In vitro seed germination and phytochemical content of kaffir lime (Citrus hystrix DC.) in response to auxin and cytokinin treatments

Kaffir lime leaf extract has a cytotoxic effect on cancer cells. This study aimed to increase the availability of aseptic and controlled leaves using in vitro seed germination to enhance the production of secondary metabolites. The growth of in vitro plantlets is influenced by plant growth regulators (PGRs) such as auxin and cytokinins, with auxin promoting rooting and cytokinins inducing leaf growth. The objective was to determine the optimal use of PGRs for kaffir lime seed germination and analyze the phytochemical content in the leaves. Kaffir lime seeds were germinated on Murashige and Skoog (MS) medium without PGRs (MS0). On day 21, the seedlings were treated with 1-naphthaleneacetic acid (NAA) as the auxin and thidiazuron (TDZ), 6-benzylaminopurine (BAP), and kinetin (KIN) as the cytokinins. Seedling growth was assessed by measuring root length, plantlet height, leaf width and height, and the number of leaves. On day 35, the leaves were harvested and analyzed using gas chromatography-mass spectrometry. The results showed that the seeds underwent germination on day 3. Adding 0.2 mg/l NAA induced the longest roots in the kaffir lime plantlets. The NAA:TDZ (0.2:1 mg/l) treatment resulted in the tallest plantlets with the longest leaves, whereas the NAA:KIN (0.2:1 mg/l) treatment produced the largest number of leaves. The bioactive compounds detected in the plantlet leaves included cyclotrisiloxane hexamethyl, which was found in all treatments except NAA:BAP (0.2:0.5 mg/l). Terpenoid compounds such as citronellyl isobutyrate were identified in BAP-treated plantlets, while phytol was detected in those grown under MS0 conditions. © 2025 Science Society of Thailand under Royal Patronage. All rights reserved.