Chapecó, Brazil
Chapecó, Brazil

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Bermudez-Cardona M.B.,Federal University of Viçosa | Bermudez-Cardona M.B.,University of Tolima | Filho J.A.W.,Laboratorio Of Fitossanidade | Rodrigues F.A.,Federal University of Viçosa
Phytopathology | Year: 2015

This study investigated the effect of macrospora leaf spot (MLS), caused by Stenocarpella macrospora, on photosynthetic gas exchange parameters and chlorophyll a fluorescence parameters determined in leaves of plants from two maize cultivars ('ECVSCS155' and 'HIB 32R48H') susceptible and highly susceptible, respectively, to S. macrospora. MLS severity was significantly lower in the leaves of plants from ECVSCS155 relative to the leaves of plants from HIB 32R48H. In both cultivars, net CO2 assimilation rate, stomatal conductance, and transpiration rate significantly decreased, while the internal to ambient CO2 concentration ratio increased in inoculated plants relative to noninoculated plants. The initial fluorescence and nonphotochemical quenching significantly increased in inoculated plants of ECVSCS155 and HIB 32R48H, respectively, relative to noninoculated plants. The maximum fluorescence, maximum PSII quantum efficiency, coefficient for photochemical quenching, and electron transport rate significantly decreased in inoculated plants relative to noninoculated plants. For both cultivars, concentrations of total chlorophyll (Chl) (a + b) and carotenoids and the Chl a/b ratio significantly decreased in inoculated plants relative to noninoculated plants. In conclusion, the results from the present study demonstrate, for the first time, that photosynthesis in the leaves of maize plants is dramatically affected during the infection process of S. macrospora, and impacts are primarily associated with limitations of a diffusive and biochemical nature. © 2015 The American Phytopathological Society.

De Souza A.D.,Instituto Biologico IB | De Souza A.D.,Laboratorio Of Fitossanidade | Aoyama E.M.,Centro Universitario Norte do Espirito Santo | Aoyama E.M.,Federal University of Espirito Santo | Furlan M.R.,São Paulo State University
Revista em Agronegocio e Meio Ambiente | Year: 2015

Passiflora ligularis Juss. is highly consumed by people, especially in natura, as juice and ice-cream. However, no successful research is extant on its development and adaptation in Brazil. The high costs of granadilla and the difficulty to buy it, even in supermarkets, justify analysis to verify the adaptability of the species, with production potential, at least in some regions of the country. Current assay is a contribution for research on the behavior of granadilla in Brazil so that information on the effect of time and storage conditions may be obtained for seed germination and the early development stages of the seedlings. Granadilla seeds came from Colombian fruit and the assay focused on the evaluation of seed quality with three different storage periods, with emergence velocity index (EVI) and percentage of seedlings' germination and development. Treatments comprised Treatment A - seeds stored for 24 months; Treatment B - seeds stored for 3 months; Treatment C - seeds without storage. Randomized design with four replications of 50 seeds was employed and comparisons made by Tukey's test at 1% probability. Seedlings should be obtained from seeds kept in cold chambers for a period of more than 101 days. Seeds which had been only recently removed from the fruit have low germination percentage and small height growth when compared with plants from seeds stored for 24 months. © 2015, University Center of Maringa. All rights reserved.

Araujo E.R.,Laboratorio Of Fitossanidade | Araujo E.R.,Laboratorio Of Fitopatologia | Araujo E.R.,University of Brasilia | Costa J.R.,Laboratorio Of Fitopatologia | And 2 more authors.
European Journal of Plant Pathology | Year: 2015

Plants of Nicandra physaloides, Solanum americanum and Euphorbia heterophylla with leaf lesions have been found naturally grown among tomato plants in commercial fields in Brazil. Tomato bacterial spot was occurring in these fields. Xanthomonad-like isolates were obtained from affected weed leaf samples. These isolates were species identified using BOX-PCR and specific primers. Isolates from N. physaloides and S. americanum were identified as Xanthomonas perforans and that of E. heterophylla were identified as X. gardneri. Each of them was able to artificially infect and cause symptoms on the three weed species and tomato plants. © 2015 Koninklijke Nederlandse Planteziektenkundige Vereniging

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