## 3 Results and Discussion  
### Daughter Plants and Stolons  
The total number of daughter plants harvested per stock plant increased with an increase of light intensity (Figure 3). For the 01 to 12 week cycle, the total number of daughter plants in 250-PPF, 350-PPF, and 450-PPF was (mean \(\pm\) SD) 38.7 \(\pm\) 5.4, 45.7 \(\pm\) 8.7, and 56.7 \(\pm\) 8.5, respectively. For the 12 to 21 week cycle, the total number of daughter plants for 250-PPF, 350-PPF, and 450-PPF was 41.9 \(\pm\) 7.7, 47.2 \(\pm\) 10, and 50.6 \(\pm\) 8.2, respectively. On a 21 week propagation cycle, the maximum production (460-PPF) was ~107 daughter plants per mother plant. To the best of our knowledge, this is the first study presenting the potential propagation yield in PIP systems for day-neutral strawberry plants. Other studies have shown the potential of controlled environment systems (greenhouses) to propagate strawberry plants, but studies have focused on short-day strawberry plants [35; 36]. Short-day strawberry plants are known to be high producers of daughter plants. For example, short-day \"Oso Grande\" and \"Sweet Charlie\" mother plants produced 84 and 80 daughter plants per stock plant in 16 weeks under a greenhouse production system [35]. The effect of light intensity on total dry mass, total fresh mass, and total leaf area of all daughter plants harvested after each growing cycle is shown in Figure 4a-c, respectively. For the 01 to 12 week cycle, the total dry mass and fresh mass of all daughter plants harvested per stock plant increased with an increase of light intensity. For the 12 to 21 week cycle, the increase was less evident, but the trend was still present (\(p\) = 0.070 and \(p\) = 0.068). The total leaf area of all daughter plants per stock plant increased with an increase of light intensity for the 01 to 12 week cycle but did not increase for the 12 to 21 week cycle. Figure 3: Effect of light intensity (mean \(\pm\) standard error) on the total number of daughter plants per stock plant of day neutral strawberry “Albion”. Open circles (\(\Circle\)) represent data collected for 01 to 12 weeks and filled circles (\(\bullet\)) represent data collected for 12 to 21 weeks. Dotted or solid lines represent significant linear regression (\(p\leq 0.05\)). Figure 4: (**a**) Effect of light intensity on the total dry mass; (**b**) total fresh mass; (**c**) total leaf area, of all daughter plants harvested after each cycle per stock plant of day neutral strawberry \"Albion\". Open circles (\(\Circinus\)) represent data collected when stock plant was 12 weeks old and filled circles (\(\bullet\)) represent data collected when stock plant was 21 weeks old. Dotted or solid line represents significant linear regression with \(p\leq 0.05\). Plants under the 450-PPF treatment produced 34.1% and 19.7% greater daughter plant dry mass and 44.7% and 20.8% greater number of daughter plants in the 01 to 12 week cycle and 12 to 21 week cycle, respectively, as compared with plants under the 250-PPF treatment. This result is expected since higher daily light integral (DLI, mol m\({}^{-2}\) d\({}^{-1}\)) is associated with higher yield. In general, a 1% increase of light increases yield by 0.25% to 1.5% [37]. Research has shown the crop specific efficacy to cumulative PPFD (grams of yield per mol of PPFD, g mol\({}^{-1}\)) of several crops, for example, crop productivity values of 7.6 to 14 g mol\({}^{-1}\), 4.6 to 6.5 g mol\({}^{-1}\), and 3.7 to 6.9 g mol\({}^{-1}\) for cluster tomato, cherry tomato, and lettuce, respectively [28]. Specifically for strawberry fruit production, a 1.5 to 2.1 g mol\({}^{-1}\) crop productivity was reported by [28]. The propagation efficacy to PPFD (daughter plants mol\({}^{-1}\)), in our experiment, was 0.36, 0.30, 0.29 for 250-PPF, 350-PPF, and 450-PPF, respectively, for the 01 to 12 week cycle; and 1.94, 1.50, and 1.30 for 250-PPF, 350-PPF, and 450-PPF, respectively, for the 12 to 21 week cycle (Figure 5).