In recent years, a technology called biopharming, in which plants are used to produce pharmaceuticals, enzymes, and other high-value proteins, has been commercialized. Infiltrating the plants via the stomata, with genes that encode for these proteins, is a critical step in biopharming, but there is limited research on how to manipulate plant morphology to optimise this process. In this study, we investigated how increasing the airflow in a hydroponic system under vertical farm condition affects the growth and morphology of Nicotiana benthamiana, the plant most commonly used in biopharming. The plants were grown in a hydroponic system under vertical farm condition equipped with LED lights, with a photoperiod of 16 hours light/8 hours dark, and a photosynthetic photon flux density of 160-180 µmol m-2 s-1. The growing beds were filled with liquid fertilizer with an electrical conductivity of 1.6 dS cm-1 and a pH of 6.0 ± 0.5. Seeds of Nicotiana benthamiana L. were sown in urethane cubes and transplanted onto the bed. In a preliminary experiment, the fresh weight, plant height, and number of leaves were measured to investigate the growth of Nicotiana benthamiana under hydroponic conditions, and at 30 days after transplanting was determined to be the optimum number of growing days for use as a control regime in the present study. The enhanced air-flow treatment employed a constant wind speed of 0.1 to 0.2 ms-1, and strategically placed air ducts were used to ensure that each plant was evenly exposed. Seven plants (each had 8 to 10 leaves) were harvested, of which the first, third, and fifth leaves were used to measure leaf area and perform stomatal observations. Applying the enhanced air-flow treatment increased the fresh weight and average stomatal aperture of the plants by 1.2 and 1.1-fold, respectively. Leaf area was also increased markedly by 1.8-fold, compared to the control regime. The same results were obtained after three replications, indicating that the method is reproducible. These results suggest that airflow is an important environmental factor that could influence the efficiency of the infiltration process in biopharming.
