Eficiência no uso da água em linhagens de arroz de terras altas: eficiência no uso da água em linhagens de arroz de terras altas

Abstract

The upland rice crop (Oryza sativa) in Brazil is affected by several biotic and abiotic factors that limit the cultivars potencial production used by the producers. About water deficiency, the selection of lines and consequent development of drought tolerance and/or water use efficiency is a priority research line in upland rice breeding programs and one of the best strategies to minimize the problem. Therefore, the objective of this work was evaluate the upland rice agronomic behavior submitted to different irrigation sheets, in order to selection of tolerant and responsive genotypes to water deficit. A total of 34 recombinant inbred lines from the crossing between BRS Soberana and Douradão genotypes, were evaluated in irrigated trial under additional sprinkler irrigation (IRR) and another trial without additional irrigation (SEQ), in Lavras/MG, 2015/16. The experimental design used was a 6x6 triple lattice and the plots consisted 3 lines of 4 m spaced 0.35 m. The evaluated characteristics were grain yield, water use efficiency, flowering days number, plant height, rice panicle blast incidence, spikelet number per panicle and spikelet sterility. The dry tolerance index was calculated for the lines. It was concluded that: there were different behavior between the lines in relation to the level of water that were submitted, being possible the selection of responsive and tolerant genotypes; drought tolerance is a complex trait that involves several characteristics in the plant development, and the grain yield is a good feature to be improved by breeders in genotype selection in upland rice drought tolerance breeding programs; the 16 line presented promising results in relation to water use efficiency, with 14.15 kg.ha -1 for each millimeter of water applied in the IRR trial and 10.91 kg.ha -1 in the SEQ trial, being interest line to be used in upland rice drought tolerance breeding programs.