Effects of Air Temperature and Vapor Pressure Deficit on Fruit Growth of June-bearing Strawberry in a Controlled Environment with Artificial Lighting

抄録

The aim of this study was to determine the responses of strawberry fruit growth to environmental factors in a plant factory with artificial lighting (PFAL). June-bearing strawberry ‘Beni hoppe’ was grown in a growth chamber under a 12-h light/12-h dark photoperiod. Three temperature treatments were applied: 1) temperature decrease from 20°C to 10°C (decreased by 5°C every 4 h during the dark period); 2) temperature increase from 15°C to 25°C (increased by 5°C every 4 h during the light period); and 3) temperature decrease from 25°C to 15°C (decreased by 5°C every 4 h during the light period). The fruit diameter was measured using a contact-type digital displacement sensor and the relative rate of change in the fruit volume (R-RCFVt) was calculated as the fruit growth rate. The R-RCFVt temporarily increased or decreased in response to the rapid change in vapor pressure deficit (VPD) when the air temperature switched to a lower or higher setpoint. The R-RCFVt remained almost constant when the air temperature and VPD were kept constant. Regression analyses indicated that R-RCFVt was positively correlated with the air temperature in both dark and light periods.