Mobilidade de Pratylenchus coffeae em solos com diferentes texturas e níveis de salinidade

Abstract

The root lesion nematode Pratylenchus coffeae parasitizes important agronomic crops in Brazil and around the world. Soil salinity is another factor that drastically limits crop yields, however, poor information about the nematode under saline conditions is available. In addition, soil texture has great importance in the movement and distribution of nematodes in soil. The objective of this study was to evaluate the mobility of juveniles and adults P. coffeae in columns filled with soils of different texture under different salinity levels. Polyvinyl chloride (PVC) columns, consisting of four rings 2.0 cm long, and one 2.0 cm long ring for 4,000 ± 400 juveniles and adults P. coffeae injection in soil, were used. The columns (10.0 cm long × 4.4 cm internal diameter) were filled with sandy or clayey soils (at densities of 1.4 and 1.3 g cm-3, respectively), and used saline solutions of NaCl, CaCl2 and MgCl2 in concentrations of 0.1, 2.1, 4.1, and 6.1 dS m-1. An additional ring with chopped yam was placed at the end of the columns to serve as attractive stimulus to the nematodes. Evaluations were carried out at 2, 4, 6 and 8 days after injection (DAI). In sandy soil, there was significant difference in P. coffeae distribution inside the columns through the days and salinity levels. At 2 DAI, about 3.6% of the specimens migrated up to 10 cm under the higher salinity level (6.1 dS m-1). The migration extended throughout the columns as the days and salinity levels increased. Within the nematodes able to migrate up to 10 cm at 8 DAI, 24% and 15% of them were under salinity levels of 0.1 and 6.1 dS m-1, respectively. The horizontal migration of juveniles and adults P. coffeae was reduced in clayey soil and was not influenced by salinity.