Objective The study aims to screen out the types, concentrations and application methods of plant growth regulators that can effectively promote early flowering and improve flowering uniformity of Gymnocalycium baldianum, and provide technical support for the regulation of flowering period of G. baldianum.

Method With uniform seed balls of G. baldianum as test materials, the effects of different concentrations (100, 200, 400 and 800 mg/L) of paclobutrazol, uniconazole, indoleacetic acid and gibberellin on its flowering was explored.

Result Spraying 100-800 mg/L paclobutrazol, uniconazole and indoleacetic acid solutions had no significant difference in the colour of seed balls, seed ball diameter increment, number of flowers and flowering rate. However, these three plant growth regulators could promote the early flowering of G. baldianum within a appropriate concentration range. The treatment of 100 mg/L paclobutrazol had the best result, which bloomed about 9.0 days earlier than that under water treatment. It could reach the full blooming period within 11.7 days, which was about 20.0 days shorter than that under water treatment, and the flowering had better uniformity. While the 100-800 mg/L gibberellin solution had an inhibitory effect on the flowering of G. baldianum, however, it could promote vegetative growth. The ball size, the number of thorns in the thorn seat, the thorn length, and the mass of the thorn seat all increased, and the colour of the seed ball was greener.

Conclusion The study results can provide technological support for promoting the early flowering of G. baldianum and improving the uniformity of flowering. At the same time, it can improve the ornamental characters of G. baldianum according to individual needs, and improve its ornamental value, which has great significance to increase market share furtherly.