The 2011 ASHS Annual Conference

In the conventional context of plant productivity, light is typically thought merely as the driving force of photosynthesis.  However, the attributes of light (wavelength, fluence rate and photoperiod) impart important information to a growing and developing plant that can profoundly influence critical traits in horticulturally-relevant products.  Light emitting diode (LED) derived light systems allow precise manipulation of plant attributes by stimulating discrete light-sensing circuits. Species-specific, tailored light programs enable the manipulation of important high-value traits in controlled environments, such as anthocyanin accumulation, chlorophyll accumulation, biomass production, and control of flowering.  For example, specific combinations of red, blue, green, amber and far-red light have been used as “finishing” treatments on red-leafed lettuce, producing high-pigment production in plants grown under other lighting systems. Plants with high per-square-foot value such as specialty lettuces and herbs, were grown under conventional lighting and LED lighting combinations in an attempt to define the treatments that maximize plant size, flavor and color. Treatments of developing strawberry fruits with supplemental LED illumination show that enrichment of light qualities can affect fruit qualities. The goal of these trials is to provide species-specific prescriptions of light treatments that will enhance consumer-desired traits, adding substantial value to plant products produced in artificial environments—using efficient, non-toxic, low-cost, reliable, light sources as the principle growth regulators.