Efeito da incorporação no solo de sementes de fedegoso (Senna obtusifolia) colonizadas por Alternaria cassiae no controle desta planta infestante
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Data
2006-09-01
Autores
Simoni, Fernanda De
Pitelli, Robinson Luiz Campos Machado [UNESP]
Pitelli, Robinson Antonio [UNESP]
Título da Revista
ISSN da Revista
Título de Volume
Editor
Grupo Paulista de Fitopatologia
Resumo
Na última década, com o uso excessivo de herbicidas, começaram a surgir alguns problemas como a resistência de plantas daninhas e seleção de flora, além do acúmulo destes produtos contaminando mananciais hídricos e solos. Como alternativa, há uma tendência recente em se estudar e desenvolver inimigos naturais para o controle das plantas daninhas, ou seja, o controle biológico. Sementes de fedegoso colonizadas por Alternaria cassiae foram incorporadas no solo, visando o controle de plantas de Senna obtusifolia. Para tanto, foram instalados dois experimentos em casa-de-vegetação com vasos. A inoculação do solo dos vasos com posterior incorporação nos primeiros 2-3 cm superficiais foi efetuada com sementes colonizadas. Após incorporação, sementes íntegras de Senna obtusifolia, previamente escarificadas, foram semeadas no solo dos vasos. O delineamento experimental adotado foi inteiramente casualizado com quatro repetições adotando as seguintes variáveis: a) duas formas de inóculo (sementes inteiras e sementes moídas); b) quatro quantidades por unidade de área (10t/ha; 6,5t/ha; 3,3t/ha e 1,7t/ha); c) testemunha sem incorporação de inóculo ao solo. Os parâmetros avaliados foram, contagem do número de plantas emergidas e pesagem da matéria seca acumulada na parte aérea e do sistema radicular das plantas. em ambos os experimentos, houve uma tendência de diminuição do número de plantas vivas, da biomassa seca da parte aérea e da matéria seca acumulada no sistema radicular à medida que foi aumentando a quantidade de inóculo incorporado no solo. Os efeitos de controle promovidos pelas duas formas de inóculo não diferiram expressivamente entre si.
In the last decade, the excessive use of chemical control resulted in changes in the weed communities, which led to strong shifting in their population and finally in resistance to several herbicides. This is a very good opportunity to use biological management as a complementary method to control the selected weeds. Sicklepod seeds colonized by Alternaria cassiae were amended to the soil to control Senna obtusifolia plants. Two experiments were conducted under greenhouse conditions, where the colonized seeds (inoculum) were applied to the soil by dispersal over its surface and incorporation in the 2-3 cm layer. After fungal application, S. obtusifolia seeds previously scarified with sulfuric acid were sown in pots. The experimental design was the completely randomized with four replications. A factorial arrangement of treatments was used and the variables were: a) two granulations of inoculum (whole and chopped colonized seeds); b) four inoculum concentrations (10, 6.5, 3.3, and 1.7 ton/ha); c) control plot without any inoculum incorporation. The evaluated parameter were counting of the number of emerged plants and weighing of dry matter accumulation in the aerial and roots tissues of the reminiscent plants. In both trials, there was a tendency to reduce the number of reminiscent plants and of the dry matter accumulation at aerial parts, as the amount of inoculum was increased. There were not important differences between the inoculum constituted by whole or chopped seeds.
In the last decade, the excessive use of chemical control resulted in changes in the weed communities, which led to strong shifting in their population and finally in resistance to several herbicides. This is a very good opportunity to use biological management as a complementary method to control the selected weeds. Sicklepod seeds colonized by Alternaria cassiae were amended to the soil to control Senna obtusifolia plants. Two experiments were conducted under greenhouse conditions, where the colonized seeds (inoculum) were applied to the soil by dispersal over its surface and incorporation in the 2-3 cm layer. After fungal application, S. obtusifolia seeds previously scarified with sulfuric acid were sown in pots. The experimental design was the completely randomized with four replications. A factorial arrangement of treatments was used and the variables were: a) two granulations of inoculum (whole and chopped colonized seeds); b) four inoculum concentrations (10, 6.5, 3.3, and 1.7 ton/ha); c) control plot without any inoculum incorporation. The evaluated parameter were counting of the number of emerged plants and weighing of dry matter accumulation in the aerial and roots tissues of the reminiscent plants. In both trials, there was a tendency to reduce the number of reminiscent plants and of the dry matter accumulation at aerial parts, as the amount of inoculum was increased. There were not important differences between the inoculum constituted by whole or chopped seeds.
Descrição
Palavras-chave
Weed, Biological control, micoherbicide, Senna obtusifolia, Alternaria cassiae, Planta daninha, Controle biológico, micoherbicida, Senna obtusifolia, Alternaria cassiae
Como citar
Summa Phytopathologica. Grupo Paulista de Fitopatologia, v. 32, n. 4, p. 367-372, 2006.