A COMPARATIVE STUDY OF THE RESPONSES OF THREE AMENITY TREE SPECIES TO DIFFERING WATER SUPPLY DURING ESTABLISHMENT

The effect of differing water supply on physiological and physical growth parameters was determined in young transplants of three amenity tree species, Betula pendula, Prunus grandiflora and Platanus hispanica. Within a fully replicated randomised trial, three regimes of irrigation were supplied with the objective of reducing soil moisture deficit fully, by one half, and by one quarter. A remaining block was covered at ground level to prevent any irrigation being received. Lateral extension and stem diameter were recorded throughout a 3 month period of growth. In addition transpiration rate and leaf water potential, were measured over a 16 hour photoperiod at the end of the 3 month growth period. There were significant differences in both stem diameter and stomatal conductance values, between irrigated and non-irrigated treatments of Betula pendula. There were, however, no similar significant differences between either the growth parameters or the physiological parameters for the other two species. The relationship between the parameters of water relations and tree growth are discussed.