Water Use Efficiency in Two-Tier Aeroponic Vertical Strawberry Farming with LEDs

Improving water use efficiency (WUE) while maintaining stable productivity is a major challenge in controlled environment agriculture.This study evaluated water balance, WUE, and yield performance of strawberry (Fragaria × ananassa Duch.cv.'Seolhyang') grown for 180 days in a closed two-tier aeroponic vertical system under lighting from LEDs.The target PPFD for the LEDs was 300 µmol•m -2 •s -1 , while measured canopy PPFD at strawberry positions averaged approximately 280 µmol•m -2 •s -1 in both tiers.Total water input was 54.0 m 3 ; 16.2 m 3 (30.0%)was recovered, UV-C-treated, and reused, giving net water consumption of 37.8 m 3 .Total fruit yield was 225 kg.WUE was defined as fruit yield divided by water input and was 4.17 kg•m -3 on a supplied-water basis and 5.95 kg•m -3 on a net-consumption basis.CO 2 was maintained at 400 ± 50 ppm during the cultivation period.Daytime tier-level microclimate monitoring showed upper/lower tier values of 22.8 ± 0.5°C/21.2± 0.5°C, 62 ± 3%/68 ± 3% RH, and 1.05 ± 0.1/0.78± 0.1 kPa air VPD.More than 50% of total water input and more than 65% of total fruit yield occurred during the reproductive period.Tier WUE was 4.32 and 4.03 kg•m -3 in the upper and lower tiers, respectively.Because the study used one pilot-scale system, tier differences are presented as quantitative system observations rather than formal treatment effects.