Phenolic Acids in Nicotiana Tobacco L. Root Exudate and Their Autotoxicity Effects

Phenolic acids in Nicotiana tobacco L. root exudate and their autotoxicity were investigated in this study in order to provide scientific basis for solving obstacles of tobacco continuous cropping. The study revealed that soil collected from tobacco continuous cropping field contained greater amount of ferulic acid and cinnamic acid. Five phenolic acids including ferulic acid,cinnamic acid,p-hydroxybenzoic acid,benzoic acid and vanillic acid were indentified in tobacco root exudates. And the secretion rate of ferulic acid was 6. 8 to 365. 0 times as high as that of cinnamic acid,p-hydroxybenzoic acid,benzoic acid and vanillic acid. Furthermore,ferulic acid( 300- 600μg/mL) significantly inhibited seed germination and radicle elongation of tobacco. Similarly,cinnamic acid,p-hydroxybenzoic acid,and benzoic acid( 100μg/mL) significantly inhibited radicle growth of tobacco. These results suggested that phenolic acids in tobacco root exudates were one of the factors restraining tobacco continuous cropping and ferulic acid may play an important role in the obstacles.