Germination ecology of wild and domesticated Ensete ventricosum: Evidence for maintenance of sexual reproductive capacity in a vegetatively propagated perennial crop

PREMISE: Loss of sexual reproductive capacity has been proposed as a syndrome of domestication in vegetatively propagated crops, but there are few empirical examples from agricultural systems. Compared to sexually propagated crops banked as seeds, vegetative crop diversity conserved as living collections may be more costly and insecure, disproportionately impacting tropical crop diversity where vegetative reproduction predominates. In this study we assess sexual reproductive capacity in wild (outcrossing) and domesticated (vegetative) populations of enset (Ensete ventricosum), a giant tropical banana relative and Ethiopian food security crop. METHODS: We harvested seeds from 20 wild and domesticated enset to survey variation in seed weight, viability, external and internal morphology. We germinated seeds across a range of constant and alternating temperature regimes to characterise the optimum germination requirements, and evaluate differences in performance. KEY RESULTS: We found no significant difference between wild and domesticated enset seed viability, days to germination and internal morphological traits. However, we report a significant and unexpected shift in seed weight and germination behaviour, with seed from domesticated plants responding to cooler temperatures with greater diurnal range. Shifts in germination behaviour appear concordant with a climatic envelope shift in the domesticated distribution. CONCLUSIONS: Our findings support a scenario where sexual reproductive capacity has been maintained despite long-term near-exclusive vegetative propagation in domesticated enset. Furthermore, certain traits such as germination behaviour, may be under continued selection through very rare sexually reproductive events. Improved understanding of sexual propagation in vegetative crops may have applications in germplasm conservation and future plant breeding.