The herbicide tolerance of a variety is the genetically determined ability of a cultivated plant to withstand the phytotoxic effects of a specific chemical agent. In practice, this allows for the application of broad-spectrum herbicides directly to the growing crop without the risk of damage or loss of the stand, which significantly simplifies weed control.
This trait is evaluated within the framework of state variety testing using field and laboratory test methods. In field conditions, plots subjected to chemical treatment are compared with control samples, where plant density preservation, the absence of phytotoxicity signs (chlorosis, necrosis), and growth rates are recorded. Laboratory methods include dose-response analysis to determine survival rates at various application rates of the chemical.
Tolerance indicators are expressed in visual damage scores, percentage of stand density preservation, or productivity levels relative to an untreated standard. High tolerance is characterized by the preservation of full productivity when the recommended full dose of herbicide is applied. With low tolerance, even reduced doses cause growth retardation and yield loss; therefore, an important parameter for variety selection is its compatibility with the specific mode of action of the applied chemical.