Giselle Mariano Lessa de Assis

Seleção de genótipos de amendoim forrageiro para cobertura do solo e produção de biomassa aérea no período de estabelecimento utilizando-se metodologia de modelos mistos

Objetivou-se estimar parâmetros geneticos e selecionar genotipos de amendoim forrageiro para maior cobertura do solo e producao de biomassa aerea durante o periodo de estabelecimento nas condicoes ambientais do Acre. A area experimental foi estabelecida em dezembro de 2005. O experimento foi realizado em delineamento de blocos ao acaso com quatro repeticoes utilizando-se 21 genotipos de amendoim forrageiro, incluindo tres cultivares (Amarillo, Alqueire 1 e Belmonte). A selecao dos genotipos foi realizada considerando a cobertura do solo e a producao de materia seca. As avaliacoes de cobertura do solo foram realizadas entre janeiro e outubro de 2006, em intervalos de quatro semanas. A producao de materia seca foi mensurada 304 dias apos o plantio. Os componentes de variância foram estimados pelo Metodo da Maxima Verossimilhanca Restrita (REML) e os valores genotipicos foram preditos pelo metodo da Melhor Predicao Linear Nao-Viesada (BLUP), conforme metodologia dos modelos mistos. Verificou-se a presenca de variabilidade genetica para ambas as caracteristicas. As herdabilidades individuais foram de magnitude mediana, com valores de 0,36 a 0,58 para as caracteristicas cobertura do solo e producao de materia seca, respectivamente. A maior variabilidade entre os genotipos para cobertura do solo ocorreu entre a 12a e a 16a semana apos o plantio, indicando que esse intervalo e o mais adequado para a selecao de genotipos de cobertura mais rapida do solo. Os valores genotipicos para producao de materia seca variaram de 1.609 a 4.132 kg/ha para os genotipos BRA 015083 e BRA 040550, respectivamente. Os genotipos selecionados para maior cobertura do solo e producao de biomassa aerea durante o periodo de estabelecimento foram Belmonte, Amarillo, BRA 040550, BRA 039187, Alqueire 1, BRA 039799 e BRA 035033.

Estimação de componentes de variância utilizando-se inferência Bayesiana e freqüentista em dados simulados sob heterogeneidade de variâncias

A genome of 3.000 centimorgans was simulated for a single quantitative trait governed by 800 loci with two alleles per locus. According to the genomic structure proposed, 1,500 males and 1,500 females constituted the base population which was used to form two (small and large) initial populations. Two types (only additive genetic variance and both additive genetic and environmental variances) and three variability levels (high, medium and low) of heterogeneity of variances were inserted in the initial populations. Variance components were estimated by Bayesian inference via Gibbs Sampling using three different levels of priors (non-informative, slightly informative and informative) and by REML. The best estimates of variance components were obtained with large populations. In small populations, the individual analyses for different variability levels presented problems related to variance components estimation due the small size of subpopulations. Both methods presented similar results for variance components when non-informative priors were used in Bayesian inference. Increasing the level of a priori information improved the estimates of variance components by Bayesian inference, especially in small populations.

Estimação de parâmetros genéticos em caprinos leiteiros por meio de análise de regressão aleatória utilizando-se a Amostragem de Gibbs

Random regression models were used to estimate genetic parameters for test-day milk yield (PLDC) of Alpine dairy goats, implemented by Bayesian methods with Gibbs Sampling. The estimates were compared with those obtained by random regression analysis, using REML. Heritability estimates obtained by Bayesian analysis ranged from 0.18 to 0.37, while those obtained by REML ranged from 0.09 to 0.32. Genetic correlations between yields of close test days approached the unit, but decreased gradually as the interval between test days increased. Results indicated that random regression models are appropriate to model the covariance structure of PLDC and to predict genetic gains and select animals along the lactation trajectory of dairy goats. Results obtained by Bayesian and REML approaches were similar, although genetic variance and heritability estimates were slightly higher with Bayesian methods.

Pegamento da enxertia em diferentes combinações de variedades e espécies utilizadas como copa e como porta-enxertos de maracujazeiro

ABSTRACT - Brazil is the largest producer of passion fruit. But, in spite of its prominent position, life of passion fruit plant has been reduced mainly due to damage caused by root diseases. As grafting with native species is resistant to diseases, presenting an alternative of production, this research aimed to evaluate the success of grafting in the combinations of scion varieties and species of rootstocks of passion fruit plant. The study was conducted in screenhouse (50% shaded) at Acre Embrapa, Rio Branco, between September and December in 2007. The scion variety used for all treatments was the yellow passion fruit ‘FB 100’ and ‘FB 200’ from Flora Brazil (Araguari, MG) nursery and 5 other regional varieties (UFAC, Universidade Federal do Acre, Rio Branco-AC) and the rootstocks were Passiflora edulis (yellow passion fruit) (Cuiaba-MT), P. alata, P. edulis (purple passion fruit) and P. quadrangularis (Guiratinga-MT), P. serrato-digitata (IAC-Campinas/SP). The seeds were previously soaked in distilled water for about 24 h and then sown in plastic tubes (25x5cm) with Plantmax

Características vegetativas e seus efeitos sobre a produção de bananeira em três ciclos

A produtividade em bananeira e um carater complexo que resulta da associacao de diferentes fatores, influenciados pelo ambiente. Este trabalho teve por objetivo estudar os efeitos diretos e indiretos de caracteristicas vegetativas sobre a producao de bananeira em tres ciclos. O trabalho foi conduzido no campo experimental da Embrapa Acre, em Rio Branco, Acre, entre os anos de 2003 e 2006. Foram avaliados 13 genotipos de bananeira (Preciosa, Japira, Pacovan-Ken, Pacovan, BRS Platina, Prata-Ana, ST12-31, Nanicao, Grande Naine, Calipso, Ambrosia, Bucaneiro e FHIA-02), no espacamento de 3 m x 2 m, no esquema de blocos ao acaso, com cinco repeticoes. Determinaram-se a altura de plantas, diâmetro do pseudocaule, numero de folhas na floracao e na colheita, peso do cacho e numero de pencas no cacho. Realizou-se a analise de variância para cada ciclo e estimaram-se os coeficientes de correlacao fenotipicos e os coeficientes de trilha. Adotou-se como variavel basica o peso do cacho, e as demais, como variaveis explicativas. O estudo dos efeitos diretos e indiretos evidenciou que o carater producao e bastante influenciado pelo ambiente no primeiro ciclo, e, nos ciclos seguintes, a producao e muito influenciada pelas caracteristicas vegetativas, principalmente numero de folhas na colheita.

Forage yield and nutritive value of Arachis spp. genotypes in the Brazilian savanna.

Forage yield, nutritive value, ground cover and mineral concentration of 10 genotypes of Arachis spp. were evaluated over 3 years in Planaltina, Federal District, Brazil. Experimental plots were arranged in a randomized complete block design with 4 replications. Treatments were 5 genotypes of A. pintoi (accessions 2, 4, 5, 6 and 8), 2 genotypes of A. repens (accessions 1 and 7), 1 hybrid A. pintoi × A. repens (accession 3) and 2 A. pintoi cultivars, BRS Mandobi and Belmonte. All genotypes established well and achieved good ground cover in the first year. Cultivar Belmonte and accessions 2 and 4 produced the highest DM yields (means of 8.8, 8.5 and 8.8 t DM/ha/yr, respectively) throughout, while cv. BRS Mandobi and accession 6 were the worst (5.7 and 5.6 t DM/ha/yr). Most genotypes maintained ground cover above 80% throughout the study but cv. BRS Mandobi plus accessions 6 and 8 had declined to 60% or less by the third year. Mean crude protein concentration overall was 166 g/kg with a range of 154‒182 g/kg among genotypes. There was no major genotypic variation in mineral concentrations, which in all cases were considered marginal to adequate for tropical forage legumes. In conclusion, genotypes 2 and 4 (accessions BRA-039799 and BRA-039187, respectively) of A. pintoi are considered the most promising forage peanut options under the edaphoclimatic conditions of the experimental site. More effort is needed to improve seed set in these accessions to increase adoption by farmers. Their persistence under grazing and impact on production should also be demonstrated. Keywords : Arachis pintoi , Arachis repens , crude protein, digestibility, minerals.

Riqueza e frequência de espécies de fungos micorrízicos arbusculares em genótipos de amendoim forrageiro no Acre, Norte do Brasil

The potential of the forage peanut crop associated with arbuscular mycorrhizal fungi (AMF) has been the subject of some studies, but the influence of the genotype on this association is poorly understood. The objective of this study was to determine the spore density, species richness, relative frequency and occurrence of AMF associated with forage peanut genotypes. Simple soil samples were collected from 45 genotypes of Active Germplasm Bank at Embrapa Acre. Soil samples were collected at 5 cm depth, with three replicates in a completely randomized design. Soil samples were taken to the Mycorrhizae Laboratory of Embrapa Agrobiologia for determination of spore density and identification of AMF species. Analysis of variance and Scott-Knott test were performed. Four genotypes of A. pintoi and two interspecific hybrids, which showed higher spore density, stood out. It was found the occurrence of 21 AMF species in the soil samples. The richness ranged between three and ten species. Three AMF species showed high relative frequency: Glomus macrocarpum (100.0%), Acaulospora tuberculata (97.8%) and Racocetra verrucosa (88.9%). It was concluded that: (i) Regarding inducement of AMF sporulation and species richness, there is genetic variability among forage peanut genotypes, (ii) Glomus macrocarpum, Acaulospora tuberculata, Racocetra verrucosa are often present in the rhizosphere of forage peanut genotypes and should be studied aiming its introduction in the culture.

Estimação de componentes de variância sob influência de genes de efeito principal, comparando-se metodologias Bayesiana e clássica sob diferentes cenários

This study aimed to evaluate the effects of major genes and population size on variance components estimation using four different types of selected populations. Variance components were estimated by classical and Bayesian methodologies, with three a priori information levels. In general, results from REML and Bayesian analyses with flat priors were similar. Except for Bayesian analysis with an informative prior, additive genetic variance estimates were not accurate in populations in which the trait is controlled by major genes. The use of pedigree information and records of all individuals back to the base-population was necessary to improve accuracy of variance component estimates, except for large populations in which the trait is controlled by a large number of genes.