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- Author or Editor: A. D. Matthias x
- HortScience x
Abstract
Wine grape (Vitis vinifera L.) vineyards in much of the desert Southwest are frequently exposed to intense solar radiation, high vapor pressure deficits, and high air temperatures. Although wine grape production in this region has increased during recent years, the harsh environment often results in growth conditions that may be suboptimal for photosynthesis and other plant processes, ultimately affecting fruit yield, wine color, and acidity.
The effects of trellising on absorption of photosynthetically active radiation (PAR, 400- to 700-nm wavelength) by foliage and fruits, on fruit composition, and yield were studied in 1988 under semi-arid conditions using field-grown Vitis vinifera L. `Petite Sirah' grapevines in a mature vineyard. A vertical inclination was obtained by attaching shoots to a vertically arranged three-wire trellis; 60° shoot inclination from horizontal was obtained by attaching shoots to a “V-type” Tatura trellis; a standard two-wire trellis (control) was used in which shoots attached to the upper wire were permitted to orient downward to the vineyard floor. PAR absorption by foliage during mid-morning to mid-afternoon periods was highest in the standard trellis and lowest in the Tatura trellis. PAR available for absorption by fruits was lowest in the standard trellis and highest in the Tatura trellis. Analysis of fruit composition at harvest revealed that total dissolved solids (°Brix) was significantly higher for berries from the Tatura trellis than for the vertical trellis or the control. The Tatura trellis resulted in the highest alcohol content of wine. Per-vine yields did not differ significantly among the three trellis systems.