WATER-USE BY EUROPEAN PEAR TREES GROWING IN DRAINAGE LYSIMETERS

Results are discussed of a four-year study on water use by European pe ar trees, of cvs Conference and Comice on slender spindle and V-trelli s training systems, growing outdoors in drainage lysimeters. The study covered the period from planting until the end of the first cropping season. During the first half of each season, weekly water use increas ed in relation to estimated potential evapotranspiration, presumably a s the evaporative leaf surface area increased. In the final year, when the tree leaf area was up to 2 m(2) m(-2) planting square area, weekl y water use was always less than 40% of the potential evapotranspirati on. Annual water use varied strongly with variety and training system. For non-fruiting trees however, annual water use per unit leaf area a t the end of the season showed a consistent relationship for trees of all variety x training system combinations. In the final year, the pre sence of fruit generally increased water use, especially per unit leaf area or per unit root weight.