Productivity of 'Chambourcin' Grape, Own-Rooted and Grafted to Seven Different Rootstocks

Abstract

The French-American interspecific hybrid grape cultivar ‘Chambourcin’ (26.205 Joannés-Seyve) was planted in 2004 at Mountain Grove, Mo., on seven different rootstocks (3309C, 101-14 Mgt, 5BB, SO4, 110R, 1103P, Freedom). Own-rooted ‘Chambourcin’ was also grown. The site characteristics are latitude 37° 9′ N, longitude 92° 16′ W, elevation 442 m, USDA plant hardiness zone 6a, and a Viraton silt loam soil with 2 to 5% slope. The soil is characterized as acidic, moderately well-drained, and slowly permeable with chert and fragipan in the subsoil. This soil restricts root growth, is prone to drought, and reduces vine vigor. Rootstocks were tested in a replicated trial during the years 2009 to 2013 to improve scion productivity. ‘Chambourcin’ grafted to 3309C, 5BB, and 1103P had significantly higher yield per vine compared to own-rooted. The remaining rootstocks were not significantly different from own-rooted. Vines grafted to 3309C and 1103P had significantly higher pruning weight per vine compared to own-rooted in three years. The remaining rootstocks were not significantly different from own-rooted. Average cluster and berry weights were not significantly affected by rootstocks in all years, but own-rooted vines were significantly lower in some years. Juice soluble solids was significantly higher for ownrooted compared to some rootstocks in two years, a likely result of lower yields on these vines. Juice titratable acidity was not affected by rootstock, and pH was affected one year. Crop load (yield to cane pruning weight ratio) ranged from 12 to 15. Lower crop loads would likely have improved fruit composition. Productivity of ‘Chambourcin’, a cultivar prone to low vigor when grown on a restrictive soil, can be improved when grafted to rootstocks. The rootstocks 3309C, 5BB, and 1103P appeared best.