Uniconazole-Mediated Growth Regulation in Ophiopogon japonicus: Yield Maximization vs. Medicinal Quality Trade-offs

Xiaoyang Cai¹Wenjing Li¹Heling Fan¹Jiaming Zhang¹Haohan Wang¹Yan Qing²Min Li^1*GOU YAN^2*

• ¹Chengdu University of Traditional Chinese Medicine, Chengdu, Sichuan Province, China
• ²Sichuan Institute for Drug Control, Chengdu, Sichuan Province, China

Ophiopogon japonicus, widely used in traditional medicine and as a health food in China and Southeast Asia, is mainly classified into Sichuan “Chuanmaidong” (CMD) and Zhejiang “Zhemaidong” (ZMD) types. This study evaluates the effects of foliar-applied Uniconazole, a triazole plant growth regulator, on the agronomic traits and medicinal quality of Sichuan CMD (cv. Chuanmaidong No.1) under field conditions. The goal is to determine whether yield improvements can be achieved without compromising pharmacological properties. Uniconazole was applied at 7.5, 15, and 30 kg/hm². Results showed that Uniconazole suppressed vegetative growth by reducing plant height and leaf biomass but significantly increased tuber yield by up to 101.59%. This yield boost was driven by hormone-mediated morphological changes, particularly disruptions in endogenous Abscisic Acid (ABA)–Gibberellic Acid (GA₃) and Indole-3-Acetic Acid (IAA)–Zeatin Riboside (ZR) balances, which altered tuber shape from spindle to cylindrical or dumbbell forms. Root diameter, length, and single tuber dry weight increased by 12.36%, 21.75%, and 49.53%, respectively. Despite modest increases in polysaccharides and flavonoids, total saponins and ophiopogonin D—key pharmacologically active compounds—decreased by 35.90% and 63.94%. Environmental residue analyses revealed first-order degradation kinetics with half-lives around 19.7 days in soil and root tissue, with final residues below detection limits, indicating good environmental safety. In conclusion, while Uniconazole effectively enhances tuber yield, it significantly compromises medicinal quality by reducing critical saponins, which may weaken clinical efficacy and complicate compliance with pharmacopoeial standards. This poses risks for adulteration and regulatory challenges. The study highlights the need for policy reforms enforcing bioactive marker quantification and residue monitoring to ensure medicinal plant quality, advocating a balanced cultivation approach that aligns yield improvement with therapeutic efficacy and safety.