Moon-Sun Yeom

Negative air ion (NAI) is one of the electrical stimulation methods known to affect plant growth and development. Since most studies on plant responses to NAI have focused on leafy vegetables, this study aimed to evaluate the potential applicability of NAI to fruiting vegetables by analyzing growth characteristics and gas exchange activity at different developmental stages-vegetative and reproductive-in dwarf tomato (Solanum lycopersicum L. 'Nurimaru F1') cultivated in a vertical farm. Dwarf tomato seedlings were grown for five weeks under the following controlled environmental conditions: 24°C air temperature, 60% relative humidity, 600 µmol•mol-1 CO 2 concentration, 320 µmol•m-2 •s-1 PPFD from white LED lighting, and a 16-hour photoperiod. During the light period, NAI were applied at a concentration of 12 × 10⁵ ions•cm-3. Growth parameters were measured weekly for five weeks after transplanting, and photosynthetic and transpiration rates were recorded weekly for four weeks. As a result, although no statistically significant differences in gas exchange were observed, the NAI-treated plants consistently showed higher numerical values than the control. Vegetative growth traits showed no marked differences between the control and NAI. However, reproductive traits (number of inflorescences, flowers, and fruits) were significantly enhanced in NAI than the control. These results suggest that NAI can promote reproductive development and increase the fruit yield of dwarf tomatoes, implying its potential application in vertical farming for the production of fruiting vegetables.