Environmental stratification in the brazilian Cerrado on the yield and fiber quality of cotton genotypes.

Environmental stratification studies are important for the plant breeding, since they allow to adequately plan the experimental network. The objective of this work was to identify similar environments for cotton cultivation in the Brazilian Cerrado regarding yield and fiber quality. Nineteen field studies were carried out in a randomized complete block design with twelve genotypes and four replicates. Agronomic (cotton seed yield and fiber percentage) and technological traits (length, micronaire, fiber strength) were evaluated. These results indicate that there are six environments (PVA3, MON, SHE1, SIN, PPA e TRIN) in which the cotton trials should be installed as a matter of priority owing to the phenotypic response pattern obtained for the evaluated traits. The remaining 13 environments are similar to each other for all traits and can be summarized in strategic locations depending on the ease of installation of the trials.Título em português: Estratificação ambiental no Cerrado brasileiro sobre o rendimento e a qualidade da fibra dos genótipos de algodão

Resistência genética de bovinos as infestações de carrapatos (Boophilus Microplus Canestrini). I. Distribuição das observações.

Foram realizadas 18 contagens de carrapatos em novilhas e vacas de seis diferentes graus de sangue Holandes vermelho e branco.Resumo

Biplot analysis of strawberry genotypes recommended for the State of Espírito Santo.

Most strawberry genotypes grown commercially in Brazil originate from breeding programs in the United States, and are therefore not adapted to the various soil and climatic conditions found in Brazil. Thus, quantifying the magnitude of genotype x environment (GE) interactions serves as a primary means for increasing average Brazilian strawberry yields, and helps provide specific recommendations for farmers on which genotypes meet high yield and phenotypic stability thresholds. The aim of this study was to use AMMI (additive main effects and multiplicative interaction) and GGE biplot (genotype main effects + genotype x environment interaction) analyses to identify high-yield, stable strawberry genotypes grown at three locations in Espírito Santo for two agricultural years. We evaluated seven strawberry genotypes (Dover, Camino Real, Ventana, Camarosa, Seascape, Diamante, and Aromas) at three locations (Domingos Martins, Iúna, and Muniz Freire) in agricultural years 2006 and 2007, totaling six study environments. Joint analysis of variance was calculated using yield data (t/ha), and AMMI and GGE biplot analysis was conducted following the detection of a significant genotypes x agricultural years x locations (G x A x L) interaction. During the two agricultural years, evaluated locations were allocated to different regions on biplot graphics using both methods, indicating distinctions among them. Based on the results obtained from the two methods used in this study to investigate the G x A x L interaction, we recommend growing the Camarosa genotype for production at the three locations assessed due to the high frequency of favorable alleles, which were expressed in all localities evaluated regardless of the agricultural year

Increasing selection gain and accuracy of harvest prediction models in Jatropha through genome-wide selection.

Abstract: Genome-wide selection (GWS) has been becoming an essential tool in the genetic breeding of long-life species, as it increases the gain per time unit. This study had a hypothesis that GWS is a tool that can decrease the breeding cycle in Jatropha. Our objective was to compare GWS with phenotypic selection in terms of accuracy and efficiency over three harvests. Models were developed throughout the harvests to evaluate their applicability in predicting genetic values in later harvests. For this purpose, 386 individuals of the breeding population obtained from crossings between 42 parents were evaluated. The population was evaluated in random block design, with six replicates over three harvests. The genetic effects of markers were predicted in the population using 811 SNP's markers with call rate = 95% and minor allele frequency (MAF) > 4%. GWS enables gains of 108 to 346% over the phenotypic selection, with a 50% reduction in the selection cycle. This technique has potential for the Jatropha breeding since it allows the accurate obtaining of GEBV and higher efficiency compared to the phenotypic selection by reducing the time necessary to complete the selection cycle. In order to apply GWS in the first harvests, a large number of individuals in the breeding population are needed. In the case of few individuals in the population, it is recommended to perform a larger number of harvests

Birefringence in nonlinear anisotropic dielectric media

Light propagation is investigated in the context of local anisotropic nonlinear dielectric media at rest with the dielectric coefficients $\epsilon^\mu{}_\nu = \epsilon^\mu{}_\nu (\vec{E},\vec{B})$ and constant $\mu$, in the limit of geometrical optics. Birefringence was examined and the general conditions for its occurrence were presented. A toy model is exhibited, in which uniaxial birefringent media with nonlinear dielectric properties could be driven by external fields in such way that birefringence may be artificially controlled. The effective geometry interpretation is also addressed.Comment: 5 pages, 1 figur

Saline stress affects the growth of Saccharum complex genotypes.

Soil salinity affects plant growth, compromising sugarcane cultivation in regions with great production potential. Saccharum complex genotypes that respond positively to growth under saline environment can be used in the diversification of sugarcane cultivars to obtain greater economic returns. The objective of this study was to evaluate growth-related traits of Saccharum genotypes grown under the presence and absence of salinity. The experiment was carried out in a 32 × 2 factorial scheme in a randomized block design with three replicates. The first factor consisted of 32 genotypes of the Saccharum complex and the second factor consisted of the presence and absence of salinity. The salinity provided higher mean values than the environment without salinity for plant height in the genotypes G9, G11, G13, G22 and G28, leaf number for G9 and G24, leaf area index for G9 and stem diameter for G1, G11 and G24. Among the genotypes tested, G1, G9, G11, G13, G22, G24 and G28 were the most promising genotypes and could be used for breeding new sugarcane cultivars of enhanced salinity tolerance.On-line

Impacts of saline stress on the physiology of Saccharum complex genotypes.

Knowledge of the physiological mechanisms in saline environment may boost sugarcane breeding programmes targeting abiotic stresses. Our hypothesis is that the physiology of Saccharum genotypes responds differently under salt stress. Thus, the objective of the study was to evaluate the physiological performance of Saccharum complex genotypes grown under presence and absence of saline stress. The experimental design used was randomized blocks arranged in a 32 × 2 factorial scheme (32 genotypes × 2 salinity levels). The presence of salinity provided higher mean values for photosynthetic rate in genotypes G4, G18, G22, G25 and G29 compared with the environment without salinity, with mean values (17.26, 21.49, 24.22 and 26.19 µmol CO2m?2s ?1), respectively, for internal CO2 concentration in G2, G6, G9, G14, G17, G19, G23 and G29, with mean values (323.45, 399.64, 386.88, 412.14, 366.31, 250.48, 379.10 and 380.75 µmol CO2 mol air?1), respectively, for transpiration in G18, G24, G25 and G29, with mean values (5.05, 3.30, 4.39 and 4.01 mmol H2O m?2s ?1), respectively, and for chlorophyll content in G3, G5, G6, G8, G10, G13, G20, G22, G23, G25, G31 and G32, with mean values (34.18, 43.01, 38.08, 32.38, 37.09, 37.18, 32.47, 38.38, 38.04, 36.95 and 33.32 SPAD units) respectively. Genotypes that under salt stress increase their physiological performance demonstrate superiority over others and should be considered in breeding programmes. Photosynthesis and transpiration is the most adequate combination for screening, but the spad index is the most viable tool because of its ease of determination and cost

Inibição de crescimento de plantas espontâneas por leguminosas herbáceas perenes na Caatinga Mineira - primeiro ano.

Publicado também na: Revista Brasileira de Agroecologia, v. 6. n. 2, dez. 2011

Estimates of repeatability coefficients and the number of the optimum measure to select superior genotypes in Annona muricata L.

The aim of this study was to evaluate repeated measures over the years to estimate repeatability coefficient and the number of the optimum measure to select superior genotypes in Annona muricata L. The fruit production was evaluated over 16 years in 71 genotypes without an experimental design. The estimation of variance components and the prediction of the permanent phenotypic value were performed using REML/BLUP proceedings. The coefficient of determination, accuracy, and selective efficiency increased when measures increased. The coefficient of determination of 80% was reached beyond 8 crop seasons with high accuracy and selective efficiency. Thus, the evaluation of 8 crop seasons can be suitable to select superior genotypes in the A. muricata L. breeding program. Predicted selection gain had a high magnitude for fruit production indicating that it is possible to take a progressive genetic advance for this trait over cycle breeding