Fitopatologia - Artigos
URI permanente para esta coleçãohttps://locus.ufv.br/handle/123456789/11741
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Item A set of standard area diagrams to assess severity of frogeye leaf spot on soybean(European Journal of Plant Pathology, 2015-03-14) Debona, Daniel; Nascimento, Kelly Juliane Telles; Rezende, Danielle; Rios, Jonas Alberto; Bernardeli, Arthur Martins Almeida; Silva, Leandro Castro; Rodrigues, Fabrício ÁvilaA set of standard area diagrams (SADs) was developed and validated to aid visual assessment of severity of frogeye leaf spot (FLS) caused by Cercospora sojina. The SAD has eight color images of diseased leaflets with severity values that ranged from 0.1 to 39.9 %. The SAD was validated by a group of 20 raters [10 experienced (ER) and 10 inexperienced (IR)], who assessed the same set of 50 images twice, the first without SADs and the second using SADs as an aid. The SADs significantly improved accuracy [coefficients of bias (C b ) were 0.64 and 0.99 for IR and 0.98 and 0.99 for ER, without and with SADs, respectively], precision [correlation coefficients (r) were 0.89 and 0.95 for IR and 0.94 and 0.97 for ER, without and with SADs, respectively] and overall agreement [Lin’s concordance correlation coefficients (ρ c ) were 0.57 and 0.94 for IR and 0.92 and 0.97 for ER without and with SADs, respectively]. The estimates of severity of FLS were more reliable when using SADs. Both the inter-rater reliability (coefficient of determination, R:^2 ) and intra-class coefficient (ρ) were significantly increased by using SADs. Therefore, it is believed that the SADs proposed in the present study will be a useful tool to aid accurate, precise and reliable estimates of severity of FLS in experiments (e.g., fungicide screening, assessment of partial resistance of soybean genotypes to FLS) and to aid in decision-making purposes.Item Silício no processo infeccioso de Phakopsora pachyrhizi em folíolos de plantas de soja(Pesquisa Agropecuária Brasileira, 2011-12-30) Cruz, Maria Fernanda Antunes da; Silva, Larisse de Freitas; Rodrigues, Fabrício Ávila; Araujo, João Marcos de; Barros, Everaldo Gonçalves deThe objective of this work was to evaluate the effect of silicon (Si) on the infection process of Phakopsora pachyrhizi in leaflets of soybean plants grown in nutrient solution with or without Si. Observations done with light microscope and scanning electron microscope indicated that, in leaflets of plants supplied with Si, uredia were smaller and fewer in number. There were reductions of 27, 23 and 60% in the number of lesions, closed uredia and open uredia, respectively, in leaflets of plants with Si. Soybean plants supplied with Si show reduction in Asian soybean rust symptoms.Item Inducers of resistance and silicon on the activity of defense enzymes in the soybean-Phakopsora pachyrhizi interaction(Bragantia, 2013-04-08) Cruz, Maria Fernanda Antunes da; Rodrigues, Fabrício Ávila; Polanco, Leonora Rodriguez; Curvêlo, Carmen Rosa da Silva; Nascimento, Kelly Juliane Telles; Moreira, Maurílio Alves; Barros, Everaldo Gonçalvespt-BRThis study aimed to determine the effect of jasmonic acid (JA), Acibenzolar-S-Methyl (ASM) and calcium silicate (a source of soluble silicon, Si), on the potentiation of soybean resistance to Asian soybean rust (ASR). The ASR severity was significantly reduced on plants sprayed with ASM or supplied with Si in comparison to plants sprayed with JA or deionized water. For chitinases (CHI), significant differences in activity between non-inoculated and inoculated plants sprayed with deionized water or with ASM occurred at 72 hours after inoculation (hai), at 24 and 72 hai when sprayed with JA and at 141 hai when supplied with Si. For β-1,3-glucanases (GLU), significant differences in activity between non-inoculated and inoculated plants sprayed with deionized water occurred at 24, 48 and 141 hai, but not until 72 for plants sprayed with ASM. For phenylalanine ammonia-lyases (PAL), significant differences in activity between non-inoculated and inoculated plants occurred only for plants sprayed with ASM at 72 and 141 hai. In conclusion, the ASR symptoms can be mild on plants sprayed with ASM or supplied with Si and that this amelioration likely involved the defense enzymes.