Development of the Controlled Environment Facilities at the School of Plant Science has been ongoing since the 1960s. Our most recent development (2005) is the construction of two high light intensity (up to 1000 micromoles m-2s-1) capable of maintaining 2 degrees C or less for extended periods.

The University recently completed a 1 million dollar re-development of the Plant Science glasshouse complex. An extensive review and consultative period identified the urgent need to upgrade our existing infrastructure in order to maintain our current teaching and research programmes. The process identified the additional facilities needed to improve and extend these programmes to allow us to continue to compete on the highest level for students and research funds.

The School of Plant Science has always been an innovator in the field of plant research, particularly photomorphogenic (i.e. plant responses to light) research. As the Botany Department, the original glasshouses were on the lower part of the campus, near the current Sport and Recreation centre. Our misting glasshouse was one of the first glasshouses, and was moved to its current position from the old site in the early 1960's. Under threat from this re-development, it was recognised that its high humidity moist environment was ideal for the ferns and mosses used in classes, and this environment would be difficult to replicate. Hence design of the new glasshouse was altered to accommodate this important and somewhat historic part of the complex.

A strong focus within the school has been the photomorphogenic research, beginning in the late 1950's. It is the need to isolate environmental effects such as temperature and light that has driven the development of this complex. A prototype phytotron (ie light control) glasshouse was built on the old site in the late 1950's. The plants were grown on trolleys that could be drawn into night chambers or left out under lights. In this way, identical plants could be simultaneously grown under long or short day photoperiods to study the effect of daylength on plant development.

The current main phytotron, built in 1963, operates on the same principle. The phytotron bays operate automatically using a complex electronic and mechanical sequence developed in house. As with many areas of this upgrade, the operation of this system is unchanged, such is the effectiveness of the system.

The three bays were not completed until 1970, but demand was such that an additional phytotron with another four dark bays was constructed in the early 70's using the same principles. The system of dark chambers and trolleys has a number of advantages over other light control systems. It allows for the large scale screening necessary to search for anomalous plants- the “mutant” lines used for further work. It allows for large scale side by side comparisons of a range of photoperiods or light conditions. The chambers are also light proof and temperature controlled with timed light outlets, allowing for any conceivable comparison of photoperiod, light source and temperature.

It was this latter feature that was extended into the development of growth cabinets. Growth cabinets with very accurate temperature control allow for comparison of a range of light wavelength and/or photoperiod at identical temperature, or at a range of temperatures and temperature cycles. Both small (reach in) and large (walk in) growth cabinets were constructed in the 70's. Four small growth cabinets for seed germination were designed and constructed on site. These had a complex control system that allowed for photoperiod, light intensity and wavelength to be varied electronically. They were operated until this upgrade, when due to increasing difficulty maintaining accurate operation, they were replaced with four commercial growth cabinets constructed by Thermoline Australia.

The large growth cabinets, also designed and constructed on site, operate on a much simpler system. A refrigeration and heating unit in each cabinet controlled electronically provide very accurate temperature control. This is the same system used in all cabinets to this day. Light intensity is varied by raising or lowering the light rack. Light wavelength is varied by changing and/or filtering the light source. Photoperiod is varied via timed power outlets. These cabinets are still operational, and the design was copied for the construction of the four new large growth cabinets built as part of this upgrade.

During this period plant growth cabinets became available commercially, and in the late 70's two cabinets built by the Canadian company Conviron were purchased. These operate in the same manor as the large growth cabinets, except the light loft is at fixed height, and intensity is varied by raising and lowering the rack the plants sit on. The Convirons are still operational.

Demand for cabinets continued, leading to the construction in house of our four mid-sized cabinets (imaginatively called Medium Growth Cabinets 1-4) in the early 1980's. These offered unprecedented temperature range and control, with a wider temperature range and accuracy than anything available before or since. They remain a cornerstone of our operation. A climate controlled dark room was also constructed. The success of this phase of the complex owes a great deal to Doug Madden, our electronics engineer until his retirement in the late 1980's.

Operation of the complex- i.e. switching times for trucks, lights and temperature cycles- was controlled via a master clock that was added to as more cabinets and bays were constructed. This operated with a very high degree of accuracy, as is essential for our work, until very recently when concern over its inevitable deterioration due to age and a lack of repair expertise prompted its replacement. This involved a complete re-wiring of the sensor and control network. Monitoring is now by a central computer with alarm functions to alert us to any unacceptable variation in the controlled environments. Operation of the complex is now via a series of independent touch screens.

Development of the growth cabinet assets continued with the purchase of 6 custom built Thermoline growth cabinets in 1996. These are stand alone units with dual light sources- the traditional fluorescent/incandescent mix and high intensity discharge lamps. These have allowed the study of plant responses at much higher light intensities, closer to natural sunlight levels. These have been modified to include humidity control, as well as carbon dioxide raising and lowering capacity, allowing us to move into more ecological studies. To further enhance these lines of research, it became clear that what was required was the ability to accurately control these factors in natural light conditions. This has led to the design and construction of the new state of the art 6 cell controlled environment glasshouse. Each cell is independently controllable for side by side comparisons, varying only one environmental factor at a time. It has already proven to be a major asset in the increasingly competitive market for students and research funds.

This upgrade has also included a range of improvements to enhance the versatility, safety, environmental control and longevity of this facility. Safety in the main phytotron had become an issue with the loss of glass in high winds. The roof has been strengthened and replaced with laminated glass to comply with Australian standards. Our existing Quarantine house and all new structures, including the new 6 cell glasshouse, dark rooms and cabinets have all been constructed to Plant Containment Level 2 (PC2) standard, to allow for work with transgenic plants. Temperature control in the main phytotron, top phytotron and eucalypt house has been improved with the addition of extraction fans, evaporative coolers, air conditioning units and fog lines. Age and reliability of the existing refrigeration plant has been addressed by the review and replacement of all necessary components.

Photomorphogenic research has been greatly enhanced by the construction of new dark facilities. A dark transition area has been constructed around four existing growth cabinets to improve the integrity of the light environments within these cabinets. This area leads to a newly constructed totally dark area encompassing four new walk in cabinets and two climate controlled dark rooms. This allows for individual or comparative dark, specific wavelength and light transfer experiments with absolutely no cross contamination from other light sources. This work will be further enhanced by our design and development in house of very specific wavelength LED lighting.

This has been a bare-bones re-development of the glasshouse complex. The upgrade has been intensively researched and targeted to give us maximum benefit in terms of accuracy, longevity and versatility of the controlled environments. In keeping with the history of the development of this complex, the latest upgrades will maintain us as not only one of the best facilities in Australia, but one of the very best plant research facilities in the world