The Influence of Heavy Metals Contained in Sludge Used as Fertilizer for the Dahlia Variabilis Plant on Photosynthetic Traits

This study examines the effects of sewage sludge and wastewater on soil parameters and photosynthetic traits in Dahlia variabilis. Applying sewage sludge to soil reduces pH, increases electrical conductivity, and enhances soil fertility by boosting nitrogen (N) and phosphorus (P) availability. Plants treated with sludge show increased assimilation rates, higher stomatal conductance, and elevated chlorophyll content, particularly at sludge levels above 8 g/kg soil. However, zeaxanthin levels, which contribute to photoprotection, decrease with high sludge treatment while increasing in wastewater-treated plants, indicating stress. This study highlights the complex relationship between nutrient availability and photosynthetic efficiency in Dahlia variabilis.