No abstract

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 NUsErelated 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.