ABSTRACT Nematodes of the Meloidogyne genus are among the main limiting factors of world agricultural productivity. Its management is quite complex and alternative methods such as the use of extracts have been widely studied. This study aimed to evaluate the penetration and development of M. javanica in soybean (Glycine max (L.) Merr.) treated with Ascophyllum nodosum extract and assess this algal product and its nutrient components in nematode management. Experiment 1 comprised five sampling times (5, 10, 15, 20, and 25 d after nematode inoculation) and three application methods (planting hole, foliar spraying, and untreated control). Soybean plants were inoculated with 2000 eggs+second-stage juveniles of M. javanica and treated with algal extract. Total nematode number, number of nematodes per developmental stage, and population density (nematodes g-1 root) were determined. Experiment 2 consisted of 11 treatments: Algal extract, N, K, P, Ca, Mg, Cu, Zn, Mn, Fe, combined nutrients, and untreated control. Soybean crops were evaluated for total nematode number, population density, gall index, plant height, root fresh weight, shoot fresh weight, and shoot dry weight. In Experiment 1, algal extract reduced nematode penetration, regardless of application method. There was a decrease in the total number of nematodes and number of nematode g-1 root by 83% and 56% in the application via furrow and 68% and 70% via foliar application, respectively. In Experiment 2, all nutrient treatments reduced at least one nematode parameter, with P, Ca, Mg, Fe, and combined nutrients (Trial 1) and algal extract, P, Ca, Mg, Cu, Zn, Mn, Fe and combined nutrients (Trial 2) achieving 83% to 95% reductions in population density. Nutrient treatments positively influenced vegetative development, as a 20% increase in height for the nutrients A. nodosum, N, K, P, Ca, Mg, Cu and Fe. Ascophyllum nodosum and its nutrient components have potential in the management of M. javanica in soybean.

RESUMO Nematoides das lesões radiculares limitam a produtividade de diversas culturas de importância econômica, sendo necessárias alternativas para seu manejo. Os indutores de resistência ativam enzimas envolvidas nos mecanismos de defesa e os micronutrientes podem influenciar esse processo, por atuarem como cofatores enzimáticos. Desta forma, objetivou-se avaliar o efeito da aplicação foliar de um fertilizante organomineral comercial e sua associação com os micronutrientes: zinco (Zn) e manganês (Mn) no controle de Pratylenchus brachyurus e no desenvolvimento da soja. As plantas tiveram sua parte aérea tratada, após 10 dias da germinação e foram inoculadas cinco dias após o tratamento, usando-se plantas não tratadas como testemunha. Os tratamentos consistiram de um produto comercial a base de mannanoligossacarídeos derivados da parede celular de Saccharomyces cerevisiae (aqui codificado como MOS), Zn, Mn, MOS+Zn, MOS+Mn ou MOS+Zn+Mn. Após 60 dias da inoculação, as plantas foram coletadas e avaliadas quanto aos parâmetros vegetativos, nematológicos e teores de macro e micronutrientes. Todos os tratamentos foram eficientes em controlar P. brachyurus em pelo menos um dos parâmetros nematológicos, com redução de 28 a 70% da população do nematoide comparativamente à testemunha, porém somente o tratamento da soja com MOS+Zn resultou em redução significativa da população total de P. brachyurus e número de nematoide por grama de raiz nos dois experimentos. Além disso, a pulverização das plantas com Mn proporcionou aumento da matéria seca da parte aérea e todos os tratamentos resultaram em maiores concentrações de cobre, Zn e Mn nas folhas em comparação a testemunha.

ABSTRACT Root lesion nematodes limit the productivity of several crops of economic importance, requiring alternatives for their management. Resistance inducers activate enzymes involved in defense mechanisms and micronutrients can influence this process by acting as enzymatic cofactors. Thus, the objective of this study was to evaluate the effect of foliar application of a commercial organomineral fertilizer and its association or not with zinc (Zn) and manganese (Mn) micronutrients on the Pratylenchus brachyurus suppression and soybean plant development under greenhouse conditions. Shoots of soybean were treated 10 days after germination and inoculated with 5000 nematodes/plant five days after the treatments, using untreated plants as controls. Treatments consisted of a commercial product based on phosphorylated mannanoligosaccharide derived from the cell wall of Saccharomyces cerevisiae (here coded as MOS), Zn, Mn, MOS+Zn, MOS+Mn or MOS+Zn+Mn. At sixty days after establishment of treatments, the plants were collected and evaluated for vegetative analysis, nematological analysis and nutrient contents. The work was repeated at different times: experiment 1 from November 2016 to January 2017 and experiment 2 from October to November 2017. All treatments were efficient in controlling P. brachyurus in at least one of the evaluated nematological parameters, compared to the control. However, only the plant spraying with MOS+Zn results in significative reduction of the total number of nematodes and the number of P. brachyurus nematodes per gram of soybean root in both experiments. In addition, spraying of plants with Mn increased shoot dry weight and all treatments resulted in higher concentrations of copper, Zn and Mn in soybeans leaves compared to control.