Abstract
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.
Highlights
Soybean (Glycine max (L.) Merril) is a crop of economic importance in the national and international scenario, being one of the main agricultural products commercialized worldwide.continuous and extensive cultivation has raised concerns regarding the occurrence of pests and diseases, especially nematodes, which may become a limiting factor for the crop.In recent years, Pratylenchus brachyurus (Godfrey, 1929) Filipjev and Schuurmans Stekhoven became the predominant parasite among nematodes in soybean due to changes in the production system and incorporation of areas with sandy soil, which increased the vulnerability of the crop (ALVES et al, 2011)
Most of the treatments affected the reproduction of P. brachyurus in soybean negatively, reducing the total nematode population by 49% compared to the control (Table 2)
There is inequality in the values of the two experiments, this fact may be related to the weather conditions; in experiment 2 the temperature remained lower throughout the experimental conduction, which led to the decrease of nematodes in all treatments compared to the experiment 1, but either in 2 experiments the results corroborate and showed promising control of P. brachyurus, as previously mentioned
Summary
Soybean (Glycine max (L.) Merril) is a crop of economic importance in the national and international scenario, being one of the main agricultural products commercialized worldwide.continuous and extensive cultivation has raised concerns regarding the occurrence of pests and diseases, especially nematodes, which may become a limiting factor for the crop.In recent years, Pratylenchus brachyurus (Godfrey, 1929) Filipjev and Schuurmans Stekhoven became the predominant parasite among nematodes in soybean due to changes in the production system and incorporation of areas with sandy soil, which increased the vulnerability of the crop (ALVES et al, 2011). Changes in the cropping system, such as the adoption of no-till system, succession with host crops, such as soybean and maize, and the gradual growth of soybean cultivation in areas with sandy soils, have increased the losses caused by this pathogen (EMBRAPA, 2010). This nematode is a migratory endoparasite, whose infection causes rupture and destruction of the cortical tissue, causing necrotic lesions which compromise the absorption of water and nutrients; plants in the field exhibit unequal size and reduction in productivity (ALVES et al, 2011). Resistance inducers can act in different ways, involving several stages and pathways, but always leading to the activation of plant defense system
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