Due mainly to the taste and appearance, the strawberry stands out in relation to the other fruits. and for the presence of antioxidant compounds. However, little attention has been devoted to the impact of abiotic stresses on the quality of strawberry and its agronomic performance. On the present study, we evaluated the effect of two levels of DS (L1 -70% and L2 -50% of crop evapotranspiration) on the quality of strawberry fruit and on some agronomic and physiological variables. There was a dose-dependent reduction in the evaluated agronomic variables in the DS plants, and the content of some minerals in the fruit and leaves was modified. The activities of the oxidative enzymes were higher in the fruit of L2 treatment, and the content of sucrose, reduced sugars, phenolic compounds and the total antioxidant activity were increased in the fruit from L2 treatment; while those of anthocyanins and L-ascorbic acid were reduced in L1 and L2 treatments, respectively. The phenylalanine ammonia lyase gene was upregulated and other genes related to phenylpropanoid and ascorbate pathways were downregulated in the fruit of stressed plants. Thus, our results indicate that DS seems to be a promising strategy to improve the content of antioxidant compounds and sugars.Practical Application: Drought stress might be applied to induce antioxidant and sugars in strawberry fruit.

bEmbrapa Clima Temperado, Rodovia BR 392, km 78, Brasil Recebido em 06/04/2018; aceito em 02/08/2018; publicado na web em 19/09/2018 DETERMINATION OF POTASSIUM IN SILICATE ROCKS BY FLAME ATOMIC EMISSION SPECTROMETRY AFTER ULTRASOUND DISSOLUTION. This work presents the development of an analytical method for sample preparation aiming at the K determination in silicate rocks (basalt, monzogranite and shale fines) following ultrasound dissolution and analysis by F AES. Sample preparation method was optimized by using fractional factorial designs. The following optimal conditions were obtained for each silicate rock: 0.1 g of sample mass for any of the three samples, and volumes of HNO 3 , HCl and HF, respectively, of 2.5, 0.8 and 2.5 mL for basalt; 3.5, 0.8 and 2.5 mL for monzogranite, and 2.5, 1.0 and 2.0 mL for shale fines. Sample dissolution was achieved by using the ultrasound bath at room temperature (25 ºC) for 1 hour. The accuracy was evaluated through the analysis of two certified reference materials, for which there was no statistical difference between the certified and the found K concentration values (95% confidence level). The K concentrations determined were: 1.45 ± 0.01 for basalt; 4.19 ± 0.03 for monzogranite and 1.60 ± 0.02 for shale fines. The developed method presented accurate and reliable results for K amounts in silicate rocks and is simple and safe, which are important features for the implementation of a methodology as a routine analysis.

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