Influence of selected soil-climatic parameters and application method of tribenuron methyl on biomass productivity and amino acids content in weeds

Abstract

Pot experiments were carried out in controlled environment chambers to investigate the influence of climatic factors and application methods on tribenuron methyl activity on three weed species: Anthemis arvensis, Galium aparine and Stellaria media. Tribenuron methyl was used at a dose of 15 g a.i. ha−1 solo or in mixture with a surfactant. Herbicide activity was subjected to the influence of environmental conditions such as: air temperature (25/16°C and 8/2°C day/night), relative humidity (75% and 50%) and soil moisture (60% and 30%). Herbicide efficacy was evaluated on fresh weight and reduction in free branched-chain amino acids content. The surfactant affected tribenuron methyl efficacy differently, depending on the environmental conditions and weed species susceptibility. Control of S. media did not require addition of a surfactant to achieve a high efficacy. The joint application enhanced herbicide efficacy against A. arvensis compared to solo application under low relative humidity (RH). Galium aparine was satisfactory controlled only when the surfactant was added to the spray solution, even under optimal environmental conditions. In most cases the amino acids content declined after exposure to tribenuron methyl and tank mix with the surfactant further improved its reduction. Increased amino acid content was observed in G. aparine and A. arvensis exposed to low soil moisture and G. aparine exposed to 50% RH, probably due to amino acids overproduction as a response to environmental conditions.