Accumulation of cinnamic acid and vanillin in eggplant root exudates and the relationship with continuous cropping obstacle

Abstract

The contents of cinnamic acid and vanillin in eggplant root exudates and soil were determined by HPLC. The results showed that cinnamic acid and vanillin might remain in soil after the root of eggplant is released. With the extending growth stage and planting year of eggplant, the contents in root exudates, rhizosphere and continuous cropping soil increased. In bioassay and field studies, the allelopathy of cinnamic acid and vanillin to the verticillium wilt (V. dahliae) and the eggplant was observed, and when the concentration of cinnamic acid or vanillin was at 1 and 4 mmol. L-1, it inhibited the eggplant growth, while the occurrence of verticillium wilt was promoted. A high concentration of cinnamic acid and vanillin caused eggplant autotoxicity and increased the risk of disease infection, which finally led to continuous cropping obstacle. Key words: Cinnamic acid, vanillin, root exudates, soil, verticillium wilt, continuous cropping obstacle.