In years 2005-2007, sensitivity assessment of four maize hybrids took place – Gazelle, LG 3225, Lober, and PR 39H32, depending on the time and method of herbicide Mustang 306 SE application. Varietal experiment was established using the method of randomized blocks, in three replications, on soil classified as good wheat complex. Weeding was performed mechanically. Hybrids were sprayed with herbicide Mustang 306 SE at the dose of 0.6 dm³·ha^-1 at the 3-4- or 6-7-leaf stage, as well as with a dose limited by 50% at the 3-4- and 6-7-leaf stage. The objects on which the herbicide was applied were compared with the control (no herbicide used). In order to assess the yield variability of the analyzed maize hybrids within the realm defined by four variables (three variants of herbicide application + control), the methods of discriminatory analysis and cluster analysis were used. Gazelle hybrid was characterized by the highest yield variability depending on the date and dose of the applied herbicide in comparison with the control. Significantly higher yield stability was characteristic to hybrids LG 3225 and PR 39H32. Application of herbicide at the 6-7-leaf stage resulted in considerable yield reduction of all the studied maize hybrids (9.09 t·ha^-1). Maize hybrid yield on plots sprayed with split Mustang 306 SE herbicide doses at the 3-4-leaf stage (9.83 t·ha^-1) and 6-7-leaf stage (10.29 t·ha^-1) did not differ, however, from the yield obtained on the control (10.32 t·ha^-1).

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