Fitopatologia - Artigos
URI permanente para esta coleçãohttps://locus.ufv.br/handle/123456789/11741
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Item Tratamento de sementes com fungicidas e inseticidas como redutores dos efeitos do estresse hídrico em plantas de soja(Ciência Rural, 2011-07) Debona, Daniel; Balardin, Ricardo Silveiro; Silva, Felipe Dalla Lana da; Corte, Gerson Dalla; Favera, Diego Dalla; Tormen, Nédio RodrigoO objetivo do trabalho foi avaliar o efeito de quatro tratamentos de sementes: água (T1), carbendazim + thiram (T2), fipronil + tiofanato metílico + piraclostrobina (T3) e abamectina + thiamethoxam + fludioxonil + mefenoxan + thiabendazole (T4) sobre parâmetros de crescimento de plantas de soja submetidas a dois regimes hídricos (presença e ausência de estresse hídrico) estabelecidos logo após a emergência das plântulas. O experimento foi conduzido em casa de vegetação e campo. Na casa de vegetação, nos tratamentos sem estresse hídrico, foram feitas quatro irrigações por dia e, nos tratamentos com estresse hídrico, foi realizada uma irrigação a cada três dias. Neste ensaio, foi avaliada a estatura de plantas, comprimento radicular, volume radicular, massa seca da parte aérea, massa seca radicular e área foliar. No ensaio de campo, o estresse hídrico foi estabelecido pela construção de túneis baixos de polietileno que impediram o fornecimento de água pela irrigação e chuva. No campo, foram avaliados estatura de planta, teor relativo de clorofila, emergência, ataque de lagarta-elasmo e rendimento de grãos. Nos dois ambientes, as plantas foram mantidas sob estresse até 28 dias após a emergência. Em casa de vegetação, todos os parâmetros foram influenciados pelo tratamento de sementes na presença e ausência de estresse hídrico. No campo, o tratamento com fipronil + tiofanato metílico + piraclostrobina (T3) e abamectina + thiamethoxam + fludioxonil + mefenoxan + thiabendazole (T4) proporcionaram maior estatura de planta e teor relativo de clorofila em ambos os regimes hídricos e maior emergência e rendimento de grãos em plantas sem e com restrição hídrica, respectivamente. Conclui-se que o tratamento de sementes com esses produtos promove alterações benéficas nas plantas, aumentando sua tolerância ao estresse hídrico, com efeito positivo sobre o rendimento de grãos da soja.Item Defence‐related enzymes in soybean resistance to target spot(Journal Phytopathology, 2015-09) Rodrigues, Fabrício A.; Fortunato, Alessandro A.; Debona, Daniel; Bernardeli, Arthur M. A.Target spot, caused by the fungus Corynespora cassiicola, has become a serious foliar disease in soybean production in the Brazilian Cerrado. Information in the literature regarding the biochemical defence responses of soybean to C. cassiicola infection is rare. Therefore, the objective of this study was to determine the biochemical features associated with soybean resistance to target spot. The activities of chitinases (CHI), β‐1‐3‐glucanases (GLU), phenylalanine ammonia‐lyases (PAL), peroxidases (POX), polyphenol oxidases (PPO) and lipoxygenases (LOX), as well as the concentrations of total soluble phenolics (TSP) and lignin‐thioglycolic acid (LTGA) derivatives, were determined in soybean leaves from both a resistant (FUNDACEP 59) and a susceptible (TMG 132) cultivar. The target spot severity, number of lesions per cm2 of leaflet and area under the disease progress curve were significantly lower for plants from cv. FUNDACEP 59 compared to plants from cv. TMG 132. The GLU, CHI, PAL, POX and PPO activities and the concentration of LTGA derivatives increased significantly, whereas LOX activity decreased significantly on the leaves infected by C. cassiicola. Inoculated plants from cv. FUNDACEP 59 showed a higher PPO activity and concentrations of TSP and LTGA derivatives at 4 and 6 days after inoculation compared to plants from cv. TMG 132. In conclusion, the results of this study demonstrated that the defence‐related enzyme activities increased upon C. cassiicola infection, regardless of the basal level of resistance of the cultivar studied. The increases in PPO activity and concentrations of TSP and LTGA derivatives, but lower LOX activity, at early stages of C. cassiicola infection were highly associated with soybean resistance to target spot.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 QTLs for resistance to soybean cyst nematode, races 3, 9, and 14 in cultivar Hartwig(Pesquisa Agropecuária Brasileira, 2011-03-14) Santana, Fernanda Abreu; Ferreira, Marcia Flores da Silva; Cervigni, Gerardo Domingo Lucio; Ferreira, Adésio; Schuster, Ivan; Pereira, Waldir Dias; Barros, Everaldo Gonçalves de; Moreira, Maurilio AlvesThe objective of this work was to identify major and minor-effect quantitative trait loci (QTL) for resistance to races 3, 9, and 14 of soybean cyst nematode (SCN) in Hartwig cultivar; to map new resistance QTLs for these races; and to check for the existence of epistatic interactions between QTLs. Cultivar Hartwig is an important resistance source to SCN. Recombinant inbred lines (RIL) obtained from a cross between 'Hartwig' (resistant) and Y23 (susceptible) were evaluated regarding resistance to the three races. New genomic regions for resistance to SCN were identified by microsatellites. Four QTLs, which explained between 12 and 34% of phenotypic variance, were detected for resistance to race 3 in linkage groups (LG) A2, G, J, and M. The QTL in LG G is also important for resistance to race 9. Epistatic interactions were detected between loci, which indicate resistance to races 9 and 14. There are high and low-effect resistance QTLs to SCN.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.