Response of herbicides in different rice varieties under wet direct-seeded ecosystem

Abstract

The present study was conducted to evaluate the imazethapyr tolerant variety with different weed management methods. A field experiment was conducted in the experimental farm of the Department of Rice, TNAU, Coimbatore, Tamil Nadu during rabi season 2020 in split plot design with three replications. The treatments in main plot consisted of nine rice varieties viz HTM-N 22, N 22, Anna (R) 4, CO 53, CO 51, ADT 53, ADT 37, ADT 43 and ADT 45. In sub-plot weed management methods included early post-emergence herbicide application of imazethapyr @ 75 g ai/ha at 30 DAS, early post-emergence herbicide application of bispyribac sodium @ 25 g ai/ha at 15-20 DAS, pre-emergence herbicide application of pretilachlor @ 0.75 kg ai/ha at 8 DAS followed by early post-emergence herbicide application of bispyribac sodium @ 25 g ai/ha at 20-25 DAS, hand weeding twice at 20 and 40 DAS and un-weeded check. There were marked variations in the effect of various weed management practices in direct-seeded rice. In weed management methods, pre-emergence herbicide application of pretilachlor @ 0.75 kg ai/ha at 8 DAS followed by early post-emergence herbicide application of bispyribac sodium @ 25 g ai/ha at 20-25 DAS effectively controlled the weeds in wet direct-seeded rice ecosystem. Among the varieties tested, HTM-N 22 and N 22 only survived with the early post-emergence herbicide application of imazethapyr @ 75 g ai/ha at 30 DAS. The varieties HTM-N 22 and N 22 can be utilised for rice breeding programme for the development of herbicide tolerant varieties.