FLOWER BUD FORMATION IN SHORT-DAY STRAWBERRY CULTIVAR UNDER NON-PHOTO INDUCTIVE CONDITIONS

A scheme for producing short-day type strawberry cultivars that initiate flowers under long-day photoperiod was used to investigate the flower bud induction. When runner tips of short-day type ‘Carmine’ were started as plug plants in early July and field planted 1 September 86% of transplants flowered by mid October. When the July-plugged transplants were retained in tray flats at high plant density during July and August the leaves formed a full canopy or high leaf area index above the plant crowns and the crown near the base of leaf petioles was completely in the shade. A spectral analysis showed that wavelengths less than 700 nm did not reach the crown because of chlorophyll absorbance. Illuminating the crown for 16 h•day^-1 for 4 weeks in August with 662 nm light decreased transplants that flowered by mid October. The results suggest that fall-flowering transplants of short-day strawberries were produced by rooting runner tips in early July and having a plant canopy that alters the quality of light that illuminates the crown.