Comparative assessment of foliar application of iron sulfate, chitosan, and chitosan-enriched iron oxide nanoparticles on morpho-physiological traits, flower productivity and antioxidant defense in Matricaria chamomilla L.

Abstract

Matricaria chamomilla L. (Asteraceae) is a high-value aromatic herb, due to its inherent functional properties and aromatic flavour. In recent years, the demand for chamomile flowers has increased tremendously due to their wide application in the food, cosmetic, and pharmaceutical industries, leading to intentional and unintentional adulteration of the raw herb. Thus, the market faces a substantial gap between demand and supply. The present study aimed to investigate the effects of iron sulfate (Fe), chitosan (CH), and chitosan-enriched iron oxide nanoparticles (NP) at various concentrations (50, 100, 250, and 500 ppm) on the floral productivity, agro-morphological, physiological, and biochemical traits of M. chamomilla L. Further, chitosan-enriched iron nanoparticles (NP) were prepared by co-precipitation method and characterized by TEM, FTIR, XRD, and XPS. The results showed significant variation among treatments for growth, floral yield, pigment, and antioxidant metabolites. Among all treatments, applications of nanoparticle, at NP-250 and NP-500, exhibited superior enhancement in biomass accumulation, flower yield, chlorophyll content, flavonoids, phenolics, and antioxidant enzyme activities, including SOD, catalase, and peroxidase. In contrast, control and lower-dose treatments showed comparatively reduced metabolic and growth responses. The findings suggest that NPs serve as an efficient plant growth promoter and bio-stimulant for the sustainable cultivation of chamomile, with improved floral productivity compared to individual iron sulfate and chitosan salts. This study highlights the potential of chitosan-enriched iron oxide nanoparticles (NP) as a sustainable alternative to chemical fertilizers to boost plant growth and floral productivity in medicinal and aromatic plants, thereby enhancing agricultural sustainability and crop production.