Gibberellic acid and cold stratification improve sparkleberry (Vaccinium arboreum) germination under different collection times

Abstract Sparkleberry (Vaccinium arboreum), a native species, has the potential as a blueberry rootstock due to its broader adaptation and less yield loss during mechanical harvesting. However, propagating sparkleberry on a large scale is difficult and little information about its seed germination can be found. To improve sparkleberry germination rate, a germination study was conducted with seeds collected in November and December 2018. Seeds were treated with gibberellic acid (GA3) at three levels (0, 500, and 1,000 mg L−1) and cold stratification at four levels (0, 3, 6, and 9 weeks). Emergence percentage (EP), emergence index (EI), and the number of days needed for the first seed to emerge (NDE) were recorded and calculated. Results showed that the combination of GA3 and cold stratification could increase V. arboreum EP, while in the control (no GA3 or cold stratification) no seeds germinated by the end of the experiment. Seeds collected from November treated with 500 mg L−1 GA3 and 9-week cold stratification reached an EP at 70.4% with 12.6 DNE. Seeds collected from December treated with 1,000 mg L−1 GA3 and 3-week cold stratification reached an EP at 61.2% with 19 DNE. In conclusion, applying GA3 at 500 mg L−1 or 1,000 mg L−1 combined with weeks of cold stratification can be used to improve V. arboreum seed germination.