Foliar-applied silicate potassium modulates growth, phytochemical, and physiological traits in Cichorium intybus L. under salinity stress.

One of the major problems endangering plant growth and productivity worldwide is salt stress. This study aimed to assess the effects of potassium silicate (KOSi) on the physical, biochemical, and morphological characteristics of chicory (Cichorium intybus L.) under various levels of salinity stress. The plants were treated with KOSi at concentrations of 0, 1, 2, and 3 mM and cultivated under different salt stress conditions (0, 80, 160, and 240 mM NaCl). The findings revealed that salt stress led to decreased root and shoot dry weights, Fv/Fm ratio, chlorophyll a, b, and total chlorophyll, as well as inulin contents. However, foliar exposure to KOSi at all salinity levels resulted in improvements in the measured traits. As salinity levels increased, there was a corresponding increase in the accumulation of sodium ions (Na) and a sharp reduction in potassium ions (K +) in the shoot. Nonetheless, treatment with KOSi caused a decrease in Na + accumulation and an improvement in K content under all salinity levels. Carotenoid content increased under 80 mM salinity stress, but decreased with higher salinity levels. Application of KOSi at all levels resulted in increased carotenoid content under salinity stress conditions. The content of MDA increased significantly with increasing salinity stress, particularly at 240 mM. However, foliar spraying with KOSi significantly decreased MDA content at all salinity levels. Salinity stress up to 160 mM increased the total phenol, flavonoid, and anthocyanin contents, while 240 mM NaCl decreased the biosynthesis of phytochemicals. Additionally, the use of KOSi increased the content of total phenol, flavonoid, and anthocyanin at all salt levels. Foliar application of KOSi increased the tolerance of chicory plants to salinity stress by reducing MDA and increasing phenolic compounds and potassium content. These results suggest that exogenous KOSi can be a practical strategy to improve the growth and yield of chicory plants exposed to saline environments.