Seed Yield, Heritability of Pod Traits, and Antibacterial Potential of Yam Bean (Pachyrhizus spp.) Progenies in the Central Amazon

Yam bean (Pachyrhizus spp.) is a promising, yet underutilized, leguminous crop with considerable potential for biopesticide development. However, baseline data on seed yield, the heritability of pod traits, and antibacterial effects against Ralstonia solanacearum (RS) are lacking, limiting informed selection for seed production and biopesticide use. This study evaluated the morpho-agronomic traits of nine Amazonian yam bean progenies and screened their seed extracts for in vitro antibacterial activity against RS. We conducted the experiment on a Spodosol, using a trellis system in a randomized complete block design with four replications and four plants per plot. Seed yield varied from 0.56 to 0.98 t ha−1, with progenies P14, P20, and P23 exhibiting the highest numerical yields. Broad-sense heritability (H2) was high for pod length (0.77), pod width (0.81), and 100-seed mass (0.85), suggesting considerable potential for genetic improvement of these traits. In vitro antibacterial assays revealed concentration-dependent biphasic activity: 0.5% (w/v) extracts initially stimulated bacterial growth at 6 and 12 h but suppressed multiplication by 88–90% at 24 h, whereas 5% (w/v) extracts promoted growth throughout the 24 h period. These findings establish baseline seed yield data for yam bean grown in Amazonian Spodosols and highlight the genetic variability available for breeding programs in the region. Progenies P14, P20, and P23 warrant further investigation as sources of natural compounds for sustainable plant protection, underscoring the need for optimized formulations and extended exposure periods.