Qual a influência do cultivo de pessegueiro em sistemas agroecológico e convencional sob a macrofauna edáfica?

Abstract

The peach tree (Prunus persica (L.) Batsch) is one of the most produced fruit in the world, Brazil is the thirteenth world producer of peach. However, many producers use the conventional production system, which is strongly based on the use of herbicides causing losses in soil biodiversity. Therefore, the objective of the present study was to evaluate the abundance, diversity, richness, relative frequency and possible association of groups of the edaphic macrofauna with soil properties and compare the richness and diversity of ant assemblages in an agroecological and conventional system under peach orchard cultivation. The study was carried out on two family farms in the region of Colônia São Manoel, 8th district of Pelotas, RS, being a peach orchard system under agroecological cultivation (PA), a peach orchard system under conventional cultivation (PC) and an area of native vegetation (VN). Collections were carried out at a depth of 0.00 - 0.20 m for physical analysis of the soil such as density (Ds), total porosity (Pt), aggregates weighted average diameter (DMP), as well as for macro and micronutrient analysis and organic carbon total (COT). Pitfall traps were installed during the summer and winter of 2017 and 2018. The macrofauna diversity was compared using the Shannon Diversity indices (H '), Equability (J'), Simpson, the relative frequency (FR) was calculated, Principal Component Analysis (PCA) and Canonical Correspondence Analysis (CCA). Wealth, abundance, rarefaction curve, Shannon diversity, Equability, Chao1 and PCA were calculated for ant assemblages. The highest Shannon index was found for PA during the two years of evaluation. The greatest abundance for the year 2017 was found for the VN, while for the year 2018 this result was verified for the PC, given the high number of individuals of the order Isopoda. In the first year of sampling, high FR was observed for the order Coleoptera in all systems. The PCA for the entire study period, associated the order Araneae to the PA, the order Isopoda to the PC and the orders Coleoptera, Amphipoda and Dermaptera to VN. Through CCA analysis, the variables that stood out to respond to changes in soil quality and related to the edaphic macrofauna were organic matter, phosphorus, calcium, copper, pH and DMP. The PA agroecosystem had the highest number of occurrences and richness, while the conventional orchard the lowest number. Camponotus sp.1, Pogonomyrmex naegelli, Nylanderia fulva, Pheidole sp.1 and Solenopsis saevissima showed a positive association with PC and PA. Acromyrmex ambiguus, Pachycondyla striatra, Gnamptogenys striatula, Gnamptogenys sp.1 and Cyphormymex rimosus showed a positive association with VN and PA. The results found corroborate the hypothesis that agroecological systems are an important alternative to conventional systems, since they can preserve the physical and chemical quality of the soil, in addition to increasing and preserving the diversity and richness of the edaphic macrofauna, as well as the assemblages of ants, favoring predatory species and contributing to ecological pest management.