The Physiological and Morphological Effects of Seaweed Application On Tobacco Seedling Characters and Quality (Nicotiana tabacum L.) Plants Under Salt Stress

Abstract This study aimed to evaluate the effects of seaweed extract application on the morphological, physiological, and nutrient characteristics of tobacco plants (Nicotiana tabacum L.) grown under salt stress conditions. Plant growth, biomass production, leaf morphology, chrophyll content, quality traits, and macro nutrient contents were assessed. The evaluated parameters included plant height, root and stem fresh and dry weights, leaf length, width, area, number of leaves, chlorophyll content, nicotine and ash ratios, and the concentrations of nitrogen, phosphorus, potassium, calcium, and magnesium. Salt stress markedly reduced plant growth and nutrient accumulation in tobacco plants. In contrast, seaweed extract application significantly improved all measured traits except stem fresh weight. Notable increases were observed in leaf length (44 cm), leaf area (726.5 cm 2 ), chlorophyll content (48.8 SPAD units), and nitrogen concentration (3.25%). Moreover, the combined application of seaweed extract and salt stress substantially alleviated stress induced damage, leading to a 14% increase in leaf area and a 27% increase in potassium content compared to salt stressed plants. Seaweed based biostimulants therefore represent a promising and sustainable strategy to mitigate salt stress effects in tobacco cultivation.