Modified TOMGRO outputs as guide factors to estimate evapotranspiration and water use efficiency of three tomato fresh cultivars, grown in a low-tech Italian glasshouse

In Low-Tech Italian greenhouses, the adoption of more rational criteria in resources management would lead to significant economic and environmental advantages for producers. Reliable crop growth and evapotranspiration models, may allow real time assessment of water and nutrient plant requirements and the evaluation of the productive system efficiency, supporting decision-making processes for short, long and medium-Term strategies. This paper presents the results of an experimental trial carried out in 2011, in the research facilities of the DISAAA-A at Pisa University, to set a cross-control method for the evaluation of the Water Use Efficiency (WUE) and of the real plant water requirements. A modified version of TOMGRO model was used to simulate Leaf Area Index (LAI) and total dry biomass (shoot and fruits) of three different cultivars of tomato (Solanum lycopersicum L.), grown in the same environmental conditions. For each cultivar, the hourly values of LAI provided by the TOMGRO model were used as input in the Baille equation for the estimation of the evapotranspiration (ET) rate, finding a significant agreement between simulated and measured ET values (R2=0.8 on average). A good prediction of the WUE of each thesis was also obtained (R2>0.8), offering interesting elements for plant performance evaluation. Considering these evidences, a synthetic index (estimated biomass/estimated ET) may be used for a direct comparison between different scenarios.