Estudo da competitividade entre espécies de Meloidogyne e Pratylenchus

Abstract

In Brazilian conditions, nematodes of the genus Meloidogyne spp. and Pratylenchus spp., are known to be important for crops of sugar cane and soybeans. The losses caused by species of these genera may vary from 20 to 50% in these cultures. The losses may be exacerbated by the occurrence of these species in mixed farming areas. Thus, the study aimed to evaluate the competition of M. incognita and P. zeae in culture of sugar cane and M. javanica and P. brachyurus on soybean and its effects on the development of plant. The study consisted of two experiments. In Experiment 1 was conducted two tests: the first the initial population was set P. zeae in 1000 specimens per plant and varied the level of inoculum of M. incognita, using zero 1000, 2000 and 4000 eggs, the other of the initial population was set M. incognita eggs in 2000 and increased the population of P. zeae inoculating zero, 500, 1000 and 2000 specimens. Each of these trials was conducted at two different times and evaluated after 90 days of inoculation. In experiment 2, the first test was to establish the initial population of P. brachyurus in 1000 specimens per plant and vary, the level of inoculum of M. javanica, using zero 1000, 2000 and 4000 eggs. The other , to fix the initial population of M. javanica eggs in 2000 and increase the population of P. brachyurus inoculating zero , 500, 1000 and 2000 specimens . The tests were conducted at two different times and evaluated after 65 days of inoculation. In both experiments, we observed that the increase in the initial population of a species always resulted in a reduction in the reproduction of the other. However, both species significantly increased their populations. When subjected to the same level of inoculum, P. zeae was more efficient than reproduce M. incognita in cane sugar and M. javanica was more efficient reproduce than P. brachyurus soybeans. The vegetative growth (height, root weight, fresh and dry mass) of sugar cane was not affected by mixed infections or increasing the concentration of the inoculum of a nematode, but there was a reduction in all parameters evaluated for soybean.