Multilinha visando estabilidade fenotípica e resistência a brusone em arroz

Abstract

Rice (Oryza sativa L.) is the second most cultivated specie in the world, especially in developing countries. In recent years, there has been a significant reduction in rice cultivated area in Brazil due to the lower usage of the crop to the incorporation of new agricultural areas and also to the great competition with other crops, mainly soybean. Another factor responsible for providing large oscillations in rice cultivation is the occurrence of a large number of biotic stresses in agricultural crops, especially fungal diseases. For rice cultivation, it stands out Pyriculariagrisea, a fungus that causes blast, a disease that provoke great damage in rice grain yield. A recommended alternative for blast control is the use of resistant cultivars. In addition, the use of multiline cultivars, which are mixtures of lines with similar agronomic characteristics, it is an efficient strategy aiming at stability of production and resistance to this pathogen. Therefore, the aiming of this study was to verify the efficiency of the multilines as a strategy to reduce the progress of blast and therefore its possible benefits to rice grain yield. The experiments were conducted in the 2016/17 and 2017/18 agricultural year, in Patos de Minas / MG, Lavras / MG, Lambari / MG and Registro / SP, totaling 8 environments (enviroments x agricultural year). The experimental design was a randomized block design with three replications and it was evaluated 12 lines and the multiline,which was composed of five lines selected from the cultivation and use value (VCU) trials. The characteristics of grain yield, number of days for flowering leaf blast incidence and neck blast incidence were evaluated.After analyzing the data, it can be inferred that the multiline presented grain yield estimation above the average of the experiments, having produced a further 7 bags per hectare, showing a high phenotypic stability. Regarding the reaction to blast incidence, the multiline presented a performance above the resistance average compared to the most susceptible lines. The selection of the lines that composed the varietal mixture was also efficient, indicating a favorable multi-character selection according to the performance obtained by the multiline in the experiments. In this case, the selection of the lines for the multiline composition was favorable and efficient, highlighted by the superior grain yield performance to most of the lines of the VCU trials performed. Therefore, it can be concluded that the multiline is a good strategy to provide greater phenotypic stability, besides reducing the progress of blast in the crops.