Estimating transpiration rate and canopy resistance of a rose crop in a fan-ventilated greenhouse

Abstract

The influence of solar radiation (G) and saturation deficit (VPD air) of the greenhouse air on transpiration rate, canopy resistance was investigated on a soilless rose crop (cv. First Red), grown on perlite, during the 1998 summer growing period. Measurements of TR, G, Tair, VPDair, Tleaf were carried out in a fan-ventilated glasshouse located in the region of Magnesia on the coastal area of Eastern Greece. Transpiration rate was found to be dependent on solar radiation and VPDair during daytime. A clear diurnal hysteresis of TR vs. VPD air, was evidenced. The above measurements were used for (i) the calibration of a model based on a simplified form of the Penman-Monteith equation: TR= α f1(LAI)G + β f2(LAI)VPD air, and (ii) the determination of a relationship between canopy resistance rc and climate variables. Application of both models gave satisfactory results.