Codrea, M.M.Valdiviesso, T.Oliveira, Cristina M.Mitre, V.Oliveira, P.B.Palha, M.G.2021-09-212021-09-212021Codrea, M.M., Valdiviesso, T., Oliveira, C.M., Mitre, V., Oliveira, P.B., Palha, M.G.2021 The effect of LED illumination on flower differentiation of strawberry short-day cultivars in winter production season. Acta Horticulturae 1309: 653-658http://hdl.handle.net/10400.5/21879Proc. IX International Strawberry SymposiumPlants such as tray and mini-tray (in replace of bare-root plants) and artificial assimilation lighting systems on strawberry tunnels have been used to ensure better crop productivity and to increase the competitiveness of the Portuguese strawberry sector. In order to observe if LED (light emitting diodes) supplemental illumination will affect flower differentiation and development of short-day strawberry cultivars in southern Portugal, a field trial was established with tray and mini-tray plants of ‘Dream’ and ‘Darselect’ cultivars, grown under and without LED light (deep red/white/far-red). The artificial lighting was applied from October to January in complement to natural daylight keeping 16 h day-1 photoperiod. Plant architecture was established by plant dissection into crowns, leaves, inflorescences, flowers and fruits, and all the meristems of apical and lateral shoots were counted and distinguished as vegetative or reproductive. Tray plants were significantly more vigorous than mini-tray plants. Through meristems observation it was found that both cultivars developed inflorescences and flowers primordia that were differentiated in the nursery and no new differentiation occurred at 50 days after plantation (DAP). Afterward, flower differentiation took place again till the end of the growing season (110 DAP). LED light did not improve flower development during the first growing season. Although plants stop fruiting in January the apical meristems were in high activity. Further studies should be done to determine the flowering differentiation pattern throughout the first and second tray plant cropengfloral architectureFragaria × ananassamini-traytraysubstrate culturejournal articlehttp://dx.doi.org/10.17660/ActaHortic.2021.1309.94