FLOWER THINNING EFFECTS ON ANNUAL PLASTICULTURE STRAWBERRY PRODUCTION IN CHINESE TAIPEI

Strawberry (Fragaria × ananassa Duch.) plants continuously produce flowers and berries in subtropical winter conditions and berry size declines in late harvest windows. Fruit or flower thinning has been applied on many fruit crops to improve fruit size or fruit quality. We hypothesized that positive effects of thinning are also appreciable in annual plasticulture strawberry production. Field grown ‘Toyonoka’ strawberry plants were unthinned (CK) or hand thinned to remove 1) primary flowers, 2) quaternary and younger flowers, or 3) quinary and younger flowers, upon bloom. Leaf area, fruit growth, yield, and total soluble solids (TSS) were measured. Reducing berry number by flower thinning treatments had little effect on leaf area development and plant growth. Growth and final size of tertiary berries of the second and the third harvest windows were improved by removing primary flowers. Number of unmarketable berries was also reduced by thinning treatments. However, TSS and total marketable yield were not improved by flower thinning. Considering the intensive input of labor and time for flower thinning, we conclude that flower thinning is not economical in Chinese Taipei’s strawberry production.