THE EFFECT OF SOIL VOLUME ON YOUNG PEACH-TREE GROWTH AND WATER-USE

An experiment designed to study the effects of different root volumes was installed in Fall 1991. 'Golden Queen' peach trees [Prunus persica (L.) Batsch.] were planted into different isolated soil volumes (0.02 5, 0.06, 0.15, 0.4, and 1.0 m(3)), which were essentially individual d rainage lysimeters. Trunk cross-sectional area (TCA) increased from 5. 76 to 14.23 cm(2) for the smallest and largest volumes, respectively, while leaf area was 4.56 and 21.32 m(2) for the respective treatments. Leaf size was not affected by soil volume. Soil volume was positively related to the number of lateral shoots produced, lateral shoot densi ty, and internode length. Total flower bud number and flower bud densi ty were inversely related to soil volume. Fruit set was similar among treatments despite an almost 4-fold difference in tree size. Tree wate r use (liters.mm(-1) pan evaporation) increased with soil volume; howe ver, when adjusted for tree size (tree water use per TCA), there were no consistent differences between treatments for tree water use over t he season. These results suggest that trees planted in the smaller soi l volumes were more efficient reproductively per unit of tree size and would be easier to manage in an ultra-high-density planting.