Using temperature integration over 24 hours in soilless tomato cultivation in greenhouse: application in the west of France.

摘要

The current context of predicted fossil energy supply shortage and, as a consequence, a trend in high energy prices, has strongly affected the greenhouse sector. Nowadays, energy consumption can reach 30% of the operating expenses in the west of France. As a response to this problem, the Technical Institute for Fruits and Vegetables decided to study different ways of reducing energy consumption in actual greenhouses. One of these is temperature integration over 24 hours, which consists in changing the night heating temperature set point according to the last realised day temperature. When a high day temperature is obtained, a low night temperature heating set point is applied and inversely. Studies were carried out from 2006 to 2008. The main objectives of these studies were to estimate the impact of different integration strategies on greenhouse climate, energy consumption and tomato crop agronomic results. Temperature integration strategy over 24 hours showed great potentialities in the Nantes area: (1) energy consumption decrease of 5 to 15% compared to a traditional control, without any loss of yield and precocity; (2) higher CO₂ concentration in greenhouse during the day period of time despite lower CO₂ supply; (3) higher average fruit weight. These studies also highlighted technical possibilities of improving temperature integration (a) by using vigorous cultivars able to tolerate a large gap between day and night temperatures, and (b) by using a specific climate management in order to prevent condensation and damage caused by Botrytis cinerea. These results will help greenhouse growers to minimize heating costs while maintaining crop growth.