Silicon In Aluminum Tolerance In Plants of Upland Rice.

The upland rice has characteristics of rusticity, with some tolerance to soil acidity and toxic aluminum, besides to accumulate high levels of silicon. The silicon absorbed provides improvements to plants, among them alleviates the toxicity of aluminum, however, the mechanisms involved in the interaction of Si with Al³⁺ are still poorly understood. Given the above, the objective of this study was to evaluate the mineral nutrition of plants of upland rice with Si subsequently subjected to stress Al³⁺. The experiment was conducted in nutrient solution for 42 days, 7 ½ days with the ionic strength, total strength 14 days, 14 days with full strength and (+Si) – (-Al³⁺), 7 days with full strength (-Si) – (+Al³⁺). The experimental design was randomized blocks, arranged in 2x5 factorial design with four replications. The treatments were two cultivars of upland rice: BRS Talento - not toxic Al³⁺ tolerant, modern, Guarani - tolerant to toxic Al³⁺, traditional, and added to the nutrient solution five Si rates (0, 30, 60, 90, 120 mg dm-3). The results show that height and number of tillers per plant were not influenced by Si in the nutrient solution and the dry matter production of shoot and root. However, there were differences among cultivars, Guarani cultivar showed higher dry matter production of shoots probably due to its height. BRS Talento showed higher roots dry matter production and number of tillers per plant. These results indicate that plants of upland rice nourished before with Si and subsequently subjected to Al³⁺ stress tolerance has not differentiated the Al³⁺.