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Goiânia, Brazil

Pires L.P.M.,Federal University of Lavras | Ramalho M.A.P.,Federal University of Lavras | Abreu A.F.B.,Embrapa Rice and Beans | Ferreira M.C.,University of Sao Paulo
Scientia Agricola | Year: 2014

Plant with a more upright architecture offers many advantages to farmers. Recurrent mass selection (RS) programs for carioca type common bean have been implemented for the purpose of obtaining new lines that will generate the high yields that are associated with upright plant architecture. This study aimed to assess the efficiency of recurrent mass selection (RS) for upright plant architecture in common bean (Phaseolus vulgaris) and the effect of RS on grain yield and to verify whether or not there is still variability in the population that favors continuing selection programs, using information obtained from progenies evaluated in cycle five (CV) and cycle eight (CVIII) of the RS program. Mass selection for more upright plants was performed visually in the "S0" generation before flowering. Progenies S0:3 and S0:4 were evaluated in 2009 (CV) and 2011 (CVIII). Heritability (h2) and RS progress were estimated using adjusted means. After eight selection cycles, the population subjected to RS still had enough genetic variability to achieve continued success through recurrent selection. The RS progress was 1.62 % per cycle for the growth habit scores and 6.81 % for grain yield.

Mascarin G.M.,Embrapa Rice and Beans | Mascarin G.M.,National United University | Mascarin G.M.,University of Sao Paulo | Jackson M.A.,National United University | And 3 more authors.
Journal of Invertebrate Pathology | Year: 2015

A major constraint to the commercial use of fungal biocontrol agents is the availability of low-cost production media and processes. Previous attempts in producing Beauveria blastospores using liquid culture fermentation processes required long fermentation times (6-8days) and produced cells that had poor survival after desiccation and storage. In this study, isolates of Beauveria bassiana and Isaria fumosorosea were evaluated for blastospore yield, desiccation tolerance, storage stability, and biocontrol efficacy using fermentation media containing acid hydrolyzed casein or cottonseed flour as the nitrogen source. Cultures of B. bassiana and I. fumosorosea grown in media containing cottonseed flour produced high blastospore concentrations (>1×109mL-1) after 3days which is comparatively less expensive nitrogen source than acid hydrolyzed casein. The resultant air-dried blastospores (<3% moisture) of all fungal isolates survived drying (61-86% viability), irrespective of the nitrogen source tested. Storage stability at 4°C varied with nitrogen source and fungal strain. Air-dried blastospores of B. bassiana strains showed half-lives >14months in contrast to 9.2-13.1months for I. fumosorosea. Blastospores of B. bassiana and I. fumosorosea killed Bemisia tabaci whitefly nymphs faster and required lower concentrations compared with aerial conidia. Our findings support the use of liquid culture fermentation as a cost-effective process to rapidly produce high yields of stable and infective blastospores of either B. bassiana or I. fumosorosea. These results support further evaluation of blastospore sprayable formulations for the control of soft-bodied insects. © 2014 Elsevier Inc.

Moreira A.S.,Embrapa Rice and Beans | Filho A.B.,University of Sao Paulo | Rezende J.A.M.,University of Sao Paulo
Journal of Phytopathology | Year: 2015

Zucchini yellow mosaic virus (ZYMV), Papaya ringspot virus - type W (PRSV-W) and Zucchini lethal chlorosis virus (ZLCV) cause important diseases on zucchini squash crops in Brazil. ZYMV and PRSV-W belong to the genus Potyvirus and are transmitted by aphids, whereas ZLCV belongs to Tospovirus and is transmitted by the thrips Frankliniella zucchini. These three viruses may occur simultaneously in the field, and the epidemiology of the corresponding diseases may be determined by interactions among viruses, hosts and vectors. In this work, the progress of the diseases caused by these viruses was studied over a temporal and geographic range for three planting seasons (PS). For the lethal chlorosis (ZLCV), a monomolecular model was found to be the best fit for the data, though only during the third PS. For data collected during the first two PS, the Gompertz model was found to fit the data best. The spatial distribution of disease indicated disease aggregation at the end of the crop cycle. For the yellow mosaic (ZYMV), the model that best fit in the 1st PS was the logistic and in the 2nd and 3rd PS was monomolecular. The spatial pattern of the disease was random when the disease incidence was low but aggregated when the disease incidence was high. The common mosaic (PRSV-W) showed the lowest incidence in all three PS. An exponential model was the best fit for data collected during all PS, and the spatial pattern of the disease was random. Interactions among the three viruses apparently did not result in changes in the epidemiology of the diseases. Removal of sources of inoculum and planting at an unfavourable time for reproduction of virus vectors are the two main measures recommended for the control of these diseases. The use of insecticide is indicated only for the control of the F. zucchini. © 2014 Blackwell Verlag GmbH.

Moreira A.S.,Embrapa Rice and Beans | Consoli R.C.M.,University of Sao Paulo | Barbosa J.C.,State University of Ponta Grossa | Filho A.B.,University of Sao Paulo | Rezende J.A.M.,University of Sao Paulo
Journal of Phytopathology | Year: 2014

Lethal chlorosis of cucurbits, caused by the tospovirus Zucchini lethal chlorosis virus (ZLCV), is an important disease in the Brazilian zucchini squash crop. The virus is transmitted by the thrips Frankliniella zucchini. Progress of the disease in time and space was studied in zucchini squash experimental fields to better understand disease epidemiology. Nine independent experiments were carried out between December 2006 and September 2010. The effects of the disease were assessed every 2-7 days, depending on the experiment. The thrips population was monitored in five of these experiments. For disease progress over time, four models (exponential, monomolecular, logistic and Gompertz) were tested. Disease progress in space analysis included both the index of dispersion and Taylor's power law. The monomolecular model was the best fit to the disease incidence data, and spatial analysis indicated aggregated diseased plants at the end of the season in most experiments. A correlation was detected between the number of collected thrips and the incidence of zucchini squash lethal chlorosis. The results indicate that the thrips population significantly contributed to the primary spread of disease incidence. We propose that disease management should focus mainly on the elimination of the source of the inoculum. © 2014 Blackwell Verlag GmbH.

Colombari Filho J.M.,Embrapa Rice and Beans | Geraldi I.O.,University of Sao Paulo
Crop Breeding and Applied Biotechnology | Year: 2014

In plant breeding programs, the knowledge about the appropriate sample size for the evaluation of populations is very important. A small sample reduces the chance of selecting superior genotypes, whereas a very large sample may lead to unnecessary increases in cost and labor. A population consisting of 192 soybean lines was divided in groups of 24 lines, which were assessed for grain yield in eight randomized complete block experiments. Analyses of variance were performed for each experiment as well as for groups of experiments, resulting in analyses of variance consisting of 24, 48, 72, 96, 120, 144, 168, and 192 lines. As the sample size increased, the width of confidence intervals of parameter estimates decreased, stabilizing with samples of 144 lines. Therefore, an appropriate sample size for the evaluation of soybean inbred populations should contain about 150 lines.

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