INCREASING LETTUCE COLORATION WITH LEDS

 

 

Using LED grow lights in plant production is a relatively new branch of science. In vertical farming where artificial light sources are used in closed environment it is important to collect data about the individual plant species to be able to produce the right spectrum and light intensity for vegetative and generative growth. Light spectrums can also be used to manipulate the plants growth cycle for example in plant breeding (see blog post: Light Approaches To Speed Up The Generation Turnover) or secondary metabolite contents (anthocyanins, flavonoids, antioxidants, polyphenols etc.).

 

WHY DOES LETTUCE TURN RED?

When cultivating red baby leaf lettuce in closed environments like vertical farms, without natural light conditions the artificial light quality and quantity plays a key role in production of good quality vegetables. Of course, in the case of red leaf lettuce the deep red color that is caused by the higher anthocyanin content must be produced without affecting the other good qualities of the leafy green. Anthocyanin accumulation is generally linked to the abiotic stress the plant is experiencing or it’s a way for the plant to protect itself against herbivores and plant pathogens. For instance, in the case of high light conditions the anthocyanins serve the plant as an optical filter, redirecting excess light away from the saturated photosynthetic electron transport chain (Gould 2004). This means that the anthocyanins are protecting the plant leaves from harmful structural damage to their photosystems. Raising light intensity is therefore an effective way to increase the leaves anthocyanin content but it’s not a very energy efficient way to do this.