Dynamic climate control in combination with average temperature control saves energy in ornamentals.

摘要

In the past decades, attempts have been made to produce pot plants in dynamic environments based on models for plant growth and gas exchange aiming at a reduced energy use. The energy minimizing and daylight dependent control system IntelliGrow has been developed for production of pot plants and vegetables. The basic principles are simple, as temperature and CO2 concentration are regulated according to outdoor photosynthetic photon flux density (PPFD), based on photosynthesis models. The experiments in spring 2003 included 6 climate strategies. Four were dynamic controls optimized to 80 or 90% of potential photosynthesis with a base temperature of 15 or 17 degrees C, in all cases with ventilation at 30 degrees C. Two reference climates were used; one of 18 degrees C day and 17 degrees C night temperature and one average temperature control set at 18 degrees C, both ventilated at 4 degrees C above the temperature set point. A dynamic climate allows the temperature to fluctuate within the wide range from minimum to ventilation set point, but to ensure a reliable development of the plants (Campanula carpatica, Primula obconica and Argyrathemum frutescens [Argyranthemum frutescens]) an average temperature of 18 degrees C was used in all treatments. The climate strategy reached the predetermined average temperature January to March and an overshoot was seen in March to May. The lowest energy use was found in the 15 degrees C 80% photosynthesis climate. The production time of the plants (time to flowering) did not differ between the treatments. The plants responded positively in terms of dry weight accumulation to dynamic climates even though the differences were small and in many cases not significant. The results indicate, that using a combination of a dynamic climate control based on photosynthesis with an average temperature control can yield a significant energy saving, but also plants with improved external quality..