Sistema de plantio e doses de calcário no manejo de Pratylenchus brachyurus em soja

Abstract

The soybean is grown in virtually all states in Brazil for a total of 36 million ha. The Midwest region stands out as the largest producer of grain in Brazil. With the expansion of the soybean crop, new problems arose, among them, the diseases caused by phytonematodes. Pratylenchus brachyurus has become a major problem for national soybean, as it causes great losses and does not have many control methods. The damages caused by this phytoparasite are aggravated in a no-tillage system, considering that this system does not cause the soil to be disturbed. Thus, the objective of the work was to evaluate the influence of limestone doses after two years of application and planting system in the management of P. brachyurus in soybean grown in the municipality of Nova Xavantina, region of Vale do Araguaia Matogrossense. The experiment was carried out in a commercial field naturally infested with the nematode. The experimental design used was in randomized blocks, in a 5x2 factorial scheme, with the treatments: 5 limestone doses (0, 1.25, 2.5, 3.75 and 5 t / ha) and 2 cultivation systems (planting no-tillage and conventional tillage using a leveling harrow). The plots were demarcated with the dimensions of 5x6 m and distributed in 4 blocks. The collection of soil and roots for nematological analyzes were carried out when the soybean was at the reproductive stage R5.4, in January 2018 and 2019, to evaluate the population of P. brachyurus. The beans were harvested for productivity analysis. In the first year, a reduction in the population of Pratylenchus brachyurus in the roots was observed in the order of 34.8% in the harrow system when compared with the no-till system, in the second year this value was even greater, reaching 85.3%. Under the conditions of study, the use of the grid was efficient to reduce the nematode population in both harvests. The application of lime did not have a reduction effect on the nematode population, but it did increase soybean productivity. The no-till system was efficient to increase soybean productivity.