Impact of crop control strategies on performance of high-yielding sangiovese grapevines

Climate change will require grapegrowers to develop improved viticultural practices to control vine yield and the rate of fruit maturation. The impacts of five canopy management regimens on vegetative growth, yield, and grape quality were investigated over three years, and carryover effects on vines in the fourth year were examined. Winter pruning (Wp, the control), shoot thinning (St), shoot thinning with preanthesis defoliation (St+Dpa), shoot thinning with preveraison defoliation (St+Dpv), and shoot thinning with preveraison defoliation plus cluster thinning (St+Dpv+Ct) were applied to Sangiovese vines from 2011 to 2013. Neither St nor St+Dpv changed yield or grape quality compared to Wp. The St+Dpa treatment reduced leaf area and yield by 33% compared to Wp and St and led to increased sugar concentrations and a carryover effect into 2014 that reduced vine capacity. A management strategy that combines shoot thinning with preanthesis defoliation, which will increase sugar concentrations and suppress yield, offers the strongest potential for long-term regulation of vine yield and grape quality. However, in a nonirrigated vineyard of medium vigor, Wp, St, and St+Dpv could be used to achieve yield and fruit quality levels that meet defined thresholds while reducing costs in respect to other additional interventions such as Dpa or Ct.