Abstract
The major factor responsible for low yield of upland rice is draught due to the high speed of water infiltration and low moisture retention capacity of savannah soils. Silicates, besides correcting soil acidity and supplying Ca and Mg in the soil solution, also supply Si. A Si accumulating plant can be more tolerant to draught because it can regulate transpiration more effectively, producing the same amount of dry matter with lower water consumption. This study evaluated the effect of silicate rates on upland rice growth and yield, in two savannah soils with different moisture levels. The experimental design was randomized factorial (2 x 3 x 4) with 4 repetitions, 2 soil classes, 3 soil moisture levels (60, 70 or 80% field capacity) and 4 Si rates (0, 200, 400 or 600 kg ha-1). The variables evaluated were: grain yield, root and above ground dry matter, plant height, number of stalks and soil and rice aboveground matter Si contents. The use of increasing calcium silicate rates increased Si levels in the soil and in rice aboveground matter. Si levels in the clay soil were greater than those found in the sandy soil. The increase in water availability promoted an increase in Si levels for rice. Increasing rates of calcium silicate increased grain yield, plant height and reduced the number of stalks. The use of silicate resulted in more resistant and productive rice plants, especially under water stress. Even under greater water availability conditions, the use of silicate resulted in greater rice yield.
AbstractThe major factor responsible for low yield of upland rice is draught due to the high speed of water infiltration and low moisture retention capacity of savannah soils. Silicates, besides correcting soil acidity and supplying Ca and Mg in the soil solution, also supply Si. A Si accumulating plant can be more tolerant to draught because it can regulate transpiration more effectively, producing the same amount of dry matter with lower water consumption. This study evaluated the effect of silicate rates on upland rice growth and yield, in two savannah soils with different moisture levels. The experimental design was randomized factorial (2 x 3 x 4) with 4 repetitions, 2 soil classes, 3 soil moisture levels (60, 70 or 80% field capacity) and 4 Si rates (0, 200, 400 or 600 kg ha-1). The variables evaluated were: grain yield, root and above ground dry matter, plant height, number of stalks and soil and rice aboveground matter Si contents. The use of increasing calcium silicate rates increased Si levels in the soil and in rice aboveground matter. Si levels in the clay soil were greater than those found in the sandy soil. The increase in water availability promoted an increase in Si levels for rice. Increasing rates of calcium silicate increased grain yield, plant height and reduced the number of stalks. The use of silicate resulted in more resistant and productive rice plants, especially under water stress. Even under greater water availability conditions, the use of silicate resulted in greater rice yield.
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