Effects of exogenous gibberellin pretreatment on seed germination and seedling growth of Coffea arabica L.

As a specialty cash crop in Yunnan, the seed germination cycle of Coffea arabica L. is relatively long, which to a certain extent restricts the breeding of good seeds and the process of industrial development. There are fewer studies on the germination of Coffea arabica L. seeds, In this study, we used the seeds of Coffea arabica L. 'Catimor 7963' as the experimental material, and used different concentrations of gibberellin (1, 10, 100 μmol/L) to immerse the seeds of Coffea arabica L. for different times (12, 24, 36 h) to determine the seed germination indexes and seedling growth indexes, to investigate the seed germination indexes and seedling growth indexes of exogenous GA₃. Seed germination indexes and seedling growth indexes were measured to investigate the effects of exogenous GA₃ on seed germination and seedling growth of coffee plantlets. The results showed that the low concentration (1−10 μmol/L) and short duration (12−24 h) of GA₃ treatment favored the germination and seedling growth of C. plantarum, while the high concentration (≥100 μmol/L) or long duration (≥36 h) of GA₃ treatment inhibited the germination and seedling growth of Coffea arabica L. Among the treatments tested, soaking seeds in 1 μmol/L GA₃ for 24 hours was identified as the optimal condition. This treatment significantly enhanced seed germination by 19.64%, increased primary root length by 14.11%, and improved seedling leaf length, leaf width, and leaf area by 10.96%, 20.94%, and 33.69%, respectively. Additionally, it boosted aboveground fresh weight by 13.05% and dry weight by 25.37%, relative to the control group.