Published in Scientific Papers. Series B, Horticulture, Vol. LXVIV, Issue 2
Written by Yihan ZHANG, Florin STĂNICĂ, Ruifeng CHENG，Yuxin TONG
To address the current issues in plant factories including stagnant airflow in plant canopies, uneven distribution of environmental factors, and high complexity of environmental control systems, this study developed an integrated double-channel aeration cultivation system (DCAS) combining ventilation ducts with cultivation tanks. A three-dimensional computer fluid dynamic model was developed and validated through simulating the airflow distribution within the plant canopy under different ventilation parameters. According to the simulated results, a ventilation angle of 45° with an intake air velocity of 8 m s-1 showed the best airflow uniformity and highest proportion of suitable zone. Based on the optimized parameters, a lettuce cultivation experiment was conducted in a plant factory. The experiments investigated the effects of traditional ventilation mode and DCAS ventilation on lettuce growth, canopy environmental factors and heat exchange parameters. The experimental groups used DCAS ventilation with canopy airflow velocities set at 0.6 m s-1 (T1), 0.9 m s-1 (T2) and 1.2 m s-1(T3) respectively, while the control group (CK) used the conventional side-inlet top-outlet ventilation mode with canopy airflow velocity of 0.2 m s-1. Results showed that compared with CK, the experimental groups demonstrated better performance in lettuce growth, canopy microenvironment and heat exchange with the surrounding environment. Under T2 treatment, the dry and fresh weights of lettuce shoots increased by 24% and 14%, respectively, compared to those under the CK. The canopy microenvironment and heat exchange reached optimal status under T3 treatment, where the average relative humidity and air temperature in lettuce canopy decreased by 8.8% and 2.8°C, respectively, compared to those under the CK. Additionally, DCAS ventilation effectively reduced the incidence of tipburn in lettuce. The above results indicate that the DCAS can be considered as an effective system for improving canopy microenvironment, plant growth and reducing tipburn occurrence.
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