Plant Material
Cuttings of poplar (Populus deltoides Barr. S7c8 East Texas day neutral clone; and Populus trichocarpa BESC2074639) were grown at the University of New Mexico (35.0843° N, 106.6198° W, 1587 m a.s.l.) at 18.3 to 21.1/15.6 to 21.1 °C day/night temperature in a rooftop greenhouse, and bell pepper (Capsicum annuum var. V6220 California Wonder Bell Pepper) were grown in an indoor greenhouse at 22/16 °C day/night temperature with 12/12 day/night photoperiod maintained using a SPYDR 600 LED lighting system (BML Horticulture, Austin, TX, USA) at a minimum intensity of 170 μmol m-2 s-1 (maximum light intensity of ~720 μmol m-2 s-1including the natural light in the indoor greenhouse). Populus deltoides were grown in 28 L pots and were ~2 years old during measurements, Populus trichocarpa were grown in 7 L pots and were <6 months old during measurements, and Capsicum annuum were grown in 28 L pots. All three greenhouse species were grown in Metro-Mix 300 potting soil (Sun Gro Horticulture, Seba Beach, AB, Canada), and were fertilized twice weekly with Peters 20-20-20 (Scotts Miracle-Gro, Marysville, OH, USA) and once weekly with chelated liquid iron (Ferti-Lome, Bonham, TX, USA). USDA-certified organic Granny Smith apple trees (Malus domestica Borkh.) were grown in Los Lunas, NM at the New Mexico State University Agricultural Science Center (34.6007° N, 103.2139° W, 1793 m a.s.l., MAP: 241 mm, MAT: 13.9 °C, Soil: loam, Slope: 0 – 1%; USDA, 2018). Showy milkweed (Asclepias speciosa ), mature Chinquapin oak (Quercus muehlenbergii ), and Queen Elizabeth rose (Rosa grandiflora ) were grown at the ABQ BioPark Botanic Garden in Albuquerque, NM (35.0933° N 106.6813° W, 1587 m a.s.l., MAP: 203 mm, MAT: 17.5 °C, Soil: fine sandy loam, Slope: 0 – 1%, USDA, 2018). Mature ponderosa pine (Pinus ponderosa ) were measured at Las Huertas Upper Picnic Grounds in Cibola National Forest, Sandoval County, NM (35.235458° N, 106.413012° W, 2316 m a.s.l., MAP: 546 mm, MAT: 6.1 °C, Soil: stony loam, Slope: 35 – 70%, USDA, 2018). Measurements were made on October 26th, 2017, and observed sunrise/sunset was 8:30am and 5:00pm due to the location of the measurement site in a canyon with mountains on all sides. Mature Deodar cedar (Cedrus deodar , sample size limited to 4 available trees) and mature ginkgo (Ginkgo biloba , sample size limited to 3 available trees) from the University of New Mexico Arboretum (35.0843° N, 106.6198° W, 1587 m a.s.l., MAP: 203 mm, MAT: 17.5 °C, Soil: cut and fill, USDA, 2018) were measured on August 24th, 2018. Unless stated above, sample size for each species was one leaf (or branch for needleleaf species) from each of six individuals. Note: the timing of measurements and sample size varied depending on access to equipment, facilities and biological material (especially for field measurements), however this should not affect the presence or absence of diurnal changes in Vcmax .