Plant architecture of 'Albion' strawberry (<i>Fragaria</i> × <i>ananassa</i> Duch.) is not influenced by light source during conditioning

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Architectural analysis describes the position and fate (vegetative or floral) of plant meristems to account for differences in meristem sensitivity to stimuli depending on developmental stage and position on the plant. To provide further insight into the flowering responses of long-day strawberries to nitrogen (N), photoperiod and light source, ‘Albion’ strawberry plants were conditioned with 100 or 800 ppm N under ND (natural daylength) or LD (long days, natural days plus 24-hr supplementary illumination provided by either 60- or 7-watt incandescent bulbs) and greenhouse growth was evaluated for a total of 10 weeks following conditioning. After greenhouse forcing, plants were dissected and their floral architecture evaluated. Additional plants were established in early July in off-season plasticulture production where fruit, crown and stolon production were evaluated. Both light sources were equally effective in eliciting long-day photoperiod responses. No photoperiod effect on floral precocity, leaf, crown, or runner production was observed during greenhouse forcing. Plants under ND tended to produce more inflorescences during the first 5 weeks while LD enhanced inflorescence and flower production during the last 3 weeks of forcing. In dissected plants, maximum floral initiation was observed in plants receiving elevated N under LD. LD inhibited branch crown formation, but had no effect on the number of vegetative, floral or stolon producing axillary meristems regardless of N treatment. LD conditioning enhanced early yield (through 4 September). Field stolon and branch crown formation was supressed in plants receiving low N with LD conditioning. Stolon and branch crown inhibition by LD conditioning was not observed with elevated N. Growth data combined with architectural mapping of meristems allows more conclusive statements regarding treatment effects on specific stages of floral physiology (i.e. induction, initiation, differentiation and development) compared to more generalized conclusions obtained with growth data alone. The separation of direct and indirect effects on floral physiology is possible with floral architectural analysis.