Determined Efficiency and some correlations between growth and Efficiency were evaluated in a set of 24 apricot Constitution. Even though the planting stock came from the same nursery, was of even age and on the same rootstock, the tree size of constitution varied from planting to a permanent site. Differences in the tree size of constitution slightly diminished over the six-year period, likely under the influence of uniform pruning used for all trees. Nevertheless, tree size evaluated from the

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... area of stem cross-section can be considered as a genotype disposition. It is proved by a positive, highly significant correlation (r = 0.84++) between the rank constitution according to the area of stem cross-section in the fourth and eleventh year after planting. Confidence intervals also confirmed significance of differences in Determined Efficiency. In total, Determined Efficiency of twelve Constitution was significantly higher than in the control cultivar Velkopavlovická. A negative, significant moderate correlation (r = -0.40+) was calculated between tree size and Determined Efficiency expressed as yield weight per unit area of stem cross-section. Weakly growing Constitution had higher Determined Efficiency. The highest Determined Efficiency was recorded in cultivars Vynoslivyj and Priusadebnyj and in LE-1321 and LE-390 hybrids.