IMPACT OF TEMPERATURE INTEGRATION UNDER GREENHOUSE ON ENERGY USE EFFICIENCY, PLANT GROWTH AND DEVELOPMENT AND TOMATO FRUIT QUALITY DEPENDING ON CULTIVAR ROOTSTOCK COMBINATION

The present study on soilless tomato crops aims to evaluate and compare on contrasted genotypes the impact of temperature integration (TI) on plant growth and development as well as on fruit yield and quality. TI, taking advantage of plant plasticity towards temperature, consists in modulating the set points for heating (lower during the night) and ventilation (higher during the day) keeping similar mean 24 h temperature for plant development. Four cultivar-rootstock combinations of tomato plants were studied for two consecutive years (2010 and 2011). Two climate managements were compared: a temperature integration technique (TI) and a control (grower’s technique). In order to test the limit of the TI system, TI application lasted longer in 2011 and with temperature settings colder compared to 2010.
During the first year of experiment (2010), energy saving was about 22% during TI period. Yield was not modified, nor was leaf growth. In 2011, TI led to an 8.6% energy saving compared to control. Yield significantly increased for ‘Plaisance’-‘Beaufort’ combination and was not affected in other cultivar-rootstock combinations. In conclusion, for both years TI increased energy use efficiency.
Plant developmental rate was not significantly modified by TI. Leaf area slightly decreased (-11%). Fruit size and composition (sugars, acids, vitamin C) were not modified by TI. Carotenoids (specifically phytoene and lycopene) were improved by TI in particular for ‘Plaisance’-‘Beaufort’; this might be related to the reduced leaf area that allowed more light to reach the fruit and consequently promoted carotenoid synthesis. Temperature integration appears as a profitable alternative to classic management of greenhouse climate.