A preliminary evaluation of phenotypic traits of tepary bean (Phaseolus acutifolius A. Gray)

Abstract

Background: Tepary bean (Phaseolus acutifolius A. Gray) is an underutilised grain legume crop and important source of food, nutrition and income. To date, there are no significant breeding efforts aimed at cultivar development and the crop remains under-utilised and under-researched. Aim: Therefore, the aim of this study was to evaluate eight phenotypic traits and their relationships among 42 genotypes of tepary bean in a controlled drought screening greenhouse environment. Setting: Agricultural Research Council – Vegetable, Industrial and Medicinal Plants, South Africa in drought screening glasshouse. Method: A 6 × 7 rectangular lattice design replicated three times was used in the study. Results: There were highly significant (p < 0.01) differences in all the phenotypic traits that were measured. The highest number (30) of secondary roots was recorded for genotype ‘Ac-39’, which exceeded the trial, mean value by 62.87%. In comparison with the check, only Ac-33’, ‘Ac-39’, ‘Ac-40’ and ‘Ac-7’, ‘Ac-8’, ‘Ac-40’, ‘Ac-41’ genotypes achieved a significantly (p < 0.05) higher secondary root length (SRL) and shoot dry weight (SDW), respectively. A highly significant (p < 0.01) positive association was observed between the shoot fresh weight and the SDW suggesting that there was a strong linear relationship between the two parameters. Similarly, at least 68.0% of the changes in root dry weight were attributed to the changes in the SRL. Conclusion: These results suggested that the observed phenotypic variability in this germplasm which could be exploited for the enhancement of tepary bean. Contribution: There will be merit in validating these results on a field basis together with grain yield evaluation and genotyping over multiple locations and seasons to determine elite germplasm for production and utilisation by growers.