Elicitation of Plant Yield and Production of Secondary Metabolites in Hydroponically Grown Medicinal Plants

Abstract

Medicinal plants are of great commercial and economic importance due to the presence of special chemical constituents known as bioactive phytochemicals or secondary metabolites (SMs). However, their increasing demand and the lack of proper cultivation systems have resulted in increased pressure on wild populations. Consequently, these populations now face the threats of overexploitation and habitat loss. Additionally, various factors such as specific growth and development stages, tissue or organ specificity, as well as stress and climate change, can adversely affect the population of medicinal plants and the production of SMs. Elicitation is an effective technique built on the understanding of a plant's natural defense mechanism, utilizing various biotic and abiotic factors. In this study, two types of abiotic elicitors were employed: biosynthesized silver nanoparticles derived from an endophytic bacterium and salicylic acid. These elicitors were applied using the elicitation technique on four types of hydroponically grown medicinal plants viz., Fenugreek, Flax, Cumin, and Black Cumin. The aim was to observe the effects of elicitation on different plant parameters, including growth and the content of primary and SMs, with the goal of enhancing plant yield and medicinal properties. The analysis of the results revealed a significant increase in all tested parameters at various concentrations of the applied elicitors. The highest significant results were mostly observed at the lowest possible concentration, such as 1 mM of AgNPs, 2 mM of SA, and a ratio of 1:2 or 2:1 of AgNPs+SA. The utilization of elicitation techniques with efficient and cost effective methodologies holds great future potential in sustainable agricultural practices for cultivating medicinal plants. This approach can not only enhance yield and therapeutic properties but also alleviate pressure on wild populations and aid in the conservation of natural resources.