Mitigating drought stress in Catharanthus roseus along with nano-iron enriched algal fertilizer application: a sustainable approach for enhanced growth and secondary metabolite production

Abstract

Algal biomass enriched with iron nanoparticles, termed as Nano-Phyco Fertilizer (NPF) offers a novel and sustainable strategy to improve plant growth and secondary metabolite production in Catharanthus roseus, particularly under drought conditions. This study evaluated the effects of NPF and NPF combined with drought stress (NPF+DS) on plant morphology, growth parameters, and the biosynthesis of key alkaloids including vinblastine, vincristine, catharanthine, and vindoline. While NPF alone significantly enhanced growth traits such as shoot and root length, leaf number, and biomass accumulation, it did not markedly increase alkaloid content. In contrast, the NPF+DS treatment not only improved growth performance relative to drought-stressed controls but also significantly elevated secondary metabolite levels. Total alkaloid content increased by 3.5-fold, with vinblastine, vincristine, catharanthine, and vindoline levels rising by 4.16, 3.3, 3.2, and 2.1 fold respectively, compared to the control. These findings suggest that NPF application under drought stress can mitigate the adverse effects of water scarcity while simultaneously promoting the accumulation of valuable therapeutic compounds. This dual effect makes NPF a promising, eco-friendly tool for enhancing both biomass and phytochemical yield in medicinal plant cultivation under challenging environmental conditions