Field and In-Vitro Studies on the Use of Low Glyphosate doses for Broomrape Control in Tobacco

Abstract

This study was conducted to investigate the potential use of low doses of glyphosate, normally a recommended herbicide, for controlling broomrape that is one of the most significant weed problems in tobacco cultivation. In the first stage of the study, the resistance of tobacco varieties, important for our country, to different doses of glyphosate was determined. Although glyphosate, which acts as a perfect herbicide at high doses, was also tested at lower doses and Atonik containing 1 g sodium 5-nitroguaiacolate, 2 g sodium orto-nitrophenolate, and 3 g sodium para-nitrophenolate per liter was added to the experimental treatments to prevent potential phytotoxicity. Applications were conducted using doses and sub-doses of glyphosate that tobacco varieties could tolerate. Broomrape was inoculated into tobacco plants under in vitro conditions, and the biological efficacy of glyphosate against broomrape was determined. Based on the obtained results, field trials were established in naturally infested areas. The collected broomrape samples were identified as Phelipanche ramosa (L.) Pomel, characterized by its prominent branching structure. When the results were evaluated in terms of dry weight, scale values, and chlorophyll content, the İzmir Özbaş standard tobacco variety proved to be the most resistant to glyphosate doses. This variety was found to be resistant even when glyphosate was applied at intervals of ten days up to a dose of 4 ml da^-1 active ingredient. This result was considered promising for potential use in broomrape control in tobacco, as intended.