Abstract Carioca grains are the most cultivated commercial group of common bean and Fusarium oxysporum f. sp. phaseoli (Fop) is an important disease under field conditions. Genetic resistance is the most effective control strategy. Thus, our objective was to study the inheritance of Fop resistance in the carioca grain type common bean. Lines CNFC 11965 (S) and CVIII 8511 (R) were crossed to obtain F1 and F2 generations and backcrosses, inoculated with the isolate FOP UFV 01, and severity grades used to estimate genetic parameters. Segregation of resistant and susceptible plants in the F2 generations and backcrosses resulted in dominant monogenic inheritance of Fop resistance. The high values of heritability emphasized the probability of success in the selection processes because environmental factors were not significant. The carioca grain line CVIII 8511 is promising, and its Fop resistance gene can be transferred to commercial cultivars of this group using the backcross method.

RESUMO A murcha de Fusarium, causada por Fusarium oxysporum f. sp. tracheiphilum (Fot), reduz a produtividade de feijão-caupi. Este estudo teve como objetivo identificar genotipos com resistência à Fot oriundos do banco germoplasma do Instituto agronômico de Pernambuco, Embrapa Meio Norte e outras regiões produtoras da região Nordeste e Norte do Brasil. A cultivar BR-17 Gurguéia foi utilizada como controle suscetivel e a MNC01-649F-2-1 como controle resistente. Dois experimentos foram conduzidos em um delineamento inteiramente casualizado em casa de vegetação pertencente ao Departamento de Agronomia da Universidade Federal Rural de Pernambuco. Plantas apresentando o primeiro par de folhas desenvolvidas foram inoculadas com uma suspensão de conidios (106 conídios/mL) utilizando a metodologia de imersão de raízes. A severidade da murcha de Fusarium foi determinada aos 21 dias após a inoculação através de uma escala descritiva. No primeiro experimento foi avaliado a resistência de 38 genotipos de feijão-caupi, sendo que 19 genotipos (5 moderadamente resistentes e 14 resistentes) foram selecionados para o segundo experimento. No primeiro experimento 4 genotipos (Canapu PE, Miranda IPA 207, Esperança e BRS Pujante) apresentaram ausência de sintomas. Para o segundo experimento, 15 genotipos apresentaram alto nível de resistência à infecção por Fot, com destaque para Canapu PE e Miranda IPA 207, aos quais novamente apresentaram ausência de sintomas de murcha. Em conclusão, este estudo identificou que os genotipos Canapu PE, Miranda IPA 207, Esperança e BRS Pujante apresentam maior resistência à murcha de Fusarium.

ABSTRACT Fusarium wilt, caused by soil-borne Fusarium oxysporum f. sp. tracheiphilum (Fot), can reduce cowpea bean yield. Considering that genetic control through resistant genotypes is pivotal for Fusarium wilt control, the aim of the present study was to identify cowpea genotypes that are resistant to Fot from the Germplasm Bank of the Pernambuco Agronomic Institute, Embrapa Middle North, and other producing areas in the North and Northeast regions of Brazil. The cultivar BR-17 Gurguéia was used as a susceptible control and MNC01-649F-2-1 was used as a resistant control. Two experiments were carried out in a completely randomized design in the greenhouse of the Department of Agronomy of the University Federal Rural of Pernambuco. Plants with the first pair of expanded leaves were inoculated with a conidial suspension (106 conidia/mL) using the conidia root-immersion methodology. Fusarium wilt severity in plants was assessed 21 d after inoculation, with the aid of a descriptive scale. In the first experiment, we evaluated the resistance of 38 cowpea genotypes, of which 19 (5 moderately resistant and 14 resistant) were selected for the second experiment. In the first experiment, four genotypes (Canapu PE, Miranda IPA 207, Esperança, and BRS Pujante) did not show any symptoms of Fusarium wilt. In the second, 15 genotypes showed high resistance to Fot, including Canapu PE and Miranda IPA 207, which again had no symptoms of Fusarium wilt. In conclusion, this study identified that the genotypes, Canapu PE, Miranda IPA 207, Esperança, and BRS Pujante have greater resistance to Fusarium wilt.

RESUMO A murcha bacteriana limita a produção do tomateiro sob condições de alta temperatura e umidade, e porta-enxertos resistentes são importantes para o manejo integrado da doença. Visto que existe interação entre isolados locais e genótipos de tomateiros, objetivou-se avaliar 14 porta-enxertos de tomateiro à murcha bacteriana na mesorregião da Mata de Pernambuco, Brasil. A reação dos porta-enxertos a dois sequevares de Ralstonia solanacearum e dois de R. pseudosolanacearum foi avaliada em quatro experimentos realizados em casa de vegetação em delineamento inteiramente casualizado, com quatro repetições, com quatro plantas cada. Sete genótipos foram selecionados para avaliar a reação à doença como porta-enxertos de tomateiro ‘Tomini F1’ em uma área de produção com histórico da doença em Chã Grande, Pernambuco, Brasil, utilizando delineamento em blocos casualizados, com quatro plantas por tratamento por bloco. Não foram observados sintomas da doença nas plantas enxertadas em ‘Guardião’, ‘Woodstock’ e ‘Yoshimatsu’. Considerando todos os experimentos, ‘Guardião’ e ‘Muralha’ apresentaram os melhores níveis de resistência, podendo ser utilizados no manejo integrado da murcha bacteriana e estudados em programas de melhoramento.

ABSTRACT Bacterial wilt limits tomato production and resistant rootstocks could be important for the integrated management of the disease. Since there is an interaction between local bacterial strains and tomato genotype, this study aimed to evaluate 14 tomato rootstocks to bacterial wilt in the Mata mesoregion of Pernambuco state, Brazil. The rootstocks reaction to two sequevars of Ralstonia solanacearum and two of R. pseudosolanacearum was evaluated in four experiments carried out in the greenhouse using the completely randomized experimental design, with four replications composed of four plants each. Seven genotypes were selected to evaluate the reaction to bacterial wilt as rootstocks grafting in tomato plants ‘Tomini F1’ in a production area with disease history in the Chã Grande municipality, using randomized block design with four plants per treatment in each block. In the field experiment, disease symptoms were not observed in the grafted plants in ‘Guardião’, ‘Woodstock’, and ‘Yoshimatsu’. Regarding all experiments, ‘Guardião’ and ‘Muralha’ showed the best resistance levels and could be used in the integrated management of bacterial wilt and studied in plant breeding programs.

Resumo: O objetivo deste trabalho foi avaliar a herança de resistência ao Cowpea aphid-borne mosaic virus (CABMV) em feijão-caupi (Vigna unguiculata). O estudo foi realizado entre os genótipos parentais IT85F-2687 (resistente) e 'BR-14 Mulato' (suscetível), tendo-se obtido populações F1, F2 e F7 e retrocruzamentos com ambos os genótipos parentais. O CABMV foi inoculado nas plantas de todas as gerações, que foram, então, avaliadas por inspeção visual e pela descrição dos sintomas característicos. O teste do qui-quadrado foi aplicado após a classificação fenotípica de todas as plantas. Uma proporção de segregação de 1:3 (resistente:suscetível) na população F2 e de 1:1 na população F7 foi aceita, tendo indicado herança monogênica recessiva.

Abstract: The objective of this work was to evaluate the inheritance of resistance to Cowpea aphid-borne mosaic virus (CABMV) in cowpea (Vigna unguiculata). The study was performed between parental genotypes IT85F-2687 (resistant) and 'BR-14 Mulato' (susceptible), generating F1, F2, and F7 populations and backcrosses with both parental genotypes. CABMV was inoculated on plants from all generations, which were then evaluated through visual inspection and description of characteristic symptoms. A chi-square test was performed after the phenotypic classification of all plants. A segregation proportion of 1:3 (resistant:susceptible) in population F2 and of 1:1 in population F7 was accepted, showing a recessive monogenic inheritance.

RESUMO: O uso de cultivares resistentes é a principal medida para o manejo da antracnose do colmo em milho. Neste trabalho, objetivou-se identificar linhagens com níveis de resistência à antracnose do colmo, similar ao híbrido 2B710, considerado resistente. Dois experimentos foram conduzidos na Embrapa Milho e Sorgo. No primeiro experimento, foram avaliados 234 linhagens e os híbridos BRS1010 (suscetível) e 2B710 (resistente). Foi realizada inoculação artificial com um isolado de C. graminicola , na fase de pré-pendoamento e, após 30 dias, foi realizada a avaliação da severidade da antracnose no colmo. O segundo experimento foi conduzido com 48 linhagens e os híbridos inoculados com dois isolados de C. graminicola . No primeiro experimento, os genótipos formaram oito grupos com base na severidade da doença e as linhagens do último grupo foram consideradas as mais resistentes, incluindo o híbrido 2B710, em que os genótipos apresentaram valores de severidade entre 11,50 a 23%. No segundo experimento, houve interação entre os fatores linhagens e isolados e, de modo geral, as linhagens apresentaram a mesma tendência de reação obtida no primeiro experimento, no entanto, a severidade da doença foi maior para a maioria das linhagens, mesmo quando utilizado o outro isolado. Com isso, foi possível realizar a seleção de linhagens com bons níveis de resistência, as quais podem ser utilizadas em programas de melhoramento, em estudos de herança, desenvolvimento de híbridos e identificação de marcadores moleculares, associados com resistência à antracnose do colmo.

ABSTRACT: Adoption of resistant cultivars is the primary measure used to control anthracnose stalk rot. The goal of this study was to identify maize-resistant genotypes to anthracnose stalk rot, which are similar to the hybrid 2B710. Experiments were performed at Embrapa Maize and Sorghum experimental fields in Brazil. The first experimental trial evaluated 234 maize lines as well as two commercials hybrids, BRS1010 (susceptible) and 2B710 (resistant). Artificial inoculations were performed with a strain at the blister (R2) phase, and evaluation of disease severity was performed after 30 days. The second experimental trial evaluated 48 maize lines and hybrids, inoculated with two Colletotrichum graminicola strains. In the first trial, eight resistance groups were formed, and the last lines were more resistant, as was the hybrid 2B710, with values between 11.50% and 23.0% of severity. In the second trial, there was an interaction between the two factors, lines and isolates, and the lines often showed the same reaction features as those obtained in the first trial. However, the disease severity was higher for most lines, even when using other isolates. These lines with effective levels of resistance could be used in future studies of inheritance, in programs to develop hybrids, and to identify molecular markers associated with resistance to anthracnose stalk rot in maize.

Abstract In breeding programs, understanding the potential of parents should be a way to spend significantly less time and costs to obtain new cultivars. For this, the objective of this study was to estimate the general and specific combining ability of parents aiming common bean breeding for resistance to Fusarium wilt (FW) based on disease severity and reduction in plant growth. Eight common bean genotypes were crossed in a 3 x 5 partial diallel mating scheme to obtain F1 hybrids. The parents and their 15 F1 hybrids were evaluated for severity of Fusarium wilt, area under the disease progress curve, percentage of plant height reduction and plant shoot fresh weight reduction and grain yield. The resistance of common bean to FW is controlled by a few dominant genes. The reduction in plant growth is controlled by a different set of genes that can increase the selection efficiency of parents for common bean breeding.

Objetivou-se propor e validar uma escala diagramática para quantificar a antracnose do colmo em milho. A severidade da antracnose foi estimada por dez avaliadores sem o uso de escala em 139 entrenós, e os mesmos avaliadores avaliaram os entrenós usando uma escala publicada anteriormente na literatura (primeira escala) e uma nova escala proposta. Com o uso da escala proposta, todas as variáveis foram significativamente diferentes em relação à primeira escala, e os valores foram mais próximos de uma medição acurada (r=0,97, Cb=0.98, u=0.09, υ=1.06, ρc=0.96). Os maiores desvios do erro foram observados quando os avaliadores atribuíram notas sem o uso de escalas e com a primeira escala, com vários exemplos de erros maiores do que 30% do valor real. Com a escala proposta, poucos erros acima de 15% do valor real foram encontrados, e a maioria das notas dos avaliadores não ultrapassou, para mais ou para menos, 10% do valor real. Uma maior confiabilidade na estimativa da severidade da doença foi obtida com o uso da escala proposta, com a qual 100% das comparações resultaram em um R2>0,90. A nova escala diagramática proposta no presente trabalho melhorou a acurácia, precisão e confiabilidade das estimativas da severidade da antracnose do colmo em milho

This study aimed to validate a new diagrammatic scale to anthracnose stalk in corn. Anthracnose severity was estimated by ten raters without and with use of new scale on 139 internodes with different severity degrees and all evaluators rated the same internodes using the old scale published in the literature and a new proposed scale. All variables of the propose scale, were significantly different than those of old scale, and the values were closer to an accurate measurement (r=0.97, Cb=0.98, u=0:09, υ=1:06, ρc=0.96). The large error deviations were observed when evaluators given notes without the use of scales and also with the old scale, for examples with errors up to 30%. On the other hand the majority errors with the use the new scale were lower than 10%. Higher reliability was achieved with the use of the proposed scale, where 100% of the comparisons were achieved R2>0.90. According to the results the diagrammatic scale proposed in this study improves accuracy, precision and reliability of the evaluators to estimates the anthracnose stalk severity in corn

Fusarium root rot caused by Fusarium solani f. sp. phaseoli (Fsp) is widely distributed in Latin America. Experiments involving artificial inoculations could be better compared whether the number of Fsp infective propagules is well quantified by using chlamydospores. This study aimed to define the adequate concentration of chlamydospores of Fsp for assessment of the disease severity under controlled conditions. In greenhouse, two experiments were performed, where common bean susceptible genotypes were sown in a substrate infested with 0, 1000, 2000, 3000, 4000, 5000 or 6000 chlamydospores g-1 of substrate. Plants were rated for disease severity at 30 d after emergence. Linear response plateau was used to represent the relationship between disease severity and concentration of chlamydospores in the substrate. According to our results, concentrations between 4500 and 5000 chlamydospores g-1 of substrate maximizes the disease severity and can be recommended to evaluate large-scale screenings of bean germplasm.

Fusarium root rot (FRR) is a distributed disease of common beans in Brazil. Our main aim was to verify if there are genotypes, mainly advanced lines from the common bean breeding program with levels of resistance to FRR similar to those of the line A-300. We also compared three developmental stages for FRR assessment. Genotypes of six classes were evaluated in greenhouse and field experiments. In greenhouse, substrate was infested with chlamydospores. In field, genotypes were screened in area infested with Fusarium solani f. sp. phaseoli. Plants were rated for disease at V3, R5 and R7 stages. Correlation among area under the disease progress curve (AUDPC) in greenhouse and in the field experiments was significant. Genotypes were ranked into four groups based on AUDPC. Sixteen advanced lines were as resistant to FRR as A-300. Correlation between the disease rating at R5 stages and AUDPC was higher than those among AUDPC and either disease rating at V3 or R7 in all experiments. Our results indicate that there are advanced lines with levels of FRR resistance similar to those of A-300 and that the FRR assessment at the R5 stage is more appropriated than at either V3 or R7.