LEVELS OF INHIBITORS IN FLOWER BUDS DURING BUD DORMANCY OF THREE PEACH CULTIVARS

Irregular flowering in many peach cultivars is caused by insufficient chilling needed to break the dormancy of flower buds.
This phenomenon probably results from an imbalance of plant hormones in the bud.
A study was conducted on the levels of abscisic acid (ABA) and (ABA)-like substances in buds during the dormant stage of three peach cultivars grown at Ang Khang Station, Amphur Fang, Chiang Mai, North Thailand.
Three peach cultivars with varied chilling requirements namely Flordabelle, Ang Khang White and Ventura were studied, by sampling the terminal shoots fornightly from the beginning of bud dormancy until bud break.
Flower buds were excised from terminal shoots, extracted and analysed for ABA content with a gas chromatograph.
ABA-like inhibitors were also measured using the rice seedling bioassay.

Results showed that the levels of free-form ABA and ABA-like inhibitors in flower buds were very high at the onset of dormancy and then sharply decreased within two weeks.
This trend was seen in all cultivars.
After two weeks of dormancy the level of inhibitors fluctuated until the last four weeks before the termination of dormancy, after which the levels rapidly decreased.
This trend was seen with Flordabelle and Ang Khang White.
However, with Ventura the inhibitor levels were found to decrease about six weeks before flowering and the level increased again in the last two weeks.
No relationship was found between the inhibitor levels in flower buds and the dormancy period of these three peach cultivars.

III International Workshop on Temperate Zone Fruits in the Tropics and Subtropics

W. Pongsomboon, S. Subhadrabandhu, K.R. Chapman

https://doi.org/10.17660/ActaHortic.1990.279.39