Fruit Quality of Pierce's Disease Resistant 87.5% Vitis vinifera Selections

Three recently developed Pierce's disease (PD) resistant 87.5% V. vinifera selections from the U.C.-Davis grape breeding program, namely ‘502-10’, ‘502-01’, and ‘501-12’, were planted at the Chilton Research and Extension Center (CREC) near Clanton, Alabama in 2010 to evaluate  their fruit quality characteristics and their field PD resistance in a high PD risk zone. The experimental vineyard is a RCBD with 6 blocks and 5 vines per block. Vines are trained to a vertical shoot positioning trellis system. The first commercial crop was produced in 2012. Fruit quality data collection continued in 2013. Our results suggest selection ‘502-10’ had the lowest pruning weight of 2.1 kg/vine, while ‘501-12’ had the highest (2.3 kg). Selection ‘502-10’ matured early in the season, while ‘501-12’ ripened late. The selections differed in total yield per vine with the late maturing ‘501-12’ producing the largest crop of 8.1 kg/vine.  ‘502-10’ and ‘501-01’ also produced very good yield. Selection ‘501-12’ had the largest number of clusters per vine – 89, while ‘502-10’ had 33 clusters per vine on average. Early-season selection ‘502-10’ had the largest cluster weight of 210 g, while mid-season selection ‘502-01’ produced the largest size berries. Late season selection ‘501-12’ had the sweetest berries with soluble solids content of 24.2%. The preliminary results of our study are very encouraging. Further research is needed to fully assess the fruit quality of newly introduced V. vinifera selections in multiple years.