Desenvolvimento de protocolo otimizado para coletas de amostras nematológicas em lavoura de soja

Abstract

The soybean crop(Glycine max) occupies approximately 56% of the agricultural areas destined for grain production in Brazil and is the main source of protein used in animal feed for a variety of animals. However, farmers face a number of challenges in maintaining the crop's grain yield, especially due to attacks by pathogens such as nematodes, which reduce grain yields and significantly increase production costs. Nematodes are invertebrate animals belonging to the phylum Nematoda, phytonematoids being those that attack plants, inhabiting the soil and affecting the roots and underground organs of plants. Although there are around 1 million nematode species, the five most important species for soybeans in Brazil are: Meloidogyne javanica and Meloidogyne incognita (gall nematodes); Heterodera glycines (soybean cyst nematode); Rotylenchulus reniformis (reniform nematode); and Pratylenchus brachyurus (root lesion nematode). The aim of this study is to evaluate different collection points inside and outside a plot, with a view to proposing more effective methods for collecting soil and roots in order to carry out quantitative and qualitative analyses of nematodes. This aims to facilitate the implementation of appropriate control measures in the soybean crop. For the soil and root collections in the field, a straight shovel was used, following the procedures for collecting subsamples to form composite samples at each collection point, transport to the laboratory identified at each point and in a thermal box, while the extraction of nematodes present in the soil was carried out using the JENKINS 1964 method and for the extraction of nematodes present in the roots, the COOLEN and D`HERDE 1972 method was used, and the postextraction samples were analyzed using a microscope. When analyzing the four nematode species found in the areas where soil and soybean root samples were collected, it was observed that, for the nematodes P. brachyurus and H. glycines, the points with the highest population representativeness are located in the center and inside the plot, respectively. For the nematode M. incognita, the best collection point is outside or on the edge of the plot.