Efeito de fontes de silício na incidência e na severidade da antracnose do feijoeiro

Abstract

RESUMOForam realizados três experimentos para estudar a influência do silício na redução da antracnose, causada por Colletotrichum lindemuthianum, em feijoeiro (Phaseolum vulgaris). No primeiro experimento plantas tratadas com silicato de cálcio foram inoculadas com 0, 10 3 , 10 4 , 5x10 4 , 10 5 , 5x10 5 e 10 6 conídios/ml de C. lindemuthianum. Na concentração de 10 6 conídios/ml avaliou-se a diferença entre o silicato de cálcio e uma fonte de cálcio (óxido de cálcio). No segundo experimento foi avaliado o silicato de cálcio e de sódio na redução da antracnose. No terceiro experimento, por meio da microscopia eletrônica de varredura (MEV) e da microanálise de raios-X (MAX), estudou-se o efeito do silício nos mecanismos de resistência. Foram realizadas cinco avaliações da doença, utilizadas para calcular a área abaixo da curva de progresso da incidência (AACPI), da severidade (AACPS) e a duração da área foliar sadia (HAD), nos dois primeiros experimentos. Com o aumento da concentração do inóculo houve aumento na AACPI e AACPS e redução na HAD, porém a testemunha inoculada com a maior concentração de inóculo, e tratada apenas com cálcio (CaO), sem silicato, teve maiores AACPI e AACPS do que as plantas tratadas com silicato de cálcio. No segundo experimento, a menor AACPS e maior HAD foram obtidas no tratamento com silicato de sódio via foliar, que proporcionou redução de 62,4% na AACPS. Na MEV e na microanálise de raios X não se observaram a formação de barreira física e o acúmulo de silício externamente com a aplicação de silicato de cálcio, embora o elemento tenha contribuído para reduzir a antracnose.Palavras-chave adicionais: Colletotrichum lindemuthianum, nutrição mineral, concentração de inóculo, Phaseolus vulgaris. ABSTRACTEffects of silicon sources on the incidence and severity of the common beans anthracnose Three experiments were performed to study the influence of the silicon on the reduction of the common bean (Phaseolum vulgaris) anthracnose. The first experiment involved a plant fertilized with calcium silicate and different inoculum concentrations of the Colletotrichum lindemuthianum (0, 10 3 , 10 4 , 5x10 4 , 10 5 , 5x10 5 and 10 6 conidia/ml). In the concentration 10 6 conidia/ml the difference between calcium silicate and calcium oxide was evaluated for effects on the disease. The second experiment evaluated the influence of sodium and calcium silicate on the reduction of the anthracnose. In the third experiment, the scanning electron microscopy (SEM) and X-ray micro-analysis (EDAX) were used to study the effect of the silicon on the plant resistance mechanism. Five evaluations of the incidence, severity and leaf area were done, in the first and second experiment. Disease evaluation was made using area under disease progress curve for incidence (AUDPCI) and severity (AUDPCS) and healthy leaf area duration (HAD). Inoculum concentration was found to increase the AUDPCI and AUDPCS. In contrast, the HAD had decreased. Fertilization of plants with calcium silicate significantly reduced the AUDPCI and...

Photosynthetic gas exchange and antioxidative system in common bean plants infected by Colletotrichum lindemuthianum and supplied with silicon

“…Polanco et al (2012) reported that higher Si concentrations in the leaf tissues of bean plants supplied with this element were associated with a reduced area under the anthracnose progress curve in association with higher activities of chitinases, phenylalanine ammonia-lyases and lipoxygenases and an increased concentration of lignin. In the C. lindemuthianum-bean pathosystem, Si reduced both the area under the anthracnose incidence progress curve and the area under the anthracnose severity progress curve (Moraes et al, 2006). According to Menzies et al (1992), phenolics accumulated more rapidly in the epidermal cells of cucumber plants supplied with Si and colonized by Podosphaera xanthii.…”

Use of sodium metasilicate for management of peach brown rot

“…The results of the present study, considered pioneering in the foliar application of Si to peach trees, suggest that sodium metasilicate has the potential to control M. fructicola, when applied at 14 to 7 days preharvest. The use of Si in the field to control diseases has been widely studied in recent years, for various species (Moraes et al 2006, Buck et al 2008, Duarte et al 2008, as well as its effect on inducing resistance, such as the formation of physical barriers, polyphenol synthesis (Chérif et al 1994, Gomes et al 2005, Hayasaka et al 2008) and fungal inhibition , Yang et al 2010. Spore germination was totally inhibited with the use of 6 g L -1 of sodium metasilicate ( Figure 2A) With respect to the assessment of fruit quality, no effect of sodium metasilicate application was observed on soluble solids and titratable acidity ( Figures 4A and 4B).…”

Eficiência de Trichoderma harzianum e Gliocladium viride na redução da incidência de Botrytis cinerea em tomateiro cultivado sob ambiente protegido

“…As informações obtidas foram integradas em curvas de progresso da doença e em áreas abaixo da curva de progresso da doença (AACPD) em cada tratamento (MORAES et al, 2006).…”