Resistência induzida em trigo ao pulgão Schizaphis graminum (Rondani, 1852) (hemiptera: aphididae) por silício e acibenzolar-s-methyl / Induced resistance on wheat to Schizaphis graminum (Rondani, 1852) (Hemiptera: Aphididae) by silicon and acibenzolar-s-methyl

RESUMO

Conduziu-se este trabalho com o objetivo de avaliar o efeito do silício e do acibenzolar-S-methyl na indução de resistência ao pulgão-verde Schizaphis graminum (Rondani, 1852) em trigo. Foram realizados dois experimentos, sendo, no primeiro, as plantas de trigo pulverizadas com ácido silícico e no segundo com silicato de cálcio e/ou acibenzolar-S-methyl. As avaliações foram realizadas através de testes de livre escolha e de tolerância (contagem do número dos pulgões presentes nas plantas e peso seco da parte aérea). Os dados foram submetidos à análise de variância, sendo as médias comparadas pelo teste de Scott-Knott (P<0,05). Os resultados do experimento com ácido silícico revelaram que o número de pulgões na testemunha foi nove vezes maior que nas plantas que receberam aplicação de ácido silícico, porém não houve diferença significativa no peso seco das plantas entre os tratamentos testados. No segundo experimento, os tratamentos com acibenzolar-S-methyl e posteriormente silício (silicato de cálcio) ou apenas acibenzolar-S-methyl, tiveram menor aceitação pelos pulgões. De maneira geral, a aplicação de silício e/ou acibenzolar-S-methyl aumentou a proteção das plantas de trigo.

ABSTRACT

The objective of this work was to evaluate the effect of silicon and acibenzolar-S-methyl on the induction of resistance on greenbug Schizaphis graminum (Rondani, 1852) on wheat plants. Two experiments were performed in which in the former wheat plants were sprayed with silicic acid and the other ones' with calcium silicate and/or acibenzolar-S-methyl. The evaluations were by free choice and tolerance tests (counting the number of aphids present on plants and by dry weight of the shoot). The data were submitted to the analysis of variance, the means being compared with by Scott-Knott test (P<0.05). The results of the experiment with silicic acid showed that the number of aphids on the treatment control was nine times higher compared to sprayed plants with silicic acid. There was no significant difference in the dry weight of the plants among the treatments tested. The plants sprayed with acibenzolar-S-methyl and afterwards with silicon (calcium silicate) or only acibenzolar-S-methyl were less preferred by the aphids. In general, the spray of silicon and/or acibenzolar-S-methyl increases the protection of wheat plants against Schizaphis graminum.