Response of Urochloa brizantha cv. BRS Piatã to different levels of aluminum and to silicon application

Resumen

The aim of the present study was to evaluate the response of the forage Urochloa brizantha cv. BRS Piatã to different levels of aluminum (Al) and the use of silicon (Si) as an attenuator of Al toxicity. For this, plants of U. brizantha were cultivated in plastic pots with a capacity of 2.5 L filled with nutrient solution. A completely randomized design was used in a 4 x 2 factorial scheme consisting of four concentrations of Al (0, 2, 4, and 8 mmol L⁻¹) and application or non-application of Si. Four replications were used for each treatment. After 14 days, the plants were collected for the following evaluations: plant height, fresh and dry mass of shoot and roots, root/shoot ratio, leaf area, number of tillers, electrolyte extravasation, and accumulation of Si and Al. The data were submitted to polynomial regression analysis, applying linear and quadratic mathematical models to select the one with the best adjustment. In general, Al accumulated in both roots and shoots of plants, reducing the growth of both organs. In addition, there was a strong increase in electrolyte extravasation, indicating increased oxidative stress. On the other hand, the foliar application of Si reduced the accumulation of Al and the leakage of electrolytes while increasing the growth of both the shoot and the roots. Thus, it is concluded that, although Al causes severe damage to U. brizantha, the foliar application of Si is a potential mitigator of this stress.