Effects of training system, pruning severity, nodes per bearing unit and shoot positioning on yield and quality of Concord gra

IN ARKANSAS, 'Concord' grapevines trained to the Geneva Double Curtain system have consistently produced larger yields than vines trained to the bilateral cordon or Umbrella Kniffen systems [Ark. Farm Res. 28(5):12; 1978]. However, information was needed on the influence of pruning severity, cane length and shoot positioning on yield and juice quality as determined by percentage of soluble solids, acidity, pH and color. This study was conducted for 6 consecutive years in a 17-year-old, own-rooted, nonirrigated 'Concord' vineyard at the Arkansas Agricultural Experiment Station, Fayetteville. Treatments included: 1) three pruning severities: 30 + 10, 50 + 10, and 70 + 10 [30, 50, or 70 nodes retained for the 1st 454 g (1 .0 lb) of dormant prunings and 10 additional nodes retained for each additional pound of prunings removed]; 2) three levels of nodes/ bearing unit: 3, 6, or 9 nodes per spur or cane; 3) two training systems, bilateral cordon (BC) or Geneva Double Curtain (GDC), and 4) two canopy positioning treatments: not positioned (NP: shoots allowed to grow at random) or shoot positioned (P: shoots positioned vertically toward the vineyard floor). Each plot had five vines and all treatments were replicated three times. Vine yields and pruning weights were determined. Fruit samples, consisting of three whole basal clusters from each plot, were frozen in polyethylene bags for subsequent quality analysis.