Proportion of short shoots developed in 2009 and 2010 still alive along the branch axis in 2010 (2009/2010) and 2011 (2010/2011), respectively.

The survival of all shoots, either one and two years old, developed either in 2009 or 2010, and observed in 2011 are represented with (2009-10/2011). Comparisons between cultivars/clones and survival year for shoots living in the next year were performed using a Pearson χ2 test. The proportion of two-year surviving short shoots among cultivars and VP clones was compared separately.