Extratos de plantas de cobertura no desenvolvimento de Sclerotinia sclerotiorum

Abstract

RESUMOExtratos vegetais podem interferir no ciclo de vida dos fitopatógenos por promover ou inibir o desenvolvimento. Com base nessa propriedade, este trabalho foi realizado com o objetivo de estudar o efeito dos extratos aquosos das plantas de cobertura crotalária (Crotalaria juncea), braquiária (Brachiaria ruziziensis), capim-mombaça (Panicum maximum cv. mombaça), milheto (Pennisetum glaucum), feijão-guandu-anão (Cajanus cajan) e estilosantes (Stylosanthes capitata x Stylosanthes macrocephala) sobre o crescimento micelial, germinação carpogênica e micelial dos escleródios e germinação dos ascósporos do fungo Sclerotinia sclerotiorum. As etapas do experimento foram desenvolvidas em casa de vegetação, câmaras de crescimento e laboratório. As concentrações dos extratos utilizadas foram de 1%, 5%, 10% e 25%. Para verificar a influência dos extratos sobre a germinação micelial e carpogênica dos escleródios, foi utilizada somente a concentração de 25%. Os resultados sobre o crescimento micelial mostraram que o extrato da planta de Stylosanthes sp. inibiu o desenvolvimento do patógeno apenas na concentração de 25%. Para a germinação micelial dos escleródios, verificou-se que os extratos induziram a germinação 12 horas após a instalação do experimento, exceto o Stylosanthes sp. Na germinação dos ascósporos, apenas o extrato de Stylosanthes sp. impediu a germinação. PALAVRAS-CHAVE: Mofo branco, manejo cultural, ascósporos, escleródios, apotécios. ABSTRACT PLANT EXTRACTS OF COVER CROPS IN THE DEVELOPMENT OF SCLEROTINIA SCLEROTIORUM.Plant extracts may interfere with the life cycle of pathogens by promoting or inhibiting development. Based on this property, the present study aimed to evaluate the effect of aqueous extracts of the cover plants crotalaria (Crotalaria juncea), brachiaria (Brachiaria ruziziensis), panicum maximum grass (Panicum maximum cv. mombaça), millet (Pennisetum glaucum), pigeon pea dwarf bean (Cajanus cajan.) and stylosanthes (Stylosanthes macrocephala x Stylosanthes capitata) on the mycelial growth, mycelial and carpogenic germination of sclerotia, and ascospore germination of Sclerotinia sclerotiorum. The stages of the experiment were carried out in a greenhouse, growth chambers and laboratory. The concentrations of the extracts used were 1%, 5%, 10% and 25%. To assess the influence of extracts on the mycelial and carpogenic germination of the sclerotia only the concentration of 25% was used. The results on the mycelial growth showed that the Stylosanthes sp. plant extract was effective for inhibiting the pathogen only at concentration of 25%. For mycelial germination of sclerotia, it was found that with the exception of Stylosanthes sp. the extracts induced germination 12 hours after the experiment. In regard to the germination of ascospores, only the extract from Stylosanthes sp. successfully prevented germination.KEY WORDS: White mold, cultural management, ascospores, sclerotia, apothecium.2 Universidade Federal do Piauí, Departamento de Fitotecnia, Bom Jesus, PI, Brasil. INTRODUÇÃONos últimos ano...

Nitrogen management alternatives using Azospirillum brasilense in wheat

“…It should be noted that differences in the number of tillers might be due to the inherent traits of each cultivar, whereas the emission of tillers depends on environmental, nutritional, and genetic conditions. The cultivar influences the microbial community present in the roots by specific signaling between root and bacterium (Monteiro et al, 2012). Furthermore, nodulation alters the morphology of roots and can improve the absorption of nutrients, mainly nitrogen (Bashan & de-Bashan, 2010).…”

Soil phosphorus fractions in an apple orchard with different weed managements

“…This result was due to the stress caused by the cut of weeds, which have mechanisms to resume metabolic activities and growth. This occurs because their root system, which has the functions of plant support and absorption of water and nutrient, also produces exudates that are used to access soil P (Monteiro et al, 2012). Yang et al (2019) evaluated three weed species in a greenhouse experiment using different sources of P (Po and Pi) and found higher root development for organic P forms, denoting the increasing exudate production and the capacity of the species to access P in the soil.…”