Intensidade da mancha de Phoma em mudas de cafeeiro em função de doses de cálcio e de potássio

Abstract

This study aimed to evaluate the intensity of Phoma leaf spot of coffee and nutrition in seedlings supplied with doses of Ca and K in nutrient solution. The test was repeated two times under the same conditions, to confirm the results. We used an isolate of Phoma tarda, from the Collection Micologica of Lavras - 720. Seedlings of IAC 62, were subjected to solution adaptation to 20%, 50%, 75% and 100% ionic strength, staying for 15 days each. Later they were transferred to the solution that consisted of five K (3, 4, 5, 6 and 7 mmol.L-1) and five doses of Ca (2, 4, 6, 8 and 10 mmol.L- 1). The pH was maintained between 5.0 and 5.5. The design was a randomized block with 25 treatments and three replications and two plants per experimental unit. Seedlings was inoculated with a suspension of 2 x 106 conidia.mL-1 of the leaflets adaxially, performing seven ratings for the incidence and severity of the disease, every seven days, at the end, he walked up the seedling to the Department of Soil Science, to determine the levels of macro and micronutrients. The supply of Ca and K showed significant interaction for area under incidence progress curve (AUIPC) and severity (AUSPC) Phoma leaf spot of coffee, for total dry matter (TDM) and the nutrient content in seedlings coffee. The lowest dose of Ca (2 mmol.L-1) and larger K (7 mmol.L-1) had smaller AUIPC (1235,85). The lowest dose of Ca and lower K, was smaller AUSPC (27,19) and larger TDM (4,20g). Increasing levels of K in nutrient solution caused a significant increase of K and Mn and significant reduction of P, Ca, Mg, S, Cu, Zn, B and Fe. Increasing levels of Ca, a significant increase on N, K, Ca and Zn and a significant reduction of P, Cu, Mn, Fe and B.