HERBOLOGIA - anubih

B. Konstantinović et al.
and Shaner, 2001; Rashid et al., 2003; Rubin et al., 2004) and in Vojvodina
(Konstantinovic et al., 2003a; 2003b; 2003c).
Primary action target site of these herbicides is the enzyme of
acetolactate synthase that participate in biosynthesis of amino acids
isoleucine, leucine and valine (Ray, 1984; Gerwick et al., 1990; Takahashi et
al., 1991, Babczinski, 2002), and resistance develops as the consequence of
the single mutation points that ALS structure makes less susceptible to
herbicides.
After five years of permanent use of the ALS inhibiting herbicides in
monoculture of Triticum aestivum L. crop (Mallory-Smith et al., 1990) in
1987 the first weed resistant to ALS inhibitors, Lactuca serriola (Smith and
Cairns, 2001) was determined. Stellaria media (L.) Vill (Kudsk et al., 1995)
was the first weed species resistant to Sulfonylureas found in Europe. Until
now, resistance has been described for 93 weed biotypes from all over the
world, and this number is constantly increasing (Heap, 2006). In regard to the
other herbicide groups, weed biotypes resistant to herbicide that inhibit ALS
enzyme are the most numerous.
In the paper the occurrence of herbicide resistance development of the
weed species Amaranthus retroflexus L. from various localities in Vojvodina
to herbicide imazethapyr from the chemical family Imidazolinones. On the
studied localities Imidazolinones had long history of use in weed control.
Material and methods
During 2005 and 2006 study of weed species Amaranthus retroflexus
L. resistance to imazethapyr was performed according to the methods applied
in laboratory conditions and climatic chamber (Clay and Underwood, 1990;
Moss, 1995). In bioassays a range of imazethapyr rates were used, e.g. 0 ,
0.04 , 0.08 , 0.10 , 0.15 , 0.20 and 0.40 kg a.i./l. During assays seedling
epicotyls and hypocotyls length, stem height, foliage fresh weights and seed
germination and shooting were measured. Statistical data processing was
performed by variance analysis (ANOVA), and significant difference was
evaluated by t-test (Hadzivukovic, 1991). Resistance can be determined only
if there are statistically significant differences between the studied population
and the susceptible standard and if resistant population can not be controlled
by herbicide rate that is efficient in control of the susceptible one (Beckie et
all., 2000). Results of the measured parameters – epicotyls and hypocotyls
length, stem height and germination percentage and shooting are presented as
a quantity-response curve, while values of the foliage fresh weight and
resistance indices were given in a table.
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