FITONEMATOIDES ASSOCIADOS À CULTURA DA CANA-DE-AÇÚCAR NO RIO GRANDE DO SUL, BRASIL

Sugarcane is a major feedstock source for producing sugar, alcohol, and spirits as well as supplement in animal feeding. Among the pathogens that affect this crop, plant-parasitic nematodes cause serious damage to sugar cane plantations in different growing regions of Brazil. However, little is known about the diversity and population levels of these pathogens in sugar cane in the extreme south of Brazil. Therefore, the aim of this study was to characterize morphologically the nematofauna associated with sugar cane crop in the State of Rio Grande do Sul (RS) from 65 soil and root samples collected in sugar cane fields of 21 municipalities located in the RS. The nematode generic diversity and species of Pratylenchusspp. were evaluated by morphological and morphometric characteristics of specimens collected. Pratylenchusspp. and Helicotylenchusspp. (100%) followed by Meloidogynespp. (70.76%) were the most frequent plant-parasitic nematodes associated with sugarcane root samples and their population levels ranged from 1500-4450, 15-170 and 0-3025/50g of roots, respectively. In the soil samples, Pratylenchus spp. and Helicotylenchus spp. were also the most frequent (100%), followed by Meloidogyne spp. (72.31%), Mesocriconema spp. (70.77%), Xiphinemaspp. (63.08%), Tylenchusspp. (58.46%), Paratrichodorus spp. (66.15%), Hemicycliophora spp. (52.31%), Aphelenchus spp. (53.85%) and Aphelenchoides spp. (35.38). Two Pratylenchus species were identified, and 51 populations were characterized as P. zeae(84.61%) and 23 as P. brachyurus (35.38%). In addition, both species of Pratylenhuswere detected in 20.96% of samples simultaneously.A cana-de-acucar e uma das principais fontes de materia-prima para fabricacao de acucar, alcool, aguardente; assim como tambem, e utilizada na alimentacao animal. Dentre os patogenos que afetam a cultura, os fitonematoides causam serios danos em diferentes regioes de cultivo do Brasil. Porem, pouco se sabe sobre a diversidade e niveis populacionais desses patogenos em cana-de-acucar, no extremo sul do Pais. Desta forma, teve-se por objetivo no presente trabalho, caracterizar morfologicamente a nematofauna associada a cultura da cana-de-acucar no Estado do Rio Grande do Sul (RS). A partir de 65 amostras de solo e raizes de cana-de-acucar, coletadas em lavouras de 21 municipios do RS, avaliou-se a diversidade dos generos dos fitonematoides e das especies de Pratylenchus spp. pelas caracteristicas morfologicas e morfometricas dos especimes observados. Nas amostras provenientes das raizes, especimes dos generos Pratylenchuse Helicotylenchusforam os mais frequentes (100%), seguidos por Meloidogyne(70,76%) e seus niveis populacionais variaram 1500-4450, 15-170 e 0-3025/50g de raizes, respectivamente. No solo, Pratylenchusspp. e Helicotylenchusspp. tambem foram os mais frequentes (100%) seguidos por Meloidogynespp. (72,31%), Mesocriconemaspp. (70,77%), Xiphinemaspp. (63,08%), Tylenchus spp. (58,46%), Paratrichodorusspp. (66,15%), Hemicycliophoraspp. (52,31%), Aphelenchusspp. (53,85%) e Aphelenchoidesspp. (35,38). Entre as especies de Pratylenchuscaracterizadas, foram identificadas 51 populacoes de P. zeae(84,61%) e 23 de P. brachyurus(35,38%), alem de ter sido detectada a ocorrencia simultânea de ambas as especies em 20,96% das amostras.