Efeito do extrato de alga e da argila silicatada na severidade da alternariose e na produtividade da cebolinha comum (Allium fistulosum L.)

Abstract

RESUMOA alternariose é uma das doenças mais importantes da cebolinha em cultivo orgânico. Assim, o objetivo deste trabalho foi avaliar o efeito de pulverizações semanais de argila silicatada (Rocksil ® ) e extrato de Ulva fasciata no controle da doença e produtividade da cebolinha neste sistema de cultivo. Avaliou-se a severidade final e a área abaixo da curva de progresso da doença nas folhas centrais (Yf e AACPDf), bem como da planta inteira (Yp e AACPDp). Na colheita, determinou-se o comprimento e peso fresco das folhas. O experimento foi repetido em quatro ciclos da cultura. Os dados de severidade da doença e produtividade foram submetidos à análise de variância e teste de Duncan (P≤0.05). Na maioria dos ciclos experimentais, diferenças significativas foram verificadas na sanidade e produtividade dos tratamentos em relação à testemunha (plantas tratadas com água). Ambos preparados propiciaram reduções médias de 41 a 62% na severidade final (Yf e Yp) e de 28 a 58% na área abaixo da curva de progresso da doença (AACPDf e AACPDp). Os tratamentos das plantas com argila silicatada e extrato de alga aumentaram o peso fresco das folhas em média de 46% e 32%, respectivamente. Apesar deste trabalho indicar que a argila silicatada e o extrato de algo têm potencial para o controle da alternariose da cebolinha, mais estudos são necessários para elucidar os níveis de controle desses tratamentos em diferentes condições edafoclimáticas. Palavras-chave: Alternaria porri, cultivo orgânico, extrato de algas, pó de rocha ABSTRACT Effect of seaweed extract and silicate clay on Alternaria leaf spot and on the yield of green onion (Allium fistulosum L.)Alternaria leaf spot is one of the most important diseases of green onion in organic farming. The objective of this study was to evaluate the effect of weekly sprays of silicate clay (Rocksil ® ) and extract of Ulva fasciata in disease control and yield of the green onion in organic farming. Final disease severity and area under the disease progress curve were evaluated on central leaves (Yl and AUDPCl) as well as the whole plant (Yp and AACPDp). Length and fresh weight of leaves was determined at harvest. The experiment was repeated in four crop cycles. Data on disease severity and yield were subjected to analysis of variance and Duncan test (P < 0.05). In most of the experimental cycles, significant differences were observed in the sanity and yield of the treatments compared to the control (plants treated with water). Overall, both preparations reduced the final disease severity (Yf and Yp (by 41-62% ) and the AUDPCs by 28-58%. Treatments of plants with silicate clay and seaweed extract increased the fresh weight of leaves by 46% and 32%, respectively. Although this study indicates that silicate clay and seaweed extract have the potential for disease control, further studies are needed to elucidate the control levels of these treatments in different edaphoclimatic conditions. Key words: Alternaria porri, organic system, silicate clay, seaweed extract A cebolinha comum (Allium fis...

Algal polysaccharides as source of plant resistance inducers

“…Thus, this polysaccharide may be efficient against necrotrophic pathogens, because this pathway is generally involved in defense responses against these pathogens (Glazebrook, 2005;Araújo et al, 2012). However, it was also demonstrated that ulvan can control biotrophic (Borsato et al, 2010;Paulert et al, 2010) and hemibiotrophic fungi (Paulert et al, 2009;Freitas & Stadnik, 2012).…”

Morphological and Biochemical Responses of Glycine max (L.) Merr. to the Use of Seaweed Extract

“…Foliar application of biostimulants that are based on seaweeds is an agrotechnical treatment that brought many advantages in numerous cultivations, including grapevine, watermelon, strawberry, apple, tomato, spinach, onion, bean, pepper, carrot, potato, wheat, corn, barley, rice, and turf grass. The results show that plants treated with lower concentrations of extract indicated a stronger growth, higher yield, and higher mineral and nutritive elements content relative to the control [28][29][30][31][32][33]. Positive reactions also included an improved flowering and fructification ability, product quality and efficiency, and resistance to abiotic stress [31,34,35].…”

Efecto del extracto de alga Ulva fasciata sobre Pseudocercospora griseola en el cultivo de frijol

“…Fuente: Elaboración propia El extracto de U. fasciata disminuyó la severidad nal (gura 1) y la ABCPE (gura 2) de mancha angular únicamente en los genotipos Mouro graúdo (52 %) e IPR Uirapuru (37 %), en los años 2005 y 2006, respectivamente. En estos genotipos, el efecto protector del extracto es semejante a lo relatado en otras enfermedades, como la antracnosis del frijol (Colletotrichum lindemuthianum) en 44 % (Abreu et al, 2008), la alternariosis (Alternaria porri) de la cebolla pequeña en 70 % (Araújo et al, 2012) de la vid, pepino y frijol, en niveles de 77, 80 y 90 %, respectivamente (Jaulneau et al, 2011). Sin embargo, Delgado et al (2013) no encontraron diferencias en la severidad de la mancha angular en el frijol, entre las plantas tratadas con el polisacárido algal ulvana (principal constituyente de las paredes celulares de esa alga).…”

“…Por ejemplo, extractos acuosos de Ulva spp. reducen la severidad de la antracnosis (Colletotrichum lindemuthianum) del frijol en 44 % (Abreu et al, 2008), la alternariosis (Alternaria porri) de la cebolla pequeña en 70 % (Araújo et al, 2012), y de los oídios de la vid, pepino y frijol, en 77, 80 y 90 %, respectivamente (Jaulneau et al, 2011). Asimismo, aplicaciones preventivas de Ulva spp., aparte de proteger plantas de carretón (Medicago truncatula) del hongo Colletotrichum trifolii, pueden activar genes relacionados con la biosíntesis de toalexinas y de proteínas asociadas a la patogénesis y la pared celular (Cluzet et al, 2004).…”