Genotype-specific yield responses of Bambara groundnut ( Vigna subterranea (L.) Verdc.) to paired colchicine and phytogenic silver nanoparticle treatments

Bambara groundnut (Vigna subterranea (L.) Verdc.) is an underutilised legume with limited yield improvement despite its nutritional value and adaptation to marginal environments. This study evaluated three genotypes under paired colchicine and phytogenic silver nanoparticle treatments in a randomised complete block design. Colchicine and silver nanoparticle (AgNP) concentrations were paired by treatment level rather than arranged in a fully crossed factorial design. Silver nanoparticles synthesised from Moringa oleifera leaf extract were characterised by ultraviolet–visible spectroscopy, Fourier-transform infrared spectroscopy, scanning electron microscopy, energy-dispersive X-ray spectroscopy and dynamic light scattering, while nuclear DNA changes were assessed by flow cytometry. Treatments were 0%/0, 0.025%/20, 0.05%/40, and 0.075%/60 mg l−1 colchicine/silver nanoparticles. We measured vegetative, flowering, pod, seed and yield traits. The nanoparticles showed a surface plasmon resonance peak at 408.5 nm and a Z-average diameter of 44.71 nm. Flow cytometry indicated DNA-content shifts at 0.05% colchicine. Vegetative traits were largely unaffected, but reproductive responses were genotype-dependent. Yield increased to 9.00 g in the landrace MOK 02 and 9.50 g in landrace PTG 01 at intermediate treatments, while MOK 01 responded mainly through pod length. Higher treatment intensity was not consistently beneficial. Further multi-environment and multi-season validation is required before these responses can support broad practical application.