ABSTRACT
The aim of this study was to determine the potential of different concentrations of Ascophyllum nodosum marine algae extract (AN), potassium phosphite (PF), neem oil (NO) and pyroligneous extract (EP), all commercially available natural products, to induce phytoalexin accumulation in soybean cotyledons and sorghum mesocotyls. Five different concentrations were used for each product, as follows: 0.0, 0.1, 0.2, 0.3 and 0.4 mL/L for PF and 0.0, 0.1, 0.3, 0.5 and 1.0 mL/L for the remaining products. In addition, treatment with acibenzolar-S-methyl (ASM) served as a positive control. Analysis of variance showed that all tested products were effective in inducing phytoalexins in soybean cotyledons and sorghum mesocotyls, specially AN which, at the two highest concentrations, significantly differed from both the concentration zero and the positive control. Moreover, AN was numerically superior to the other products. The progressive increase in concentrations also resulted in progressive phytoalexin increases in soybean and sorghum, showing high correlation of the ‘concentration factor’ with the amount of produced phytoalexin. These results point out to the possibility of using these products as promising components in the integrated management of plant diseases.
Keywords
Ascophyllum nodosum; potassium phosphite; neem oil; pyroligneus extract
