landrace (‘Broccolo Nero’) and the broccoli standard (‘Cavolo broccolo Ramoso Calabrese’), and the standard commercial cultivar of kale (‘Cavolo Lacinato Nero di Toscana’). All biomasses collected were freeze-dried for PPH, AA, FCI, DPPH and ROO analysis. The highest polyphenol content was observed for ‘Broccolo Nero’ (BN) and ‘Cavolo Broccolo Ramoso Calabrese’ (CR), and generally sprouts showed significantly higher values compared to the microgreens and the baby leaves. The AA, FCI, DDPH and ROO significantly vary with regards to the cultivar and the plant growth stage, showing interaction between the two experimental factors analyzed. The interaction detected showed higher values for the antioxidant traits of the proposed novel food, especially for the two broccoli cultivars in the sprout growth stage in comparison to the microgreens and baby leaves. Our results suggest that the antioxidant activity is partially dependent on kaempferol and apigenin. The PPH compounds showed the highest values of kaempferol and apigenin for ‘Broccolo nero’, whereas for the other two cultivars studied, only kaempferol was the main compound represented. The data acquired are of interest for increasing the healthy traits of the novel food proposed showing the contribution offered by the neglected LRs until now underutilized and at risk of extinction. The germplasm conserved in several world genebanks could support and diversify the organic vegetable items, providing us with added-value products for organic food supply chains.

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