Plant material
Individuals of both species were grown from seed in pots in a mix of
Indiana Miami topsoil, ground pine bark and sand at a 0.5:1:0.5 ratio.
Plants were between three and five years of age at the time of
experiment. The plants were grown at Purdue University under
controlled glasshouse conditions with approximately 12h natural light
supplemented with LEDs (16h day, 8h night; Illumitex Power Harvest I4,
TX, USA) providing a minimum photon flux at pot height of 150 μmol
quanta m–2 s–1. Under well-watered
conditions, plants received daily irrigation and complete liquid
nutrients (Miracle-Gro® Water-Soluble All Purpose Plant Food, The Scotts
Company LLC, OH, USA) once every month. Glasshouse temperatures were set
at 28 °C during the day and 22 °C during the night. Air circulation fans
in the glasshouse ensured continual air circulation, reducing boundary
layer conductance.