Optimizing light intensity and airflow for improved lettuce growth and reduced tip burn disease in a plant factory

In practical plant factory production, light intensity and airflow were major environmental factors that significantly impacted lettuce growth and tip burn disease. This study investigated the effects of light intensity (100, 200, and 300 mu mol center dot m-2 center dot s-1) and airflow rate (100, 200, and 300 m3/h) on the comprehensive quality of lettuce. The Analytic Hierarchy Process (AHP) was employed to determine the weight of various growth and physiological indices of lettuce, while fuzzy mathematics principles were used to evaluate its comprehensive indices. The findings revealed that higher light intensity increased Ca2+ demand and decreased stomatal conductance, exacerbating tip burn disease. In contrast, increasing the airflow rate reduced leaf temperature, promoted transpiration, and facilitated calcium ion transport, thereby alleviating the occurrence of tip burn. Increasing the airflow rate to 300 m3/h effectively improved plant transpiration and Ca2+ transport, which further reduced tip burn. The comprehensive results indicated that under the conditions of a light intensity of 200 mu mol center dot m-2 center dot s-1 and an airflow rate of 300 m3/h, lettuce achieved the best comprehensive quality score of 0.6490, with a Ca2+ content of 21.83 mg/100 g, and tip burn was effectively suppressed. The study provided valuable scientific support for the precise control of environmental conditions in plant factories.