Abstract

This work aims to evaluate the performance of the grapevine (Vitis vinifera L.) cultivar Romeiko under the influence of limited water availability and additional UV-B radiation exposure, applied alone or in combination. Three-year-old grapevines were exposed to two water regimes (well watered and water stressed) and two levels of UV-B radiation (ambient UV-B and ambient plus 15% UV-B). Predawn leaf water potential (Ψ_PD) and leaf relative water content (RWC) were significantly higher in well watered plants and on the other hand, no significant effect of UV-B on leaf tissue hydration was revealed. Both abiotic stressors significantly affected shoot growth rate (SGR), leaf fresh weight (FW) and leaf dry eight (DW), with the effect of water shortage on vegetative growth being more pronounced. Deficit irrigation had negative effects on yield both because of the reduced berry fresh weight and the lesser number of berries per cluster, while the yield response (quantity and quality attributes) of cv. Romeiko was similar between the two UV-B radiation regimes. In summary, limited water supply had a high potential for restricting vegetative growth and yield, whereas the effects of enhanced UV-B radiation were less evident on allometric parameters and nonexistent on fruit yield and quality characteristics. In addition, the combination of supplemental UV-B and deficit irrigation did not cause any pronounced effects compared to the single application of limited water supply.

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