Giovani Benin

Association between genetic distances in wheat (Triticum aestivum L.) as estimated by AFLP and morphological markers

Molecular and morphological data analyses matrices are very informative tools for the estimation of genetic distances. We used AFLP markers, morphological traits and combined analysis to estimate the genetic distances between wheat genotypes and ascertain any associations between the two techneques. Nineteen wheat (Triticum aestivum L.) genotypes were analyzed using amplified fragment length polymorphism (AFLP) markers and field evaluated for two years. The matrices obtained by morphological and molecular marker data analyses revealed a significant but moderate correlation (r = 0.47), indicating that such techniques sample distinct genome regions. The combined analysis was found to be highly correlated with AFLP (r = 0.97) and moderately correlated with morphological (r = 0.59) markers. A possible explanation for such results is a bias caused by the much higher number of AFLP (229) than morphological (17) markers. Thus, it is evident that the combined analysis is not efficient when a very dissimilar number of markers are used in each isolated technique. Therefore, to obtain a better knowledge of the degree of divergence among genotypes it is necessary to consider each analysis separately.

Seeding density in wheat genotypes as a function of tillering potential

Seeding density adjustments is one of the practices that most influence grain yield, as well as other agronomic traits. Therefore, the objective of this study was to determine the ideal plant stand to achieve the maximum grain yield in genotypes showing differential tillering ability. Also, to establish the associations between the genotypes used with tillering and other agronomically important traits as weight of a thousand grains. Two experiments were conducted in 2005 and 2006 in Capao do Leao, Rio Grande do Sul state, Brazil. Five low (JURITI, BR 18, CEP 29, BR 18 and CD 108) and five high (CD 114, SAFIRA, FIGUEIRA, BRS 177 and UMBU) tillering potential wheat cultivars were tested for two years on a split-plot design. The results indicate the need for recommending cultivars based on more than one year of cultivation, especially when dealing with contrasting genotypes for the trait fertile tillers. Regarding the ideal plant stand, seeding density of low tillering ability genotypes ranges from 417 to 555 seeds m-2, in order to obtain maximum yield and grain weight. On the other hand, for high tillering ability genotypes, the ideal stand ranges from 221 to 422 seeds m-2. These results were year independent. Furthermore, low tillering ability genotypes showed a closer association of number of fertile tillers with grain yield. However, an inverse association was found between number of fertile tillers and weight of a thousand grains.

Épocas de semeadura e desempenho agronômico de cultivares de soja

O objetivo deste trabalho foi avaliar o efeito de epocas de semeadura no desempenho agronomico de cultivares de soja em Sao Domingos, SC, e indicar as cultivares mais estaveis e adaptadas a cada epoca. O experimento foi conduzido durante dois anos agricolas (2008/2009 e 2009/2010), com seis cultivares e quatro epocas de semeadura (15/10, 15/11, 15/12 e 15/1), em delineamento experimental de blocos ao acaso, com tres repeticoes e parcelas com area util de 3,6 m². A metodologia AMMI (modelos de efeitos principais aditivos com interacao multiplicativa) foi utilizada para avaliar o desempenho produtivo das cultivares, e a GGE (genotipo e interacao genotipo x ambiente) para avaliar a adaptabilidade e a estabilidade das cultivares nas diferentes epocas de semeadura. Em ambos os anos agricolas, as semeaduras em 15/10 e 15/11 maximizaram o numero de vagens por planta, o numero de graos por vagem, a estatura das plantas, o numero de ramos, a massa de mil sementes e, consequentemente, a produtividade de graos. As cultivares de ciclo medio ou precoce com porte elevado sao mais adequadas para semeaduras tardias.

Adaptabilidade e estabilidade de cultivares de trigo em diferentes épocas de semeadura, no Paraná

The objective of this work was to identify the best sowing dates and to evaluate the adaptability and stability of wheat cultivars in two wheat growing regions of the state of Parana, Brazil. Seven cultivars were evaluated at Guarapuava and nine at Palotina as to grain yield, at four sowing seasons, in 2006, 2007 and 2008. The experimental design was a randomized complete block design, with four and three replicates, for Guarapuava and Palotina, respectively. The methodologies REML/BLUP and genotype main effect and genotype x environment interaction (GGE biplot) were used for adaptability and stability analysis, and the AMMI model was used to identify the best sowing dates. Sowing in July, at Guarapuava, and in April, at Palotina, maximized grain yield. The cultivars Safira, at Guarapuava, and CD 113, at Palotina, are stable, highly adapted and show high grain yield.

Métodos para análise de adaptabilidade e estabilidade em cultivares de trigo no estado do Paraná

This investigation had the objective to evaluate grain yield adaptability and stability of 17 wheat cultivars (Triticum aestivum L.) for Parana State, Brazil, occording to four different methods. The experiments were carried out in 2007, at different locations of Parana, in complete randomized blocks experimental design, with 4 replicates. The Wricke (1965) methodology indicates stable cultivars, independently of average yield. Eberhart and Russell (1966) and Cruz et al. (1989) methodologies were equally efficient to evaluate stability and indicate cultivars that are stable and also adapted to favorable and unfavorable environments. Lin and Binns (1988) methodology showed to be of easy interpretation and was efficient to indicate cultivars of high yield and with good stability, where more responsive materials showed a lesser Pi, and high negative correlation of Spearman between grain yields. It was concluded that LIN and BINNS methodology is very specific and when associated to Wi offers more assurance in recommending cultivars for high stability.

Comparação entre medidas de distância genealógica, morfológica e molecular em aveia em experimentos com e sem a aplicação de fungicida

Estimatives of genetic dissimilarity between cultivars can be useful in a breeding program for directing crosses and evaluating the available germplasm. The objective of this work was to estimate the genetic dissimilarity between oat genotypes through AFLP markers and inbreeding coefficient and to intercorrelate these estimate with each other and with an estimate based on agronomical traits in experiments with and without fungicide application. Eleven oat cultivars were used to estimate the molecular genetic distance, from which nine were evaluated in the field to obtain the morphological estimatives. For the estimates of inbreeding coefficients, eight genotypes had known pedigree and were considered for the analyisis. A comparison of the matrices was obtained through a correlation analysis. Among the dissimilarity measures evaluated, the estimated distances based on molecular data and the inbreeding coefficient, were those evidencing the highest correlation (0.45). The second highest correlation was obtained between the morphological distances in experiments with and without fungicide application (0.44), no other correlation obtained was significant. Then, it is evident the presence of high genetic variability among the studied genotypes and the necessity of all three techniques to be used in a joined manner for obtaining a more precise estimate of genetic dissimilarity.

Comparações entre medidas de dissimilaridade e estatísticas multivariadas como critérios no direcionamento de hibridações em aveia

Genetic dissimilarity measures are commonly used by plant breeders to identify different genotypes to get desired segregant populations. This study was proposed to establish the relationship between different multivariate techniques to estimate divergence. The experiment was performed during the growing season of 2001, where twelve oat cultivars were tested for seven agronomic traits, using the random blocks experimental design with four replications. Euclidian and Mahalanobis distances showed low correlation (0.529) and when used to build dendrograms did not show similar clustering. The graphic techniques analysis through principal components and canonical variables also showed distinct spreading patterns. However, in spite of the observed discrepancies among the methodology analyzed, it was possible to recognize dissimilar genotypes with high average that can be used with large success probability in selected artificial hybridizations in oats.

Qualidade industrial do trigo em resposta à adubação verde e doses de nitrogênio

The objective this study was to investigate the effects of green manures cultivated between the maize and wheat crop and nitrogen rates on baking quality of spring wheat. Treatments consisted of four nitrogen fertilization rates: without N addition, 40, 80 and 120 kg ha-1 using the amidic form, and six managements before wheat crop: four green manures forage pea, common pea, oilseed radish and lupine, common bean grown for commercial purposes, and the fallow between the corn harvest and wheat cropping. The experimental design was in randomized blocks and factorial scheme, with three replicates. The protein yield increased linearly with the application of mineral N rates. The nitrogen rates of 80 and 120 kg ha-1 improved the baking wheat quality. The forage pea, oilseed radish and common pea allowed ideal index of baking quality and satisfactory crop yield, reducing the demand for mineral N fertilization.

Agronomic performance of wheat cultivars in response to nitrogen fertilization levels

The release of wheat cultivars with different nutritional demands and yield potential hinders generalized recommendations for nitrogen fertilization. This study was designed to evaluate the effects of different nitrogen fertilization levels (0, 60, 120 and 180 kg ha -1 of N) on the agronomic performance of six wheat cultivars ( Triticum aestivum L.) in two harvests. A randomized block factorial design with three replications was used. The response to fertilization levels was evaluated through AMMI (Additive Main effects and Multiplicative Interaction) and GGE (Genotype main effects and Genotype x Environment interaction) biplot graphic methodologies and polynomial regression. There was genetic variability in response to nitrogen fertilization in the cultivars studied. The biggest increases in yield were observed under a more suitable water regime. The higher performance of yield components was associated with higher nitrogen fertilization levels.

Morphological, pedigree, and molecular distances and their association with hybrid wheat performance

The objectives of this work were to estimate the genetic distance among wheat genotypes using morphological, pedigree, molecular, and combined morphological and molecular measures, to determine the correlations between these measures, and to evaluate the combining ability of the genotypes. Three generations and two planting designs were studied. Six wheat genotypes were crossed using a diallel design. The F1, F2 and F3generations were evaluated in the field, in the crop seasons of 2003, 2004 and 2005, under spaced plant and full-row planting designs. The estimated general and specific combining abilities of tested hybrids were influenced both by the generation and the planting design. The correlation coefficients among the distance measures and between these measures and genotype performances of different generations for the two planting designs were low to moderate. In order to obtain a more precise estimate of the genetic distance among cultivars and its association with the hybrid performance, more than one generation, planting design, and genetic distance estimation technique should be employed.