Under-Trellis Cover Crop and Rootstock Affect Growth, Yield Components, and Fruit Composition of Cabernet Sauvignon

Abstract

We compared the effectiveness of an under-trellis cover crop treatment (CC, Festuca rubra) and an 85-cm-wide herbicide-treated strip treatment (HTS) and rootstock (101-14, 420-A, or riparia) for regulating vegetative growth and improving fruit composition in Cabernet Sauvignon over a six- to seven-year period of data collection. The cover crop reduced average vine pruning weight by 26% and increased fruit exposure by 35% compared to the HTS floor management scheme. Vines grafted to riparia rootstock had pruning weights that were lower than those of vines grafted to 101-14 in two years; however, effects of rootstock were insignificant when averaged over the seven-year experiment. There was a measurable crop yield penalty for the CC floor management: vines grown with CC averaged 610 kg/ha/year lower crop yields, and had reduced cluster weight, berries per cluster, and berry weight compared to vines in the HTS floor management. Riparia rootstock increased berry weight, cluster weight, and crop yield per vine compared to 101-14. Fruit from vines grown with CC averaged greater soluble solids compared to vines grown with HTS. Rootstock 420-A produced fruit with lower pH than fruit from 101-14 or riparia vines. Compared to 420-A, inconsistent increases in grape anthocyanins and phenolics were observed in riparia (both) and 101-14 (phenolics only). The use of an under-trellis cover crop favorably reduced vine size, especially during the earlier years of the experiment.