ABSTRACT. We evaluated the effects of split molybdenum (Mo) application at the reproductive stage of the common bean on seed Mo content (SMoC) and seed quality in two trials in the Zona da Mata region, Minas Gerais. Plants were sprayed with 100 or 600 g Mo ha -1 at the V4 stage. The higher dose was also split into 100(V4)+500(R5), 100(V4)+500(R7), 100(V4)+250(R5)+250(R7), and 100(V4)+150(R5)+350(R7). SMoC from plants sprayed with 600 g (five treatments) was 3.7-or 62-fold higher than those sprayed with 100 g, with seeds from the former treatments exhibiting slightly poorer quality. Application of 100 g at V4 + 500 g at the reproductive stage (four treatments) increased SMoC 1.6-or 2.7-fold compared with SMoC from plants sprayed with 600 g at V4. Split application of 500 g with two sprays increased SMoC by 11% (p = 0.257) or 16% (p = 0.013) compared with one spray of 500 g. SMoC can be higher with Mo applied at R7 (pod formation) instead of at R5 (pre-flowering), without impairing seed quality. Thus, split Mo application between the R5 and R7 stages of the common bean saves molybdic fertilizer to produce Morich seeds, with only a slight decrease in seed quality.Keywords: Phaseolus vulgaris, seed molybdenum, seed quality, seed vigor, seed germination.Parcelamento da aplicação do adubo molíbdico na fase reprodutiva do feijão-comum aumenta o conteúdo de molibdênio na semente RESUMO. Avaliamos os efeitos de parcelamentos da aplicação de molibdênio (Mo) na fase reprodutiva do feijão-comum no conteúdo de Mo na semente (CMoS) e na sua qualidade fisiológica em dois ensaios na Zona da Mata, Minas Gerais. Pulverizaram-se feijoeiros com 100 ou 600 g Mo ha -1 na fase V4. Esta última dose também foi parcelada: 100(V4)+500(R5), 100(V4)+500(R7), 100(V4)+250(R5)+250(R7) e 100(V4)+150(R5)+350(R7). O CMoS de plantas pulverizadas com 600 g (cinco tratamentos) foi 3,7 ou 62 vezes maior que o das pulverizadas com 100 g; sementes deste tratamento apresentaram qualidade ligeiramente melhor que as daqueles. Aplicação de 100 g em V4 + 500 g na fase reprodutiva (quatro tratamentos) aumentou 1,6 ou 2,7 vezes o CMoS comparativamente ao CMoS de plantas adubadas com 600 g em V4. Parcelamento de 500 g em duas pulverizações aumentou em 11% (p = 0,257) ou 16% (p = 0,013) o CMoS comparativamente a uma pulverização. O CMoS pode ser mais alto quando se pulveriza o Mo em R7 (formação de vagens) comparativamente a R5 (pré-floração), sem prejuízo à qualidade da semente. Logo, o parcelamento do Mo nessas duas fases do feijão-comum economiza fertilizante molíbdico para produzir sementes ricas em Mo, com ligeira redução da qualidade da semente. Palavras-chave:Phaseolus vulgaris, molibdênio na semente, qualidade da semente, vigor da semente, germinação da semente.

No abstract

-The cultivar BRSMG Madrepérola, 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.

Foi instalado um experimento em Viçosa, MG, em 11 de abril, em área infestada por escleródios de Sclerotinia sclerotiorum, com o objetivo de testar a eficiência de quatro fungicidas aplicados via água de irrigação por aspersão no controle do mofo-branco do feijoeiro (Phaseolus vulgaris). Os seguintes fungicidas e doses do ingrediente ativo por hectare foram testados: benomyl (1 kg), iprodione (0,75 kg), procimidone (0,5 kg) e fluazinam (0,5 l). As aplicações foram simuladas com regadores (35.000 l/ha). A primeira aplicação foi feita aos 39 dias após a emergência (DAE); a segunda, 13 dias depois. Nesses mesmos dias, o fluazinam também foi aplicado com pulverizador (667 l/ha) ou com regador (35.000 l/ha) entre as fileiras de feijão e rente ao solo. Este último tratamento teve por objetivo verificar se o fluazinam aplicado apenas no solo tem efeito no controle da doença. Ademais, foi utilizada uma testemunha que não recebeu fungicida. Após a colheita, avaliou-se a incidência do fungo nas sementes. Os fungicidas fluazinam (aplicado com pulverizador ou via água de irrigação sobre as plantas), benomyl e procimidone foram os mais eficientes no controle do mofo-branco e, dentre eles, apenas o procimidone não proporcionou rendimento maior que o da testemunha. O fluazinam aplicado apenas no solo reduziu a incidência da doença e a quantidade de escleródios produzidos. Os rendimentos variaram de 1.406 (testemunha) a 2.054 kg/ha (fluazinam, pulverização). Não houve influência dos tratamentos na incidência do fungo nas sementes, a qual variou de 0,25% (procimidone) a 1,08% (fluazinam aplicado no solo).

Sclerotinia sclerotiorum populations from tropical agricultural zones have been suggested to be more variable compared to those from temperate zones. However, no data were available comparing populations from both zones using the same set of markers. In this study, we compared S. sclerotiorum populations from the United States of America (USA, temperate) and southeast Brazil (tropical) using the frequency of mycelial compatibility groups (MCGs) and 13 microsatellite (SSR) markers. Populations were sourced from diseased plants within leguminous crops in New York, USA (NY; n = 78 isolates), and Minas Gerais State, Brazil (MG; n = 109). Twenty MCGs were identified in NY and 14 were previously reported in MG. The effective number of genotypes based on Hill’s number of order 0, which corresponded to the number of multilocus genotypes (MLGs) were 22 (95% CI = 15.6–28.4) and 24 (95% CI = 18.9–29.1) in NY and MG, respectively. Clonal fractions of MLGs were 71.8% (NY) and 78.0% (MG). The effective number of genotypes based on Hill’s number of orders 1 and 2 in NY were 8.9 (95% CI = 5.2–12.6) and 4.4 (95% CI = 2.6–6.1), respectively. For MG these indices were 11.4 (95% CI = 8.7–14.1) and 7.1 (95% CI = 5.1–9.0), respectively. There were no significant differences of allelic richness, private allelic richness, gene diversity, effective number of alleles and genotype evenness between the NY and MG populations. The populations were differentiated, with 29% of total variance attributed to differences between them and G''ST and Jost’s D indices higher than 0.50. Cluster analysis revealed dissimilarity higher than 80% among most MLGs from both populations. Different alleles segregated in the populations but both had similar levels of genotypic variability.

ABSTRACT. The aim of this study was to evaluate the CROPGRO-Dry bean model for simulating dry bean yield. The model's genetic coefficients were calibrated based on the cultivars 'Pérola', 'Ouro Negro' and 'Ouro Vermelho' in Viçosa, State of Minas Gerais, Brazil. The coefficients were adjusted based on two experiments that were performed in 2003 with irrigated and nonirrigated water regimes. An additional experiment with irrigation was conducted in 2004. After calibration, the model simulated the bean yield for the period from 1975 through 2006. The simulations were based on daily data on maximum and minimum air temperatures, total precipitation and global solar radiation. The physical and hydric characteristics of the soil and crop management practices were also included. The results show that the crop model can correctly reproduce the observed yield. This finding may indicate that the model is a useful tool to evaluate the crop response to variability and changing climate.

White mold caused by the fungus Sclerotinia sclerotiorum is the most yield-limiting disease of common bean in Brazil. To date, there has been no commercial cultivar resistant to this disease. In a greenhouse we evaluated white mold resistance sources (Cornell 605, A195 and G122) against eight isolates of S. sclerotiorum from five Brazilian states. A Brazilian cultivar (BRSMG Madrepérola) and a susceptible check (Beryl) were used as control. Treatments were arranged in factorial combinations (5 × 8) in a completely random design with four replicates.Disease severity was assessed on a rating scale of 1-to-9 together with lesion length, which was used to determine an area under the disease progress curve (AUDPC). Polymorphisms detected in ten microsatellite loci were used to assess variability between the isolates. Each isolate was a distinct haplotype; they formed a genetic tree with two clusters. One cluster was formed by three isolates collected from the states of Minas Gerais and São Paulo (southeastern); the others, by isolates from Paraná, Santa Catarina (southern), Goiás (Mid-western), and again, Minas Gerais.Genotype × isolate interaction was significant. In general, Beryl was more susceptible than BRSMG Madrepérola. Considering the AUDPC and/or the white mold reaction score, Cornell 605 exhibited more physiological resistance than BRSMG Madrepérola to seven isolates, A195 to five isolates, and G122 to two isolates. Our results suggest that Cornell 605 is the best source of resistance to white mold for the southern region, whereas Cornell 605 and A195 are somewhat superior to G122 for the southeastern and mid-western regions.

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.