Avaliação nutricional de plantas de erva-mate atacadas e não atacadas pelo Hedypathes betulinus (Klug, 1825)

Abstract

A pesquisa teve por objetivo avaliar e comparar os teores nutricionais de plantas de erva- -mate, Ilex paraguariensis St. Hil., atacadas e não-atacadas pela broca-da-erva-mate Hedypathes betulinus (Klug, 1825) (Col.: Cerambycidae), para identificar possíveis desequilíbrios nutricionais no solo e nas folhas. A área amostrada está localizada no município de Catanduvas, SC. O erval estudado é homogêneo, com idade de 8 anos e densidade de 2.100 plantas/ha. As amostragens de folhas e de solo foram realizadas nos meses de fevereiro e abril de 1999. As amostras foram submetidas à análise química, em Laboratório de Análise Química. Foram interpretados os teores para cada elemento químico, realizaram-se os testes de comparações de médias “t” e “f” e o teste de homogeneidade de variâncias. Observou-se que o solo apresenta teores considerados adequados de N e P, teores baixos de K, Ca e Mg e altos para S, B, Fe, Mn, Zn, Cu, Na, Al, Al+H, Ph e SMP, para a erva-mate. Já na análise foliar, as plantas apresentam teores considerados adequados de K, Ca, B, Zn e Na, teores baixos de P, Mn e S e altos de N, Mg, Fe, e Cu. Nessa análise, chamou a atenção, as altas concentrações de N e os baixos níveis de S no tecido foliar. O teste “t” registrou diferença significativa para o P do solo e de folhas e o teste “f”, revelou o ferro do solo, como elemento químico com diferença significativa entre as médias das duas condições de plantas. O P e o Fe do solo e ainda, o K, S e Mn de folhas foram os elementos químicos que registraram heterogeneidade significativa de variâncias. Das variáveis estudadas, as plantas atacadas foram as que revelaram maior variação entre as médias.

The present research aimed at evaluating and comparing the nutritional levels of erva mate (Ilex paraguariensis St. Hil.), plants which were attacked by Hedypathes betulinus (Klug, 1825) (Col.: Cerambycidae), and plants of the same specie, which were not attacked by this insect. This objective was established in order to identify possible nutritional instabilities in the soil and in the leaves of these erva mate plants. The area where the investigation was conducted is localized in Catanduvas (SC). The plantation of erva mate, which had density of 2100 plants/ha, was eight years old and it was homogeneous. The samples of the plants and the soil were collected between February and April in 1999. They also were submitted to chemical analysis on Soil Analysis Laboratory. In this place, it was interpreted the levels of each chemical element and it was applied the tests of comparisons means “t” and “f” and test of homogeneity of variances, of erva mate plants. Soil showed levels adequate of N and P, low levels of K, Ca and Mg and right to S, B, Fe, Mn, Zn, Cu, Na, Al, Al+H, ph and SMP. In the tissue analysis, plants presented levels adequate of K, Ca, B, Zn and Na low levels of P, Mn and S and right to N, Mg, Fe and Cu. The test “t” demonstrated expressive difference for the P of the soil and leaves. The test “f” demonstrated Fe of soil as chemical variables with significant differences. P and Fe of the soil and K, S and Mn of the leaves were the chemical elements that showed expressive heterogeneity of variances. Comparing the two varieties of erva mate plants, the ones, which were attacked by the insect, revealed more variation beween the means.