Temperature (T-FACE) Effects On Wheat Yield.

Wheat growth will be affected by future increases in global temperatures thought to be related to greenhouse gases.  However, we are not certain how small increases in temperature affect wheat yield.  In order to study this phenomenon, we increased temperature in field plots by arranging infrared heaters in 3-m circular arrays over multiple plantings from September through March at Maricopa, AZ.  The heating system is commonly referred to as Temperature Free-Air-Controlled Enhancement (T-FACE),  which warmed the canopy 1.5°C during the day and 3.0°C during the night.  The heaters had no effect on grain yield in the January planting, and decreased yield from 509 to 368 g m^-2 in the March planting.  However, somewhat unexpected were the results from the late September planting where almost no grain (3 g m^-2) was harvested from the control plots in contrast to the substantial amount of grain (422 g m^-2) harvested from the heated plots due to the effect of warming of a few degrees on reducing frost damage.  The infrared heating system provides a valuable tool for examining crop response to elevated temperatures.