Fábio de Lima Gurgel

Estimates of genetic parameters for physic nut traits based in the germplasm two years evaluation

In spite of increasingly widespread interest in planting physic nut, breeding efforts are still in its infancy. In that context, an important resource recently established aiming future breeding efforts was the assembly of a germplasm bank with near 200 accessions. The objective of this study was to estimate genetic parameters, repeatibility coefficients and genetic correlation between seven traits, measured in 110 accessions (half sib families) of this germplasm bank in different stages of development. The results show that higher relative values of additive variance were only found for yield and height, and the existence of low environmental variation (either of temporary or permanent nature) among plots within blocks. Given the high repeatibility values found for all traits, on average three measurements are necessary to predict, accurately and efficiently, the true breeding value of an individual. Based on the results of genetic correlations, breeding effort should initially be use track trees with increased stem diameter, elevated number of branches and canopy volume so as to increase the chances of finding an exceptionally highly productive tree.

Estimate of genetic parameters and predicted gains with early selection of physic nut families.

An initial evaluation of early selection of physic nut genotypes based on phenotypic data is presented. In order to predict the genetic gains with early selection, genetic parameters, e.g. additive genetic variance, were first obtained for grain yield along with other numerous traits. The results demonstrated that additive genetic variance exists not only for grain yield, which is considered to be the most important trait for oil and biodiesel production, but also for numerous other traits. The predicted genetic gains for grain yield, considering the selection of the 30, 20, 10 and 5 best families in the second crop year are respectively, 40.47, 48.43, 61.78 and 70.28%. With the selection of highly yielding physic nut genotypes indirectly genotypes with enhanced volume would be also selected, because yield exhibits moderate to high genetic correlations with height e canopy volume. The results here presented demonstrate the potential of the population gathered in the Brazilian physic nut germplasm bank for genetic breeding purposes and that superior physic nut families can be selected with high accuracy based on the evaluation of its second crop.

Phenology and biometry of physic nut in the brazilian savannah

Estudos fenologicos de tres acessos morfologicamente distintos de pinhao-manso (Jatropha curcas L.) foram conduzidos no bioma Cerrado brasileiro. A taxa de crescimento da planta, florescimento, formacao e desenvolvimento dos frutos foram medidos, a fim de se estabelecer praticas de manejo eficientes para o aumento de produtividade. Os acessos estudados foram: CNPAE-102 (toxico, susceptivel a oidio), CNPAE-169 (nao-toxico, susceptivel a oidio) e CNPAE-259 (toxico, resistente a oidio). Os materiais considerados nao-toxicos nao possuem esteres de forbol detectaveis nos graos. No periodo de um ano (agosto de 2009 a julho de 2010) registraram-se, quinzenalmente, as variaveis agronomicas (altura de plantas, numero de inflorescencias, numero de frutos verdes e maduros por planta) de cada acesso, correlacionando-as com as variaveis climaticas, por meio da analise de correlacao de Pearson. O acesso CNPAE-102 apresentou a maior taxa de crescimento (0,76 cm dia-1), incremento 1,10 m na altura e altura final de 2,60 m; o CNPAE-169 apresentou menor incremento (0,63 cm dia-1), atingindo altura final de 1,85 m. Os acessos CNPAE-259 e CNPAE-102 foram os mais precoces, e o CNPAE-169 o mais tardio. A temperatura minima foi a variavel climatica que determinou o maior numero de inflorescencias.

Pré-melhoramento do camucamuzeiro: estudo de parâmetros genéticos e dissimilaridade

O camucamuzeiro pertence a familia Myrtaceae e e especie em processo de domesticacao, encontrada na forma extrativa, a partir de plantas crescendo naturalmente nas margens dos rios e lagos, ou cultivadas em pequenas areas de terra firme. As estimativas e a compreensao dos parâmetros geneticos desta especie sao importantes para o conhecimento da estrutura genetica das populacoes e para a inferencia da diversidade genetica presente, alem de proporcionar subsidios para predizer os ganhos geneticos e o possivel sucesso no programa de melhoramento dessa cultura. Neste sentido, o objetivo deste trabalho foi estimar parâmetros geneticos e a dissimilaridade genetica, em acessos existentes no Banco Ativo de Germoplasma de camucamuzeiro, da Embrapa Amazonia Oriental. Para o estudo, foram analisados 46 progenies, colhidos 40 frutos por planta matriz em completo estadio de maturacao (frutos com epicarpo totalmente roxo), sendo avaliados sete caracteres morfoagronomicos: peso de fruto (g, PFR), comprimento de fruto (cm, CFR), diâmetro de fruto (cm, DFR), peso da casca (g, PCS), espessura da casca (cm, ECS), numero de sementes (n, NSE), peso de sementes (g, PSE). Por meio do Programa Genes, estimaram-se os componentes de variância, herdabilidade e a variabilidade. A importância relativa de caracteres e dissimilaridades entre as progenies, bem como as correlacoes geneticas entres os caracteres avaliados tambem foram estudadas. Verificou-se que ha dissimilaridade entre os acessos do BAG de camucamuzeiro e que, por causa das correlacoes significativas entre as variaveis, podem-se adotar metodos de selecao indireta como ferramenta auxiliar no processo de domesticacao e melhoramento desta especie.

Extensão bivariada do índice de confiabilidade univariado para avaliação da estabilidade fenotípica

The objective of this work was to obtain the theoretical derivation of the bivariate extension to the methods proposed by Annicchiarico (1992) and Annicchiarico et al. (1995) for studing phenotypic stability. Considering assays with genotypes in environments and two variates, every genotype had the response of each variate (k = 1, 2) standardized. This standardization has been made using the environment means as follows: Wijk = Yijk/×100 ; where Wijk represents the ith genotype standard value in the jth environment for the kth variate; represents the observed mean of the ith genotype, in jth environment for the kth variate e the overall genotypes means for jth environment to kth variate. Considering the standardized values, the genotypes mean vector and covariance matrix were estimated. The theoretical derivation of the bivariate reliability index (Ii) of Annicchiarico was wasked out and a second risk index was proposed based on the bivariate probabilities (Prbi); the two indexes proposed has shown good agreement to the results in an example with melon genotypes.

SISTEMA DE PRODUÇÃO DE MUDAS EM HÍBRIDOS INTERESPECÍFICOS ENTRE CAIAUÉ E DENDÊ

The objective of this study was to evaluate three systems of seedling production of interspecific hybrids of American oil palm and African oil palm (HIE), difference between 12 sib progenies of BRS Manicore cultivar and the interaction between these two factors. The production systems were evaluated: (i) two-stage nursery with the initial shading (conventional system), (ii) two-stage nursery without shading and (iii) one-stage nursery without shading. The variables evaluated were plant height, number of leaves and stem diameter at 106, 191 and 393 days after sowing. In all variables and periods analyzed, the genotype and environmental factors were significant to F test, but the interaction genotype x environment was not significant. The best development of seedlings in the nursery production system occurred in one-step nursery without shading. The two stages nursery with shading in pre-nursery, which is currently the most widely adopted, resulted in lower seedling development.

Repeatability reveals to be a useful method to evaluate the quality of an experiment with common beans

Field experiment should be carried out with high accuracy since the discarding of a trial involves waste of time and resources, and can mislead breeders in selecting inferior genotypes. The simulation of a large number of experiments with great variability of traits is the main strategy to assist breeders on how to perform the experiment. Therefore, the objective of this study was to evaluate two criteria to infer the experimental quality: Coefficient of Variation (CV) and repeatability coefficient. Experimental data from evaluations of common bean lines carried out in 104 experiments were used in this study. The simulation of the scenarios used the following parameters: number of cultivars, number of blocks, genetic variance, mean yield, and coefficient of variation. Two thousand replications for each scenario were simulated. Genotypes means were arranged in an order, and the Spearman correlation was obtained between the estimated genotypes mean and the true genotypic values. Results revealed that CV is not a reliable parameter to evaluate the quality of experiment in the field. In conclusion, repeatability coefficient is the parameter that defines the discarding criteria of evaluation experiments and the recommendation of cultivars, as long as the values for each response variable are established.