Withholding Irrigation During the Establishment Phase Affected Growth and Physiology of Norway Maple (Acer platanoides) and Linden (Tilia spp.)

The aim of this work was to investigate the drought tolerance of different Tilia species and of different cultivars of Acer platanoides grown during the establishment phase, and to evaluate irrigation effect on their growth and physiology. In winter 2004–2005, 168 trees [8–10 cm (3–4 in) circumference] of Tilia platyphyllos, T. cordata, T. × europaea, T. tomentosa, Acer platanoides ‘Summershade’, A. platanoides ‘Deborah’, and A. platanoides ‘Emerald Queen’ were planted in the field. Eighty-four plants were irrigated with a drip irrigation system (4 l/h) and eighty-four were not. Height, trunk diameter, and shoot elongation were measured at the end of the growing season in 2005, 2006, and 2007. Leaf gas exchange and chlorophyll fluorescence were measured monthly during the 2006 and 2007 growing seasons. Leaf greenness index content was measured in 2006 and 2007. Results indicate that T. tomentosa and T. cordata are more drought tolerant during establishment than T. platyphyllos, while Acer platanoides ‘Summershade’ is less drought tolerant during establishment than the cultivars ‘Emerald Queen’ and ‘Deborah’.