Enhanced flowering of the F1 long-day strawberry cultivars ‘Tarpan’ and ‘Gasana’ with nitrogen and daylength management

Interest in sustainable self-sufficiency, particularly when considering produce has increased. Strawberries, especially particularly the seed propagated, long-day, F1 hybrids such as ‘Tarpan’ and ‘Gasana’, fit self-sufficient, sustainable production models well. They provide aesthetic as well as culinary benefits producing colorful, attractive blossoms and flavorful fruit. To determine if ‘Tarpan’ and ‘Gasana’ flowering would respond to photoperiod and nitrogen, seedlings were fertilized with 100 or 800 ppm nitrogen for 4 weeks in September beginning one week after exposure to either short days, the natural photoperiod, or long days, the natural photoperiod supplemented with 24 hours of incandescent radiation. Plants were then greenhouse forced under both photoperiods and floral phenology evaluated. Photoperiod and N fertility during floral initiation in September affected subsequent flowering of both cultivars. The response was rapid with significant differences observed 4 weeks after the commencement of treatment. Both cultivars responded with increased rate (enhanced precocity) and intensity (enhanced inflorescence/flower number) of flowering with elevated N. In ‘Gasana’ elevated N accelerated flowering by 2–3 weeks. There was a slight acceleration of flowering in lower N plants with long-day forcing, however, elevated N was much more effective in accelerating flowering than long-day forcing. In ‘Tarpan’, long-day forcing and elevated N were equally effective in accelerating flowering. Inflorescence production per plant or crown and the number of flowers per plant were enhanced with elevated N in both cultivars. Long-day forcing stimulated the number of inflorescences produced per crown in both cultivars. The number of flowers per plant in ‘Tarpan’ was also enhanced by long-day initiation or forcing. Elevated N, short-day initiation or long-day forcing enhanced the number of flowers per inflorescence in ‘Gasana’. Elevated N under long-day initiation or under short-day initiation when followed by long-day forcing enhanced the number of flowers per inflorescence in ‘Tarpan’