Hydrogen cyanamide accelerates vegetative budbreak and shortens fruit development period of blueberry

Jeffrey G. Williamson, Brian E. Maust, E. Paul Miller, Gerard Krewer

Abstract


Experiments were conducted to determine the effects of hydrogen cyanamide (H2CN2) sprays on vegetative and reproductive growth of blueberry in north-central Florida and south Georgia. In Florida, 6-year-old, field-grown 'Misty' southern highbush (Vaccinium corymbosum L. hybrid) blueberry plants were sprayed to run-off with 0, 1.0 and 2.0% (v/v) H[sub2]CN[sub2]) on 20 Dec. 1996 and 7 Jan. 1997. During the following winter, mature 'Misty' southern highbush and 'Climax' rabbiteye (V. ashei Reade) plants were sprayed to run-off with 0, 0.75 and 1.5% (v/v) H[sub2]CN[sub2]) on 17 Dec. 1997and 6 Jan. 1998. Plants were dormant and nearly leafless, with slightly swollen flower buds, when treated. Generally, H[sub2]CN[sub2] treatments increased the extent and earliness of vegetative budbreak and advanced flowering slightly. The number of vegetative bud breaks tended to increase with increasing H[sub2]CN[sub2] concentrations. For the Florida studies, H[sub2]CN[sub2] (0.75 to 1.0%) sprays increased mean fruit fresh weight and yield, and shortened the fruit development period by up to 1.5 weeks when compared to controls. However, 1.5 to 2.0% H[sub2]CN[sub2] sprays significantly injured flower buds and reduced total fruit yield compared to controls. In south Georgia, 27 of 37 field trials conducted during the 1990s on several RE and SHB cultivars demonstrated that leaf development was significantly enhanced by H[sub2]CN[sub2]·H[sub2]CN[sub2] shows potential for advancing fruit maturity, and increasing fruit size and yield of some southern highbush and rabbiteye blueberry cultivars in low-chill production regions.

Keywords


vaccinium corymbosum; vaccinium ashei; dormancy; leaf bud; chilling requirement; rabbiteye; highbush

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Proc. Fla. State Hort. Soc.     ISSN 0886-7283