Photoperiod and temperature treatments affect vegetative and reproductive growth of an everbearing blueberry genotype

• Everbearing blueberry plants are day neutral regarding flower bud initiation. • Everbearing blueberry plants bloom immediately after flower bud initiation. • Everbearing blueberry plants exhibit atypical inflorescence morphology. • Long days and high temperatures promote vegetative growth in blueberry genotypes. Photoperiod and temperature are critical environmental signals that regulate vegetative and reproductive growth in perennial crops. Blueberry ( Vaccinium spp.) is typically classified as a short day plant regarding flower bud initiation (FBI). However, field observations of genotypes with everbearing phenology challenge this paradigm. This study aimed to investigate the effects of photoperiod and temperature on vegetative and reproductive growth in two southern highbush blueberry (SHB; V. corymbosum interspecific hybrids) genotypes with contrasting phenologies: ‘Arcadia’, a spring-bearing cultivar, and ‘FL16–64′, an everbearing genotype. Plants were exposed to four photoperiod treatments (8 h, 8 h + 1 h night interruption, 12 h, and 16 h) at two different temperatures (28 °C day / 20 °C night and 18 °C day / 10 °C night) for 10 weeks in a controlled environment experiment. ‘Arcadia’ SHB initiated flower buds only in shorter photoperiods and at cooler temperatures. In contrast, ‘FL16–64′ SHB initiated flower buds in all photoperiods and temperatures tested. Additionally, ‘FL16–64’ SHB bypassed endodormancy, leading to immediate bloom in inflorescences with atypical morphology. Vegetative growth was enhanced by longer photoperiods and higher temperatures. These results suggest that everbearing SHB genotypes are day neutral plants capable of reproductive growth throughout the year. Everbearing blueberry genotypes might be useful for season extension or off season production.