S08 - Session P5 - Spectral effects of sole-source lighting on plant growth, flowering, and fruit development of indoor strawberries

Authors: Yujin Park *, Tristan Lewis, Lin Li

There is an increasing interest in growing strawberries ( Fragaria × ananassa ) in indoor vertical farms. For indoor strawberry production, ever-bearing cultivars are considered more desirable than short-day cultivars, because they can produce fruits for a longer period and their growth and flowering can be promoted under long-day conditions. A long photoperiod delivered with red (R, 600-700 nm) and far-red light (FR, 700-800 nm) is most effective at stimulating flowering in many long-day plants. This study investigated if providing sole-source lighting with R and FR light and a long photoperiod promotes flowering and subsequently, fruit development in ever-bearing strawberries 'Albion' and 'Monterey'. We grew bare-root strawberry plants at 23 °C with a 20-h photoperiod under three sole-source LED lighting conditions [with photon flux density in µmol∙m -2 ∙s -1 from blue (B, 400-500 nm), green (G, 500-600 nm), R, and FR waveband in subscript]: B 84 G 36 R 180 , B 90 G 24 R 144 FR 42 , and B 105 G 28 R 167 FR 49 . After five weeks grown under sole-source lighting, strawberry plants had similar plant diameter, crown diameter, leaf number, petiole length, leaf size, relative chlorophyll concentration, and shoot and root fresh and dry weights among treatments in both cultivars. Similarly, sole-source lighting treatments did not influence the time to flower in strawberry 'Albion' and 'Monterey'. Both cultivars flowered similarly in an average of 51 days after sole-source lighting treatments. The effects of the sole-source lighting with FR light on harvest time, fruit yield, and fruit quality will also be presented.