India - Herbicide-tolerant rice developed at NRRI

Weed infestation causes 18–48% yield loss in rice. The weeds are managed by keeping stagnant water in the field or through manual or mechanical weeding. Thus, availability of any cost-effective weed control method will make rice cultivation economically viable and sustainable.

Besides, broad leaf and grassy weeds, weedy rice is an emerging problem under direct seeded conditions. Its competitive ability is very high and traditional herbicides can’t control such weeds. Herbicides which kill the weedy rice also kill the rice crop. Thus, there is a need for developing rice varieties which can control weedy rice as well as other weeds.

In India, scientists could successfully develop a mutant line ‘Robin’ in upland variety N22 which tolerates the herbicide Imazethapyr due to a mutation in Acetohydroxy Acid Synthase (AHAS) gene.

At the ICAR-National Rice Research Institute here, this herbicide-tolerant gene has been introgressed in four popular rice varieties, (Sahbhagidhan, Naveen, SwarnaSub1 and Pooja) and are currently under national testing.

Imazethapyr herbicide, when sprayed 21 days after sowing, effectively controls the weeds of rice as well as weedy rice without affecting the yield potential of the tolerant variety. Release and large-scale adoption of the herbicide tolerant rice can significantly reduce the cost of cultivation and enhance the acreage under direct seeded rice in India.