Agriculture Reference
In-Depth Information
However, CYP76B1 was not induced in susceptible
P. minor
biotypes and iso-
proturon was degraded more slowly. The validity of this hypothesis needs
experimental confirmation.
Agricultural practices and herbicide efficacy
Agricultural practices specific to the region may influence herbicide activity.
After harvesting wheat or rice, unharvested straw is left in the field, and some-
times is burned to reduce the amount of straw (Fig. 4). Farmers in northwest-
ern India incorporate unharvested straw (unburned or burned) into soil [38].
Kaushik and Inderjit [39] studied the effect of rice straw (unburned and
burned) incorporation on phytotoxicity of isoxaflutole to
P. minor
. The soil
amended with rice straw, especially burned rice straw, reduced the level of
P.
minor
control attained with isoxaflutole.
Chhokar and Malik [22] suggested that rotation of crops and herbicides are
two effective ways to minimize herbicide resistance in
P. minor
. Heavy infesta-
tions of
P. minor
are found mainly with a wheat-rice cropping system, which
provides favorable conditions for emergence, growth, and development of
P.
minor
seedlings [40, 41]. Malik and Singh [41] surveyed wheat fields at 10 km
intervals and interviewed 100 growers. They concluded that evolution of resist-
ant
P. minor
biotypes was higher (67%) in the areas with rotations of continu-
ous wheat-rice compared to rice-berseem (
Trifolium hybridum)
-sunflower
(
Helianthus annuus
)-wheat (8%), cotton (
Gossypium hirsutum
)-pigeon pea
(
Cajanus cajan
)-wheat (16%) or sugarcane (
Saccharum officinarum)
/vegeta-
bles-wheat (9%). The rotation of wheat with non-cereal crops, such as sun-
flower or sugarcane, likely stimulates seed germination of
P. minor,
which then
Figure 4. A cultivated field showing unharvested rice straw, both unburned and burned.
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