Gene introgression for imidazolinone group chemical herbicide tolerance.

Genes of tolerance for herbicide has become one of the options more used in world level for the weed control. This study had as objective to evaluated crosses between tolerant irrigated rice plants and sensitive to herbicides of the imidazolinone chemical group, through the evaluation of F₂ populations. Five genotypes of irrigated rice were crossed. Three of these parents are sensitive to the herbicide: BRS Querência, BRS Fronteira and BRS Pampa and two genotypes, BRS Sinuelo CL and Puitá INTA CL, tolerant to the herbicide. F₁ seeds were obtained in greenhouse, and generation advance was performed in Embrapa Rice and Beans, resulting in the F₂ population. F₂ plants in the stage V4 received herbicide applications of (Only^®) at a dose of 75 and 25 g a.i. L⁻¹, and Dash^® in dose of 0.5% v/v. A second application was performed after one week. The degree of phytotoxicity was scored as dead leaves and phytotoxicity intensity, percent survival of leaves and the relative growth. The results showed that the F₂ hybrids, resulting of the crosses between the cultivars carriers of the gene of herbicide tolerance of the imidazolinone (Only^®) class and conventional irrigated rice cultivars, are viable, thus enabling the establishment of herbicide-tolerant irrigated rice populations, with greater capacity to fight the red rice and with characteristics of agronomic interest. F₂ progenies descending from crosses with the cultivar Puitá INTA CL presented more tolerance when compared with progenies descending from crosses with the cultivar BRS Sinuelo CL. [ABSTRACT FROM AUTHOR]