Effect of light quality and extended photoperiod on flower bud induction during transplant production of day-neutral strawberry cultivars
Varinder Sidhu, Valérie Bernier-English, Marianne Lamontagne-Drolet, Valérie Gravel
Abstract
Day-neutral (DN) strawberry cultivars are increasingly grown in Canada because they produce flowers and fruits continuously until October. Appropriate artificial lighting conditions during preparation of high-quality transplants is critical. Unfortunately, systematic evaluation of appropriate artificial lighting conditions during transplant production is limited. The objective of this study was to determine how an extended photoperiod supplemented with different light quality affects the vegetative and reproductive growth of a day-neutral cultivar during transplant production. In the first trial, we investigated the photoperiodic nature of the DN cultivar ‘Albion’ under low intensity incandescent light. Transplants were grown under three light combinations with different far-red : blue ratios (1:5, 5:1 and 1:1), supplemented for long day (LD; 24 h), short day (SD; 10 h) photoperiods and during a night interruption (NI) for 2 h. ‘Albion’ cultivar exhibited similar degree of flowering sensitivity regardless of photoperiod duration when incandescent light was used as predominant light source. In case of light emitting diodes (LEDs), dominant blue (1:5) LEDs prompted a significant increase in flower bud induction (FBI), more explicitly under the LD photoperiod. Furthermore, transplants grown under dominant blue light (1:5) supplied during NI produced eight flower buds per plant, the highest among all treatments, and promoted flower development outside the crown. Based on the results, it appears that lower wavelengths advance flowering and higher wavelengths contribute towards the morphological traits especially during transplant production. Results suggest that combination of far-red and blue LEDs at 1:5 ratio could be a potential light source to improve flower bud induction and floral development to subsequently increase fruit production.