Phytotoxic effects of pentachlorophenol in a wood-preservative industrial formulation: Early growth and biochemical responses of kale, lettuce, and sunflower

Pentachlorophenol (PCP), a persistent pesticide and wood preservative, poses risks to plant and soil health. This study assessed the effects of PCP on seed germination, growth, and biochemical responses in kale ( Brassica oleracea var. sabellica ), lettuce ( Lactuca sativa ), and sunflower ( Helianthus annuus ). Crops were exposed to varying PCP concentrations using west coast oil (WCO) as a solvent, applied directly or via contaminated soil in three setups: petriplate germination, pouch analysis, and soil tests. PCP significantly ( p < 0.05) inhibited germination, especially at higher concentrations (P3.1% and P4.6%), where no germination was observed. Root and shoot lengths declined by 70–100% in a concentration-dependent manner. Interestingly, PCP exposure reduced shoot growth, while increased root elongation in one treatment suggested a possible stress-related growth response. PCP exposure also reduced chlorophyll and sugar content while increasing reactive oxygen species (ROS), suggesting oxidative stress and impaired photosynthesis. Soil nutrient levels and pH showed slight variations, though not consistently linked to treatments. Sunflowers showed greater tolerance to PCP exposure than kale and lettuce, indicating species-specific differences in phytotoxic response that should be further evaluated under field conditions. Overall, these findings indicate that PCP-containing preservative formulations can impair early crop growth and plant physiological function, providing a baseline for future comparisons with alternative wood preservatives.