Author
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Shellie, Krista |
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Submitted to: American Journal of Enology and Viticulture
Publication Type: Peer Reviewed Journal Publication Acceptance Date: 5/31/2019 Publication Date: 10/1/2019 Citation: Shellie, K. 2019. Comparison of sustained deficit and pre- and postveraison regulated deficit irrigation on Malbec and Syrah grapevines. American Journal of Enology and Viticulture. 70:382-389. https://doi.org/10.5344/ajev.2019.18078. DOI: https://doi.org/10.5344/ajev.2019.18078 Interpretive Summary: Deficit irrigation is a management tool used with wine grapes in arid regions to control vine vigor and induce beneficial changes in berry composition. However, the benefits of vine water stress are often achieved at the expense of a reduction in yield and therefore vineyard profitability. Sustained deficit irrigation (SDI) and Regulated deficit irrigation (RDI) are two irrigation strategies that attempt to minimize undesirable responses to water deficit. The objective of this study was to compare the effect of SDI and RDI on the yield and berry composition of the wine grape cultivars Malbec and Syrah. The vines were drip-irrigated to provide 35 or 70% of estimated water demand, either as a sustained deficit from fruit set until harvest (35 and 70, respectively), or as a pre- or post-veraison regulated deficit with irrigation amount altered at veraison (3570 and 7035, respectively). The three year average amount of water usage and yield of vines under the RDI treatments were similar and were ~23 and 21% less than the SDI 70 treatment and ~58 and 35% greater than the SDI 35 treatment. For both cultivars, the RDI treatments had similar yield per vine and average berry weight at fruit maturity; however, the RDI post-veraison treatment (7035) had a greater concentration of anthocyanins and phenolics than the RDI pre-veraison treatment (3570). In both cultivars, the SDI 35 and RDI 3570 treatments had the lowest pruning weight and lowest cluster number per vine. Despite seasonal effects and cultivar differences, the 7035 treatment consistently produced fruit with a concentration of phenolics similar to the SDI 35 treatment. Under the conditions of this study, the post-veraison RDI treatment was superior to the pre-veraison RDI treatment because it induced a greater concentration of phenolics and mitigated a water-stress-associated reduction in cluster number. Technical Abstract: The objective of this study was to compare the effect of sustained deficit irrigation and regulated deficit irrigation strategies on the yield components and berry composition of two wine grape cultivars (Vitis vinifera L.) that differ in their hydraulic behavior. Malbec and Syrah grapevines were grown in southern Idaho under arid conditions and drip-irrigated to provide 35 or 70% of estimated water demand, either as a sustained deficit from fruit set until harvest (35 and 70, respectively), or as a pre- or post-veraison regulated deficit with irrigation amount altered at veraison (3570 and 7035, respectively). The three year average amount of water usage and yield of vines under the RDI treatments were similar and were ~23 and 21% less than the SDI 70 treatment and ~58 and 35% greater than the SDI 35 treatment. For both cultivars, the RDI treatments had similar dC13, yield per vine and average berry weight at fruit maturity; however, the RDI post-veraison treatment (7035) had a greater concentration of anthocyanins and phenolics than the RDI pre-veraison treatment (3570). In both cultivars, the SDI 35 and RDI 3570 treatments had the lowest pruning weight and lowest cluster number per vine. Despite seasonal effects and cultivar differences, the 7035 treatment consistently produced fruit with a concentration of phenolics similar to the SDI 35 treatment. Under the conditions of this study, the post-veraison RDI treatment was superior to the pre-veraison RDI treatment because it induced a greater concentration of phenolics and mitigated a water-stress-associated reduction in cluster number. |
