GA₃ AS A FLOWERING INHIBITOR IN BLUEBERRIES

Field and nursery studies were undertaken to evaluate the effect of GA₃ on flower initiation (FI) of young highbush (Vaccinium corymbosum L.) and half-high (V. corymbosum x V. angustifolium) blueberries.
In a factorial experiment, GA₃ (150 or 300 ppm) applied 7, 9, 11 or 13 weeks after full bloom (AFB), significantly reduced flower formation in nursery-grown 2-year-old ‘Bluecrop’ and ‘Elliott’ plants; the magnitude of the effect was dependent on cultivar and date of application.
Plants suffered cold damage during winter.
The intensity of the damage at a given GA₃ concentration varied depending on cultivar and date of application, with lowest bud survival for ‘Bluecrop’ sprayed 7 weeks AFB with 300 ppm.
GA₃ also inhibited FI in ‘Northblue’ and ‘Northsky’ half-high blueberries, when applied 6 weeks AFB; greater effects were observed in ‘Northblue’. In both species, GA₃ effects on FI were due to its reduction of flower bud number, while flowers per bud was unaffected.
GA₃ (150 or 300 ppm) did not affect flower initiation in 3-year-old field-grown ‘Bluecrop’ plants when applied 7, 9 or 11 weeks AFB. However, in a separate field trial on 4-year old ‘Bluecrop’ plants, 300 ppm GA₃ applied at 15 or 15 and 18 weeks AFB, significantly reduced the number of flower buds per shoot, while the number of vegetative buds was unaffected; in this trial, GA₃ application significantly reduced fruit yield and total number of flowers per plant, while fruit weight was significantly increased.

International Symposium on Growth and Development of Fruit Crops

Jorge B. Retamales, Eric J. Hanson, Martin J. Bukovac

flower initiation, fruit load, Vaccinium corymbosum

https://doi.org/10.17660/ActaHortic.2000.527.16