Physiological and Biochemical Mechanisms of Wood Vinegar-Induced Stress Response against Tomato Fusarium Wilt Disease

Wood vinegar, a by-product of charcoal biomass pyrolysis, has been used as a biofungicide in plant disease management because of its antimicrobial properties. However, the physiological and biochemical mechanisms through which wood vinegar alleviates biotic stress are poorly understood. In this study, pot experiments were conducted to investigate the resistance and regulation mechanism of wood vinegar prepared from different raw materials (ZM) and from a single raw material (SM) in controlling tomato (<i>Solanum lycopersicum</i> “Bonny Best”) Fusarium wilt at different concentrations (0.3%, 0.6%, 0.9%, 1.2%, and 1.5%). The results showed that ZM and SM had significant control effects on tomato fusarium wilt under different concentrations in the same growth cycle. Under biotic stress, the two kinds of wood vinegar significantly increased the plant height, stem diameter, leaf area and yield of tomato under the concentration of 0.3%, 0.6%, 0.9% and 1.2%, and significantly reduced the content of malondialdehyde (MDA) and hydrogen peroxide (H₂O₂) in tomato leaves. The effect of 0.9% treatment was the most significant, ZM and SM significantly increased tomato yield by 122% and 74%, respectively, compared with CK under 0.9% treatment. However, the plant height, stem diameter and leaf area of tomato were significantly reduced under 1.5% treatment, but the content of soluble sugar, soluble protein and vitamin C in tomato fruit was the best. Compared with CK, ZM significantly increased by 14%, 193% and 67%, respectively, and SM significantly increased by 28%, 300% and 159%, respectively. Except for 0.3% treatment, both significantly increased the activities of catalase (CAT), peroxidase (POD) and superoxide dismutase (SOD) in tomato leaves. The response intensity of two kinds of wood vinegar—physiological and biochemical—to tomato disease resistance, growth and development, showed ZM > SM. The disease index of tomato showed highly significant negative correlation with plant height, stem thickness, leaf area and antioxidant physiology CAT, and highly significant positive correlation with MDA and H₂O₂ content. In conclusion, ZM was more effective than SM in enhancing tomato disease resistance by promoting tomato growth and development, decreasing leaf MDA and H₂O₂ content, and inducing antioxidant enzyme activity in leaves at moderate concentrations.