Comunidades de fitonematoides nas culturas do tabaco e macieira no Sul do Brasil

Abstract

Among other crops, tobacco and apple trees in Soutern Brazil stand out. However, like other crops, these plants are attacked by pathogens such as Plant-Parasitic Nematodes (PPNs), whose damage should be better investigated. In view of this, the current study aimed to: (i) identify and quantify the major PPNs occurring in areas cultivated with tobacco and apple trees in the southern Brazil; (ii) to evaluate the relationship between bioclimatic, altitude, and types of soil and the occurrence of PPNs and, still, (iii) to characterize (morphologically and/or biochemically) the Meloidogyne species detected from tobacco growing areas and to characterize (morphologically and morphometrically) the Pratylenchus species obtained from the apple orchards. In tobacco crops, 7 genera of PPNs were identified, Meloidogyne (100%), Helicotylenchus (100%), Tylenchus (92%), Xiphinema (75.67%), Pratylenchus (86%), Paratylenchus (16.21%) and Mesocriconema (10.81%). In apple orchards, Pratylenchus (95%), Helicotylenchus (95%), Tylenchus (90%), Xiphinema (90%) and Mesocriconema (21%). In tobacco areas, annual temperature and precipitation were those that established the greatest influences on the abundance of PPNs and the genera. In the apple orchards sampled, the abundance of PPNs was still influenced by temperature seasonality, annual temperature range and average temperature of the wettest quarter, while the incidence was not influenced by temperature, precipitation and altitude factors. The species M. javanica, M. arenaria and M. incognita were predominant in the tobacco crop, with the presence of M. hispanica (not reported in the crop) and an atypical phenotype of esterase. In apple culture, it was possible to identify two species of Pratylenchus, P. zeae and P. penetrans; the latter not yet reported in the culture in the Brazil. There are several PPNs incident in both simultaneously cultures evaluated (Helicotylenchus, Pratylenchus, Tylenchus, Xiphinema and Mesocriconema), in variable frequencies and abundances. The bioclimatic variables of average annual temperature and annual precipitation, in general, are those that exert the greatest influence on the abundance of the main PPNs in tobacco and apple trees. The verification of more than one species of the most important genera for each crop (Meloidogyne – tobacco and Pratylenchus – apple) expose the importance of a careful analysis for the diagnosis and elaboration of a correct management schedule and control.