Response of “Sangiovese” grapevines to partial root-zone drying: Gas-exchange,growth and grape composition |
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Authors: | S Poni F BernizzoniS Civardi |
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Institution: | Istituto di Frutti-Viticoltura, Università Cattolica del Sacro Cuore, Via Emilia Parmense, 84, 29100 Piacenza, Italy |
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Abstract: | Our study focuses on the physiological response and yield-quality performance of split-root potted Sangiovese grapevines under a partial root-zone drying (PRD) regime from pre-veraison to harvest by withholding water from one of the two pots and comparing the results to a well-watered control (WW). While predawn water potential (ψpd) tended to equilibrate in PRD with the soil moisture level of the wet pot, both stem (ψst) and mid-day leaf-water potential (ψl) were markedly lower in PRD as compared to WW vines, indicating that Sangiovese shows anisohydric response. On the other hand, the seasonal reduction of leaf assimilation rate (A) in PRD over the 6-week stress period versus WW was 16% as compared to a 41 and 25% for leaf stomatal conductance (gs) and transpiration (E), respectively. As a consequence, intrinsic WUE (A/gs) was markedly increased in the half-stressed vines, suggesting a response more typical of an isohydric strategy. Shoot growth was promptly checked in PRD vines, which had no limitation in yield and better grape composition as per soluble solids and total anthocyanins. These responses occurred in spite of sub-optimal leaf photosynthesis rates and lowered leaf-to-fruit ratio and qualify Sangiovese as a good candidate for adapting to regulated deficit irrigation strategies. |
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Keywords: | A leaf assimilation rate E leaf transpiration gs leaf stomatal conductance PRD partial root-zone drying WUE water use efficiency ψpd predawn leaf-water potential ψst stem water potential ψl mid-day leaf-water potential |
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