Author: Aaron WhitlatchPublisher:
ISBN: 9781303444142
Category :
Languages : en
Pages :
Book Description
Pre-veraison or "early" deficit irrigation has been shown to produce smaller berry sizes and higher anthocyanin concentrations (Kennedy et al. 2002, Matthews and Anderson 1989, Matthews et al. 1990, Roby and Matthews 2004). However, modification of irrigation regimes following an early deficit treatment has not been studied to the same extent. In order to observe the effects of varying post-veraison irrigation regimes following pre-veraison water stress, six irrigation treatments were applied to Cabernet Sauvignon over the course of one growing season. The treatments differed in target leaf water potentials (LWPs) and included a highly-irrigated control (CTL: greater than -10 bar all season), a grower standard practice (RHP: -11 to -12 bar all season), a post-veraison deficit irrigated treatment (LD: -11 pre-veraison, -14 post-veraison), and three early deficit treatments with -14 bar pre-veraison LWPs. Following veraison, these three treatments had different target LWPs--one continued with water stress (ED-: -14 bar pre-verasion, -14 bar post-veraison), one represented a standard early deficit treatment with little stress following veraison (ED: -14 bar pre-veraison, -11 bar post-veraison), one was irrigated much more than the control (ED+: -14 bar pre-veraison, greater than -9 bar post-veraison). While the ED and ED- were the smallest berries, the ED+ treatment had significantly higher berry elasticity as well as berry diameters equal to the CTL. ED+ had lower anthocyanin concentration than the other EDs, but nearly the same anthocyanin concentration as the RHP (and more than CTL and LD). Measurements were taken for shoot growth, berry elasticity, fruit composition, phenolic content, and 2-methoxy-3-isobutylpyrazine concentration. Additionally, a full sensory descriptive analysis was performed for the 2011 wines made from these six treatments as well as for the 2010 and 2009 wines made from similar irrigation treatments from this same vineyard. Across all years, there was no clear relationship between fruit aromas or vegetative aromas with irrigation regime. All treatments and years had very low levels of MIBP bordering on the limit of detection both by sensory analysis (bell pepper aroma) and GC/MS/MS quantification. For 2011 wines, the ED and ED- grouped near red fruit aroma in sensory analysis. While ED+ was not significantly different than these treatments, it did have lower anthocyanins, tannins, as well as higher mean scores in cooked vegetable and barnyard aromas. The ED+ treatment allowed for less berry weight loss prior to harvest and yields equivalent to the CTL while using much less water to do so.
