Abstract:

To investigate the effects of plant growth regulators on rare and endangered plants Firmiana kwangsiensis seedlings, 16 treatments were established including naphthaleneacetic acid (NAA at 50, 100 and 200 mg/L), indoleacetic acid (IAA at 50, 100 and 200 mg/L), gibberellin (GA₃ at 50, 100 and 200 mg/L), salicylic acid (SA at 50, 100 and 200 mg/L), 6-benzylaminopurine (6-BA at 50, 100 and 200 mg/L), and a control group with pure water. Growth indicators of the seedlings were measured. The results showed that during the experimental period (4 months), the growth regulators promoted the growth of F. kwangsiensis seedlings, increasing the relative increments in plant height and ground diameter, the number of new leaves, the total number of leaves, the length and width of new leaves, the total internode length of the main branch, the number of internodes on the main branch, and the average internode length of the main branch. Among these, 200 mg/L IAA yielded the best results, followed by 50 mg/L SA, 100 mg/L GA₃, and 50 mg/L GA₃. In contrast, high-concentration treatments such as 200 mg/L NAA and 200 mg/L 6-BA inhibited growth and were unfavorable for seedling cultivation. This study can provide experimental references for the early cultivation of F. kwangsiensis seedlings. However, in order to evaluate the long-term benefits of growth regulators more comprehensively, continuous effect observation is still needed in the future.

Key words: growth regulators, Firmiana kwangsiensis, growth indicators, rare and endangered plants, seedlings