This study compared the performance of four models to estimate the daily evapotranspiration (ET) in the greenhouse. The studied models were De Villele model (ETDV), Penman-Monteith model (ETPM), Stanghellini model (ETST) and finally Takakura (ETTK) transpiration model, based on heat balance equation of the crop canopy. The study was conducted during two tomato cropping seasons (2012 and 2013) under two greenhouses types (Monospan and Canarian), at INRA Melk Zhar Experiment Station (Agadir, Morocco). ETST and ETPM models correctly simulated tomato transpiration for both measured values and daily gain of the tomato stem (MC/DG) in the Monospan greenhouse (R² = 0,55 and 0,62). Similarly, we have reached a satisfactory relationship between the Eff-TR (the efficiency of plant transpiration) and the ratio MC/DG using the ETST model under Monospan and Canarian greenhouses (R² = 0,67; 0,58) respectively. The study identified critical thresholds or water status baselines of tomato: water comfort (0,40 <MC/DG < 0,50 and 70 < Eff-TR <90%); overestimation of irrigation (MC/DG < 0,42 and Eff-TR < 70% and water stress (MC/DG > 0,46 and Eff-TR > 90%). In addition, the comparison of means according to yield level identified three groups of ET models; ETST (318 T/ha)> ETTK (272 t/ha)> ~ ETDV~ETPM (236-249 t/ha).

Keywords: Evapotranspiration model, greenhouse tomato, daily gain of stem, transpiration efficiency, plant water status, yield.