Zinc Fertilizer Applications to Ocimum basilicum L. under Water Stress: Changes in the Total Phenolic and Flavonoid Content, Essential Oil Compounds and Morphological Properties

Abstract

Water stress poses a significant challenge for plant growth and productivity, impacting both yield and quality. With the ongoing changes in global climate, mitigating the adverse effects of water deficiency on plants has become crucial. In this study, the focus is on enhancing the tolerance of Ocimum basilicum L., a plant highly susceptible to water stress. To achieve this, in this study examined the effects of zinc fertilizer supplementation at varying rates (2.5 - 5 and 10 mg/kg) on O. basilicum grown in silty sandy soil and subjected to water stress conditions. Several parameters, including mineral uptake, morphological characteristics, total phenol and flavonoid contents, and essential oil compounds, were evaluated in sweet basil. The results revealed that water stress had a detrimental impact on the morphological properties and secondary metabolites analysed. Estragole emerged as the main compound in the essential oil analysis, with the highest concentration (69.37%) observed in the group treated with 10 mg/kg of zinc fertilizer. Conversely, the lowest concentration (66.14%) was recorded in the water-stressed group without fertilizer. Notably, the application of zinc fertilizer at concentrations of 5 and 10 mg/kg significantly ameliorated the negative effects induced by water stress. Furthermore, zinc exhibited diverse mechanisms of action concerning the uptake of other nutrients from the soil.