The effects of GA₃ treatment on yield, carbohydrate, and endogenous hormone changes in Memecik olive cultivar

Authors: SALİH ÜLGER, SABRİYE ATMACA, SARA DEMİRAL

Abstract: In this experiment, 100 ppm gibberellic acid (GA₃) was applied to Memecik olive trees in the middle of June in the `on' (bearing) year to research the effects on yield, reducing sugar amount, and endogenous hormones with the purpose of bearing fruit regularly. The yield was 19.33 kg/tree in control plants and 17.33 kg/tree in GA<sub>3</sub>-treated plants in the `on' year. The yield was 7.17 kg/tree in GA₃-treated plants and 4.00 kg/tree in control plants in the 'off' year. While GA₃ treatment was not very effective on the decrease of fruit amount in the `on' year, it increased fruit amount in the `off' year. Moreover, GA₃ treatment did not significantly affect total reducing sugar amount, but it affected endogenous hormones. Total reducing sugar amount was determined at the 4% level in both years (`on' and `off'). Glucose content was determined to be higher than sucrose and fructose in all plant organs and during flower bud formation periods (induction, initiation, and differentiation). Furthermore, GA₃ treatment increased abscisic acid, GA₃, indole-3-acetic acid, and zeatin levels during flower bud formation periods and in all plant organs (leaf, node, and fruit) in both years.

Keywords: Gibberellic acid, hormone, olive, sugar, yield

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