| Summary: | Precision irrigation of wine grape is hindered by the lack of an automated method for monitoring vine water status. The objectives of this study were to: Validate an automated model for remote calculation of a daily crop water stress index (<i>CWSI</i>) for the wine grape (<i>Vitis vinifera</i> L.) cultivar Malbec and evaluate its suitability for use in irrigation scheduling. Vines were supplied weekly with different percentages of evapotranspiration-based estimated water demand (ET<sub>c</sub>) over four growing seasons. In the fifth growing season, different daily <i>CWSI</i> threshold values were used to trigger an irrigation event that supplied 28 mm of water. All three indicators of vine water status (<i>CWSI</i>, midday leaf water potential (Ψ<sub>lmd</sub>), and juice carbon isotope ratio (δ<sup>13</sup>C)) detected an increase in stress severity as the irrigation amount decreased. When the irrigation amount decreased from 100% to 50% ET<sub>c</sub>, 70% to 35% ET<sub>c</sub>, or the daily <i>CWSI</i> threshold value increased from 0.4 to 0.6, berry fresh weight and juice titratable acidity decreased, juice δ<sup>13</sup>C increased, the weekly <i>CWSI</i> increased, and Ψ<sub>lmd</sub> decreased. Under the semi-arid conditions of this study, utilizing a daily <i>CWSI</i> threshold for irrigation scheduling reduced the irrigation amount without compromising the yield or changes in berry composition and remotely provided automated decision support for managing water stress severity in grapevine.
|
|---|