Abstract:
Weeds cause serious yield reduction in rice production worldwide and
herbicide-based weed management is the most popular method to overcome
this problem. Glyphosate, the most effective herbicide in controlling weeds
led to decrease the final yield due to o
effects can supersede by developing herbicide resistant (HR) rice. This study
was conducted to determine the most effective glyphosate concentration on
cultivated rice varieties and the variability of resistance betwee
preliminary study was conducted with five varieties (Bg300, Bg352, At362,
Bg379-2 and H4) to identify the most effective glyphosate concentration.
Five different concentrations of glyphosate (0.25, 0.5, 1.0, 2.0 and 3.0 g/l)
were applied to plants at three different time periods (2, 3, and 4 weeks after
sawing-WAS). Then the most effective concentration was applied to 24
varieties to evaluate their resistance. Complete randomize design was used
with three replicates. Plants with ≥50% survival were
varieties. Preliminary study revealed 0.5g/l at 3WAS, as the most effective
concentration where most of the rice varieties showed resistance. Twelve
varieties (Bg352, Bg359, Bg362, Bw364, Ld365, Bg366, Bg369, Bg379
“Madel” Pachcha Perumal”, “Kalu Heenati” and “Kurulu Thuda”) showed a
higher resistance (≥50%) compared to others. Agro
did not significantly differ among treatments and controls (p
number of fertile spikelets/panicle and 1000 grain
(p≤0.05) indicating a considerable yield penalty. Developing broad
HR rice varieties offers a novel efficient weed controlling method. Rice
varieties with natural HR have a higher potential in rice breeding progr
leading to develop new HR rice varieties in future.
