Assessing the Efficiency of Night Interruption Light Therapy on the Growth of Short-Day Plants in Virginia. 1Department of Physics, Emory & Henry College, Emory, VA, 2Kelly Ridge Farms, Meadowview, VA.

The per plant production of Humulus Lupulus, commonly known as a hop plant, in the northwest of the United States far exceeds that of Virginia. Hops are short-day plants dependent on night length to reach maturity before flowering. Lower latitude regions have longer nights during the growing season which influences the flowering process. Night Interruption is the use of artificial light to mislead the plants, causing them to register night as day-time. This process targets two different forms of phytochrome photoreceptors: the active form (Pfr - phytochrome far-red) which controls flowering, leaf and chloroplast development; and the inactive form (Pr - phytochrome red). At night, only the Pr form is synthesized. When red light with peak wavelength of 657 nanometers is applied, Pr phytochromes convert to Pfr. As part of a larger project, we propose to study night interruption light therapy in hops and biological equivalents. This experiment will include field testing with delivery of red light over different time intervals throughout the night on hop plants. The goal is to compare the growth of hops under varying conditions to provide information on the most efficient application of night interruption in this region.