Response of inbred and traditional rice varieties (Oryza sativa L.) to broad spectrum herbicide glyphosate

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.