Submitted to: International Strawberry Symposium
Publication Type: Abstract Only
Publication Acceptance Date: December 1, 2007
Publication Date: March 3, 2008
Citation: Takeda, F., Glenn, D.M. 2008. Flower bud formation in short-day cultivars under non-photoinductive conditions. International Strawberry Symposium. Book of Abstracts Pg No. 69. Technical Abstract: In the mid-Atlantic coast region (39 degrees Latitude N, 77 degrees Longitude W), the main strawberry harvest season is from early May to late June. Out-of-season fruit production in the region is low. We developed a simple propagation scheme for short-day type strawberry cultivars to produce fruit in fall and spring in high tunnels without using standard conditioning treatments such as chilling or artificial short-day photoperiod, during the nursery phase. When runner tips of short-day type 'Carmine' were started as plug plants in early July and field planted around 1 September more than 86 percent flowered by mid October and produced greater than 300 g by late December. Less than 30 percent of those transplants started as plug plants in early August produced flowers in the fall. With strawberry plug transplants being retained in tray flats at high plant density during July and August the leaves form a full canopy or high leaf area above the plant crowns, the crown near the base of leaf petioles is illuminated only by solar radiation in the far-red and near-infrared region. Promotion of flowering in July-plugged transplants is correlated with a high ratio of far-red light to visible light reaching the crown. Spectral analyses showed that wavelengths less than 700 nm did not reach the crown because all shorter wavelength light is absorbed through photosynthesis. Where plants are grown at wider spacing or have low leaf area, the crown is illuminated by direct sunlight irradiance and reflection between the plants resulting in a higher red: farred ratio of intercepted radiation. The results of this study suggest that transplants of short-day type strawberries that will flower in fall can be produced by developing a plant canopy that alter the quality of light that illuminates the crown. The key physiological mechanism operating in production of strawberry transplants with high fall flowering potential will be discussed.