ABSTRACT Black node disease is one of the most limiting biotic stresses affecting bean production in the Andean countries. The objective of the study was to evaluate the degree of resistance to Boeremia noackiana against genotypes of Phaseolus vulgaris, Phaseolus polyanthus, and their interspecific crosses using two disease evaluation methods (pathogenicity test in the greenhouse and in vitro) to contribute the generation knowledge towards the use of durable resistance. Black node disease severity was assessed using a descriptive scale and the leaf detached method under greenhouse and in-vitro conditions. The results of the study confirmed the isolate Ascochyta ASC 001 pathogenicity, allowing the different genotypes to be discriminated. A contrasting resistance response was confirmed for the two methodologies used to estimate severity. Accession G35575 (P. polyanthus) was the most resistant whereas NCB 226 (P. vulgaris) was the most susceptible. Regional cultivars Simijaca and Cabrera, together with Cargamanto Blanco and Bacata, showed fluctuations in their reaction to the disease from intermediate to susceptible. Resistance was confirmed in the interspecific crosses of the ASC series, which can be an alternative in breeding programs for durable resistance in common beans. The percent leaf area affected was identified as a variable that can be easily assessed, and the processing and analysis of digital images in vitro avoided the use of destructive sampling. This technique is a fast, useful, and economical tool for this type of studies, as it provides the possibility of accelerating the selection of genotypes with resistance.

RESUMO: Esta pesquisa descreve um protocolo de micropropagação eficiente para Lippia origanoides (Verbenaceae). Sementes estéreis foram utilizadas para a obtenção de mudas germinadas em meio Murashige e Skoog (MS) suplementado com sacarose e ágar. Os segmentos nodais obtidos das mudas foram cultivados em meio MS, suplementado com diferentes concentrações de ácido giberélico (GA), benzilaminopurina (BAP) e ácido 1-naftalenacético (ANA) com BAP. Foram analisados a indução de calo, comprimento de brotação, número de brotação e comprimento de raiz. Os tratamentos mostraram alta porcentagem de formação de calo com 0,5 a 1,5 mg L-1 de BAP sozinho ou em combinação com ANA (0,1 mg L-1). O maior valor de número de brotações por segmento nodal foi obtido com 1,5 mg L-1 de BAP (4,3 ± 0,8). As mudas obtidas apresentaram melhor enraizamento in vitro na ausência de reguladores de crescimento vegetal (PGRs) e demonstraram taxa de aclimatação de 90%. Contudo, relata-se um protocolo para propagação in vitro e aclimatação de L. origanoides para quimiotipos A da Colômbia.

ABSTRACT: This research described an efficient micropropagation protocol for Lippia origanoides (Verbenaceae). Sterile seeds were used to obtain germinated seedlings in Murashige and Skoog medium (MS) supplemented with sucrose and agar. The nodal segments obtained from seedlings were grown on MS medium supplemented with different concentrations of gibberellic acid (GA), benzylaminopurine (BAP) and 1-naphthalenacetic acid (NAA) with BAP. The callus induction, shoots length, shoots number and root length, were analyzed. The treatments showed high percentage of callus formation at 0.5 to 1.5 mg L-1 of BAP alone or in combination with NAA (0.1 mg L-1). The highest value of shoot number per nodal segments was obtained at 1.5 mg L-1 of BAP (4.3 ± 0.8). The obtained plantlets were better rooted in vitro in the absence of plant growth regulators (PGRs) and they showed acclimatization rate of 90%. We reported a protocol for in vitro propagation and acclimatization of L. origanoides for A chemotypes from Colombia.

RESUMO: O objetivo deste estudo foi delinear duas escalas diagramáticas para avaliação da doença do nó preto (Stagonosporopsis hortensis e Boeremia spp.) em feijoeiro (Phaseolus vulgaris L.). As escalas desenvolvidas corresponderam a intervalos logarítmicos (SADL) de sete níveis e intervalos iguais (SADE) de nove níveis. Essas escalas foram comparadas com a escala desenvolvida pelo Centro Internacional de Agricultura Tropical (CIAT), que corresponde a uma escala descritiva (NoSAD). Na validação da escala, a exatidão, precisão e concordância da repetibilidade foram determinadas usando o coeficiente de correlação de concordância de Lin, enquanto a reprodutibilidade entre avaliadores foi determinada pelo coeficiente de correlação de concordância geral (OCCC). Observou-se que, com o uso das escalas propostas, a reprodutibilidade e a repetibilidade foram significativamente melhoradas para os avaliadores inexperientes, e a reprodutibilidade foi melhorada no caso dos avaliadores experientes. Assim, as escalas diagramáticas projetadas são uma ferramenta útil para estimar a severidade em condições experimentais e de campo como parte do estudo desse sistema patológico.

ABSTRACT: The objective of this study was to design two diagrammatic scales for the evaluation of black node disease (Stagonosporopsis hortensis and Boeremia spp.) in common bean (Phaseolus vulgaris L.). The developed scales corresponded to logarithmic intervals (SADL) of seven levels and equal intervals (SADE) of nine levels. These scales were compared to the scale developed by the International Center for Tropical Agriculture (CIAT), which corresponds to a descriptive scale (NoSAD). In the scale validation the accuracy, precision, and concordance of repeatability were determined using Lin’s concordance correlation coefficient, whereas inter-rater reproducibility was determined by the overall concordance correlation coefficient (OCCC). It was observed that with the use of the proposed scales, reproducibility and repeatability were significantly improved for inexperienced raters, and reproducibility was improved in the case of experienced raters. Thus, the designed standard area diagrams with equal and logarithmic intervals are a useful tool for estimating severity under field and experimental conditions as part of the study of this patho-system.