Efficiency of Calcium Silicate and Carbonate in Soybean Disease Control

ABSTRACT

Silicon (Si) affects the susceptibility of plants to fungal attack. In plants with low Si accumulation, disease-control mechanisms involve the accumulation of phenolic compounds and Si. This study compared the effects of calcium silicate and carbonate doses on the control of soybean (Glycine max) diseases. A sandy soil was collected from Santa Vitória, Minas Gerais state, Brazil, of which 200 kg was placed in plastic drums in a protected, uncovered area. Calcium carbonate or silicate was applied superficially in amounts equivalent to 0, 1500, 3000, 6000, or 12,000 kg ha⁻¹, and soybean was cultivated for 120 d. Leaf Si concentration and incidence of Cercospora sojina (Frog's eye spot), Peronospora manshurica (downy mildew), and Phakopsora pachyrhizi (Asian rust) were evaluated. Calcium carbonate did not reduce disease incidence; however, calcium silicate was effective in the reduction of downy mildew at 47 and 66 d after soybean seeding, and of frog's eye spot incidence at all dates evaluated. Asian rust was observed only at 79 d after seeding and calcium silicate was not effective in its reduction.

Keywords:

• fertilization
• silicon
• phytoalexins
• slag
• resistance mechanism
• defense to biotic stress

ACKNOWLEDGMENTS

The authors acknowledge the Brazilian National Research Council (CNPq) for financial support and fellowships.