Effects of CO2 Enrichment and 5-aminolevulinic Acid-based Fertilizer Application on Early Growth of Limonium sinuatum (L.) Mill. under Environmental Control

We investigated the effects of CO2 enrichment and application of 5-aminolevulinic acid (ALA)-based fertilizer during raising seedling under environmental control on the early growth of Limonium sinuatum (L.) Mill. ‘Souun’. Seedlings were grown in 7.5-cm polyethylene pots in two growth chambers with a day/night temperature regime of 20 °C/15 °C and a 12-h light/12-h dark photoperiod (PPFD 74 nmol m s). Four treatments were applied to the potted plants: general liquid fertilizer applied once per week (control group); ALA-based fertilizer and general liquid fertilizer (ALA group); CO2 concentration increased to 1200 nmol mol for 5 hours of the light period (CO2 group); and ALA-based fertilizer combined with CO2 enrichment (CO2+ALA group). After 5 weeks of these treatments, there was no significant difference in any of the measured parameters between the CO2 group and the control group. The leaf area, fresh weight of aerial parts, and fresh weight of underground parts were significantly higher in the ALA group than in the control group. The number of leaves, SPAD value, leaf area, fresh and dry weight of aerial parts, dry weight of underground parts, and percentage of underground part dry matter were significantly higher in the CO2+ALA group than in the control group. After 3 months of these treatments, there was no significant difference in cut flower yield and quality among the treatment groups. These findings clarified that application of ALAbased fertilizer under CO2 enrichment conditions promotes the early growth of L. sinuatum under weak light environmental control.