Abstract
Weedy rice (WR) (Oryza sativa L.) is the most troublesome weed infesting rice paddies in Brazil. Several changes have occurred in this region regarding crop management, especially WR control based on the Clearfield™ (CL) Rice Production System launched in 2003. This survey’s objective was to evaluate the WR infestation status by assessing the producers’ perception and the management practices used in southern Brazil after eighteen years of CL use in Brazil. Rice consultants and extension agents distributed a questionnaire with 213 producers in the Rio Grande do Sul (RS) and Santa Catarina (SC) state in the 2018/19 growing season. In RS, most farms are larger than 150 ha, farmers use minimal or conventional tillage, permanent flooding, adopted the CL system for more than two years, use clomazone PRE tank-mixed with glyphosate at the rice spiking stage, and use crop rotation with soybean [Glycine max (L.) Merr.] or pasture. In SC, rice farms are small, averaging from 20 to 30 ha, farmers predominantly plant pre-germinated rice and do not rotate rice with other crops and roguing is practiced. Comparing both states, the CL System is used in 99.5, and 69.3% of the total surveyed rice area in RS and SC, respectively. Imidazolinone-resistant WR is present in 68.4 and 26.6% of rice farms in RS and SC, respectively. Rice cultivation in Brazil is currently coexisting with WR with minimal integration of control methods. However, integrated practices can control this weed and are fundamental to the sustainability of systems based on herbicide-resistant rice cultivars.
Studies on Molecular Characterization of DREB Gene in Indica Rice (Oryza sativa L.)