Effects of Daily Light Integral and Flower Thinning on Growth, Fruit Production, and Sugar Composition of ‘Kuemsil’ Strawberries in a Vertical Farm

Strawberry (Fragaria × ananassa Duch.) production in a vertical farm requires coordinated management of the light supply and reproductive growth to improve the yield and fruit quality.This study evaluated the daily light integral (DLI; 15, 17.5, and 20 mol•m -2 •d -1 ) and flower thinning (3, 5, and 7 flowers per inflorescence) in 'Kuemsil' strawberries during 83 days of reproductive growth.Increasing the DLI shifted fruit production toward larger fruits and increased the number of marketable fruits, defined as fresh weight > 10 g and soluble solids content ≥ 10 °Brix.The soluble solids content ranged from 10.1 to 11.8 °Brix and was significantly lower at DLI 15 than at DLI 20.A sugar analysis showed greater sucrose content at DLI 20, whereas fructose and glucose decreased.Flower thinning alone did not significantly affect the marketable fruit number across DLI levels, although retaining three to five flowers per inflorescence supported fruit quality under DLI 20.Overall, a DLI of 20 mol•m -2 •d -1 with three to five flowers per inflorescence was the most effective treatment combination for improving marketable production and sweetness-related characteristics of 'Kuemsil' strawberries under controlled indoor cultivation.