2019 ASHS Annual Conference

Light quality, referring to wavelength and photoperiod are the key factors regulating strawberry flowering time, phenological growth and consequently, fruit production. Night interruption (NI) is a treatment providing by artificial lighting during the dark night period to simulate LD photoperiodic conditions. While the light quality and photoperiodic control of flowering has been extensively studied in short day (SD) strawberry cultivars, little is known about the flowering behavior of day neutral (DN) strawberries, despite their rising popularity within the industry. The main objective of this study is to determine the effect of light quality and NI on flower bud induction of DN strawberry. As a first step, we investigated the effect of light quality on flower bud induction (FBI), morphogenesis and transcription of flowering genes intransplants of woodland strawberry (Fragaria vesca cv ‘Alexendria’). Plants were grown under far-red (760nm) and blue (450nm) light emitting diodes (LEDs) at a ratio of 5:1 and 1:5, supplied with long-day (LD) photoperiod (16h light/8h dark) in controlled environment. LD photoperiod supplemented with higher blue light resulted in a significant (p<0.05) increase in leaf growth and flower bud induction compared to far-red light during transplant production. Additionally, it was observed that flowering time, morphogenesis and expression of FLOWERING LOCUS (FvFT1)/ SUPPRESSOR OF THE OVEREXPRESSION OF CONSTANS (FvSOC1) can be stimulated by blue light quality. As a second step, seedlings were exposed to photoperiods of 10h (SD), 15h (LD), 10h (8h+2NI) and 15h (13h+2NI) using fluorescent lights in growth chambers under controlled conditions (25/20°C and 70% RH). Plants treated with 13h+2NI significantly induced flower bud differentiation compared to 8h+2NI. However, there was no significant difference between 10h SD and 15h LD treatments or in vegetative growth (i.e. runner and leaf count) for all treatments. The study implies that flowering in DN strawberry can be accelerated by an increased ratio of blue to far-red light supplemented during night interruption. Furthermore, NI in combination with blue light could be a successful practice to regulate flowering time during transplant production.