The Effects of Different Planting Densities and Pruning Methods on Changes of Endogenous Hormone Levels in Shoot Tips and Flowering in ‘Gemlik’ Olive Cultivar

Abstract

Olive cultivation tends to adopt new planting density and pruning systems in domestic olive types in Turkey. The effect of different planting densities and pruning types on the changes of some endogenous plant hormones in shoot tips and flowering in ‘Gemlik’ olive cultivar was studied. The two-year-old seedlings were planted at 5 × 5 m, 4 × 3 m and 4 × 1.5 m densities, and were pruned as either open vase or vertical axe styles in addition to unpruned control. The shoots were taken monthly during the two successive years for hormone analysis. The levels of ABA, IAA, GA3 and Z were determined in the shoot tips. GA3 was determined to be the highest on each month whereas Z was the lowest in shoot tip samples at most of the sampling dates. Pruning types affected ABA, GA3 and IAA, but not Z levels. Planting densities had significant effect on endogenous ABA and GA3 content. There were important differences among monthly levels of ABA, GA3, IAA, and Z. In the first year, IAA and Z content in shoot tips were higher than that of in the second year, whereas ABA level was lower in the first year. GA3 was not changed in both years. Results show that planting density, pruning style, and monthly and yearly changes in endogenous level of hormones in shoot tips play significant effect on phenological development and flowering in ‘Gemlik olive’ cultivar. High planting density reduced juvenility period and induced flower formation in olive.