Abstract
Common bean (Phaseolus vulgaris L.) is one of the most important crops worldwide and is considered an essential source of proteins, fibers, and minerals in the daily diet of several countries. Nitrogen (N) is considered the most important nutrient for common bean crop. On the other hand, the reduction of chemical fertilizers is a global challenge, and the development of cultivars with more N use efficiency (NUsE) is considered one of the main strategies to reduce the amount of N fertilizers. Genetic progress of NUsE has been reported in several crops; however, there was still no quantity in common bean. In this study, our goal was to analyze the genetic progress of seed yield (SY) and NUsE-related traits of 40 carioca common bean cultivars release from 1970 to 2017 in eight environments under low (zero) or high N (40 kg ha−1) in top-dressing. Genetic progress, principal component analysis, correlations among traits, and cultivar stability were analyzed using Bayesian approaches. The lowest values of the deviance information criterion (DIC) for the full model tested indicated the presence of the genotype × N × environment interaction for all evaluated traits. Nitrogen utilization efficiency (NUtE) and nitrogen uptake efficiency (NUpE) were the traits that most contributed to discriminate cultivars. The genetic progress of SY under high N (0.53% year−1, 95% HPD = 0.39; 0.65% year−1) was similar to that obtained in low N conditions (0.48% year−1, 95% HPD = 0.31; 0.64% year−1). These results indicate that modern cultivars do not demand more N fertilizers to be more productive. In addition, we observed a high genetic variability for NUsE-related traits, but there was no genetic progress for these variables. SY showed negative correlation with seed protein content (Prot) in both N conditions, and there was no reduction in Prot in modern cultivars. Both modern and old cultivars showed adaptability and stability under contrasting N conditions. Our study contributed to improve our knowledge about the genetic progress of common bean breeding program in Brazil in the last 47 years, and our data will help researchers to face the challenge of increase NUsE and Prot in the next few years.
Highlights
Common bean (Phaseolus vulgaris L.) is considered the main legume species for human consumption and represents an essential source of proteins, carbohydrates, fibers, and trace minerals in several countries worldwide (Myers and Kmiecik, 2017)
For trait harvest index (HI), the deviance information criterion (DIC) values difference among full, reduced 1, and reduced 2 models was less than five, indicating that there is no difference among all models tested
The positive correlations between high and low N for all environments explain the similar genetic progress among them for SY. These results indicated that even though common bean breeding programs have made selection under N fertilization, modern cultivars do not require high N levels to achieve their genetic potential
Summary
Common bean (Phaseolus vulgaris L.) is considered the main legume species for human consumption and represents an essential source of proteins, carbohydrates, fibers, and trace minerals in several countries worldwide (Myers and Kmiecik, 2017). Brazil is one of the main world producers and consumers of common beans. Common bean is a basic food used daily in the Brazilian diet with a consumption of 17 kg person−1 year−1 (Ribeiro et al, 2020). To meet this demand, common beans are grown throughout the all year under different cultivation systems and with different technological levels (Heinemann et al, 2016). Brazilian consumers prefer the Mesoamerican carioca (cream seed coat with brown stripes) and black beans, which represent around 70 and 15% of total common bean production, respectively (Pereira et al, 2019)
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