Effects of Air Anions on Growth and Economic Feasibility of Lettuce: A Plant Factory Experiment Approach

Abstract

Anions are molecules that have gained one or more extra electrons, and oxygen anions are the anions most commonly present in the atmosphere. Several studies have reported an improvement in plant respiration and growth through the application of air anions in several plants. In this study, the effect of air anions on the growth of lettuce was explored, and further, the economic feasibility of this technique was analyzed in a plant factory. Two cultivars of lettuce were cultivated for 4 weeks with the application of negatively ionized air in a commercial plant factory. The exposure to air anions improved the growth of the lettuce plants in the plant factory. A profitability analysis of applying air anions revealed that the annual net profit per 1500 m2 cultivation area was about USD 60,000 and USD 70,000 for red leaf lettuce and Lollo bionda lettuce, respectively. Therefore, the application of air anions to lettuce in plant factories or greenhouses could increase crop production and has high economic feasibility.