Weed-suppressive effect of phenolic acids.

Allelochemical substitutions salicylic acid,p-hydroxybenzonic acid,cinnamic acid,vanillic acid and ferulic acid were tested in a gyrating regression experiment to study the weed-suppressive effect of phenolic acids on the root growth of barnyardgrass.The results showed that cinnamic acid had a significant inhibitory effect,its square item regression coefficient being -6.18; salicylic acid,p-hydroxybenzonic acid and ferulic acid had the same trend of weed-suppressive potential as cinnamic acid,while vanillic acid had a different weed-suppressive effect from the others.The inhibition rate (IR) on the root growth of barnyardgrass reached its highest level (78.5%) when 0.06 mmol·L -1 salicylic acid,0.60 mmol·L -1 p-hydrobenzonic acid,0.24 mmol·L -1 cinnamic acid,0.02 mmol·L -1 vannillic acid and 0.02 mmol·L -1 ferullic acid were mixed together to apply.