Shortening the Vegetative Growth Stage of Phalaenopsis Queen Beer ‘Mantefon’ by Controlling Light with Calcium Ammonium Nitrate Levels under Enriched CO2

The vegetative growth, photosynthetic, and stomatal characteristics were investigated in Phalaenopsis Queen Beer ‘Mantefon’ to determine light’s influence with calcium ammonium nitrate (CAN) levels under 800 μmol·mol−1 CO2. Two lights (150 ± 20 and 300 ± 20 μmol·m−2·s−1) and CAN levels were employed for 40 weeks: calcium, ammonium, and nitrate levels by 0.90, 0.55, and 2.97 mmol·L−1 (CAN1), 8.63, 1.11, and 6.05 mmol·L−1 (CAN2), 12.80, 1.72, and 9.13 mmol·L−1 (CAN3), and 18.80, 2.27, and 12.20 mmol·L−1 (CAN4), respectively. The number of leaves increased in the plants grown at 300 ± 20 μmol·m−2·s−1 with CAN1 compared to control. Plants grown at 300 ± 20 μmol·m−2·s−1 with CAN4 had the lowest number of leaves among all plants. The time to the mature leaf span decreased in the plants grown at 300 ± 20 μmol·m−2·s−1 with CAN1. The net CO2 uptake was higher in the plants grown at 300 ± 20 μmol·m−2·s−1 than those grown at 150 ± 20 μmol·m−2·s−1 with CAN1–3 conditions. The water-use efficiency is higher in the plants grown with CAN1 than those with CAN2–4 at 300 ± 20 μmol·m−2·s−1. The maximum stomatal aperture was the largest in the plants grown at 300 ± 20 μmol·m−2·s−1 with CAN1–2 among all plants. Consequently, light levels of 300 ± 20 μmol·m−2·s−1 in Phalaenopsis Queen Beer ‘Mantefon’ must be accompanied by nutrient CAN1 to improve photosynthesis and stomatal activity and promote leaf growth under 800 μmol·mol−1 CO2 conditions.