Abstract The surface of Fe3O4 nanoparticles is very reactive and can oxidize to γ-Fe2O3 (maghemite) and α-Fe2O3 (hematite) structures. Based on this, the oxidation process of Fe3O4 nanoparticles must be prevented, and one of the strategies is surface functionalization with organic or inorganic molecules. Thus, this study analyzed the thermal behavior of Fe3O4 and Fe3O4-EDTA nanoparticles using X-ray diffraction (XRD), simultaneous thermogravimetry-differential thermal analysis (TG-DTA), differential scanning calorimetry (DSC). Results showed that γ- Fe2O3 was obtained as an intermediate in Fe3O4 and Fe3O4-EDTA decomposition, as confirmed by TG-DTA and DSC curves. Moreover, Fe3O4-EDTA exhibited a temperature peak (Tp = 573.5°C) of phase transformation (γ-Fe2O3 → α-Fe2O3) higher than that of Fe3O4 (Tp = 533.0°C), confirming that EDTA molecules stabilized the nanoparticles efficiently. The kinetic behavior of samples changed, and the activation energy for functionalized samples decreased.

RESUMO A reação do maracujá amarelo ‘Afruvec’ e ‘Maguary’ aos nematóides de galhas Meloidogyne incognita raça 2, M. javanica e M. hapla foi estudada em experimentos conduzidos separadamente para cada espécie de nematóide, em casa de vegetação. As plantas foram inoculadas com 5.000 ovos e eventuais juvenis infectantes. A avaliação foi realizada 60 dias após a inoculação. Os experimentos seguiram o delineamento inteiramente ao acaso com seis repetições, sendo cada parcela constituída por uma planta em vaso de 2 litros com substrato previamente autoclavado. Os parâmetros analisados foram: índice de galhas, índice de massas de ovos, população final do nematóide no sistema radicular e massa do sistema radicular, fator de reprodução do nematóide (FR = Pf/Pi) e o número total de espécimes por grama de raiz. De acordo com os resultados obtidos tanto o maracujá ‘Afruvec’ como o ‘Maguary’ se mostraram resistentes a M. incognita raça 2, M. javanica e M. hapla.

ABSTRACT The reaction of the yellow passion-fruit cultivars Afruvec and Maguary to Meloidogyne incognita race 2, M. javanica and M. hapla were studied under greenhouse conditions. Three experiments were conducted with similar methodology. The initial population was 5,000 eggs and juveniles of second-stage newly hatched (J2) of M. incognita, M. javanica or M. hapla. The experimental delineations were entirely randomized, with six replications. The evaluated parameters were: gall and egg mass index, roots fresh weight, nematode populations in roots, reproductions factor (FR) and number of nematodes per gram of root. The Afruvec and Maguary cultivars were resistant to Meloidogyne incognita race 2, M. javanica and M. hapla.