The studies referenced below were specifically conducted using basil and zinnias, but if the results they show can be replicated across many varieties of flower and food plants, the team has only begun to see the revolutionary changes that LEDs and the control they offer are going to bring to agriculture. LumiGrow Director of Research Melanie Yelton is presenting these findings at next week's combined ASA, CSSA, and SSSA International Annual Meetings in Long Beach. If any of you are attending these events, please stop by the "Crop Physiology and Metabolism: I" poster session and say hello.
Better Basil (Click here to download the poster, PDF)The results of the first study contain some parts that may be somewhat subjective — it involved a taste test — but are compelling nonetheless. In short, blue light makes better tasting basil. More importantly, it is possible to manipulate the flavour, aroma, and morphology of food using different wavelengths of light and nothing else.
The team wanted to explore the effect of various ratios of blue, white and red light on basil growth, hoping to inform growers on the use of programmable LED light spectrums to steer plant growth and flavour. To that end, they grew basil under 5 different light treatments and analysed the differences in plant morphology, flavour and flowering response.
Basil were grown in curtained chambers under 5 different light conditions with varying ratios of blue and red and a constant level of white light (Table 1). The ratios of blue light were 0%, 8%, 16%, 24%, and 32%.
In this study, 8% or 32% blue grew the best basil for bunched sale. For growers that sell by weight, the 16% blue lighting regime produced plants with the highest average weight. In our tasting panel, the 32% blue treatment was rated as having the ideal aroma, highest spice and best flavour.
So there's a new tool in the savvy grower's toolbox: light, or as we call it, spectrum control. Growers can use spectrum control to develop their own custom basil light programs to meet the needs of changing market demands.
Regulating Plant Growth Without Plant Growth Regulators (Click here to download the poster, PDF)The results of the second study Melanie will be presenting point the way to truly exciting new horticultural developments, and possibly a safer, less costly growing operation.
Using Zinnia marylandica as a model organism and LED lighting with independently controlled red, blue and white light we evaluate four different light treatments in the greenhouse. In addition to the four different LED light treatments, two additional treatments were evaluated: no supplemental lighting (NSL) and an HPS light. The results demonstrate that in the greenhouse environment supplemental light regimes can be created to control plant growth at different stages.
Plant growth regulators (PGRs) are commonly used to direct plant growth, generally Zinnias are sprayed at least once with PGRs when grown under traditional HPS lighting.
These experiments suggest that light ratios may be able reduce the need for PGRs to attain the desired plant characteristics for market. LED spectrum control could mean substantial savings to the grower — beyond the already-proven energy costs savings — in the form of reduced cost for chemicals, labour and safety equipment.
For more information
A-C-S web page: Crop Physiology and Metabolism