Two new growth chambers have been delivered some days ago and were switched-on yesterday. We have been longing for good chambers for some time, in particular chambers with a rather small size but capable of achieving high irradiance. Our chambers were supplied by Aralab with a series customizations that will make them very well suited for our research in photobiology: LED lighting using a modular design, at the moment with Valoya B50 fixtures “AP67”, but user exchangeable by other types lighting modules. Dimming is possible down to 10% on each of three “channels” allowing a range of irradiance at 20 cm from the enclosed lamp canopy ranging from 40 μmol m-2 s-1 to 1100 μmol m-2 s-1, being possible to set steady-state irradiance in steps as small as approximately 5 μmol m-2 s-1, and to program stepless irradiance ramps. Being the design modular, although currently all our B50 modules have the same spectral emission characteristics, will allow us to mix and match B50 modules as needed and control the mixing ratio between three types of spectra if desired. The main idea of this design is to be able to achieve at reasonable cost a system that will allows us to grow plants under different light spectra without sacrificing the ability to achieve a high irradiance under each of them. Another important design point for our research is that the “window” of the lamp canopies can be easily exchanged, and given the rather low downward thermal radiation emission of the LED fixtures, plastic sheeting can be used. This will allow when needed in the future to use coloured filters, or UV-radiation transmitting acrylic.
The use of LEDs together with temperature-dependent ventilation of the lamp canopies should result in irradiance in the plant growing area to remain, at a given lamp control setting almost independent of the temperature conditions used in the experiment without need for a feedback control system. This is a fundamental difference with fluorescent tubes located in the plant growth space, for which the light output is extremely temperature and air movement dependent, output decreasing with decreasing temperature.
The chambers are specified to reach a few degrees below freezing in darkness and +5 C with lights on. Humidity control is possible as well as CO2 concentration control, within the range 200 to 1500 μmol mol-1.
Our chambers are customized Aralab FITOCLIMA D1200 PLLH. The in built controller and the remote access software seems well thought out based on our experience of the last two days of on-site training. More information is available at Aralab’s web site.
I will post in coming weeks some test results and further impressions on these new chambers. Meanwhile I would like to thank the Aralab people for their willingness to listen to our wishes and work along with us in finding the best possible customization for our research needs. I should mention that I have been myself repairing and modifying growth chambers in the past, even designing and assembling simple electronic control systems for chambers already while working on my M.Sc. thesis, long ago and far away.