ABSTRACT. Anthracnose caused by the fungus Colletotrichum lindemuthianum is one of the main diseases affecting the common bean (Phaseolus vulgaris L.), and the pathogen is characterized by wide variability, with more than 50 physiological races identified in Brazil. Greater occurrences of races 65, 73, and 81 have been observed in Brazil along with the occurrence of pathogenic variability among isolates of a single race, destabilizing the resistance of commercial cultivars. Therefore, the aim of this study was to identify physiological races of C. lindemuthianum isolates collected in the states of São Paulo and Santa Catarina, Brazil and to test for variability among the isolates of race 65. The classification of 51 isolates resulted in the identification of 10 different physiological races: 4, 38, 55, 65, 73, 81, 83, 85, 321, and 351. Races 65 and 81 predominated, with frequencies of 37.25 and 35.29%, respectively. Regarding the isolates of race 65, wide physiological variability was evident, suggesting that a new differential set should be applied to detect the levels of variation among isolates of a single race of the pathogen.Keywords: physiological variability, levels of variation, anthracnose. Classificação de raças de Colletotrichum lindemuthianum em cultivares diferenciadoras de feijoeiro comum RESUMO.A antracnose causada pelo fungo Colletotrichum lindemuthianum é uma das principais doenças do feijoeiro comum (Phaseolus vulgaris L.), o patógeno caracteriza-se por apresentar uma grande variabilidade, com mais de 50 raças fisiológicas identificadas no Brasil. Tem-se evidenciado a maior ocorrência das raças 65, 73 e 81 no país e também a ocorrência de variabilidade patogênica entre isolados de uma mesma raça, que desestabilizam a resistência das cultivares comerciais. Portanto, o objetivo com este trabalho foi a identificação de raças fisiológicas de isolados de C. lindemuthianum coletados no Estado de São Paulo e Santa Catarina, Brasil e, detectar a ocorrência de variabilidade patogênica entre isolados pertencentes à raça 65. A classificação de 51 isolados resultou na identificação de 10 diferentes raças fisiológica: 4, 38, 55, 65, 73, 81, 83, 85, 321 e 351, com destaque para a raças 65 e 81, que apresentaram uma frequência de 37,25 e 35,29%, respectivamente. Com relação à avaliação entre os isolados da raça 65, ficou evidente a alta variabilidade dos mesmos, sugerindo a utilização de um novo conjunto diferenciador para detectar os níveis de variação entre isolados de uma mesma raça do patógeno.Palavras-chaves: variabilidade fisiológica, níveis de variação, antracnose.
Common bean (Phaseolus vulgaris L.) is frequently grown in weathered soils with low phosphorus (P) availability, and this is one of the main limitations on its production. This study aimed to assess 20 common bean genotypes in a hydroponic system to select the best P concentration for inducing nutritional deficiency and to classify the genotypes in terms of nutrient utilization efficiency. The concentrations of P applied were 8.00, 4.00, 2.00 and 0.05 mg L -1. At 21 days, in the plot subjected to an application of the most severe stress, the 0.05 mg L -1 dose of P, had smaller plant size and early leaf abscission was observed. The 4.00 mg L -1 dose of P was the most efficient in inducing stress for discrimination of cultivars in terms of efficiency of use of P. The following genotypes: IAPAR 81, Carioca Comum, IAC Carioca Tybatã, IAC Imperador and G 2333 stood out as being efficient and responsive to P, while the two cultivars DOR 364 and Jalo Precoce were the most inefficient and unresponsive.
This paper aimed at selecting parents to compose a common bean breeding program for drought tolerance. General and specific combining abilities were evaluated under controlled conditions, using drought tolerant parents (BAT 477 and SEA 5), elite cultivars developed at IAC (IAC Alvorada and IAC Carioca Tybatã) and their progenies obtained from a complete diallel, including the reciprocals. Sowing was done in soil following a randomized block design with three replications for both experiments, the control with irrigation and the drought stress experiment imposed from pre-flowering stage. Plants remained under drought stress for 30 days. Physiological and morphological traits as well as yield components and grain yield were evaluated, detecting additive and non-additive effects controlling these traits. The parents used in this study had contributed in different proportions in the crosses they participated in. Regarding the drought stress condition in the pre-flowering stage, the parents SEA 5 and IAC Alvorada presented greater positive effects for the general combining ability for the yield and weight of one thousand seeds, whereas the parent SEA 5 also showed a positive effect for the number of seeds per pod, suggesting the increase of these traits in the crosses they participated in. The hybrid combinations SEA 5 × IAC Alvorada showed a positive result for grain yield, related to the higher positive effect for specific combining ability and because they have as parents the cultivars which confer the best positive values for general combining ability.
Given the impact of climate issues and their direct influence on agricultural production, the aim of this study was to identify superior genotypes of dry edible common bean under water deficit. Thus, 30 common bean genotypes were evaluated under controlled greenhouse conditions in a randomized block experimental design with split plots and four replications; the plots consisted of the water treatments (irrigated and water deficit) and the split plots consisted of the genotypes. The results showed genetic variability among the accessions evaluated, and in spite of significant reduction in grain yield and stomatal conductance under water deficit, these two traits showed significant, positive correlation and are able to be applied in early selection of genotypes under this stress condition. Another important response was in relation to the genotypes SER-16, SEN 92, FT Paulistinha, Carioca Precoce, IAC Imperador, and SXB 410, which showed the best yield performances in the two water treatments applied. They can be widely used in breeding programs for development of new cultivars, especially aiming at drought tolerance.
The aim of this study was to evaluate twelve genotypes of common bean for intermittent drought stress and for root growth angle. The water deficit experiments were conducted in 2015 and 2016 in a randomized block experimental design with split plots and three replications. Two treatments were applied: an irrigated treatment and a water deficit treatment, in which irrigation was suspended in pre-flowering and remained suspended up to the time at which the matrix potential of the soil was measured to be near-199 kPa. At the maximum point of water deficit, physiological and morphological traits were evaluated, and at physiological maturity, the yield compounds and grain yield. To evaluate root growth angle in 2016, a growth pouch system was used in a randomized block design, with five replications.
IAC 1850 is a common bean cultivar with a carioca (beige-colored with brown stripes) seed coat, average cycle of 88 days, semi-upright plant architecture, tolerance to seed coat darkening, 1000 seed weight of 280 grams, resistance to the main diseases in common bean, and a high average yield (2,857 kg ha-1) obtained in 36 experiments conducted in different regions in Brazil.
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