Target-site and non-target-site based resistance to the herbicide tribenuron-methyl in flixweed (Descurainia sophia L.)

Table 1 GR₅₀ and I₅₀ values of the susceptible (SD8) and resistant (N11) flixweed populations to tribenuron-methyl, in the absence and presence of cytochrome P450 inhibitor malathion

Herbicides	SD8 (S)		N11 (R)
Herbicides	GR₅₀ ^a	I₅₀ ^b	GR₅₀ ^a	RF^c	I₅₀ ^b	RF^c
Tribenuron-methyl	0.046a	1.77a	5.35b	116.3	54.65b	30.9
Tribenuron-methyl + malathion	0.039a	-	1.12c	28.7	-	-

Resistance levels were indicated by the resistance factor (RF). GR₅₀ or I₅₀ values with different letters are significantly different at P = 0.05 significant level. Data were means of two experiments
^a GR₅₀, herbicide rate causing 50 % growth reduction of plants
^b I₅₀, herbicide concentration causing 50 % inhibition of the ALS activity
^c RF (resistance factor) = GR₅₀ or I₅₀ (R)/GR₅₀ or I₅₀ (S)

ISSN: 1471-2164