Evaluation of phenotypic variation in a collection of Apios Americana: An edible tuberous legume

Abstract

Apios (Apios americana Medik.), sometimes called “potato bean,” is a nitrogen-fixing legume, native to eastern North America, that produces protein-rich tubers at nodes along belowground stolons. Apios was used as a staple food source by Native Americans throughout eastern North America and holds promise as a crop. An Apios breeding program conducted during 1985 to 1994 involved the collection of ~210 wild accessions, followed by hybridization and selection, with assessments of >2200 lines. Of these, 53 genotypes were retained for further evaluation. The study reports the phenotypic variation in this collection, at three locations and under three growing conditions (field, pots, and growbags). We found significant (P < 0.05) variation among the genotypes for 18 of the 20 measured traits under field conditions, and for seven of 20 traits in pots and grow-bags. Internode length, plant vigor, and stem diameter at 2 and 5 mo had strong correlations (r > 0.56, P < 0.01) with belowground yield plant-1. Four phenotypically distinct clusters of genotypes were evident in the Apios collection. Several genotypes produced high yields in all locations—up to 1515 g of belowground tuber yield plant-1. The superior germplasm identified in this project may be suitable as cultivars, and will aid in further development of Apios lines as a crop.