Time filter

Source Type

Woyann L.G.,Federal Technological University of Paraná | Benin G.,Federal Technological University of Paraná | Storck L.,Federal Technological University of Paraná | Trevizan D.M.,Federal Technological University of Paraná | And 4 more authors.
Crop Science | Year: 2017

Multi-environment trials often yield unbalanced datasets, thus necessitating the estimation of missing values. It is unknown whether this estimation affects the graphic characteristics of genotype plus genotype-by-environment interaction (GGE) biplots. Therefore, our objectives were to investigate the effects of different percentages of missing values on the number of significant principal components (PCs) and on mega environments, “winner” (highest-performing) genotypes, and the amount of variation explained by the PCs. Two complete sets of two-way data from wheat (Triticum aestivum L.) were used. The first set consisted of the original data (Data1, from which we created scenarios with 0, 30, and 60% missing data. For the second dataset (Data2), we removed 50% data from the original dataset, estimated missing values to make it a new complete dataset, and created scenarios like those for Data1. Missing values were estimated via expectation-maximization–GGE (EM–GGE) and EM–additive main effects and multiplicative interaction (EM–AMMI) methods. The percentage of variation explained by the PCs was affected by the percentage of missing data; a large percentage of missing values considerably increased the amount of variation explained by PC 1 and PC 2 and reduced the complexity of the genotype-by-environment interaction because two PCs accounted for more than 80% of the variation, instead of the three PCs that were required to explain the variation in the original dataset. The EM–GGE estimation method was able to maintain the original conformation of the ‘which-won-where’ biplot when ≤ 30% of estimated data were used. The EM–GGE was superior to the EM–AMMI method for estimating missing data. The estimation of more than 30% of the data should be avoided because it can lead to significant changes in mega environment conformation and the identification of “winner” genotypes. © Crop Science Society of America.

Zorzatto C.,State University of Maringá | Chiari L.,Embrapa Gado de Corte | De Araujo Bitencourt G.,University Estadual Of Sao Paulo Julio Of Mesquita Filho | Do Valle C.B.,Embrapa Gado de Corte | And 3 more authors.
Plant Breeding | Year: 2010

A bulked segregant analysis using RAPD technique was carried out to identify molecular markers linked to apomixis in a Brachiaria humidicola F1 population that segregated 1 : 1 for the mode of reproduction (apomixis and sexual). A marker related to the apo-locus was found. Segregation data, together with this marker were used to generate a map of the region. This marker was located at 4.61 cM of the target locus, and it can be used in deploying marker-assisted selection for mode of reproduction in the hybrid progenies of this species. © 2010 Blackwell Verlag GmbH.

de Paula M.F.B.,Federal University of Viçosa | Sagio S.A.,Federal University of Lavras | Lazzari F.,Cooperativa Central de Pesquisa Agricola | Barreto H.G.,Federal University of Lavras | And 2 more authors.
Coffee Science | Year: 2012

In order to use sensitive techniques of molecular biology, such as the study of differentially expressed genes, a highquality RNA in suitable quantities is necessary. Due to the presence of several varieties and often expressive quantities of secondary compounds in plants, there is no standard method for the isolation of nucleic acids that can be used for all species. Polyphenols and polysaccharides are the compounds that interfere the most in the extraction process, and when they are present, a low-quality RNA is produced. Four RNA extraction methods (CTAB method, Hot Borate, CONCERT and Tri Reagent), in four different coffee tissues (root, leaf, flower and fruit) were tested in this work, aiming at determining which method is more efficient. It was observed that the CTAB and Hot Borate methods, in which PVP and/or β-mercaptoethanol were added and precipitation with LiCl was performed, presented more pure RNA, with no degradation observed in any of the tissues, being suitable for further gene expression analysis. High-quality RNA was not obtained from any tissue in the extraction with Tri Reagent, which includes the use of phenol, and thus expression analysis was disturbed. The CTAB macro extraction method presented samples with the highest RNA quality and largest quantities in all tissues. Future works need to be carried out aiming the standardization of this macro extraction method.

Ferreira M.F.D.S.,Federal University of Espirito Santo | Ferreira A.,Federal University of Espirito Santo | Schuster I.,Cooperativa Central de Pesquisa Agricola | Santana F.A.,Federal University of Viçosa | And 3 more authors.
Pesquisa Agropecuaria Brasileira | Year: 2011

The 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.

dos Santos L.T.,State University of Maringá | Pinto R.J.B.,State University of Maringá | Franco F.A.,Cooperativa Central de Pesquisa Agricola | Schuster I.,Cooperativa Central de Pesquisa Agricola
Crop Breeding and Applied Biotechnology | Year: 2010

The inheritance of grain color and pre-harvest sprouting in wheat was studied to identify genotypes with high resistance to pre-harvest sprouting and evaluate the possible use of grain color in indirect selection of resistant lines. The genotypes of most lines were characterized with regard to the loci that control grain color. No significant correlations between grain color and pre-harvest sprouting resistance were observed, but correlations were useful when the frequency of segregating genotypes with white grain was relatively high. Of the eight F 2:3 populations evaluated, only two differed significantly in grain sprouting between the white and red classes. Three genes for pre-harvest sprouting resistance seem to be present in the genotypes Frontana and Onix. Grain color should not be used as the only criterion for selecting wheat genotypes resistant to pre-harvest sprouting.

Nasu E.G.C.,West Parana State University | Pires E.,Cooperativa Central de Pesquisa Agricola | Formentini H.M.,West Parana State University | Furlanetto C.,University of Brasilia
Tropical Plant Pathology | Year: 2010

The aim of this work was to study the nematicidal effect of manipueira on the control of Meloidogyne incognita. In vitro tests were split into two completely randomized assays: 1. manipueira 100%, 75%, 50% and 25% in 12 replications; 2. manipueira 15%, 10%, 8%, 6%, 4% and 2% in 5 replications. The pot assay followed a completely randomized design with the treatments manipueira 10%, 25% and 50% in 5 replications. For both assays the positive control was water and the negative control was the nematicide Carbofuran (50 mg.L-1 of active ingredient (a.i.) or 2 g of commercial product/pot). For in vitro assays the variables assessed were live or dead nematodes and number of galls on inoculated plants. For the pot assay the variables evaluated were plant height, root length, number of galls, number of eggs and reproduction factor (RF). The in vitro results indicated that only the manipueira treatments from 100% to 10% dilution showed maximum control. The pot assay demonstrated that the treatment manipueira 50% caused better development of tomato shoots than the others. However, manipueira 10% and 25% were more effective against of M. incognita in pots.

Dranski J.A.L.,Cooperativa Central de Pesquisa Agricola | Malavasi U.C.,West Parana State University | Malavasi M.M.,West Parana State University | Jacobs D.F.,PurdueUniversity
Revista Arvore | Year: 2013

Immediately after planting, tree seedlings face adverse environmental and biotic stresses that must be overcome to ensure survival and to yield a desirable growth. Hardening practices in the nursery may help improve seedling stress resistance through reduction of aboveground plant tissues and increased root volume and biomass. We conducted an assay to quantify changes in the morphogenesis following application of ethephon on seedlings of Pachystroma longifolium (Ness) I. M. Johnst.during hardening. The results showed no effect of the ethephon treatments on the number of leaves but a reduction of up to 50% in seedling height increment, and an increase in stem diameter increment of up to 44% with the 600 mg L-1ethephon treatment, which consequently altered seedling Dickson Quality Index. Our results indicate that ethephon may help to promote desired morphological changes that occur during seedling hardening in nurseries.

Vieira E.S.N.,Cooperativa Central de Pesquisa Agricola | von Pinho E.V.R.,Federal University of Lavras | Carvalho M.G.G.,Federal University of Lavras | Esselink D.G.,Plant Research International | Vosman B.,Plant Research International
Genetics and Molecular Biology | Year: 2010

Microsatellite markers, also known as SSRs (Simple Sequence Repeats), have proved to be excellent tools for identifying variety and determining genetic relationships. A set of 127 SSR markers was used to analyze genetic similarity in twenty five Coffea arabica varieties. These were composed of nineteen commercially important Brazilians and six interspecific hybrids of Coffea arabica, Coffea canephora and Coffea liberica. The set used comprised 52 newly developed SSR markers derived from microsatellite enriched libraries, 56 designed on the basis of coffee SSR sequences available from public databases, 6 already published, and 13 universal chloroplast microsatellite markers. Only 22 were polymorphic, these detecting 2-7 alleles per marker, an average of 2.5. Based on the banding patterns generated by polymorphic SSR loci, the set of twenty-five coffee varieties were clustered into two main groups, one composed of only Brazilian varieties, and the other of interspecific hybrids, with a few Brazilians. Color mutants could not be separated. Clustering was in accordance with material genealogy thereby revealing high similarity. © 2010, Sociedade Brasileira de Genética.

Silva R.R.,Federal Technological University of Paraná | Benin G.,Federal Technological University of Paraná | Marchese J.A.,Federal Technological University of Paraná | da Silva E.D.B.,Federal University of Santa Maria | Marchioro V.S.,Cooperativa Central de Pesquisa Agricola
Acta Scientiarum - Agronomy | Year: 2014

The potential yield of wheat is mainly determined by temperature, solar radiation and the photothermal quotient. The objective of this study was to determine the temporal and spatial variability of the photothermal quotient and the frost risk to identify suitable sowing dates for wheat in Parana State, Brazil. The results showed that the photothermal quotient has greater spatial variability than temporal variability. The sowing date affects crop conditions that can in turn affect yield. However, the photothermal quotient and frost risk fluctuate differently in different Value for Cultivation and Use (VCU) regions. The regions VCU 1 and VCU 2 showed greater temporal variability of the photothermal quotient. The photothermal quotient ranged from 1.5 to 2.0 MJ m-2 day °C in VCU 1, from 1.1 to 1.5 MJ m-2 day °C in VCU 2 and from 1.0 to 1.2 MJ m-2 day °C in VCU 3. Sowing performed in June provided the greatest photothermal quotient in all VCU regions. However, June sowing increased the frost risk in VCU 1. Thus, the sowing date can be used as a management tool for the attainment of higher yield in wheat.

Benin G.,Federal Technological University of Paraná | Storck L.,Federal Technological University of Paraná | Marchioro V.S.,Cooperativa Central de Pesquisa Agricola | Franco F.D.A.,Cooperativa Central de Pesquisa Agricola | Schuster I.,Cooperativa Central de Pesquisa Agricola
Pesquisa Agropecuaria Brasileira | Year: 2013

The objective of this work was to evaluate the adequacy of measures of the experimental precision degree in trial sets of genotype competition in wheat (Triticum aestivum), carried out in homogeneous adaptation regions. The statistics heritability, coefficient of determination, F-test value for genotype, Fasoulas differentiation index, selective accuracy, and repeatability coefficient were calculated from results of wheat grain yield obtained in 572 competition trials with 25 genotypes, in four homogeneous adaptation regions in the crop years from 2007 to 2011. Linear correlations among the statistics were estimated and path analysis was performed. Statistics were grouped using Ward's hierarchical method. Statistical means from each adaptation region were compared by the t bootstrap test. The statistics selective accuracy, coefficient of determination, coefficient of heritability, and repeatability coefficient are algebraically related and are suitable to evaluate the experimental accuracy of wheat competition trials in different adaptation regions. The regions used for the evaluation of values for cultivation and use of wheat differ in selective accuracy and repeatability coefficient.

Loading Cooperativa Central de Pesquisa Agricola collaborators
Loading Cooperativa Central de Pesquisa Agricola collaborators