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Predicción de Valores Genéticos del Efecto de Poblaciones de Maíz Evaluadas en Brasil y Paraguay
Mora,Freddy; Scapim,Carlos Alberto;
Agricultura Técnica , 2007, DOI: 10.4067/S0365-28072007000200003
Abstract: the aim of this study was to evaluate the performance of seven popcorn ( zea mays l.) populations of avati pichinga landrace, established in different sites of brazil and paraguay, determining and analyzing the empirical best linear unbiased predictor (eblup) of population effect, and estimating covariance parameters by the restricted maximum likelihood (reml) method, for commercial and agronomic characteristics. ten models were investigated for fitting an appropriate inter-genotype covariance structure. akaike and bayesian information criteria were used to compare alternative models. the covariance structures chosen were toeplitz with three bands, for grain yield; toeplitz with two bands for both popping expansion and plant height; autoregressive for ear height; and variance component for blooming. population effect was significant for all the agronomic traits, unlike genotype-environment interaction. spearman correlation coefficients were not significant between grain yield and popping expansion ranking. p4 and p5 can be considered as promissory populations according to their predicted breeding values for grain yield; p1 and p4 for popping expansion. these populations can be regarded as useful for popcorn breeding programs.
Predicción de Valores Genéticos del Efecto de Poblaciones de Maíz Evaluadas en Brasil y Paraguay Predicting Breeding Values of Population Effect of Maize Evaluated in Brazil and Paraguay
Freddy Mora,Carlos Alberto Scapim
Agricultura Técnica , 2007,
Abstract: El objetivo de este estudio fue evaluar el comportamiento de siete poblaciones de maíz ( Zea mays L.) tipo roseta, o palomita, de la raza Avati Pichinga , establecidas en diferentes localidades de Brasil y Paraguay. Se determinó la mejor predicción lineal no sesgada empírica (EBLUP), con estimaciones de parámetros de covarianza vía método de máxima verosimilitud restringida (REML), en características de importancia comercial y agronómica. Se investigaron diez modelos con diferentes estructuras de covarianzas en la matriz intergenotípica. Los criterios de información de Akaike y Bayesiano de Schwarz se utilizaron para la comparación entre los modelos. Las estructuras de covarianza escogidas fueron Diagonal de tres bandas para el rendimiento de granos, Diagonal de dos bandas para la capacidad de expansión y la altura de planta, Auto-regresiva de primer orden para la altura de mazorca, y tipo componentes de varianza para la floración masculina. El efecto de poblaciones fue significativo, al contrario de la interacción genotipo-ambiente. Correlaciones de Spearman fueron no significativas entre rendimiento y capacidad de expansión. Las poblaciones P4 y P5 se ven promisorias al considerar su valor genético del rendimiento, y P1 y P4 para capacidad de expansión. Tales poblaciones pueden ser consideradas útiles para el programa de mejoramiento. The aim of this study was to evaluate the performance of seven popcorn ( Zea mays L.) populations of Avati Pichinga landrace, established in different sites of Brazil and Paraguay, determining and analyzing the empirical best linear unbiased predictor (EBLUP) of population effect, and estimating covariance parameters by the restricted maximum likelihood (REML) method, for commercial and agronomic characteristics. Ten models were investigated for fitting an appropriate inter-genotype covariance structure. Akaike and Bayesian information criteria were used to compare alternative models. The covariance structures chosen were Toeplitz with three bands, for grain yield; Toeplitz with two bands for both popping expansion and plant height; autoregressive for ear height; and variance component for blooming. Population effect was significant for all the agronomic traits, unlike genotype-environment interaction. Spearman correlation coefficients were not significant between grain yield and popping expansion ranking. P4 and P5 can be considered as promissory populations according to their predicted breeding values for grain yield; P1 and P4 for popping expansion. These populations can be regarded as useful for popcorn breeding prog
Mapeo de loci de caracteres cuantitativos (QTL) usando un enfoque multivariado
Mora,Freddy; Santos,Alexandra I; Scapim,Carlos A;
Ciencia e investigación agraria , 2008, DOI: 10.4067/S0718-16202008000200003
Abstract: statistical procedures for mapping quantitative trait loci (qtl) have been extensively studied because they are the essential for improving the accuracy of genetic analyses. the objective of the present study was to examine qtl using multivariate methods, considering the principie of simple interval mapping. a microsatellite marker data set from a f2 population was simulated. it was assumed that the qtl control binomial and normal traits. in the normal case, five qtl mapping models were evaluated that had the following residual covariance structures: variance components (vc), compound symmetry (cs), unstructured (un), banded main diagonal (uní) and heterogeneous toeplitz. akaike's information criterion (aic) was used to select the appropriate structure. in the binary case, the generalized estimating equations (gee) procedure was used. un structure minimized the aic valué on the interval that indicated a higher probability of the qtl. in the binomial case, a non-independent working correlation matrix (wcm) was fitted (p = 0.47). in both cases, the additive effect of qtl was significant (p < 0.01), but dominance effects were not (p > 0.05). thus, qtl mapping using a multivariate approach may be a useful tool for breeding programs that aim to improve quantitative traits that have phenotypic valúes that change over time.
Genetic parameters of growth and survival in Acacia saligna shrubs
Mora,Freddy; Perret,Sandra; Scapim,Carlos Alberto; Arnhold,Emmanuel;
Ciencia e investigación agraria , 2010, DOI: 10.4067/S0718-16202010000200001
Abstract: acacia species have valuable agronomic characteristics, such as the tolerance to unfavorable environmental conditions. in this study, genetic parameters and selection response in acacia saligna shrubs were investigated in two arid environments of northern chile: cuz-cuz and el tangue. the quantitative traits were assessed in 5 year-old shrubs. a bayesian approach, implemented using gibbs sampling algorithm, was used in the data analysis. the tree survival was 87.3% and 81.8% in cuz-cuz and el tangue, respectively, confirming the potential of a. saligna in northern chile. the estimates of posterior mode of the heritability ranged from h2=0.13 (survival) to h2=0.25 (shrub crown diameter). estimated genetic gain (individual tree selection) ranged from 6 to 14% (selection intensity of 20%). bayesian credible intervals (p=95%) for genotype-environment correlations included zero, indicating a significant interaction for survival, crown diameter and height. shrub selection in multipurpose planting will depend on optimizing economical traits by selecting genotypes that perform well on a particular environment.
Predicción del efecto de cultivares de algodón en la presencia de interacción genotipo-ambiente
Mora,Freddy; Osmério,Pupim-Junior; Scapim,Carlos Alberto;
Ciencia e investigación agraria , 2007, DOI: 10.4067/S0718-16202007000100002
Abstract: we aimed to obtain, by the best linear unbiased predictor (blup), a prediction of the cultivar effect of 14 cotton cultivars (gossypium hirsutum) established at different sites in brazil and paraguay during the 2003-2004 growing season. the blup of cotton yield was compared with classical stability analysis according to the plaisted and peterson, wricke, annicchiarico and lin and binns models. the independence chain (ic) algorithm, within a bayesian framework, was also utilized for comparison. a likelihood ratio test provided evidence of significant differences for cultivar and genotype-environment interaction effects. these results were confirmed by akaike and bayesian information criteria. most spearman and pearson correlation values were not significant site-to-site (p>0.05), varying from -0.037±0.307 to 0.565±0.290 and from -0.228±0.336 to 0.604±0.257, respectively. the plaisted and peterson and wricke methods showed no significant correlation with blup, ic, annicchiarico and lin and binns. on the other hand, spearman rank coefficients were high and significant (p<0.01) between blup and annicchiarico (0.859±0.151) and blup and lin and binns (-0.899±0.099). blup and ic, based on mean and median posterior estimates, had identical ranks. cd-406 and cd99-2221 were the cultivars that evidenced superior stability, as confirmed equally by blup, ic, annicchiarico and lin and binns, indicating a significant concordance between approaches in relation to genotypic stability. a mixed linear models methodology allows us to get important genotypic information of cotton cultivars with both high productivity and stability in the environments where they will be cultivated by farmers
Early performance of Olea europaea cv. Arbequina, Picual and Frantoio in the southern Atacama Desert
Freddy Mora,Francisco Tapia,Carlos Alberto Scapim,Elias Nunes Martins
Crop Breeding and Applied Biotechnology , 2008,
Abstract: The cultivars Arbequina, Picual and Frantoio of Olea europaea are cultivated in severalMediterranean countries. In 1999, these cultivars were planted at three locations in the region of Coquimbo,an arid, Mediterranean-like area in Chile. A generalized linear modeling approach was used in view of thenon-normal distribution of the agronomic data sets. Fruit yield (harvests of 2002-2003), precocity (2002) andtree survival (after four growing seasons) differed significantly between the cultivars. Arbequina and Picualhad a positive effect on the yield. Picual was the earliest cultivar at two sites. The survival rate of Frantoio washigh at the three sites (90-100%), as opposed to Picual (56-83%). The approach of Generalized Linear Modelswas particularly useful where the assumption of normality was not satisfied. The selection of cultivars ispromising in this arid region of Chile, while the success will depend on the selection of well-adapted genotypesto a particular location.
Evaluación genética de clones de olivo en el desierto de Atacama, Chile
Mora, Freddy;Tapia, Francisco;Ibacache, Antonio;Nunes-Martins, Elias;Scapim, Carlos Alberto;
Agrociencia , 2008,
Abstract: the olive (olea europaea l.) is an economically important species for countries that have mediterranean climate and has been an appropriate, useful alternative for intensive farming systems in the arid zones of chile. for this reason, the objective of this study was to determine the components of variance, broad-sense heritability, and prediction of genetic values using the bayesian techniques on twenty-eight olive clones in the southern part of the atacama desert. the algorithm of independent chains was used to estimate parameter distributions a posteriori. the field experiment was set up in 2000, and during six years six quantitative traits were monitored in different periods. estimations of heritability and associated credibility intervals (parentheses) were h2=0.50 (0.38-0.61), 0.50 (0.38-0.61), 0.81 (0.74-0.86), 0.53 (0.42-0.64), 0.26 (0.14-0.40), and 0.44 (0.17-0.65) for fruit production (2006), total fruit production (2003-2006), area of trunk cross section (2006), tree productivity (2006), alternation of production (2003-2006), and precocity (2003). genetic advance by direct selection varied from 16 to 55% with a selection intensity of 28.6%. pearson correlations, calculated between genetic values of alternation of production and production traits, were negative and significant. selection of olive clones for precocity would not generate any significant effect on production traits. moderate heritability for fruit production, alternation of production, and precocity suggest a positive response to the selection of olive clones under the environmental conditions of the southern part of the atacama desert.
Heredabilidad de la sobrevivencia en 169 familias de maíz-roseta de granos blancos: Un enfoque Bayesiano
Rodovalho,Marcos de Araújo; Mora,Freddy; Santos,Elisangela Mendes dos; Scapim,Carlos Alberto; Arnhold,Emmanuel;
Ciencia e investigación agraria , 2008, DOI: 10.4067/S0718-16202008000300008
Abstract: during the genetic evaluation of 169 half-sib families of white grain popcorn (zea mays), at the beginning of a breeding program conducted in southern brazil (cycle i), significant differences in family survival were detected (p < 0.01). consequently, plant survival was incorporated into the breeding program. the main objective of this study was to examine genetic parameters for plant survival, and their association with other traits of agronomic interest. a bayesian approach was used for this purpose, implemented by gibbs sampling (for individual plant selection) and independence chain algorithms (for family selection). the survival (measured as a binary trait) varied from 48 to 100% at the family level. heritability (h2) was significant and high for this trait, with a posterior mean of h2=0.63 and bayesian credible interval of 0.53-0.74. the genetic gain was 14.5% (selection intensity: 20%). survival was correlated positively and significantly with grain yield (p < 0.01), indicating that family selection based on survival alone would have a positive effect on yield and vice versa. the spearman correlation coefficient calculated between survival and popping expansión was not significantly different from zero, indicating that selection for family based on popping expansión would not have a significant effect on survival.
Generalized composite interval mapping offers improved efficiency in the analysis of loci influencing non-normal continuous traits
Mora,Freddy; Scapim,Carlos Alberto; Baharum,Adam; Teixeira do Amaral Júnior,Antonio;
Ciencia e investigación agraria , 2010, DOI: 10.4067/S0718-16202010000300007
Abstract: in genetic studies, most quantitative trait loci (qtl) mapping methods presuppose that the continuous trait of interest follows a normal (gaussian) distribution. however, many economically important traits of agricultural crops have a non-normal distribution. composite interval mapping (cim) has been successfully applied to the detection of qtl in animal and plant breeding. in this study we report a generalized cim (gcim) method that permits qtl analysis of non-normally distributed variables. gcim was based on the classic generalized linear model method. we applied the gcim method to a f2 population with co-dominant molecular markers and the existence of a qtl controlling a trait with gamma distribution. computer simulations indicated that the gcim method has superior performance in its ability to map qtl, compared with cim. qtl position differed by 5 cm and was located at different marker intervals. the likelihood ratio test values ranged from 52 (gcim) to 76 (cim). thus, wrongly assuming cim may overestimate the effect of the qtl by about 47%. the usage of gcim methodology can offer improved efficiency in the analysis of qtls controlling continuous traits of non-gaussian distribution.
Variabilidad en el florecimiento de procedencias de Eucalyptus cladocalyx en la Región de Coquimbo
Mora,Freddy; Perret,Sandra; Scapim,Carlos Alberto; Nunes Martins,Elias; Molina,María Paz;
Ciencia e investigación agraria , 2007, DOI: 10.4067/S0718-16202007000200006
Abstract: this work aimed to study the variability in flowering of five populations of eucalyptus cladocalyx established in the administrative region of coquimbo, northern chile. flowering was recorded as a binary response trait in 30-month-old trees. then, at first, a generalized linear model was fitted for analyzing provenance effect. subsequently, genetic variability was studied within the best provenance by bayesian inference via gibbs sampling. initially, two sites were considered: caracas and tunga norte, in the littoral and interior area of the choapa province, respectively. in the littoral area, only 1.3% of the trees evidenced flowering events, while in tunga norte, this value was 23.43%. for this reason, only interior site was considered. the provenance effect was significant (p < 0.01), with cowell (codified fdi-20411) being the population that evidenced a relative better flowering response, although it not was different of the trees from national plantations (fdi-illapel). however, trees from a local population evidenced a high variability, having a mean response similar to other provenances. the flowering trait analyzed within the cowell population, the selected provenance, was shown to be highly heritable (h2 = 52.3%). predicted genetic gain when considering two different breeding strategies varied from 36 to 40%. according to these results, it is possible that farmers can recover establishment costs of e. cladocalyx plantations as soon as possible whenever the selected trees are used for apicultural aims
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