Photoperiod modulation and hormonal application influence flowering, agronomic, morphological and tuber quality...

Greater yam (Dioscorea alata L.) is a vital staple crop in tropical regions, yet its genetic improvement is severely hampered by poor, irregular, or non-flowering in many genotypes. This flowering recalcitrance creates a major bottleneck for conventional breeding. This study aimed to develop methods for flowering induction in D. alata using photoperiod modulation and hormonal applications, and to evaluate the resulting agronomic, morphological and tuber-quality responses.

Over two consecutive seasons, thirteen genotypes with varying flowering abilities were subjected to short-photoperiod (SP), long-photoperiod (LP), and a range of hormonal treatments in a field-based experiment.

We show that photoperiod influences flowering induction in D. alata, with strong genotype-dependent responses. The SP treatment was highly effective, successfully inducing fertile, viable flowers in up to 75% of previously non-flowering male and female genotypes. Conversely, the LP treatment completely inhibited flowering but served as a novel tool for synchronizing flowering time among diverse genotypes upon its cessation. A clear trade-off was observed: LP promoted vegetative growth at the expense of tuber yield, whereas SP enhanced both flowering and tuber biomass. While hormonal applications failed to induce flowering, they significantly modulated tuber quality. Notably, the ethylene inhibitor silver thiosulfate increased tuber amylose content, whereas jasmonates significantly reduced it, revealing a link between stress signaling and starch metabolism.

Our findings provide useful insights for yam breeding and suggest practical approaches to induce and synchronize flowering, potentially helping to unlock the vast genetic diversity present in yam germplasm for crop improvement.