Reinaldo de Paula Ferreira

Repeatability of elephantgrass forage traits

The repeatability coefficient is widely used by geneticists as a measure of the upper limit of the heritability and as an efficient tool for predicting genotype value from successive measurements on individuals. It also allows to estimate whether the number of evaluations is sufficient to determine genotype superiority within a certain degree of reliability. The purpose of this research was to evaluate the coefficient of repeatability of crude protein concentration on stems and leaves, in 77 accesses of the Embrapas Elephantgrass Germplasm Active Bank. The experimental design consisted of was randomized blocks, with two replicates. Forage was cut on 30, 45, 60 and 75 days of croping, using 15 sprouts of each experimental unit. ANOVA was performed for each trait data set, and genetic and environmental parameters were determined. The repeatability coefficients were estimated by the methods: Analysis of variance, principal components - correlation matrix, principal components - co-variance matrix and structural analysis - correlation matrix. Genetic variability was found among the genotypes for the appraised traits, which allowed the identification of genetically superior material that can be used in breeding programs. The coefficients of estimated repeatability were not different for the traits studied. Four cuts were enough for a coefficient of determination of 0.80, for all the methods. The use of seven cuts may enable predictions with 0.90 reliability for the studied traits, using any method.

Avaliação de cultivares de alfafa e estimativas de repetibilidade de caracteres forrageiros

The objective of this study was to evaluate the performance of 42 cultivars of alfalfa (Medicago sativa L.) and to estimate the repeatability coefficient for dry matter production, leaf and stem protein content and disease tolerance features during the dry (April to September) and rainy (October to March) seasons with six cuts. Dry matter yield and leaf protein content presented signifi- cant variation in both seasons, although stem protein content and tolerance to diseases were different only during the dry season. Cultivars Crioula and Cibola had the best performance in most features. In general, the repeatability coefficient showed a low magnitude estimate (below 0,40). Regarding dry matter production, the cultivars showed similar behavior in both seasons, with repeatability coeffi- cient ranging from 0.3195 to 0.4270, genotypic determination around 65% and the possibility to predict the real value after seven to nine cuts.

Adaptabilidade e estabilidade em cultivares de sorgo

Information about cultivars behavior obtained from only one local and year may not be enough for a cultivar recommendation due to the genotype x environment interaction occurrence. Then, cultivars indication based on stability and repeatability is more consistent because it enables previewing theirs performance under many environments. This work studied the adaptability and repeatability of dry matter production of seven sorghum cultivars to be used as silage. Data came from two sites (Coronel Pacheco and Lavras, Minas Gerais) and were obtained during two years (1997/98 and 1998/99) using a casual block with three replications design. Cultivar AG 2002 was recommended because showed the best productivity, good performance preview and was the cultivar that approached more to the ideal standard. Also, Volumax cultivar may be recommended due to its good performance when growing in favorable environments.

Artificial neural networks for adaptability and stability evaluation in alfalfa genotypes

The purpose of this work was to evaluate a methodology of adaptability and phenotypic stability of alfalfa genotypes based on the training of an artificial neural network considering the methodology of Eberhart and Russell. Data from an experiment on dry matter production of 92 alfalfa genotypes (Medicago sativa L.) were used. The experimental design constituted of randomized blocks, with two repetitions. The genotypes were submitted to 20 cuttings, in the growing season of November 2004 to June 2006. Each cutting was considered an environment. The artificial neural network was able to satisfactorily classify the genotypes. In addition, the analysis presented high agreement rates, compared with the results obtained by the methodology of Eberhart and Russell.

Cultivares de alfafa em área de influência da Mata Atlântica no Estado de Minas Gerais

Este trabalho teve como objetivo avaliar o potencial forrageiro de cultivares de alfafa ( Medicago sativa L.) em area de influencia da Mata Atlântica no Estado de Minas Gerais. Foram avaliadas 30 cultivares de alfafa em delineamento de blocos ao acaso com tres repeticoes. As sementes foram infectadas com a estirpe de Rhizobium melilotii BR 7407. No periodo das chuvas e da seca houve diferencas significativas entre as cultivares quanto ao potencial de producao de forragem, relacao folha/caule e tolerância a pragas e doencas. Quanto ao teor de proteina bruta, houve diferencas significativas entre as cultivares, somente no periodo das chuvas. As cultivares que se destacaram na maioria dos parâmetros avaliados foram a Crioula, P30, Monarca e Florida 77. As maiores producoes de forragem nas estacoes das chuvas e da seca foram obtidas pela cultivar Crioula, constituindo, assim, boa opcao para o cultivo da alfafa na Zona da Mata de Minas Gerais.

Adaptabilidade e estabilidade de cultivares de alfafa em relação a diferentes épocas de corte

An experiment was carried out at the Animal Science Experimental Station of Sertaozinho, Sao Paulo, Brazil. The experimental design was a randomized block design, with three replications. Plots were constituted of 5 rows, with 5m long, separated by 0.2m. Thirty-five alfalfa cultivars were evaluated for dry matter yield in 29 yielding

Abordagem bayesiana para avaliação da adaptabilidade e estabilidade de genótipos de alfafa

The objective of this work was to propose a Bayesian approach for the Eberhart & Russell method to evaluate the phenotypic adaptability and stability of alfafa (Medicago sativa) genotypes, as well as to evaluate the efficiency of the use of prior informative and noninformative distributions. Data from a randomized block design experiment evaluating the forage dry weight of 92 genotypes were used. The Bayesian methodology proposed was implemented in the free software R by the MCMCregress function of the MCMCpack package. To represent the noninformative prior distributions, a probability distribution with high variance was used; and, to represent the informative prior, a meta‑analysis concept was adopted, characterized by the use of information provided by previous studies. The comparison between the prior distributions was done using the Bayes Factor, with the BayesFactor function of the MCMCpack package, which indicated that an informative prior is more appropriate under the conditions of this study.

Estimativas de ganho genético por diferentes critérios de seleção em genótipos de alfafa

Este estudo foi desenvolvido objetivando comparar diferentes criterios de selecao, indicar o metodo de selecao que propicia maiores estimativas de ganho genetico e identificar genotipos superiores de alfafa quanto a caracteristicas produtivas, morfologicas e bromatologicas. Foram avaliadas a producao de materia seca, altura de planta, tolerância a doencas, aceitacao fenotipica pelos animais, proteina bruta, digestibilidade in vitro da materia seca, fibra em detergente neutro e relacao caule/folha de 92 acessos provenientes do INTA-Argentina, tendo como testemunha o Crioula. Os Indices de Mulamba & Mock, distância do genotipo ao ideotipo e Elston foram os mais adequados a esse tipo de estudo. Os genotipos Sequel, CUF 101, Siriver 2, Florida 77, Diamond, Sequel 2, LE N 2, Medina, Kern, Rio Grande, DK 166, DK 181, Perla SP INTA, WL 516, Rocio, LE Semit 711 e LE N 3 foram os indicados a selecao pelos maiores indices de Mulamba e Mock, distância do genotipo ao ideotipo e indice de Elston.

Adaptabilidade e estabilidade de cultivares de milho para silagem em relação à produção de matéria seca degradável no rúmen

A study was conducted in five locations to evaluate the silage potential of eight maize cultivars estimated by the rumen degradable dry matter yield (kg/ha). A significant interaction of genotype × environment was found for this characteristic, indicating a differential behavior of the varieties when environmental conditions changed. Although the variety BR HT2X had a high dry matter yield, it was the one which contributed most to the genotype × environment interaction. Nevertheless, it presented unpredictable behavior, thus it is recommended for situations of high levels of technology when effects of unfavorable conditions are minimized. The varieties BR 205 and AGM 2010 outyielded the others and are recommended as materials of wide adaptability and high predictability. The varieties BR CMS 473 and mainly BR 106 presented lower yields. However, they exhibited a predictable behavior, indicating invariant response to environmental improvement which characterizes rusticity.

Determinação do coeficiente de repetibilidade e estabilização genotípica das características agronômicas avaliadas em genótipos de alfafa no ano de estabelecimento

Repeatibility coefficients were estimated for dry matter production (DMP), plant height at cutting time (PHC), disease tolerance (DT) and height at flowering (HF). The characteristics were evaluated in 92 genotypes in the years 2004 and 2005. Five cuttings were carried out in the rain period (November to March) and six cuttings in the dry period (April to September). The experiment was arranged in randomized block design, with two replications. The estimates of the repeatability coefficient were obtained by different methods and, then, the study of genotype stabilization was performed. The statistical analyses were done using the GENES software. During the dry period, only two cuttings were enough to achieve 85 % accuracy in the estimation of the real DMP value, whereas in the rain period, five cuttings were required to achieve the same reliability. Overall, in the rain period a larger number of evaluations was required to obtain the same data reliability. For genotype stabilization, there was increase in reliability by leaving out some cuttings. The variables DMP and PHC, during the rain period, showed larger estimates for the repeatability coefficient than the variables DT and HF.