High vapour pressure deficit influences growth, transpiration and quality of tomato fruits

Plants were grown in two glasshouse compartments under two vapour pressure deficit (vpd) levels: low vpd was obtained by increasing air humidity with a fogging system, and high vpd was obtained during sunny hours in a greenhouse where air humidity was not controlled. The mean value, of the six driest hours of the day concerning the growing period of the fruits considered, was 1.6 kPa under low vpd and 2.2 kPa under high vpd conditions. Over the whole experimental period, the difference in mean hourly temperature never exceeded 0.8°C. The oldest leaves were removed to different extents in different plots to analyse whether a different leaf/fruit ratio could modify the effect of high vpd.