Evaluation location: Iowa, United States
Observations from the summer of 2012, in growth chambers, NCRPIS Ames, Iowa. Tiffanie F. Stone (Intern) and David M. Brenner (Curator) studied photoperiod with long (16 hour) and short (10.25 hour) day length growth chambers (both 30 deg C 12 hour day, and 25 deg C 12 hour night). The chambers were in the USDA-ARS National Laboratory for Agriculture and the Environment building. The plants were grown in 32-cell rootainer flats with a volume of 175 cc per cell, in Sunshine brand LCI Professional Growing Mix made up of 73-83% Canadian sphagnum peat moss, perlite and dolomite lime. The growth chambers were both walk-in size: Conviron PGW36. The light intensity 6 inches from the lamps was 860 umoles/m2/s as published in the manufacturer's manual but not measured. The soil surface was 105 cm from the lamps.