Influência do estádio fenológico da soja e da profundidade de coleta das amostras na quantificação da população de Pratylenchus brachyurus

Abstract

Soybean is the main product on the Brazilian export list, like most crops, it faces several phytosanitary problems that contribute to reduced the yield. The most common phytosanitary problems are caused by fungi, insects and nematodes. This work aims to determine the best sampling period (soil and root) during the reproductive stage of soybean, in which the amount of Pratylenchus brachyurus in the soil and root system is higher. Samples were collected at Fazenda Bacurizal, in the municipality of Bom Jardim in Goiás, during the reproductive stages of soybean R1, R3, R5.1, R5.4 and R6, at depths of 0 – 10, 10 – 20, 20 – 30, 30 – 40 and 40 – 50 cm, with three replicates. For the extraction of nematodes from soil samples, the Jenkins methodology was used (1964) and the roots were extracted according to Coolen and D’Herde (1972). In general, the population of P. brachyurus was concentrated at a depth of 0 – 10 cm, both for soil samples and for roots. In the root system, the population of P. brachyurus was significantly higher in the reproductive stages R5.1 and R5.4, with the stage R5.4 standing out with the highest number of individuals per gram of root. The population of P. brachyurus in the soil was higher in the reproductive stage R6. It is concluded that the best time for sampling to determine the population of P. brachyurus is during the reproductive stage R5.4, preferably at a depth of 0 – 10 cm, where most of the root system is concentrated.