Exogenous hormones regulate the sequentially reproductive output in Pseudostellaria heterophylla with a chasmogamous–cleistogamous mixed mating system

Exogenous hormones are crucial for regulating reproductive output at various developmental stages in plants, including the medicinal species Pseudostellaria heterophylla, which has a chasmogamous (CH)-cleistogamous (CL) mixed mating system. This study examined the influence of phytohormones on reproductive output at different growth stages and aimed to identify strategies for optimizing genetic breeding. Phytohormones such as gibberellic acid, abscisic acid, indole-3-acetic acid, and zeatin were applied at concentrations of 0, 10, 50, 100, and 200 mg/L during the sprouting and pre-flowering stages of CH and CL flowers. Results indicated that 10 mg/L ABA during the pre-flowering stage increased CH flower numbers by about 30%, while 200 mg/L ABA reduced CH flower production by over 40%. Spraying 200 mg/L GA3 at the sprouting stage resulted in a 150% increase in CL flowers. Other hormones had negligible effects on CL flowers, with only a 9.4% reduction when 100 mg/L ZT was applied. Additionally, 200 mg/L GA3 during the pre-flowering stage significantly increased root weight by 55.6%. In conclusion, applying exogenous hormones at specific stages can effectively regulate flower numbers and root weight, aiding genetic breeding efforts.