Separating the effects of tree size and meristem maturation on shoot development of grafted scions of red spruce (Picea rubens Sarg.).

In order to separate the effects of size and meristem maturation on age-related changes in shoot growth behaviour, a reciprocal grafting experiment was conducted involving juvenile (J), mid-age (MA) and old-growth (OG) red spruce (Picea rubens Sarg.) trees as both scion donors and rootstock. The effects of rootstock and scion age on vegetative growth, foliar morphology and reproductive development were assessed over 7 years after grafting.