Jefferson Luís Meirelles Coimbra

Genetic Basis of Stay-Green Trait in Bread Wheat

ABSTRACT The stay-green trait is responsible for the preservation of green coloration in the stem and leaf, during physiological maturity. It has also been shown to play an important role in the increase of grain size. The knowledge of the inheritance of this trait can constitute valuable information to plant breeders in the developing new wheat (Triti-cum aestivum L.) varieties. This study was conducted in two environments, during the years of 1997 and 1998, to verify the genetic basis of the stay-green trait among crosses of four different genotypes in the field and three in the greenhouse. The analysis was based on three fixed (P1, P2 and F1) and three segregating (F2, BC1F1 and BC2F1) generations. Means and variances were computed for every generation for each cross and the nature of the gene and its effects were estimated. Change in stem color was used as the criterion for the stay-green trait in three phases of development in wheat, based on scores obtained from visual analysis, on a scale of 1 to 10. The results presented in the 2nd observation phase, suggest that the stay-green trait is controlled by only one gene with two alleles and gene activity with high predominance of additive effects and to a lesser degree, a partial dominance for stay green.

Análise de trilha. I: análise do rendimento de grãos e seus componentes

Thirty two bean accesses (Phaseolus vulgaris L.) were evaluated for the influence of eight characters of agronomic importance the production of grains for unit of area, in Lages/SC. The experiment, in randomized blocks with four repetitions, was conducted during the period off-season in the agricultural year of 1996/97. This work aimed estimating the degree of association between grain yield and its secondary components. The first group of variables (primary) was constituted by the number of grains per pod, number of pods per plant, weight of a thousand grains and the population of plants (POP). The second group (secondary), was constituted by the number of days between emergence and flowering (FL), number of days between emergence and harvesting point (MC), plant stature (EP) and the height of first pod insertion (PIL). For the analysis of the trail coefficient, the direct and indirect effects of primary characters NLP and PMG were characterized and evaluated, revealing the large direct effects associated with the high correlation. The NLP was highly influenced by plants of shorter cycle and higher stature. The trail coefficients allow to point out that the largest direct effects on the yield of grains NLP are mainly associated to PMG, NGL and cycle of the plant.

Correlações canônicas: II - análise do rendimento de grãos de feijão e seus componentes

Thirty two bean genotypes (Phaseolus vulgaris L.) were evaluated in Lages/SC, Brazil, on the influence of seven characters of agronomic importance on the production of grains per unit of area. The experiment, in randomized blocks with four repetitions, was driven in the off season period in the agricultural year of 1995/96. This work aimed to estimate the intensity the association between the primary and secondary components of grain yield. The first group of variables (primary) was constituted by the number of grains per pod, number of pods per plant and the weight of a thousand grains. The second group (secondary) consisted of number of days from emergency to flowering, number of days from emergency to harvesting point, plant stature and the first pod insertion point. For the analysis of canonical correlations, the importance of secondary agronomic characters was evident in the traits number of pods per plant and grains per pod and also the influence of both on the final grain yield. Therefore, the coefficients of canonical correlations indicate that, in programs bean genetic improvement programs, to increase the production of grains one should select plants with larger number of pods per plant in order to obtain plants with higher stature and longer cycle.

Análise de trilha dos componentes do rendimento de grãos em genótipos de canola

Grain yield is a variable of complex association which has an economic importance. A trial was conducted in Lages, SC, during the 1996-growing season, in order to determine the association and the direct and indirect effects of some agronomic traits on grain yield of 12 canola genotypes, through the study of the phenotypic correlation and path analysis. A randomized complete block design with four replications per treatment was used. According to the analyses performed on the trial, plant height didn’t show any association with weight of 1,000 grains and grain yield. Path analysis showed that the primary components plant population per area and number of grains per plant have the largest direct impact on grain yield. On the other hand, the number of grains produced per plant is the major responsible for the increase in the weight of 1,000 grains. Path analysis also evidenced that the secondary component number of grains per pod has the highest direct effect on grain yield.

Reflexos da interação genótipo X ambiente e suas implicações nos ganhos de seleção em genótipos de feijão (Phaseolus vulgaris L.)

The importance of grains of legume plants for human feeding, specially black beans (Phaseolus vulgaris L.), has stimulated the breeders to select genotypes with high grains yield potential and wide adaptability to different conditions of cultivation in southern Brazil. The present work aimed at evaluating the reflexes of the genotype x environment interaction and its implications in the genetic gains of different selection approaches. The results revealed that the component of the interaction between genotype and environment overestimates the prediction of genetic parameters such as genetic variance and heritability. Differences among these estimates were observed apparently due to a high percentage of the complex part of the interaction. Besides, the genetic gains obtained with the direct selection were always superior to the indirect response. Comparatively, the pair of environments 1x3 revealed correlated response inferior and of opposite sign to the other estimates for the other pairs of environments studied. The first environment was the one which accumulated the higher interaction genotype by environment. It can be concluded that the interaction component has great relevance in the estimates of genetic gains, evidencing that this influence should be considered in the selection and in the recommendation of specific genotypes of bean breeding programs.

Divergência genética em feijão preto

Vinte genotipos de feijao (Phaseolus vulgaris L.) foram avaliados, no municipio de Lages/SC; quatro caracteres de importância agronomica sobre a divergencia genetica em feijao. Esta estimativa foi realizada atraves da estatistica de Mahalanobis e, para o agrupamento dos genotipos mais similares, o metodo de Tocher. O experimento, em blocos ao acaso com tres repeticoes e tres epocas de semeadura por tratamento, foi conduzido no periodo de safra e safrinha no ano agricola de 1996/97. Os caracteres agronomicos avaliados foram: numero de dias entre a emergencia e o florescimento (EMFL), numero de dias entre a emergencia e a maturacao de colheita (EMMC), peso de mil graos (PMG) e o rendimento de graos por unidade de area. Os resultados obtidos no presente estudo permitiram caracterizar possiveis genotipos para serem utilizados em cruzamentos dirigidos. O estudo dos vinte genotipos evidenciou um alto grau de divergencia genetica e apontou os caracteres agronomicos EMFL e PMG com maior contribuicao relativa para a divergencia genetica, indicando que estes dois caracteres devem ser priorizados em programas de melhoramento de feijao.

Adaptabilidade e estabilidade fenotípica em genótipos de feijão de cor (Phaseolus vulgaris L.) em três ambientes distintos

In the biennium 1996/97, twenty-one genotypes of colored bean were evaluated, in three environments, to identify and estimate adaptability parameters and phenotypic stability for grains yield. The experimental design was randomized blocks with three replications per treatment. The genotypes revealed highly significant differences among them, in all evaluated environments. In the analysis of joint variance, the genotype effects, environment and the interaction genotype x environments were highly significant, showing differences among genotypes x environment, and the existence of a differentiated behavior among genotypes according to enviromental variation. Average grain yields varied from 1321kg.ha-1 to 801kg.ha-1, with on overall average of 1081kg.ha-1. Most of the genotypes evidenced high phenotypic stability, specially LP 93-15, LP 93,2, LP 93-38 and Ruda, which showed superior average yield compared to the overall yield average, general adaptability and predicted behavior in all the studied enviroments. Among the genotypes with grain yield below the overall average AN 9022180, LM 93204319, LR 91155315, PF 9029975, PF 9029984 and TB 94-05 presented general adaptability and high phenotipic stability in the environments evaluated.

Parâmetros genéticos do rendimento de grãos e seus componentes com implicações na seleção indireta em genótipos de feijão preto

Thirty two genotypes of black bean (Phaseolus vulgaris L.) had their field performance evaluated in the agricultural year of 1996/97 in Lages/SC. The influences of three characters of agronomic importance on the production of grains for unit per area were scored. A completely randomized block design was used with four replications. The objective of the study was to estimate some genetic and phenotypic parameters of black bean. The direct selection revealed values of genetic gains superior to the ones obtained through indirect selection. The weight of a thousand grain (PMG) contributed to genetic progress through indirect selection than, the number of pods per plant (NLP) and the number of grains per pod (NGL). The results demonstrated that the tested black bean genotypes had a wide genetic variability, which was an indication of excellent germplas sources. The employment of estimates of genetic parameters such as genetic variance between pure lines and the heritability coefficient may be used as a powerful tool for bean breeders

Agronomic potential of genebank landrace elite accessions for common bean genetic breeding

Plant breeding efficiency relies mainly on genetic diversity and selection to release new cultivars. This study aimed to identify landraces with favorable characteristics that can be used as parents of segregating populations in common bean (Phaseolus vulgaris L.) breeding programs. Firstly, ten bean genotypes were selected because they showed promising agronomic performance, and the following seven adaptive traits of four commercial bean cultivars were evaluated: i) plant height; ii) diameter of the stem; iii) height of the insertion of the first pod; iv) pod number per plant; v) grain number per pod; vi) weight of a thousand grains and vii) grain yield. The accessions BAF 07, BAF 44, and BAF 45 are promising in terms of increasing plant height, and accession BAF 01, in terms of reducing plant height. The accession BAF 07 was also the most promising in terms of a plant ideotype that combines higher plant height, maximum height of the insertion of the first pod, and increment in grain yield. Moreover, the selection can be made between and within accessions, because genetic variability is also present within landraces.

Resposta de híbridos de milho cultivados em diferentes épocas à população de plantas e ao despendoamento

Current maize hybrids are more tolerant to the increasing of plant population than the hybrids used in the past. It is possible that modern hybrid’s better adaptation to crowding is related to the lower apical dominance of the tassel over the ear. This experiment was aimed at evaluating the evolution on maize hybrids commercially released in different times the increase in plant population and at detecting if this progress is related to the reduction of apical dominance. The experiment was carried out in Lages, SC, during the 1999/ 2000 and 2000/2001 growing seasons. A split-split plot design was used. Three plant populations were tested in the main plots: 50,000, 75,000 and 100,000pl ha -1 . Four hybrids commercially released in the 60’s, 70’s, 80’s and 90’s, respectively, were assessed in the split plots. Each hybrid was analyzed with preserved tassels and with tassel removed at booting in the split-split plot. The trials were installed in 10/30/ 1999 and 11/02/2000. Grain yield was assessed using the variance and regression analyzes. The hybrid commercially released in the 90’s (Ag 9012) was more demanding in plant population to maximize grain yield when the conditions were favorable to yields higher than 10,000kg ha -1