Criteri di scelta nella progettazione del parco lampade a radiazione solare, in camere climatiche per fisiologia vegetale

CRITERIA OF CHOICE IN THE PLANNING OF A SOLAR RADIATION LAMP ARRANGEMENT, IN CLIMATIC CHAMBERS FOR PLANT PHYSIOLOGY STUDIES This Technical Note is an integration of the previous study: “Climatic chambers for plant physiology: a new project concept”. This note gives details regarding the planning of the lamp arrangement and demonstrates how by mixing, in appropriate quantities, the radiative range of various types of lamps can give apparently contrasting results: -to maximize radiation in maximum absorption range of chlorophylls and carotenes; -to minimize heat emission in the climatic chamber. With nine day-light fluorescent tubes, four sun-light metallic halide spotlights and nine red-blue fluorescent tubes, for a total of 562 W m–2 (electric), mounted on the ceiling of a 2 m high chamber with 4 m2 surface area, on the chamber floor about 130 W m–2 “total solar radiation equivalent” was obtained. This means the power emitted, in the bands of chlorophyll and carotene absorption, from a total solar radiation (black body of 5500 K) of about 130 W m–2. This radiation is sufficient to grow a large number of plant species. In the lamp arrangement there are seven other light fixtures, for fluorescent tubes, defined as “auxiliary” because tubes can be inserted which either integrate active radiation on the photoreceptors or produce particular spectral ranges. In the above cited work, fluorescent tubes producing in the ultraviolet B range were mounted in these auxiliary fixtures. Less thermal energy emitted in the climatic chamber means that it is possible to use a less powerful conditioning system and, thus, have lower costs of set-up and management. The efficiency of the lighting system is demonstrated by the fact that during 15 days of experimentation on 18-month-old, potted poplar plants (Populus Alba), symptoms of insufficient light were not detected.