Propagation of Sparkleberry (Vaccinium arboreum) and Hybrid (Southern Highbush Blueberry × Sparkleberry) Rootstocks from Softwood Stem Cuttings in Florida, USA

Sparkleberry ( Vaccinium arboreum ) is a promising rootstock for blueberry production because of its tolerance to abiotic stress; however, its commercial adoption remains limited by poor vegetative propagation from stem cuttings. We evaluated the feasibility of propagating sparkleberry, southern highbush blueberry (SHB; Vaccinium corymbosum interspecific hybrids), and hybrid genotypes (F1 and pseudo-backcross 1, BC1) using softwood stem cuttings under greenhouse mist-bench propagation conditions. Experiments were conducted Jun and Aug 2024, and May 2025. The Jun 2024 and May 2025 experiments included 15 genotypes, whereas the Aug 2024 experiment included 10 genotypes. Propagation success was assessed as rooting percentage, total root length (TRL), and projected leaf area (PLA). Rooting responses differed strongly among genotypes. ‘Sentinel’ SHB consistently exhibited the highest rooting percentage (>80%) and largest root systems (20–40 m), whereas ‘R1’ sparkleberry exhibited complete mortality across all experiments. The pseudo-BC1 hybrid exhibited intermediate but consistently high rooting performance (60%–85%), whereas most F1 hybrids rooted poorly, although select genotypes exhibited moderate rooting percentages depending on the experimental time. The PLA was associated positively with the TRL in 2024, although the relationship was weak. No significant association was detected in 2025. The broad-sense heritability of the rooting percentage was high ( H 2 = 0.97), indicating strong genetic control of propagation success. These results are consistent with previous research indicating the difficulty of propagating sparkleberry using softwood cuttings, but suggest that hybrid genotypes, particularly pseudo-BC1, may offer an improved propagation potential for rootstock development. Hybrid genotypes may therefore enable scalable nursery production of stress-tolerant blueberry rootstocks.