Influence of Trellising on Growth and Yield of 'Thompson Seedless' Vines

¹ Respectively Extension Viticulturist and Professors of Viticulture, Department of Viticulture and Enology, University of California, Davis 95616.

Vine growth, crop yield, and fruit composition were studied for 5 years (1969-1973) as affected by three trellis systems: 1) one-wire vertical (control); two-wire tee; and 3) four-wire double tee. They were installed in 1968 in a replicated trial with 3-year own-rooted `Thompson Seedless' vines growing at Parlier, California.

Treatment 3 significantly outyielded treatment 1, produced fruit with a higher °Brix, and had greater annual growth. In general, treatment 2 response did not differ significantly from treatment 1 (control). The increased yield resulted from significantly greater numbers of clusters per vine, originating from an increase in number of nodes retained. Cluster weight, berry size, and percent total acidity in the fruit did not differ significantly among treatments.