Interaction of Rootstock With Crop Load, Trellis System and Planting

This project proposed to investigate the interactions of rootstocks with cultural decisions such as pruning severity, trellis selection and spacing of vines within rows. The project was comprised of three experiments bearing on the interaction of rootstock with cultural practices. The three experiments were: Part A. Interaction of rootstock with crop load in Cabernet Sauvignon at the Oakville Experimental Vineyard. Part B. Interaction of rootstock with vine spacing on six trellis systems in Cabernet Sauvignon at the Oakville Experimental Vineyard. Part C. Interaction of rootstock with planting density in Chardonnay at the Beringer Hudson Ranch Vineyard. Data from Part A indicated that rootstocks reacted differentially to increasing bud number (cropping severity) at pruning. 039-16 was unable to ripen heavier crop loads as well as the other rootstocks. Increasing crop load for all rootstocks decreased all measures of growth. Data from Part B indicated that crop increased with canopy division whether that division was vertical (SH or TK2T) or horizontal (GDC, U and V), and that crop yield per acre increased as spacing between vines narrowed from 3 m to 2m to lm. Increase in yield for both factors was due to greater shoot numbers and cluster numbers per unit length row. In this case, 11 OR rootstock outyielded 039-16 by one ton per acre due primarily to greater numbers of shoots and clusters. Data from Part C indicated that the nine stocks could be divided into four vigor groups based on the amount of shoot growth as measured by shoot length, lateral and primary leaf areas and pruning weight. 039-16 and 420A were in classes by themselves as the highest and lowest vigor stocks, respectively. Between the two extremes, 1202, 110R, 5-C, 5BB, AXR exhibited intermediate growth while 3309 and 1616 tended toward low vigor. Shoot numbers did not vary, reflecting a constant bud number retained at pruning time but yields differed based on numbers of clusters/shoot. While crop loads per vine increased at wider spacing (due to more berries per cluster), the crop per acre was greatest at the higher planting density afforded by the 6 ft. Rows. Readers are encouraged to consult the Final Report for a complete analysis of the data.