The sugar and alcohol industry, in order to minimize production costs, has improved its applications of phytosanitary products with the use of aerial herbicide and ripening applications. Such aerial applications as well as errors in the application technology provide the risk of drift and damage adjacent crops such as citrus orchards. There are few scientific studies in the area and the number of drift complaints by producers is high. Thus, the objective of this work was to evaluate the effects of simulated drift of four chemical ripeners frequently used in sugarcane (glyphosate, sulfometuron-methyl, ethyl-trinexapac and ethephon) and increasing doses of the most harmful ripener on morphological and physiological characteristics of orange tree seedlings "Valencia". To do so, the first experiment will consist of applications of these ripeners in their recommended doses and also in half of these doses, in addition to the controls, without application of ripener. From the previous results, the most harmful seedling ripper will be used in the second experiment, which will consist of applications of a serial dosage (0 - 2x) of the recommended dose (x) of the ripener in question. In both experiments, the seedlings will be evaluated at 0, 15, 30, 60 and 120 days after application (DDA) in order to measure dominant height, stem diameter, length, number of leaves of a sprouting branch, relative of total chlorophyll in leaves in the final third of the branches and in the middle third of the budding branch and the FV/FM ratio of chlorophyll a fluorescence. Also, at the end of the experiments the leaf area and dry mass of the stem and leaves will be determined. Morpho-physiological changes in seedlings will be investigated throughout the experiments through photographic records. The data obtained will be submitted to analysis of variance by the F test, with a comparison of means by the Tukey test and regression analysis as a function of the doses applied, in the second experiment.
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