Cover Crop and Root Pruning Impacts on Vegetative Growth, Crop Yield Components, and Grape Composition of Cabernet Sauvignon

Abstract

Complete vineyard floor cover cropping (inter- and intrarow) and vine root pruning were evaluated as tools to restrict vegetative growth of Vitis vinifera cv. Cabernet Sauvignon grapevines. Treatments were arranged in a split-plot, randomized, complete block design with cover crop schemes as main plots and annual vine root pruning (RP), or not (NRP), as subplots. Five perennial grasses as complete floor cover crops were compared to a more conventional under-trellis herbicide strip combined with KY-31 fescue interrows. KY-31 fescue and orchardgrass each reduced shoot growth rate by >30% in 2006 and >20% in 2007, below that of the herbicide-strip control vines. Root pruning independently reduced shoot growth rates. The combination of cover crop and RP decreased dormant pruning weights more than did the additive effects of either factor applied alone. Pruning weights in 2010 were reduced 8% below the control by RP, by 15% by cover crop, but by 38% when both treatments were applied. Leaf petiole N concentration at bloom was ~11% lower in RP vines in two of three years evaluated, but did not differ among vines grown with different cover crops. Stem water potential (Ψ_stem) was not affected by treatments. Cover cropping did not reduce crop yield with the exception of reduced yield due to KY-31 fescue in 2006. Berry weights were slightly reduced by a RP × year interaction from 2007 to 2009 and by a year effect in 2011 compared to 2010. While complete vineyard floor cover cropping and root pruning were effective tools to reduce vine size and vigor, effects on canopy architecture and primary fruit chemistry were minimal and more influenced by seasonal variation.