NPK fertilization impact on growth, yield, and bioactive compounds of Clitoria ternatea L.

Clitoria ternatea L., or butterfly pea, is a medicinal plant whose flowers contain bioactive compounds such as flavonoids, saponins, and steroids, with antioxidant, anti-aging, and skin-protective properties. This study investigated the effects of different NPK fertilizer doses (0, 40, 80, and 120 kg ha⁻¹) on plant growth, flower yield, phytochemical accumulation, and antioxidant activity. Vegetative growth, including plant height and leaf number, increased significantly at 80–120 kg ha⁻¹, while flowering time, fruit set, flower yield, and leaf pigments were largely unaffected. Phytochemical screening confirmed the presence of flavonoids, saponins, and steroids, while tannins, triterpenoids, quinones, and alkaloids were absent. Total flavonoid content was highest at 40–80 kg ha⁻¹, whereas excessive fertilization (120 kg ha⁻¹) reduced flavonoid levels but enhanced antioxidant activity. Multivariate analysis indicated that moderate NPK doses consistently improved vegetative traits, flower development, and secondary metabolite accumulation. The results demonstrate a dose-dependent effect of NPK fertilization on growth and bioactive compounds in C. ternatea . A moderate NPK dose of 40–80 kg ha⁻¹ is recommended to optimize the balance between plant growth, flower yield, and phytochemical quality to support sustainable production of C. ternatea flowers for medicinal and cosmetic applications.