Effect of fruit gas exchange on photosynthate accumulation and fruit growth of strawberries

To clarify the effect of fruit gas exchange on photosynthate accumulation and fruit growth of strawberries (Fragaria × ananassa Duch.), fruit CO₂ and H₂O fluxes, and changes in fruit volume and sugar accumulation were investigated under limiting and non-limiting conditions of fruit gas exchange. By limiting fruit gas exchange with a combination treatment of calyx removal and vaseline coating, the daily integral values of fruit CO₂ and H₂O flux decreased to one-half of those in non-treatment. The limitations to fruit gas exchange remarkably inhibited translocation of sugars to fruits, and the concentration of total sugar (glucose + fructose + sucrose) in fruits was decreased below one-half of that in non-treated fruits. As a result, this inhibition of sugar accumulation to fruits under the limitation of fruit gas exchange brought a suspension of fruit growth. This suggests that not only leaf photosynthesis but also fruit gas exchange (respiration, transpiration) affect the sugar accumulation and growth of fruits through a process of photosynthates partitioning from leaves to fruits. It can be expected to achieve a higher strawberry productivity by the environmental control based on physiological responses of leaf photosynthesis and photosynthates translocation with the help of plant instruments.