Frontenac Response to Training System and Leaf Removal Treatments

Experiments were conducted at the North Dakota State University research vineyard near Absaraka, North Dakota, in 2013 and will be repeated in 2014 to evaluate the effects of leaf removal and training systems on yield and quality of the wine grape, Frontenac.  The applications of four leaf removal treatments exposed ripening grape clusters to various degrees of sunlight.  The four training system treatments manipulated vine growth habit, fruit bearing zones, and sunlight interception.  Variables include pruning weight, length of time to bud burst, bloom, and veraison, yield, number of grape clusters, average berry weight, pH, soluble solid concentration, and titratable acidity.  Data were analyzed as a RCBD with a split plot arrangement.      

Analysis of variance indicated that only the training system had significant effects on pH and soluble solids.  Training system had no significant effects on pruning weight, length of time to bud burst, bloom, and veraison, yield, number of grape clusters, average berry weight, and titratable acidity.  Leaf removal and it’s interaction with training systems were nonsignificant for all components.  Soluble solid concentrations were only significantly different among Vertical Shoot Positioning (VSP) and Geneva Double Curtain (GDC) training systems. The pH from the VSP training system was significantly higher than all other training systems.  Four Arm Kniffin pH values were lower than those of VSP.  The pH values from High Wire and GDC training systems differed from each other and VSP, but were similar to the Four Arm Kniffin.  This research supports the use of training system to influence fruit ripening.