Adriana Verginassi

Abstract:

Asian rust, caused by the fungus Phakopsora pachyrhizi, is currently the main soybean disease. Aimed to evaluate, in the field, the effect of potassium silicate and other nutrient foliar applications and soil applications of calcium + magnesium silicate in the control of this disease and the silicon concentration in the cultivar “Valiosa”. The experiment was carried out in Jataí, GO, Brazil, in the 2006-2007 agricultural year. The experimental design was a randomized complete block with nine treatments and four replications and each experimental plot consisted of ten lines of ten meters in length. Disease severity was assessed at weekly intervals from the onset of the first pustules to complete defoliation. The yield of each plot and the weight of 100 grains were evaluated. Leaf and soil silicon content was also quantified. Si accumulation in leaves was significantly higher in treatments where calcium + magnesium silicate was applied, but it was not different from treatments with foliar application of potassium silicate. Si application before disease onset reduced the severity of Asian soybean rust by 22.5% and increased productivity by 3 soybean bags per hectare. The zinc contents in the shoot were influenced by leaf fertilization.

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