Silício foliar no manejo da mancha de Alternaria e na produtividade do algodoeiro

Silicon (Si) has been studied as a beneficial element capable of increasing plant resistance to biotic stresses and favoring crop production, but the results of foliar application in cotton (Gossypium hirsutum L.) are still variable. This study aimed to evaluate the effect of two sources and two rates of foliar-applied silicon on plant height, yield components and boll weevil damage in two cotton cultivars. The experiment was carried out in pots, outdoors, at the Federal Institute of Triângulo Mineiro, Uberlândia campus (MG, Brazil), in a randomized block design, in a 2 × 5 factorial scheme, with four replicates. The factors were two cultivars (FM 985 GLTP and DP 1949 B3RF) and five treatments: control without silicon, Sifol (3.0 and 3.5 L ha-1) and Sifol Powder (1.5 and 2.0 kg ha-1), applied at the V3 and R1 stages. Plant height at 50, 74, 88 and 145 days after sowing, seed and fiber mass per plant, number of bolls and number of bolls damaged by the boll weevil (Anthonomus grandis) were evaluated. Data were subjected to analysis of variance and means were compared by Tukey’s test at 5% probability. Under the conditions studied, foliar silicon application did not change plant height, yield components or boll weevil damage in cotton, and further studies with more replicates and under field conditions are needed.