A research on the effects of different planting densities and pruning types on the changes of some endogenous plant hormones and fruit set in Gemlik olive

In this research, in Antalya conditions, it was observed that the effects of different plantingdensitiesand pruning types on the changes of some endogenous plant hormones and fruit setof Gemlik olive, which has a broad cultivation area in Turkey. One year old Gemlik olive was used in this research between 2008 and 2010 in Aksu Research and Experiment Field of Agriculture Faculty of Akdeniz University. One year old Gemlik olive seedlings were planted with 5x5 m, 4x3 mand4x1.5 mdensities and they were pruned as control, open vase and verticle axe styles. Plant height, trunk diameter, and also, beginning dates of inflorescence development, flowering, full flowering, the end of flowering, development of green, pink and black fruits, were observed on plants. The shoots, which were 80 cm above soil level and 360o surrounding of the olive trees, were taken every months during the two year period. After that, shoot height and diameter, internode length and the amount of the leaves on shoots were counted. Moreover, the levels of indole-3-acetic acid (IAA), gibberellic acid (GA3), abscisic acid (ABA) and zeatin (Z) were determined in the samples of leaves, nodes, and shoot tips. In the first year of the research, the trees which planted 5x5 mdensity, did not give any fruit, whereas 4x3 m and 4x1.5 mplanted trees gave fruits. However,in the second year of the research, fruits were obtained in all the pruning types and plantingdensities. Furthermore, during the first year, the fruit set rate was 0.88 %, whereas in the second year it increased to 4.85 %. In the samples of nodes and leaves, ABA, GA3, IAA and Z levels were observed higher in the second year than the first year, however, in the samples of shoot tips, levels were higher in the first year. It can be said that high levels ofIAA, GA3, ABA and Z in the samples of nodes and leaves, increased shoots height and diameter, internode height and the amount of the leaves on the shoots. The trees, which were planted with 4x3 m density, included the highest ABA, GA3, IAA and Z levels, thus, the highest tree length, trunk diameter, shoot development, shoot diameter, internode length and the amount of the leaves on shoots, were observed in these trees. In shoot tips samples, the trees which were planted with 4x1.5 mdensity, showed the highest ABA, GA3, IAA and Z levels. Control trees showed the highest IAA level in the leaves, while verticle axe type pruned trees showed the highest one in the nodes and shoot tips. The highest GA3 and Z levels in the leaves, nodes and shoot tips, were observed in control trees, whereas the highest ABA level was observed in verticle axe pruned trees. The monthly changes of ABA, IAA, GA3 and Z levels in the leaves, nodes and shoot tips, showed similar results with eachother. The highest endogenous hormone levels were observed in March, furthermore, they were high as well in August and September. Flower budsstart to be formed in June–July in olives, in these months,GA3/ABA rate changed significantly in all applications, it changed between 2.00-61.00 in the first year, and 2.00-22.00 in the second year. During the second year, getting more fruit from the trees with all planting densities, could be explained by a decrease in GA3 level, which was determined in plant organs in the flower buds developing period. At the end of the research, the best plant development and the highest fruit set were observed on the trees, which were planted with 4x3 mdensity and pruned as open vase style, therefore, 4x3 m plantingdensity and open vase style pruning can be suggested in Antalya conditions for Gemlik olive cultivar.