Although our early research has demonstrated that light manipulation by liquid CuSO4 filters have the potential for being a non-chemical alternative for height control of greenhouse plants, liquid spectral filter technology has limited value to commercial growers because of difficulties in material handling and high initial construction costs. In addition, CuSO4 is hazardous and can be phytotoxic in the event of spills.
For spectral filter technology to be acceptable commercially, an easy-to-handle plastic greenhouse covering or shading material with the ability to filter out far-red light must be developed. Although a plastic material with far-red removing properties is not commercially available at present, several plastic and pigment manufacturers have shown interest in developing such material. The Clemson University researchers are currently collaborating with Mitsui Chemicals, Inc., Tokyo, Japan to develop photoselective greenhouse plastic films or rigid plastic panels.