Reação de espécies de Crotalária à Sclerotinia sclerotiorum e Meloidogyne javanica

Abstract

The use of plants such as crotalaria increases the addition of soil organic matter that can stimulate the development of an antagonistic microflora, which favors the biological control of nematodes, besides producing alkaloids that present high toxicity to these phytoparasites. However, the choice of the plant species to be used in crop rotation and of major importance, since can affect the suppression of a population of one pathogen, it can result in non-potential increase of inoculum of others. The present work has as objective avaluate reaction to Sclerotinia sclerotiorum and efficiency in the control of nematodes of the galls under controlled conditions in Dourados, Mato Grosso do Sul, for which several experiments were installed. For evaluation of the reaction of different species of Crotalaria to Sclerotinia sclerotiorum. Different species were inoculated with S. sclerotiorum by the (toothpick colonised by pathogen mycelium) method. The incidence of symptomatic plants, severity, area under the disease progression curve (AUDPC), mass of sclerodes and mass of fresh and dry matter. An inoculation of S. sclerotiorum with infested flowers on detached leaves was also tested. For evaluation of the efficiency of the various species of crotalaria without control of nematodes Meloidogyne javanica were installed three experiments. Regarding the results of the area below the disease progress curve, the lowest values were for C. grahamiana and C. breviflora. The values highest correspond to C. ochroleuca and C. juncea. The values lowest phytomass were of C. paulina, C. ochroleuca and C. anagyroides and higher of C. grahamiana and C. breviflora. In the methodology of inoculation of leaves with colonized flowers, there were 48 hours of 72 hours of incubation of the flowers, together with the fungus, for efficient inoculation of the leaves. All species of rattlebox can be considered as susceptible to S. sclerotiorum, however C. grahamiana exhibited greater resistance than others. In evaluating the efficiency of all species of rattlebox without control of nematodes, it was demonstrated that it was reproduced for M. javanica in all rattlebox species, presenting RF less than 1, and only C. ochroleuca obtained higher values compared to the other species. In the evaluations of the roots observed that all species of crotalaria were penetrated by the nematode. The number of J2 observed in C. grahamiana, were higher than the other species; however, one species had a higher root mass among crotalaria and also had a low number of females. Crotalaria incana no females were observed inside the roots differently from C. ochroleuca that presented the largest number of females among the rattlebox. Just as C. juncea, C. ochroleuca and C. pallida had an index of females above 10%. It was concluded that all species of rattlebox showed resistance to Meloidogyne javanica even though they presented different results among themselves.