Abstract: Strawberry nurseries face many challenges, and are considering controlled environment propagation as an alternative to conventional open-field propagation. Limiting factors to economic feasibility include stock plant yield (number of daughters produced per stock plant). From published research we know that increasing CO2 concentration and light intensity increases strawberry photosynthetic rate, however there has been no research on the effects of these treatments on the total stock plant yield of daughters. Our hypothesis is that higher light intensity and CO2 concentrations will improve plant growth and lead to greater total daughter plant production. The objective of this experiment is to increase stock plant yield by increasing CO2 concentration (500, 850, and 1200 μmol mol-1) and light intensity (DLI 14.4 and 28.8 mol m-2 d-1). Strawberry (Fragaria × ananassa Duch., ‘Monterey’) stock plants were transplanted into three controlled environment growth chambers, under combinations of CO2 and DLI treatments in a split plot design under 26°C, 65% relative humidity, and a 16-hour photoperiod. The stock plants were grown under treatment conditions for 70 days, and newly-formed daughters were logged every day. At the end of the experiment the stock plants and their daughter plants were harvested, and each daughter plant was evaluated based on its size (number of leaves, leaf area, and fresh/dry mass). Increasing CO2 concentration linearly increased stock plant yield, leading to 23.96% more daughter plants per mother plant from the 500 to the 1200 μmol mol-1 treatment. Plants under higher light intensity (500 μmol m-2 s-1) had 38% higher stock plant yield than those under 250 μmol m-2 s-1. These data support our hypothesis that increasing CO2 concentration and light intensity increase the total yield of daughter plants produced per stock plant. By optimizing CO2 concentration and light intensity, strawberry nurseries may be able to grow more daughter plants more efficiently in controlled environment nurseries than in the conventional open-field system.
