engleski

Effect of combining reduced doses of herbicides with phenolic acids to reduce germination and growth Ambrosia artemisiifolia L.

Phenolic acids, a major source of allelochemicals can inhibit weed germination and growth. The aim of this study was to determine germination, radicle and hypocotyl length, seedling weight, chlorophyll a and b, carotenoids, and aboveground dry mass of Ambrosia artemisiifolia treated with dissolved p-hydroxybenzoic acid, coumaric acid, ferulic acid, and vanillic acid in aqueous solution of reduced doses of the herbicide Adengo (thiencarbazone-methyl, 90 g L-1, isoxaflutole 225 g L-1). The strongest inhibitory effect on germination and initial growth of A. artemisiifolia was observed by the addition of p- hydroxybenzoic acid and ferulic acid in reduced doses of herbicide. In the greenhouse experiment, hydroxybenzoic acid (22.3 and 177.8 µg mL-1) and ferulic acid (110.4 µg mL-1) were added at linearly decreasing herbicide doses of 1/8 - 1/128 (x) (x = 0.44 L h-1). Visual damage to the aboveground mass of A. artemisiifolia treated with ferulic and p-hydroxybenzoic acid was observed at 1/8 and at 1/16 of the herbicide dose, respectively, when ferulic acid was added. The estimated ED90 for the herbicide plus ferulic acid is 0.031 L ha-1, compared to 0.052 L ha-1 (Adengo alone). At 1/8 x Adengo plus ferulic acid, the occurrence of generative organs on treated plants was not observed. Carotenoid content was lower at reduced herbicide doses, but the addition of phenolic acids to reduced herbicide doses did not show lower carotenoid content compared to herbicide application alone, so a more relevant indicator of herbicide efficacy is visual assessment of aboveground mass damage and ragweed dry matter reduction. The results show that the herbicide dose can be significantly reduced by the addition of ferulic and p-hydroxybenzoic acid. Since the herbicide efficacy depends on a number of biotic and abiotic factors, the further studies should be conducted in maize cultivation under different pedoclimatic conditions and different stages of ragweed development.

p-hydroxybenzoic acid ; ferulic acid ; thiencarbazone methyl ; isoxaflutole ; allelopathy.

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