Light has three principal characteristics that affect plant growth: quantity, quality, and duration. Light quantity refers to the intensity or concentration of sunlight. Light quality refers to the color or wavelength reaching the plant surface. Light duration or photoperiod refers to the amount of time that a plant is exposed to sunlight.

RED/FAR-RED (660-720nm)
Plants absorb red light (660–680nm) and refl ect far-red light (720–740nm). Plants contain phytochromes, photoreceptors that control physiological and developmental reactions to fluctuations levels of red and far-red light. Some responses that are regulated by phytochromes include germination, stem elongation, flowering, gene expression as well as leaf and chloroplast development.

Plant leaves filter light allowing more far-red light to pass through than red light. This changes the red to far-red ratio below the canopy. Similarly, a low red to far-red ratio is created when plants are close together.

Knowing your red to far-red ratio can help you determine plant spacing and decide when to apply plant growth regulators. Greenhouses with high canopy closure or canopy density may need more applications of plant growth regulators to keep the plants a marketable size.

The FieldScout meter displays the Red/Far-Red ratio on the LCD screen, and with the push of a button, the 660nm and 730nm readings.

Ordering Information
3412 FieldScout Red/Far-Red Meter