ISHS Acta Horticulturae 179: V International Symposium on Growth Regulators in Fruit Production
PHENOLIC ACIDS - POSSIBLE INVOLVEMENT IN REGULATING GROWTH AND ALTERNATE FRUITING IN OLIVE TREES. |
| Authors: | S. Lavee, H. Harshemesh, N. Avidan |
| Abstract:
The involvement of phenolic acids in controlling alternate bearing of olive trees was studied. Under tissue culture conditions chlorogenic acid could replace the IAA requirement for tissue growth. Cinnamic and ferulic acids also had some partial IAA-like activity, while phenylalanine, shikimic acid and caffeic acid were not active. A combination of caffeic and quinic acids in the medium induced growth similar to chlorogenic acid. Chlorogenic acid was found to accumulate in leaves of fruiting olive trees starting after fruit set and continuing till pit hardening. Thereafter the level remained high till the next fruit set period in the following year. Chlorogenic acid was quantitatively tested during three consecutive seasons. A causal relation between fruit development and chlorogenic acid was demonstrated by removing the fruits during pit development, causing an instant drop in the level of chlorogenic acid in the leaves. The major transition in quantity of chlorogenic acid between 'on' and 'off' years was in May during the period of fruit set. Fruiting shoots enter the induction period with a high level of chlorogenic acid and non-fruiting shoots with a low one. Feeding experiments with chlorogenic acid and related compounds in the field using pressure injection, could reduce flower bud initiation by up to 50% when applied till mid-January. Thereafter chlorogenic acid had no effect on differentiation. Percent fruit set was not affected. Other phenolic acids of the lignin pathway fed to the olive tree had a weaker effect on differentiation than chlorogenic acid. Cinnamic acid at a late winter application reduced fruit set. | |
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