Field validation of 4,8‐dihydroxy‐1‐tetrahydronaphthone phytotoxicity on forestland weeds and physiological mechanism analysis on Lindernia procumbens

4,8‐Dihydroxy‐1‐tetrahydronaphthone (4,8‐DHT), an allelochemical, was isolated from the Carya cathayensis epicarp and was discovered to have phytotoxicity in laboratory tests. In this study, field experiments were designed to assess the phytotoxicity of 4,8‐DHT on weeds in Cerasus yedoensis and Lagerstroemia indica forestlands after pre‐ and post‐emergence application, in addition to physiological effect on Lindernia procumbens were also measured. The phytotoxic results of 4,8‐DHT demonstrated that the total inhibition rate of weeds was 81.3% and 68.2% in C. yedoensis forestland and L. indica forestland after pre‐emergence applied for 24 days in 2021, and enhanced by 9.9% and 27.8% compared with post‐emergence treatment. Especially, in C. yedoensis forestland, a high concentration of 4,8‐DHT sprayed at the pre‐emergence stage after 8 days had a significant inhibition rate on all weeds except Cyperus rotundus, and was still above 80.0% after 24 days of exposure. Comprehensive control efficacy of 4,8‐DHT indicates that pre‐emergence application is more favorable for weeds control. Physiological analysis showed that 4,8‐DHT stimulated the contents of thiobarbituric acid reactive substances (TBARS), hydrogen peroxide (H₂O₂), and proline and declined in the activities of antioxidant enzymes, meanwhile, accompanied by a decrease in the root vitality and chlorophyll content in L. procumbens. These results warrant further investigations of 4,8‐DHT applied in early pre‐emergence as a potential source of weed control agent.