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This study was performed to determine the effect of daylength on reproductive growth in Viola species. Materials used for this study were nine Viola species and two varieties native to Korea (V. verecunda, V. blandaeformis, V. chaerophylloides, V. variegate, V. variegate var. chinensis, V. keiskei, V. phalacrocarpa, V. patrini, V. mandshurica, V. mandshurica for. albescence, V. yedoensis), one small flowered violet (V. tricolor ´Helen Mount´), and six garden pansies (´Fame Dark-Eyed Yellow´, ´Giant Forerunner Black-Eyed White´, ´Medium-sized Maxim Yellow´, ´Crystal Bowl Deep Blue´, ´Large-F1. Regal Deep Blue W/Blotch´, ´Clear Sky Primrose´). Plantlets grown under 16h daylength were treated with five different daylength (10, 12, 14, 16, 24h). Wild Viola species came faster into bloom in short-day. On the other hand, pansies which required shorter period than wild species for flowering, came earlier into bloom in long-day. Individual plants of the earlier flowering species tended to start flowering within the shorter period. Most of wild Viola species showed 100% flowering in short-day, but when cultivated in the longer photoperiod, flowered with the lower percentage. None of wild species, except V. blandaeformis and those in the series Variegatae, were flowered in the daylength over 14h. Pansies were flowered equally 100% in most of treatment. More flowers bloomed in the shorter daylength (10h) for wild species, but in the longer daylength (16-24h) for pansies. However, the flower diameter was inversely proportional to the numbers of flowers. Capsule numbers per plants were greater in long-day over 14h for wild species, but in short-day (10-12h) for pansies. The number of seeds per capsule of wild species was generally greater in long-day. Seed numbers per capsule were inversely to seed weight in V. tricolor ´Helen Mount´. However, seed weight of wild species, except those in the series Variegatae, was lighter in daylength which produced the fewer seed numbers per capsule. The peduncle length of wild species, except V. verecunda and V. variegate, was longer in long-day.
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