diversidade de nematoides em sistemas de culturas e ... - Index of

ARIEIRA, Giovani de Oliveira. Nematode diversty in crop and soil managementsystems. 2012. 98 pages. Dissertação de Mestrado em Agronomia – UniversidadeEstadual de Londrina, Londrina, 2012.ABSTRACTNematodes are soil organisms sensitive to human intervention and widely used asbiological indicators of disturbances and changes in soil quality. They includeorganizations that participate in various food web in soil, classified primarily as plantparasitic,bacterial-feeding, fungal-feeding, carnivorous and omnivores, as to theirfeeding habits. Thus, this study aimed to quantify and qualify nematodes asbiological indicators in areas subjected to different cropping systems and tillage. Forthis purpose, soil samples were taken every 0.10 m at a depth of 0.0 to 0.30 m inareas subjected to two tillage systems (succession with soybean/wheat or croprotation) and five soil management systems (no-tillage, and conventional tillage withdisk plow, grade heavy cruiser and cruiser with no-tillage every three years). We alsoanalyzed a forest, as a reference for ecological balance. After identification andcounting in the laboratory, the nematode communities were characterized by:abundance, diversity, ecological maturity, trophic structure and soil food webcondiction. Data were subjected to analysis of variance (ANOVA) and Tukey test at5% of significance level to check the isolated and combined effects of managementand cropping systems. The abundances of nematodes guilds were subjected tomultivariate analysis (Principal Component Analysis and Cluster Analysis) todetermine the similarity between ecosystems in terms of agricultural practicesadopted. The nematodes were concentrated in the surface layers of soil, with aninverse relationship with depth. The forest showed a community with a higherdiversity of agricultural parcels and a lower dominance. Among the parcels, those inthe crop rotation had the most diverse communities, especially when there was areduction of soil disturbance. All communities were dominated by bacterial andparasitic nematodes of plants at all depths, with low occurrence of carnivorous andomnivorous nematodes. The index MI, MI2-5 and PPI differentiated agriculturalsystems in the surface layer, with greater maturity in areas under crop rotation.Communities showed high level of structure at all depths and high enrichment inlayers 0-10cm and 10-20cm and are not good parameters to evaluate the differencesbetween the systems adopted.Key-words: Soil biodiversity. Bioindicators. Nematode communities. Free-livingnematodes. Plant-parasitic nematodes.