Adjusting the Percentage of Nitrate in Nutrient Solution to Optimize Strawberry Stolon and Daughter Plant Production

Year-round production of disease-free strawberry (Fragaria ×ananassa) daughter plants can be achieved by growing mother plants in controlled environments. However, a lack of protocols exists for nutrient management of mother plants to optimize the production of stolons and daughter plants. Our objective was to identify the optimal percentage range of nitrogen (N) supplied as nitrate (% NO −3) in a nutrient solution to maximize strawberry stolon and daughter plant production. Three cultivars (Albion, Fronteras, and Monterey) were grown in 20.3-cm pots filled with a peat-based soilless substrate. A strawberry-specific nutrient solution (Yamazaki) provided 100 mg·L−1 N, and the N form supplied ranged from 0% to 100% NO−3, with the remainder supplied as ammonium (NH+4). In Expt. 1, ‘Fronteras’ stolon and daughter plant numbers were assessed every 4 weeks for 16 weeks. The harvest interval was too frequent to identify any treatment effects. In Expt. 2, ‘Albion’, ‘Fronteras’, and ‘Monterey’ stolon and daughter plant numbers were assessed at 8 and 16 weeks. Cumulative stolon number and cumulative daughter plant number exhibited linear or quadratic responses to the percentage of NO−3, and the responses were cultivar dependent. Maximum calculated cumulative stolon number occurred a64%NO− for ‘Fronteras’ and at 100% NO−3 for ‘Albion’ and ‘Monterey’. Maximum calculated cumulative daughter plant number occurred at 66% NO−3 for ‘Fronteras’, 81% NO−3 for ‘Monterey’, and 100% NO−3 for ‘Albion’. The percentage of NO−3 generally did not affect daughter plant quality, such as root number, crown diameter, dry mass, and foliar %N. Total aboveground biomass (mother plant + stolons + daughter plants) increased as the percentage of NO−3 increased from 0% to 100%. ‘Monterey’ had more total aboveground biomass than ‘Albion’ or ‘Fronteras’. A calculated range in which all three cultivars overlapped with ≥95% of maximum daughter plant number occurred between 81% to 87% NO−3. A strawberry fertilizer recipe in this target range would allow growers the opportunity to use a single fertilizer recipe to support high daughter plant productivity across multiple cultivars. Our results indicate that optimal strawberry daughter plant production occurs at a lower percentage of NO−3 than recommended for inflorescence or fruit production.