José Eustáquio de Souza Carneiro

White mold intensity on common bean in response to plant density, irrigation frequency, grass mulching, Trichoderma spp., and fungicide

The purpose of this study was to evaluate the efficiency of integrated managements on white mold control on common bean. Initially, in vitro testing was made to assess the antagonism of 11 Trichoderma isolates against Sclerotinia sclerotiorum and to investigate fungicides (fluazinam and procymidone) inhibitory effects on those fungi. In two field experiments the following combinations were tested: irrigation frequencies (seven or 14 days), plant densities (six or 12 plants per meter), and three disease controls (untreated control, fungicide or Trichoderma spp.). In a third experiment plant densities were replaced by grass mulching treatments (with or without mulching). Fluazinam was applied at 45 and 55 days after emergence (DAE). The antagonists T. harzianum (experiments 1 and 3) and T. stromatica (experiment 2) were applied through sprinkler irrigation at 10 and 25 DAE, respectively. Most of the Trichoderma spp. were effective against the pathogen in vitro. Fluazinam was more toxic than procymidone to both the pathogen and the antagonist. Fungicide applications increased yield between 32 % and 41 %. In field one application of Trichoderma spp. did not reduce disease intensity and did not increase yield. The reduction from 12 to six plants per meter did not decrease yield, and disease severity diminished in one of the two experiments. It is concluded that of the strategies for white mold control just reduction of plant density and applications of fungicide were efficient.

Performance of common bean families after different generations under natural selection

A segregant bulk population derived from a single cross between the Carioca MG cultivar and the ESAL 686 line was used to investigate whether the action of natural selection in the direction required by the breeders and the delaying line extraction would increase the chance of obtaining families with greater grain yield. The populations were advanced from F2 to F24 and obtained families F2, F8 and F24 from the plants. These families and their parents were assessed for grain yield (kg/ha) in Lavras-MG in three sowing seasons (July 2001, November 2001 and March 2002) in an 18 x 18 lattice design with two replications in the first sowing and three in the other two. The largest mean yield, regardless of sowing season, was among the families derived from the F24 plants. The frequency of superior families increased when line extraction was delayed to more advanced generations.

Potencial de caracteres na avaliação da arquitetura de plantas de feijão

O objetivo deste trabalho foi identificar indicadores efetivos da arquitetura de plantas em feijoeiro, para subsidiar, ou substituir, a avaliacao por notas. Trinta e seis linhagens de feijao foram avaliadas quanto aos principais caracteres relacionados a arquitetura de plantas e a caracteres agronomicos, em duas safras. Os experimentos foram realizados em blocos ao acaso, com tres repeticoes, em Coimbra, MG. A analise de trilha indicou que o ângulo de insercao dos ramos, a altura das plantas na colheita e o diâmetro do hipocotilo foram os principais caracteres determinantes da arquitetura de plantas do feijoeiro. O diâmetro do hipocotilo esteve fortemente associado com a nota de arquitetura e possibilitou elevada acuracia e precisao de mensuracao. Essa caracteristica e facilmente mensurada e e indicador efetivo da arquitetura de plantas do feijoeiro.

Characterization of genetic variability among common bean genotypes by morphological descriptors

The purpose of this study was to characterize the genetic variability in 100 genotypes of the Active Germplasm Bank of common bean of the Federal University of Vicosa, by morphological descriptors, classify them in groups of genetic similarity and to identify the degree of relevance of descriptors of genetic divergence. The genotypes were evaluated based on 22 quantitative and qualitative morphological descriptors. The high-yielding genotypes V 7936, Gold Gate, LM 95103904, 1829 S 349 Venezuela, and PF 9029975, CNFC 9454 and Fe 732015, with upright growth, have potential for use as parents in common bean breeding programs. By genetic divergence analysis, the genotypes were clustered in eight groups of genetic dissimilarity. By methods of principal components, 9 of the 22 descriptors were eliminated, for being redundant or little variable, suggesting that 10-20 morphological descriptors can be used in studies of characterization of genetic variation.

Management of white mold in type III common bean with plant spacing and fungicide

White mold is a yield-limiting disease during the fall-winter season in southeastern Brazil when irrigated type III common beans are generally sown 0.5 m apart with 10 to 12 plants per meter. The aim of this study was to evaluate the efficacy of combining increased row width (RW) and reduced planting density (PD), with or without fungicide, for white mold management. Treatments were arranged as a 23 factorial: RW (0.50 or 0.75 m), PD (6 or 12 plants per meter), and fungicide (sprayed or unsprayed). Two trials were conducted in Vicosa, State of Minas Gerais. In 2002, the average incidence of white mold was 43.2%, the severity index, 31.1%, and the yield, 2513 kg ha-1. In 2003, the values of these variables were 48.0%, 22.6%, and 2159 kg ha-1, respectively. Interactions involving both RW and PD were not significant for either disease intensity or yield in the combined analysis across years. Increasing RW led to reduction in white mold intensity in 2002. The lower PD reduced disease incidence in 2002 and did not affect yield in the combined analysis. In fungicide sprayed plots, wide RW decreased yield in 2002, but RW did not affect yield in 2003. In unsprayed plots, RW did not affect yield in both years. We conclude that increasing RW to 0.75 m combined with low PD is a promising strategy for white mold management when fungicide is not applied. When fungicide is applied, the current row width (0.50 m) combined with low PD maximize the yield.

Foliar application of calcium chloride and calcium silicate decreases white mold intensity on dry beans

White mold (Sclerotinia sclerotiorum) is the most important common bean disease during the fall-winter season in Brazil. Different control strategies are necessary to control this disease and increase bean yield in infested areas. The aim of this research was to evaluate the effect of application of calcium chloride (CaCl 2 ) and calcium silicate (CaSiO 3 ) on white mold control on common bean. The experiment was carried out during the 2006 fall-winter season in Vicosa MG, Brazil, in a field naturally infested with sclerotia . Both CaCl 2 and CaSiO 3 were applied at 45 days after emergence (DAE) (early bloom) over the plants with a hand sprayer (800 L ha -1 ) at the rates of 100, 200, 300 and 400 mg L -1 or at 45 and 55 DAE at 300 mg L -1 . Two additional treatments were used: water (untreated control) and the fungicide fluazinam (0.5 L ha -1 ) applied at 45 and 55 DAE. Both incidence and severity of white mold were significantly reduced with application of CaCl 2 and CaSiO 3 , but there was no effect on yield. Fluazinam reduced significantly the disease incidence and severity by 52% and 73%, respectively, and increased the yield by 31%.

Common bean breeding for resistance to anthracnose and angular leaf spot assisted by SCAR molecular markers

The objective of the present study was to assess the genetic potential of inbred carioca common bean families from five populations derived from crossings involving elite lines and a disease-resistant line (Ruda-R), and to assess the efficiency of SCAR molecular markers in selecting plants resistant to anthracnose and angular leaf spot, at the time of bulk formation. Plant architecture, yield and grain type were assessed. Significant effect among families within population was observed, suggesting wide genetic variability for the characters assessed. Twenty-six superior families were selected. The families contained the greatest number of markers, identified by SCAR molecular markers in the F4 generation. Eighteen of these families were resistant to the races 65 and 453 of Colletotrichum lindemuthianum and five were resistant to the race 63.23 of Pseudocercospora griseola. Thus selection assisted by SCAR markers, in the F4 generation, was an important tool in common bean breeding.

BRSMG Madrepérola: common bean cultivar with late-darkening Carioca grain

The cultivar BRSMG Madreperola, recommended for cultivation in Minas Gerais, has the feature of maintaining a light grain color for a longer period than other Carioca grain cultivars. The yield potential is high and the resistance level good to the major anthracnose races in the region.

Root traits of common bean genotypes used in breeding programs for disease resistance

The objective of this work was to assess root traits of 19 common bean genotypes, used in breeding programs for disease resistance. Genotypes DOR 364 and G 19833 were used as deep and shallow basal root checks, respectively. The number of whorls and basal roots were assessed on five-day old seedlings grown in germination paper. Growth pouch studies were conducted to evaluate basal root gravitropism and lateral root length from primary roots, in seven-day old seedlings. The following root gravitropic traits were estimated: basal growth angle, shallow basal root length (localized in the top 2 cm), and relative shallow basal root growth. Number of whorls varied from 1.47 to 3.07, and number of basal roots ranged from 5.67 (genotype TO) to 12.07 (cultivar Jalo MG-65). Cultivars BRS MG Talisma, Carioca, BRS Pioneiro, and Diamante Negro exhibited shallow basal roots, while genotypes Vi-10-2-1, TU, AB 136, and Mexico 54 showed deep basal roots. Cultivar Jalo MG-65 showed more lateral roots from the primary root than the other genotypes. Genotypes used on common bean breeding programs for disease resistance have great variability on basal and primary root traits.

Natural selection and family X location interaction in the common (dry) bean plant

Natural selection takes place while advancing generations of segregant populations of self pollinating species by the population (bulk) method. There is evidence that it maintains the individuals with greater grain yield. The question arises whether natural selection preserves the individuals which are more adapted only to the environment where the generation advance occurred, that is, if it contributes to increasing the genotype x environment interaction in the family assessment. This study was carried out to check this hypothesis in the common bean plant using families derived from a segregating population from a cross between the Carioca MG x ESAL 686 cultivars. The segregating populations increase in homozygosity was obtained by the population (bulk) method until the F14 generation, in three distinct locations in Minas Gerais state: Lavras, Lambari and Patos de Minas. Forty-seven F14:15 families were randomly taken from the population in each location and later multiplied to obtain F14:16 families. These families were jointly assessed with three controls using a triple 12 x 12 lattice design in the three locations of generation advance in the wet season of 1998/1999. All the estimated parameters showed that while advancing segregant populations by the population (bulk) method, natural selection acted to preserve the individuals which are more adapted to the environment in which they were advanced.