Eucalyptus plants are sensitive to biotic and abiotic stresses during their initial growth, with water deficiency being the most common of the abiotic. During the initial period of growth, previous studies have reported that the application of ethyl-trinexapac in low dosages can provide a better development of the plants, which can last up to 90 days after planting eucalyptus. However, there are no studies that report the effect of this product on eucalyptus seedlings after sequential application. Thus, the objectives will be to determine the best combination of doses of ethyl-trinexapac for sequential application in Eucalyptus urograndis (Clone 1407) seedlings; to evaluate its effect on the recovery of eucalyptus seedlings after different periods of water stress; as well as determine the best time to apply the product after the stress periods. To do so, two experiments will be conducted for 100 days after planting in semicontrolled conditions, in 15 L pots, filled with a mixture of soil and sand. In the first experiment, treatments will be arranged in a 4x4 factorial scheme, with a total of 80 experimental plots. The factors will be constituted by 4 doses (0, 30, 60 and 90 g ia ha-1) of ethyl-trinexapac applied in the eucalyptus seedlings still packed in tubes, and 4 doses (0, 100, 150 and 200 g ia ha- 1) of ethyl-trinexapac in sequential application, which will be carried out at 40 days after planting (DAP). Based on the best results of the first experiment, in the second the treatments will consist of a 3x3 factorial, being 3 periods of water stress (3, 6 and 9 days) and 3 periods of application of the product (3, 6 and 9 days) after the return of irrigation. For both experiments, evaluation of flowering and chlorophyll content will be performed. Plant height and stem diameter will be evaluated every fortnight. At the end of the experimental period (100 DAP), the leaf area and the dry mass of the leaves and stem will be determined. The data will be submitted to analysis of variance by the F test, and the means compared by the Tukey test at the 5% probability level.
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