Inflorescence Bud Initiation, Development, and Bloom in Two Southern Highbush Blueberry Cultivars

ADDITIONAL INDEX WORDS. floral development, floral initiation, growing degree days, reproductive buds, Vaccinium corymbosum ABSTRACT. Blueberry (Vaccinium spp.) production is increasing worldwide, particularly in subtropical growing regions,butinformationontimingandextentofinflorescence buddevelopmentduringsummerandfallandeffectson bloom the next season are limited. The objectives of this study were to determine time of inflorescence bud initiation, describe internal inflorescence bud development, and determine the relationship between internal inflorescence bud development and bloom period the next spring in two southern highbush blueberry (SHB (Vaccinium corymbosum interspecific hybrids)) cultivars. 'Emerald' and 'Jewel' SHB buds were collected beginning in late summer until shoot growth cessation in late fall for dissection and identification of organ development. Inflorescence bud frequency and number, vegetative and inflorescence bud length and width throughout development, and bloom were also assessed. Inflorescencebud initiation occurred earlier in'Emerald' compared with'Jewel'.Fivestages ofinternal inflorescence bud development were defined throughout fall in both cultivars, ranging from a vegetative meristem to early expansion of the inflorescence bud in late fall. 'Emerald' inflorescence buds were larger and bloomed earlier, reflecting the earlier inflorescence bud initiation and development. Although inflorescence bud initiation occurred earlierin'Emerald'comparedwith'Jewel',thepatternofdevelopmentwasnotdifferent.Timingofinflorescencebud initiation influenced timing of bloom with earlier initiation resulting in earlier bloom.