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Brazil is the world's largest producer of common beans (Phaseolus vulgaris L.). Drought stress harms the morphological and agronomic traits of beans. This study evaluates the reaction to water deficit in five genotypes of black beans. The experiment was conducted in the IDR‐IAPAR‐EMATER in Londrina‐PR, Brazil. A split‐plot design was used, with three replications. The genotypes were included in the subplots and the treatments with or without water deficit in the plots. Water deficit was induced on the pre‐flowering stage and maintained for 20 days in the plots submitted to drought stress. For the growth analysis, plants were collected at 35, 54 and 70 days after emergence. At the stage of physiological ripeness, several morphological and yield traits were evaluated. The genotypes IPR Uirapuru and BRS Esplendor can be considered tolerant and used as a tolerant source to water deficit in common bean germplasm banks. The line LP 08‐90 has morphological and agronomic adaptations efficient to overcome water deficit's effects, presenting a higher grain yield in both crop conditions, which indicates the success of black beans breeding to deal with water deficit. [ABSTRACT FROM AUTHOR]

The objective of this study was to determine the genetic diversity among Brazilian carioca common bean (Phaseolus vulgaris L.) cultivars for traits related to nitrogen use efficiency (NUsE). An additional objective was to identify potential parents and promising parental combinations to assist common bean breeding programs in the development of cultivars with improved NUsE. The experiments were carried out at the Experimental Stations of the Instituto de Desenvolvimento Rural do Paraná (IDR–Paraná) in Londrina and Ponta Grossa, Brazil, during the rainy season in 2017. Thirty‐nine common bean cultivars were evaluated under high (40 kg N ha−1) and low N (0 kg N ha−1) applied as top‐dressing. The cultivars were genotyped using the genotyping‐by‐sequencing (GBS) approach with restriction enzyme CviAII. A total of 23,823 single nucleotide polymorphism (SNP) markers were identified throughout the common bean genome. A wide genetic variability was observed for NUsE‐related traits under high and low N conditions. In addition, correlations were found between shoot dry biomass and NUsE, N uptake efficiency (NUpE), and N utilization efficiency (NUtE) under low N, indicating the possibility of indirect selection of these traits by the plant shoot dry biomass. Interestingly, the most low‐N‐tolerant cultivars were not necessarily the most responsive and/or NUsE, suggesting that different morphophysiological mechanisms control these traits. The cultivars that stood out positively in this study can be used as parents in breeding programs aimed at developing cultivars that are adapted to N limitation. Core Ideas: Determine the genetic variability present in Brazilian carioca common bean cultivarsDevelopment of cultivars with improved N use efficiencyIdentify potential parents and promising parental combinations to assist common bean breeding [ABSTRACT FROM AUTHOR]