Impact of Alleyway Management and Vegetation Diversity on Nematode Abundance in Pear Agroecosystems

Plant species identity and diversity as well as edafic variables and soil management strategies may greatly influence the composition of the nematode fauna. This work was done in two agroecosystems during the 2012-2013 growing season. The objective was to analyze the relationship between two soil alleyways management strategies, one with organic fertilization and the other one without any fertilization, and vegetation and nematode alleyways abundance in pear orchards. From the 17 plant spp. found in the organic fertilized treatment, the most representative families were Poaceae (5 spp.) and Brassicaceae (3 spp.). Bromus brevis and Cynodon dactylon were dominant. Nine spp. were registered in the non-fertilized treatment in which the most representative families were Asteraceae (4 spp.) and Fabaceae (2 spp.), with Cynodon dactylon dominant. Community structure of soil nematodes was dominated by bacterivores (Ba) (45%) in the organic fertilized alleyways at both sampling times (spring and autumn). In the non-fertilized treatment, facultative plant feeders (33%) and obligate plant feeders (FO) (30%) predominated in spring and FO (52%) in autumn. Bacterivores was approximately 4.3 times more abundant in organic fertilized than non-fertilized alleyway. These data may indicate that the application of goat manure in the alleyway soil induced an increase in microbial production supported by increasing abundance of Ba. This trophic group contributes to nitrogen mineralization that is available subsequently to plants. Among the FO, the endoparasitic Pratylenchus sp. dominated in organic fertilized alleyways, whereas the ectoparasitic Helicotylenchus sp. predominated in the ones without fertilization. Pratylenchus sp. decreased in autumn in organic fertilized treatment. The omnivores-predators (OP) dynamic was 2.4 times more abundant in organic fertilized than in the non-fertilized plots in spring. Omnivores-predators may reduce abundance of other nematodes, such as FO. Behavior patterns of nematodes associated with the alleyway vegetation and soil management should be considered to attain fruit agroecosystems sustainability.